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July 31, 2019
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https://www.sciencedaily.com/releases/2019/07/190731102126.htm
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Citizen scientists offer ray of hope
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Volunteer snorkelers and scuba divers have been helping capture images of reef manta rays to better protect the threatened species.
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The University of Queensland initiative -- Project Manta -- relied on these citizen scientists to photograph or video individual reef manta rays (Mobula alfredi) across Australia's east coast.UQ PhD candidate Asia Armstrong, who led the study, hopes the data will inform conservation planning and management along the coast."Manta rays are a great ambassador species for conservation," Ms Armstrong said."Everyone loves them, and they offer a wonderful platform for getting people involved in marine conservation, as people protect what they love."With Project Manta, we relied on the cameras and eyes of both trained researchers and volunteers, who helped us build a catalogue of more than 1300 individual reef manta rays, from in excess of 7000 sightings."Once images and videos were captured, they were analysed to isolate the distances individual rays were travelling."Manta rays have a unique spot pattern on their belly, which allows individuals to be identified from one another," Ms Armstrong said."Each time an animal is photographed we record the date, time and location of the sighting, along with any additional information, like its sex, maturity status, injuries and behaviour."When a sighting is matched to an existing record we gain insights into the ray's movements and population dynamics."The researchers were surprised to discover that individual rays had travelled from North Stradbroke Island to the wreck of SS Yongala, just south of Townsville, a distance of more than 1,000 kilometres."This is a record breaking point-to-point movement for a reef manta ray, improving our understanding of the potential home range for this species," Ms Armstrong said."Globally, reef manta rays are listed as vulnerable to extinction, so this information can help inform conservation planning internationally, particularly in regions where this species may be exposed to increased risks and threats."It's important now to connect with regional research groups to enable us to compare catalogues, which may reveal longer distance movements than those we've discovered."So far, there haven't been any records of cross-jurisdictional movements of this species -- that is, movements between the waters of different countries -- which is important to know for conservation planning."With the help of international researchers, along with passionate citizen scientists and conservationists, we can really improve the long-term chances for this incredible species."
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July 29, 2019
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https://www.sciencedaily.com/releases/2019/07/190729123857.htm
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Improved estimates of Brazilian Amazon gains and losses
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A University of Oklahoma-led study generated improved annual maps of tropical forest cover in the Brazilian Amazon in 2000-2017 and provided better characterization on the spatio-temporal dynamics of forest area, loss and gain in this region. The Amazon basin has the largest tropical forests in the world. Rapid changes in land use, climate and other human activities have resulted in substantial deforestation in the Brazilian Amazon over the past several decades.
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"Monitoring, verification and reporting of tropical forest dynamics in the Brazilian Amazon have been a critical but challenging task for the research community and society-at-large. Available maps of tropical forest cover in the region have large uncertainty. In 2015, we assembled an international team from the United States, Brazil and China to tackle the challenging problem," said Xiangming Xiao, George Lynn Cross Research Professor, Department of Microbiology and Plant Biology, OU College of Arts and Sciences."The international team used both optical and microwave images acquired by satellite-based sensors and advanced algorithms to improve annual maps of tropical forests in the Brazilian Amazon during 2000-2017," said Yuanwei Qin, lead author for the study and research scientist, Center for Spatial Analysis, OU College of Atmospheric and Geographic Sciences.The estimates of tropical forest area in the Brazilian Amazon from this study were ~15% higher than estimates from the PRODES forest dataset that has been widely used in research communities. This study also reveals a renewed increase of tropical forest area loss after 2013, driven in part by land use change and strong El Nino in 2015/2016. The findings from the OU-led study could have significant implications for land-use policy, forest management and conservation, terrestrial carbon-cycle, hydrology and climate.
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Extinction
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July 25, 2019
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https://www.sciencedaily.com/releases/2019/07/190725114340.htm
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Bacteria enhance coral resilience to climate change effects
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Coral reefs are delicate ecosystems that are particularly sensitive to human influences such as climate change and environmental pollution. Even if the warming of the earth does not exceed 1.5 to 2 degrees Celsius -- a limit set by the International Panel of Climate Change (IPCC) -- more than 70 percent of coral reef ecosystems are likely to be lost, resulting in an economic and ecological catastrophe.
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How do corals adapt to changing environmental conditions? How can we protect corals? Christian Voolstra, Professor of Genetics of Adaptation in Aquatic Systems at the University of Konstanz, assigns great importance to bacteria and other microorganisms. He emphasizes that no animal or plant lives alone -- they are constantly interacting with bacteria and other microbes. Researchers call this a metaorganism -- a tribute to the notion that all animal and plant hosts interact closely with their associated microbes. Corals are particular illustrative examples of metaorganisms, given that their association with photosynthetic microbial algae allows them to live like sessile plants. Since corals are bound to the place they settle, they have no choice but to adjust to the local environmental conditions. Bacteria and other microorganisms help with this by playing roles in the nutrition, metabolism and immune defence of a coral.Different studies have shown that corals are associated with various bacteria that assumingly perform different functions. The following question, however, remained to be answered: Do the bacterial communities vary with prevailing environmental conditions or do they stay the same? Researchers have observed both cases. Based on this knowledge, the research team led by Professor Voolstra investigated two species of coral they believed to have considerable differences in terms of their strategies for associating with bacteria: The species Acropora hemprichii, assumed to flexibly associate with bacteria, and the species Pocillopora verrucosa that harbours highly consistent bacterial communities, irrespective of environmental differences. Their experiment was carried out over a period of 21 months in a marine ecosystem that is greatly affected by human activities: the Red Sea near Jeddah in Saudi Arabia. In order to investigate changes in coral associated bacterial communities that are exposed to stress, the researchers transplanted fragments of the same coral colonies into marine environments exposed to varying degrees of human influence. Using coral fragments from the same colony ensured that the samples had identical genetic material and that any changes could only be the result of environmental conditions."We could show that some corals respond flexibly to changing environmental conditions by associating themselves with certain bacteria, while other corals looked the same everywhere," explains Professor Voolstra. In their study, the researchers were able to confirm their hypothesis that there are generalists among corals who are flexible and versatile, and that other species are specialized and consistent in their association with bacteria. The generalists' ability to adapt provides cause for optimism because evolutionary adaptation processes would take far too long to allow coral to cope with the rapid changes brought about by climate change. By associating with new bacteria, the corals are able to react much faster -- these changes became apparent after only a few months. Furthermore, by transplanting the coral back into its original environment, the researchers discovered that the associated bacterial communities were able to return to their original state, thus recovering.The example of Pocillopora verrucosa also shows that specialised corals can implement a successful survival strategy. "We must remember that the species we examined are those that have survived the tremendous changes of the past decade -- thus, both types of corals harbour successful strategies," emphasizes Voolstra. This study shows that corals take advantage of the symbiotic relationship with bacteria in different ways. The research results contribute to the further development of coral probiotics -- a method by which corals are specifically exposed to bacteria that help corals to adapt to changing conditions. The aim is to enhance the corals' resilience to the extreme and rapid changes to their natural habitats and to prevent reefs from going extinct.
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Extinction
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July 23, 2019
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https://www.sciencedaily.com/releases/2019/07/190723104043.htm
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Fussy fish can have their coral, and eat it too
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Being a fussy eater is a problem for reef fish who seek refuge from climate change on deeper reefs. But, scientists discovered, the coral that these fussy fish eat can support them.
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The study was led by Dr Chancey MacDonald at the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU).Dr MacDonald said it's increasingly difficult for species to deal with rapidly changing environments across the globe. He says while some species are likely to find refuges in marginal environments, survival may be difficult. Especially if they're fussy eaters."Some animals are likely to be pushed close to the borders of their environmental range, where living will be more difficult," Dr MacDonald said."On coral reefs this could mean deeper waters for fish, where you'd expect them to experience a reduced quantity and quality of their preferred foods," he said."However, we found that fish who are fussy about the corals they feed on can continue to thrive in deeper reef waters if their prey engage in a less 'precious' approach to what they themselves eat."Although the corals some fish preferred to eat were sparse at depth, the team found the energy content of these corals remained constant, as they adapted their diet to rely less on sunlight and include more plankton.Coral bleaching, large storms and other destructive events are increasing on tropical reefs."Shallow-water coral habitats are rapidly degrading," co-author Dr Tom Bridge, also from Coral CoE at JCU, said."And the deeper coral habitats, which may act as a refuge for some reef fish species, have less light available," Dr Bridge said."Corals mostly depend on light as an energy source to survive, which means there are less corals at depth."Fish that eat coral, such as the Triangle and Eight-Band butterflyfish, can live on deeper reefs by either feeding more on their usual resource -- or by adapting their diets.Triangle butterflyfish are fussy eaters (dietary specialists). The Eight-band Butterflyfish are not fussy eaters (dietary generalists). The study compared the diets of the two from shallow to deep depths.The researchers found that while overall feeding rates did not change with depth, the Triangle Butterflyfish -- a dietary specialist -- fed more selectively on their preferred corals, which are sparser at greater depths than in shallow waters.In contrast, the dietary flexibility of the Eight-band Butterflyfish increased with depth as the amount of different coral types changed."These observations were compared with lab investigations of light-related changes in the energy content of corals," Dr MacDonald said."Surprisingly, the energy content of the corals that the Triangle butterflyfish preferred to feed on did not decline with depth as expected," he said."However, the pathways through which carbon passed from the corals to the fish did.""Our results suggest that the expected declines in the quality of deeper corals as prey for fish are buffered by increased plankton intake by the corals via their polyps," co-author Prof Geoff Jones, also from Coral CoE at JCU, said."This means the corals adjust to the lack of light at depth, as they usually rely on energy from their internal photosynthetic zooxanthellae," Prof Jones said.Dr MacDonald said the increase in plankton uptake was as much as 20 percent."This may be why we see healthy members of these fussy fish in both deep and shallow waters," he said."Climate change and other disturbances have increasing impacts on the habitats and compositions of coral reefs.""Our study shines a light on the importance of the versatile relationship between species as they seek refuge on the edges of their environmental range -- even if one species is fussier than another."
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Extinction
| 2,019 |
July 19, 2019
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https://www.sciencedaily.com/releases/2019/07/190719102122.htm
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Unusually high carbon stocks and tree diversity in Panama's Darien forest
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Forests in Darien, an eastern province of Panama, are crucial for carbon storage, biodiversity conservation and the livelihoods of indigenous groups, yet they are under threat due to illegal logging. Through a participatory forest-carbon monitoring project, scientists from the Smithsonian Tropical Research Institute (STRI), McGill University and the National Research Council of Canada uncovered sources of above-ground biomass (AGB) variation and explored considerations for implementing Reducing Emissions from Deforestation and Forest Degradation (REDD+) in Darien.
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"Indigenous authorities were interested in quantifying forest-carbon stocks using field-based measurements to validate the REDD+ potential of their forests and engage in informed discussions with REDD+ proponents in the country," said Javier Mateo-Vega, former research fellow at STRI and main author of the study.As part of the study, the scientists and a team of trained indigenous technicians analyzed 30 one-hectare plots distributed across a large, mature forest landscape, in undisturbed and disturbed areas. They found that Darien has the highest carbon stocks among nine mature forest sites across the Neotropics, and the second-highest tree species richness among five mature forest sites in the region, supporting the need to protect it in a culturally appropriate way with the region's indigenous peoples."I have been working in Darien since 1993 and also perceived these forests as exceptional. It was very exciting when we analyzed the results to see just 'how' exceptional they really are," said Catherine Potvin, research associate at STRI and Canada Research Chair in Climate Change Mitigation and Tropical Forests at McGill University. "Hopefully our results will help give visibility to their global importance for carbon and for biodiversity."They also discovered that, although half of the plots in the sample had experienced traditional indigenous extractive activities, satellite analyses of vegetation cover did not detect changes in canopy height or noticeable damage to the landscape like agriculture or cattle ranching would. In the field, however, disturbed plots harbored 54% less biomass than intact forests, so their AGB volumes differed vastly from those of undisturbed plots, but their structure and characteristics did not.This led researchers to ascertain that the main determinant of AGB variation is the level of disturbance in the forest. That is, the amount of organic matter above the ground -- in standing trees -- and the amount of carbon it stores, is mainly affected by the selective extraction of large trees rather than by differences across forest types or any other factors.The study also revealed that even when disturbed forests lost half of their carbon as compared to undisturbed ones, they maintained the same tree species richness. In addition, disturbed forests still maintained a disproportionately high capacity to sequester carbon, suggesting that they should not necessarily be excluded from REDD+ investments given its interest in targeting areas where climate-change mitigation and biodiversity conservation can be achieved simultaneously."Decades of efforts to protect Darien's natural and cultural heritage through different protected areas' management categories and land-tenure regimes for indigenous peoples are being stripped away by rampant illegal logging," Mateo-Vega said. "Our study conclusively demonstrates how important these forests are for climate-change mitigation, biodiversity conservation and the well-being of indigenous peoples."
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Extinction
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July 18, 2019
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https://www.sciencedaily.com/releases/2019/07/190718112419.htm
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New frog species discovered
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UCF student Veronica Urgiles has helped describe two new frog species discovered in Ecuador, and she named one of them after one of her professors.
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Urgiles and an international team of researchers just published their findings in the journal "Frogs are by far my favorite," said Urgiles, who is pursuing a master's degree in biology. "So, getting to describe and name two of them is terrific. I have been looking at these frogs for years now, so going over the whole process of observing them in their habitats and then analyzing them and comparing them under the microscope, to finally naming them is a long, but very satisfying journey."Urgiles, a 2017 Fulbright scholar and the lead author, said she chose to attend UCF for its integration of genetics and genomics in biodiversity research and the emphasis on real-world application. She works with Assistant Professor Anna Savage who specializes in species diversity based on molecular analyses."One of the things that I found most interesting about these guys is that they don't have metamorphosis like a regular frog, but instead they develop entirely inside eggs that adult females deposit in the ground," Urgiles said. "They really don't need water bodies for their development. Both of the new frog species inhabit high elevation ecosystems in the mountain range over 8,000 feet, so even though we are right there in the equator, it's very cold and windy most of the year."The team of researchers has been studying frogs in Ecuador the past few years. In 2017, Urgiles found the first new species and named it Pristimantis quintanai, after one of her biology professors -- Pedro Quintana-Ascencio. She and Savage found the second species -- Pristimantis cajanuma -- in 2018. Both were found in the Paramo and montane forest of the southern Ecuadorean Andes.The frogs are tiny, measuring .8 inch. Pristimantis quintanai females are brown and black and Pristimantis cajanuma are green and black, both easily blending into the foliage. They have a distinct call that is sharp and continuous, sounding like tik-tik-tik-tik.Urgiles examined DNA samples collected by the international team back in Savage's lab at UCF, generated genetic sequences, and constructed the phylogenetic analysis. Other team members also worked the morphological diagnosis and comparisons with other frogs and an acoustic analysis of the frogs' calls."In these analyses, we use all of the genetic similarities and differences we find to build phylogenetic trees, and when we find that a 'branch' on the 'tree' has strong support and contains all of the individuals that share the same morphological characteristics, then we have good evidence to describe it as a new species," says Savage, whose expertise includes describing species diversity based on molecular analyses. "We used this method, along with vocalization and location data, to conclude that the two species we describe are distinct from any other species that have ever been characterized."The work is critical because of the vast diversity that has yet to be discovered in the tropical Andes of South America, Urgiles says. In 2018, 13 new species of frogs were documented in the tropical Andes of Ecuador and so far in 2019 five new frogs have been documented.There are potentially thousands of new plants and animals in the area that may hold the key to other discoveries. It's important to know what is there, to better understand the threats to habitat loss and disease so conservation methods can be established to protect the resources.
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Extinction
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July 17, 2019
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https://www.sciencedaily.com/releases/2019/07/190717105352.htm
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Little genes, big conservation: Scientists study genetic rescue
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At first glance, there aren't many similarities between westslope cutthroat trout in Montana, wolves on Isle Royale National Park in Michigan and Australia's mountain pygmy possum, a mouse-sized alpine marsupial.
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With all three, though, managers have attempted or explored the possibility of genetic rescue, a conservation approach that involves moving a small number of individual animals from one population to another to reduce genetic problems and decrease extinction risk.Now, a new paper by University of Montana scientists examines the potential and uncertainties of attempting genetic rescue. The peer-reviewed paper, published this month in the journal The authors define genetic rescue as a decrease in population extinction probability owning to gene flow, best measured as in increase in population growth."Inbreeding can cause genetic defects that lower survival," said Donovan Bell, paper co-author and a doctoral candidate in UM's W.A. Franke College of Forestry and Conservation. "In small populations, every individual becomes closely related and the resulting genetic problems put these populations at a higher risk of extinction. With genetic rescue, introducing unrelated individuals from another population can alleviate these genetic problems.""It allows natural selection to increase the amount of beneficial genetic material introduced by managers," said co-author Zak Robinson, also a doctoral candidate in the forestry college. "It increases individual survival and lifetime reproductive success, which can increase the population's size and health."As human development increases, so does fragmentation, and animal populations are increasingly splintered into smaller, isolated populations, the authors say."Even if fragmentation was to stop today, there are already millions of populations that are limited to small habitats," Robinson said. "In order to address issues with small, fragmented populations and maintain biodiversity, we're going to have to find ways to mitigate the impacts of inbreeding and the genetic problems it brings."That's where genetic rescue comes in."Habitat fragmentation is incredibly common, and it's a huge problem for conservation," Bell said. "There are a few research groups that are strongly advocating that we start implementing genetic rescue in a much more widespread manner to address issues with habitat fragmentation. We think that genetic rescue is very valuable, but there is a lot left to understand about genetic rescue."In their paper, Bell, Robinson and their co-authors focus on what is still unknown about genetic rescue and areas where future research could prove beneficial. Some of those big questions include: how long the effects of genetic rescue will last; under what conditions potential negative consequences could occur, including genetic swamping (the loss of unique local adaptations), and outbreeding depression (reduced fitness of offspring with evolutionarily divergent parents); how populations and individuals should be selected for genetic rescue attempts; and how advances in genomics -- the study of genomes -- fits into the whole picture.The authors also draw attention to the relationships between genetic rescue and boots-on-the-ground conservation efforts -- a pairing emphasized by successful genetic rescue stories like the Florida panther or Australia's mountain pygmy possum."Genetic rescue is unlikely to be a conservation silver bullet on its own, but instead needs to be attempted as part of a broader conservation strategy that includes habitat improvements," Bell said."Genetics and ecology are fundamentally intertwined," Robinson said. "There's a complex relationship between the genetic composition of a population and extinction. We need to understand this better in order to mitigate the part of extinction risk that's associated with the genetic composition of a population."The synthesis closely ties to Bell and Robinson's ongoing research efforts. As part of their wildlife biology doctoral programs, each is running a genetic rescue experiment testing the conservation approach on wild fish populations.In partnership with Montana Fish, Wildlife and Parks and with funding from the National Science Foundation, Bell is studying westslope cutthroat trout in Montana -- Big Sky Country's state fish and currently listed as at-risk in Montana. On the east side of the Continental Divide, most of the populations that haven't hybridized with rainbow trout are isolated in small headwater streams, and there are concerns that these populations could suffer from genetic problems, Bell said.Robinson's project, also funded by NSF, encompasses similar research on Eastern brook trout in his home state of Virginia, research he originally embarked on as an undergraduate student.They hope these projects will help answer some of the questions they acknowledge in their latest paper."These are tests. We want to see how it works and see if it's ready for popular consumption for the state agencies managing isolated trout populations," Robinson said. "What we want to do is understand genetic rescue well enough so that managers can prioritize their activities and weigh it against other competing strategies on a limited budget.""Attempting genetic rescue is a really promising conservation strategy, but there are still uncertainties we need to address in order to make it as useful as possible for conservation and also to increase confidence in using the strategy," Bell said. "It's actually implemented very rarely right now."Other co-authors include UM professors Fred Allendorf and Andrew Whiteley, and UM alumni Chris Funk and David Tallmon. Co-authors also include researchers from Colorado State University and Michigan State University.
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Extinction
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July 15, 2019
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https://www.sciencedaily.com/releases/2019/07/190715164652.htm
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Thirty years of unique data reveal what's really killing coral reefs
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Coral reefs are considered one of the most threatened ecosystems on the planet and are dying at alarming rates around the world. Scientists attribute coral bleaching and ultimately massive coral death to a number of environmental stressors, in particular, warming water temperatures due to climate change.
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A study published in the international journal Improperly treated sewage, fertilizers and top soil are elevating nitrogen levels, which are causing phosphorus starvation in the corals, reducing their temperature threshold for "bleaching." These coral reefs were dying off long before they were impacted by rising water temperatures. This study represents the longest record of reactive nutrients and algae concentrations for coral reefs anywhere in the world."Our results provide compelling evidence that nitrogen loading from the Florida Keys and greater Everglades ecosystem caused by humans, rather than warming temperatures, is the primary driver of coral reef degradation at Looe Key Sanctuary Preservation Area during our long-term study," said Brian Lapointe, Ph.D., senior author and a research professor at FAU's Harbor Branch.A key finding from the study is that land-based nutrient runoff has increased the nitrogen:phosphorus ratio (N:P) in reef algae, which indicates an increasing degree of phosphorus limitation known to cause metabolic stress and eventually starvation in corals. Concentrations of reactive nitrogen are above critical ecosystem threshold levels previously established for the Florida Keys as are phytoplankton levels for offshore reefs as evidenced by the presence of macroalgae and other harmful algal blooms due to excessive levels of nutrients.Researchers gathered data from 1984 to 2014 and collected seawater samples during wet and dry seasons. Lapointe and collaborators from the University of Georgia and the University of South Florida also monitored the living coral and collected abundant species of seaweed (macroalgae) for tissue nutrient analysis. They monitored seawater salinity, temperature and nutrient gradients between the Everglades and Looe Key. They wanted to better understand how nitrogen traveled from the Everglades downstream to the coral reefs of the Florida Keys National Marine Sanctuary, which now has the lowest amount of coral cover of any reefs in the wider Caribbean region.Data revealed that living coral cover at Looe Key Sanctuary Preservation Area declined from nearly 33 percent in 1984 to less than 6 percent in 2008. The annual rate of coral loss varied during the study, but increased from 1985 to 1987 and 1996 to 1999 following periods of heavy rainfall and increased water deliveries from the Everglades. Between 1991 to 1995, significant increases in Everglades runoff and heavy rainfall resulted in increases of reactive nitrogen and phytoplankton levels at Looe Key above levels known to stress and cause die-off of coral reefs. Despite reduced Everglades flows, the water quality has not yet recovered to the levels of the 1980s.Nitrogen loading to the coast is predicted to increase by 19 percent globally simply as a result of changes in rainfall due to climate change, which suggests the need for urgent management actions to prevent further degradation."The future success of the Comprehensive Everglades Restoration Plan will rely on recognizing the hydrological and nitrogen linkages between the Everglades, Florida Bay and the Florida Keys," said Lapointe. "The good news is that we can do something about the nitrogen problem such as better sewage treatment, reducing fertilizer inputs, and increasing storage and treatment of stormwater on the Florida mainland."The impact of local land-based nitrogen contributions from sewage treatment plants that service 76,000 year-round residents and an estimated 3.8 million tourists annually is currently being mitigated by completion of centralized wastewater collection and advanced wastewater treatment plants and nutrient removal facilities throughout the Florida Keys.According to the Florida Keys National Marine Sanctuary, ocean-related activities associated with coral reefs add more than $8.5 billion each year and 70,400 jobs to the local economy in southeast Florida."The Bonaire coral reefs in the Caribbean Netherlands is a great example of effective nitrogen pollution mitigation. These coral reefs are beginning to recover following the construction of a new sewage treatment plant in 2011, which has significantly reduced nitrogen loading from septic tanks," said Lapointe.The study's co-authors are Rachel A. Brewton and Laura W. Herren of FAU's Harbor Branch; James W. Porter, Ph.D., emeritus professor of ecology at the University of Georgia; and Chuanmin Hu, Ph.D., of the College of Marine Science at the University of South Florida."Citing climate change as the exclusive cause of coral reef demise worldwide misses the critical point that water quality plays a role, too," said Porter. "While there is little that communities living near coral reefs can do to stop global warming, there is a lot they can do to reduce nitrogen runoff. Our study shows that the fight to preserve coral reefs requires local, not just global, action."
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Extinction
| 2,019 |
July 11, 2019
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https://www.sciencedaily.com/releases/2019/07/190711141407.htm
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Bird with unusually long toes found fossilized in amber
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Meet the ancient bird that had toes longer than its lower legs. Researchers have discovered a bird foot from 99 million years ago preserved in amber that had a hyper-elongated third toe. The study, published in the journal
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"I was very surprised when I saw the amber," says first author Lida Xing at China University of Geosciences (Beijing). "It shows that ancient birds were way more diverse than we thought. They had evolved many different features to adapt to their environments."To study the Cretaceous period fossil, Xing and his colleagues scanned the amber with micro-CT and created a 3D reconstruction of the foot. They found that the bird's third toe, measuring 9.8 millimeters, is 41 percent longer than its second toe and 20 percent longer than its tarsometatarsus, which is a bone in the lower legs of birds. The team compared the ratios with those of 20 other extinct birds from the same era and 62 living birds. No bird has a foot that resembles this one.The researchers named it Elektorornis chenguangi. Elektorornis means "amber bird," and it belongs to a group of extinct birds called Enantiornithes, the most abundant type of bird known from the Mesozoic era. It is thought that Enantiornithines became extinct during the Cretaceous-Paleogene extinction event about 66 million years ago, along with dinosaurs. They have no living descendants.Based on the fossil, the team estimates that the Elektorornis was smaller than a sparrow, and it was arboreal, meaning it spent most of its time in trees as opposed to on the ground or in water."Elongated toes are something you commonly see in arboreal animals because they need to be able to grip these branches and wrap their toes around them," says co-author Jingmai O'Connor at the Chinese Academy of Sciences. "But this extreme difference in toe lengths, as far as we know, has never been seen before."The amber the foot was found in, measuring 3.5 centimeters long and weighing 5.5 grams, was discovered around 2014 in the Hukawng Valley of Myanmar. During the Mesozoic era, the valley was full of trees that produced resin, a gooey substance that oozes out of the tree bark. Plants and small animals, such as geckos and spiders, often get trapped in the resin and become fossilized with the amber after millions of years. Scientists have discovered many extinct animals, including the oldest known bee and a feathered dinosaur tail, in amber from this valley.Xing obtained the amber from a local amber trader, who didn't know what animal this weird foot belonged to."Some traders thought it's a lizard foot, because lizards tend to have long toes," Xing says. "Although I've never seen a bird claw that looks like this before, I know it's a bird. Like most birds, this foot has four toes, while lizards have five."It remains unknown why the amber bird evolved such an unusual feature. The only known animal with disproportionally long digits is the aye-aye. The aye-aye is a lemur that uses its long middle fingers to fish larvae and insects out of tree trunks for food. Therefore, the researchers suggest Elektorornis might have used its toe for the same purpose."This is the best guess we have," O'Connor says. "There is no bird with a similar morphology that could be considered a modern analog for this fossil bird. A lot of ancient birds were probably doing completely different things than living birds. This fossil exposes a different ecological niche that these early birds were experimenting as they evolved."Moving forward, the team hopes to extract the proteins and pigments from some feathers exposed on the surface of the amber. Xing says such data could help them better understand the bird's adaptation to the environment, such as whether it had camouflage plumage.
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Extinction
| 2,019 |
July 11, 2019
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https://www.sciencedaily.com/releases/2019/07/190711105602.htm
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Wakanda forever! Scientists describe new species of 'twilight zone' fish from Africa
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Africa has new purple-clad warriors more than 200 feet beneath the ocean's surface. Deep-diving scientists from the California Academy of Sciences'
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"When we thought about the secretive and isolated nature of these unexplored African reefs, we knew we had to name this new species after Wakanda," says Yi-Kai Tea, lead author and ichthyology PhD student from the University of Sydney. "We've known about other related fairy wrasses from the Indian Ocean, but always thought there was a missing species along the continent's eastern edge. When I saw this amazing purple fish, I knew instantly we were dealing with the missing piece of the puzzle."The Academy scientists say "Preparation for these deep dives is very intense and our dive gear often weighs more than us," says Dr. Luiz Rocha, Academy Curator of Fishes and co-leader of the Using a microscope, the team examined the specimens' scales, fin rays, and body structures. DNA and morphological analyses revealed the new fairy wrasse to be different from the other seven species in the western Indian Ocean as well as other relatives in the Pacific. The new species' common name is inspired by the fictional metal vibranium, a rare, and, according to Rocha, "totally awesome" substance found in the Black Panther nation of Wakanda. The Vibranium Fairy Wrasse's purple chain-link scale pattern reminded the scientists of Black Panther's super-strong suit and the fabric motifs worn by Wakandans in the hit film.In a recent landmark paper, the Academy team found that twilight zone reefs are unique ecosystems bursting with life and are just as vulnerable to human threats as their shallow counterparts. Their findings upended the long-standing assumption that species might avoid human-related stressors on those deeper reefs. The In addition to this new fish from Zanzibar, Rocha and his colleagues recently published descriptions of mesophotic fish from Rapa Nui [Easter Island] and Micronesia. "It's a time of global crisis for coral reefs, and exploring little-known habitats and the life they support is now more important than ever," says Rocha. "Because they are out of sight, these deeper reefs are often left out of marine reserves, so we hope our discoveries inspire their protection."
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Extinction
| 2,019 |
July 9, 2019
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https://www.sciencedaily.com/releases/2019/07/190709160136.htm
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Coral reefs shifting away from equator
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Coral reefs are retreating from equatorial waters and establishing new reefs in more temperate regions, according to new research in the journal
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"Climate change seems to be redistributing coral reefs, the same way it is shifting many other marine species," said Nichole Price, a senior research scientist at Bigelow Laboratory for Ocean Sciences and lead author of the paper. "The clarity in this trend is stunning, but we don't yet know whether the new reefs can support the incredible diversity of tropical systems."As climate change warms the ocean, subtropical environments are becoming more favorable for corals than the equatorial waters where they traditionally thrived. This is allowing drifting coral larvae to settle and grow in new regions. These subtropical reefs could provide refuge for other species challenged by climate change and new opportunities to protect these fledgling ecosystems.The researchers believe that only certain types of coral are able to reach these new locations, based on how far the microscopic larvae can swim and drift on currents before they run out of their limited fat stores. The exact composition of most new reefs is currently unknown, due to the expense of collecting genetic and species diversity data."We are seeing ecosystems transition to new blends of species that have never coexisted, and it's not yet clear how long it takes for these systems to reach equilibrium," said Satoshi Mitarai, an associate professor at Okinawa Institute of Science and Technology Graduate University and an author of the study. "The lines are really starting to blur about what a native species is, and when ecosystems are functioning or falling apart."New coral reefs grow when larvae settle on suitable seafloor away from the reef where they originated. The research team examined latitudes up to 35 degrees north and south of the equator, and found that the shift of coral reefs is perfectly mirrored on either side. The paper assesses where and when "refugee corals" could settle in the future -- potentially bringing new resources and opportunities such as fishing and tourism.The researchers, an international group from 17 institutions in 6 countries, compiled a global database of studies dating back to 1974, when record-keeping began. They hope that other scientists will add to the database, making it increasingly comprehensive and useful to other research questions."The results of this paper highlight the importance of truly long-term studies documenting change in coral reef communities," said Peter Edmunds, a professor at the University of California Northridge and author of the paper. "The trends we identified in this analysis are exceptionally difficult to detect, yet of the greatest importance in understanding how reefs will change in the coming decades. As the coral reef crisis deepens, the international community will need to intensify efforts to combine and synthesize results as we have been able to accomplish with this study."Coral reefs are intricately interconnected systems, and it is the interplay between species that enables their healthy functioning. It is unclear which other species, such as coralline algae that facilitate the survival of vulnerable coral larvae, are also expanding into new areas ¬- or how successful young corals can be without them. Price wants to investigate the relationships and diversity of species in new reefs to understand the dynamics of these evolving ecosystems."So many questions remain about which species are and are not making it to these new locations, and we don't yet know the fate of these young corals over longer time frames," Price said. "The changes we are seeing in coral reef ecosystems are mind-boggling, and we need to work hard to document how these systems work and learn what we can do to save them before it's too late."Some of the research that informed this study was conducted at the National Science Foundation's Moorea Coral Reef Long-Term Ecological Research site near French Polynesia, one of 28 such long-term research sites across the country and around the globe."This report addresses the important question of whether warming waters have resulted in increases in coral populations," says David Garrison, a program director in the National Science Foundation's Division of Ocean Sciences, which funded the research. "Whether this offers hope for the sustainability of coral reefs requires more research and monitoring."
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Extinction
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July 8, 2019
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https://www.sciencedaily.com/releases/2019/07/190708154031.htm
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Genetic pathway could enhance survival of coral
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Three researchers at The University of Texas at Arlington have made a groundbreaking discovery that could enhance the ability of reef-building corals to survive a rapidly warming and disease-filled ocean.
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In a newly published paper in The cellular stress response promotes mitochondrial protein homeostasis, free radical detoxification and innate immunity. Its existence in corals was previously unknown."We understood that there is a target gene essentially used as a biomarker for diseased and distressed corals, and that gene is induced by the response pathway that my lab studies," said Pellegrino, assistant professor of biology.Pellegrino, who had never previously studied coral, is an expert in mitochondria and cell biology. In discussions with Mydlarz, whose portfolio is focused on coral immunity, the two hypothesized that investigating the mitochondrial unfolded protein response in coral could have relevance in protecting the coral reefs. They were right."This is a true collaboration bringing together the tools in Mark's lab with the data available in my lab," said Mydlarz, professor of biology. "But it wasn't until Brad joined my lab, with his experience in studying mitochondria, and took this on as his project that we were able to investigate."Dimos, a second-year graduate student in Mydlarz's lab and first author on the paper, said the gene they discovered acts as a "master regulator" that unlocks hundreds of other genes."There has been a lot of well-done work in the past that has identified various genes that could be important for immunity in coral, but our gene potentially regulates a lot of those," Dimos said. "We've uncovered a single target that has a broad scope of impact. This is a huge step forward in making any interventions to preserve coral more efficiently."The team plans to move forward with testing the genetic pathway in a model organism to determine if the newly discovered gene can protect against the heat stress and infection that corals face in the ocean, Pellegrino said."A lot of these genes in this pathway are involved in protecting the mitochondria," Pellegrino said. "In addition to protecting against heat stress, this stress response pathway could also possibly protect against infection owing to its role in regulating innate immunity."Coral reefs not only create vibrant underwater landscapes, but they support 25% of all marine species on the planet. But they have recently experienced massive declines driven by disease and thermally induced mass coral bleaching in the face of increased environmental disturbances."Corals build the reef and are the base of the ecosystem," Mydlarz said. "Without live coral, the reef doesn't have the structure it needs to support the life that relies on it. It's ecologically important, but also has great socioeconomic significance. Understanding the existence of this gene means that there is now the potential to identify if corals are experiencing stress before they appear dead or bleached."Dimos said the ability to predict coral survival will help scientists and conservationists allocate resources and determine which species to prioritize as the environment increasingly becomes more unstable.Clay Clark, chair of the Department of Biology, said the work of Dimos, Mydlarz and Pellegrino is making significant contributions to UTA's commitment to address critical issues related to the global environment."It is exciting to see two labs combine their strengths and resources to tackle a major issue with numerous critical implications," Clark said. "Bradford, Laura and Mark are showcasing the power of research as they move swiftly and thoroughly in response to a rapidly growing issue. I look forward to how this breakthrough will lead them to protect these vital organisms to secure invaluable biodiversity."
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Extinction
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July 8, 2019
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https://www.sciencedaily.com/releases/2019/07/190708112443.htm
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Wind, warmth boost insect migration
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Wind and warmth can improve travel time for the billions of insects worldwide that migrate each year, according to a first-ever radio-tracking study by University of Guelph biologists.
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Researchers equipped monarch butterflies and green darner dragonflies with radio transmitters and tracked them through southern Ontario and several northern States to learn how environmental factors affect daytime insect migration.Learning more about what happens to insects during their physically taxing migration period may help in efforts to conserve them, particularly threatened species, said the researchers.The study, which was recently published in As part of their multigenerational migration, monarchs from Canada overwinter in Mexico and green darners travel to the southern United States.Until recently, their small size has made individual insects hard to track. But it's increasingly critical to do just that, said lead author Samantha Knight.Insects on the wing play vital roles in pollinating crops and in maintaining ecosystems as both prey and predators.Threatened by habitat loss, land use changes and global warming, she said, "some 40 per cent of insect species risk extinction, yet we know little about what happens to organisms when they migrate."Study co-author Prof. Ryan Norris, Department of Integrative Biology, added, "Migration is not an easy period for insects. They are likely pushed to their physiological limits. If we have a way to track and understand what habitats they're using, that goes a long way to understanding what might be causing declines."As part of the study, researchers captured insects on Ontario's Bruce Peninsula in fall 2015 and 2016 and outfitted them with battery-powered radio transmitters weighing about as much as a raindrop. Those devices emitted signals picked up by an array of telemetry towers across the southern part of the province and into the northern United States.The team downloaded data from the towers to track individuals' flight distances and speeds.On average, monarchs flew about 12 kilometres per hour and darners about 16 kilometres per hour. The farthest a monarch travelled in one day was 143 kilometres at 31 km per hour, including windspeed. In a single day, a darner flew 122 kilometres at up to 77 km per hour."A darner would get a speeding ticket in Guelph," quipped Norris, adding that insects may fly even farther and faster in single spurts.To attain their fastest airspeeds, the insects are likely flying high in the atmosphere to take advantage of the wind, although the researchers don't know how high."That means insects are migrating over our heads and we don't know it," said Norris.Unlike birds, insects need a minimum air temperature of about 10-15 C for daytime flight. Monarchs and darners fly faster as it warms up. However, flight is impeded when it gets too hot, said Norris. At temperatures above 23 C -- higher than in this new study -- darners have been seen flying slower.Norris said insects probably have an upper temperature limit for efficient flight, suggesting that global warming might ultimately affect their migration.The researchers were surprised that rain had no effect on flight speed. Light rain might not have deterred the insects, or they might have made up for lost time after rainfall.Knight said tracking technology enables researchers to learn more about insect migration under varying conditions. Many species have been studied while breeding and overwintering, but scientists lack information about migration, including human impacts on habitat and feeding en route."For insects, land use changes are a major driver of declines in numbers," she said. "If we understand where they're going, we can maybe shed light on land use change impacts during migration."This spring, Norris was named as the Weston Family Senior Scientist for the Nature Conservancy of Canada (NCC). He retains his faculty appointment while conducting research intended to help the NCC preserve Canadian habitat and biodiversity.A 2017 master's graduate of U of G, Knight is program manager for the Weston Family Science Program at the NCC.
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Extinction
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July 8, 2019
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https://www.sciencedaily.com/releases/2019/07/190708112412.htm
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Coral bleaching: Altered gene expression may trigger collapse of symbiotic relationship
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Researchers in Japan have identified the potential genes responsible for coral bleaching caused by temperature elevation.
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Researchers carried out a transcriptomic analysis with the symbiotic sea anemone Exaiptasia diaphana, an emerging model cnidarian, under multiple culture conditions. The temperature rise and the shift to a non-symbiotic state (a state in which two organisms are not interdependent on one another) caused the expression levels of 292 genes to alter dramatically and irreversibly. The research group argues that the 292 "Heat Induced Bleaching Associated" (HIBA) genes include factors of coral bleaching as a result of temperature elevation.Coral reefs are a major reservoir of biodiversity in the sea. Their ecosystem relies on a stable symbiotic relationship between the host cnidarian animals, including corals and sea anemones, and the symbiont dinoflagellate. Ongoing environmental changes due to global warming can permanently damage the symbiosis: a phenomenon known as 'coral bleaching.' However, mechanisms for maintaining stable symbiosis are poorly understood.In the study, the HIBA genes were subjected to a functional classification analysis and divided into four major functional groups: transporters, oxidation-reduction, lysosomes, and carbohydrate metabolism. According to Shinchiro Maruyama, an assistant professor at Tohoku University "Lysosome is a versatile organelle that degrades various substances in a cell." He adds that "inhabitance of the symbiont dinoflagellate in an organelle called 'symbiosome,' something that resembles lysosomes, suggests a relationship between lysosomes and bleaching; a situation where number of symbionts has decreased in the host cnidarian animal." In addition, symbiont carbohydrates have long been believed to contribute to symbiosis. Based on these factors, the team hypothesizes that degradation of carbohydrates in lysosomes is the central function of the HIBA genes, and generates the need for further investigation.
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Extinction
| 2,019 |
July 1, 2019
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https://www.sciencedaily.com/releases/2019/07/190701144527.htm
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How to protect corals facing climate change
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The best way to protect corals threatened by climate change is to conserve a wide range of their habitats, according to a study in
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"Rather than conserving just the cold places with corals, we found that the best strategies will conserve a wide diversity of sites," said co-author Malin Pinsky, an associate professor in the Department of Ecology, Evolution, and Natural Resources at Rutgers University-New Brunswick. "Hot reefs are important sources of heat-tolerant corals, while cold sites and those in between are important future refuges and stepping stones for corals as the water heats up."Worldwide, about 500 million people rely on coral reefs for food and livelihoods, with billions of dollars a year boosting economies, according to the National Oceanic and Atmospheric Administration. Reefs protect coastlines from storms and erosion; provide habitat as well as spawning and nursery grounds for fish; and result in income from fishing, recreation and tourism, among other benefits.But corals face several threats, including global warming, warm water bleaching episodes, reef destruction, nutrient pollution and ocean acidification from carbon dioxide emitted when fossils fuels burn.Predictions about the future of corals are generally grim, the study notes, but there is growing recognition that they can adapt rapidly to a changing climate.Pinsky and scientists at the University of Washington, Utah State University, Coral Reef Alliance, Stanford University and University of Queensland in Australia modeled how different conservation strategies might help coral reefs survive climate change. Previous research addressed where to establish marine protected areas to help corals, but nearly all studies overlooked the fact that corals can also evolve in response to climate change, Pinsky said.The researchers evaluated a range of potential conservation strategies, including those that: protected sites where existing coral populations appeared to be "preadapted" to future conditions; conserved sites suitable for corals to move to in the future; conserved sites with large populations of certain species; conserved the smallest populations; or protected reef sites chosen at random. The researchers found that conserving many different kinds of reefs would work best."Corals are facing a gauntlet over the coming years and decades from warming oceans, but we found that reef conservation in general can really boost corals' ability to evolve and cope with these changes," Pinsky said. "There is strength in diversity, even when it comes to corals. We need to think not only about saving the cooler places, where corals can best survive in the future, but also the hot places that already have heat-resistant corals. It's about protecting a diversity of habitats, which scientists hadn't fully appreciated before."The researchers are developing regional models to test conservation strategies for the Caribbean Sea, the central Pacific Ocean and the Coral Triangle in the western Pacific, he said. They want to understand how the most effective conservation strategies differ from one region to the next."We are working closely with conservation groups that will be applying the guidelines and findings from this study to coral reef conservation around the world," Pinsky said.
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Extinction
| 2,019 |
July 1, 2019
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https://www.sciencedaily.com/releases/2019/07/190701144252.htm
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Corals in Singapore likely to survive sea-level rise
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Global sea levels are expected to rise by at least half a metre by the year 2100 due to climate change. The projected rise can affect important environmental factors such as habitat suitability and availability of light, threatening the health and survival of marine ecosystems.
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For the corals dwelling in the sedimented, turbid waters around Singapore, rising sea levels can imperil species, as those living among the deepest waters could starve due to insufficient light for them to make food.A team from the National University of Singapore (NUS), led by Assistant Professor Huang Danwei from the Department of Biological Sciences at the NUS Faculty of Science, examined nearly 3,000 corals from 124 species at two reef sites in Singapore, namely Pulau Hantu and Raffles Lighthouse.The research team discovered that the corals in Singapore waters typically do not extend deeper than eight metres, as light levels beyond this depth are not sufficient to support coral growth. The researchers also found that species present in deeper areas are able to tolerate a wider range of conditions, and are unlikely to be threatened by a rise in sea level, provided that other stress factors such as sedimentation do not increase.The findings, published online in the journal
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Extinction
| 2,019 |
June 28, 2019
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https://www.sciencedaily.com/releases/2019/06/190628182312.htm
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Nonnative pear trees are showing up in US forests
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A popular imported tree that became a neighborhood favorite in the 1990s now threatens to crowd out native trees in some Eastern forests.
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University of Cincinnati biologist Theresa Culley warns that for some parts of Ohio, it might be too late to stop the spread of the Callery pear. But she is urging other states to be vigilant before the invasive trees begin taking over their forests, too.Culley presented her findings to botanists from around the world during the Society of Economic Botany conference this year hosted at UC's McMicken College of Arts and Sciences.Like a lot of invasive species, the Callery pear, also known as the Bradford pear, was a problem of our own making, she said. Named for China historian Joseph-Marie Callery, who sent samples back to Europe in the 1800s, the tree captured the interest of American botanists a century later."At one point it was named urban street tree of the year," she said. "In the mid-1990s they started to show up in the wild. Now people have recognized they're starting to spread and it's a problem."The original strain of pear tree was "self-incompatible," incapable of reproducing with other trees of its kind. They became a best-seller because they grew quickly, regardless of climate or soil conditions. The trees bloom pretty white flowers in the spring and have leaves that turn a vibrant purple in the autumn.For years, the pears were a welcome addition to tree-lined streets."I call them the lollipop tree because they have this perfect shape," Culley said.But homeowners soon learned the mature trees had weak trunks that split easily and toppled in heavy snow or strong winds."The Bradford pear was a beautiful tree with a service life of about 15 years," said David Listerman, an Ohio landscaping broker and consultant. "But the canopy would get so heavy that in a windstorm, it would break in half."The solution for growers was to introduce sturdier varieties. But besides their sturdy trunks, the replacement trees had something else: genetic diversity. Suddenly, the old pear trees could now cross-pollinate with the new varieties. Their fertilized flowers began producing fruit that birds carried off into the forest. A monster was born.Today, Listerman says the wild newcomers represent an existential threat to native trees. Their fallen leaves leach chemicals into the ground that can kill native rivals."Most invasives tend to have advantages over native plants. The Callery pear holds its leaves late into the fall -- right up to Christmas. It grows another month to two months longer, outcompeting native species that go dormant in October," he said. "They encroach along interstates where they need to have visual clearance. So highway departments wind up having to do more mowing or treating."And while some birds will eat their fruit, pear trees don't provide as much benefit to wildlife as many native species, he said.Listerman serves with UC's Culley on the Ohio Invasive Plants Council, which helps the Ohio Department of Agriculture identify potentially harmful invasive species.Listerman said pear trees aren't just popping up along roadsides. Forest surveys are finding them in unexpected places far from the nearest subdivision. The wild pears grow in thick stands with unpleasant spur-like thorns.On a recent field trip, Culley picked her way through the woods at the Harris Benedict Nature Preserve to show how resilient pear trees have become. UC owns the forested preserve about 15 miles north of the Uptown campus and uses it for some of its biological sciences programs and research. It's adjacent to the Johnson Preserve in Montgomery, Ohio.The trail is lined with several memorials to victims of a 1999 F4 tornado that killed four people and destroyed nearly 130 nearby homes and businesses. The storm cut a 10-mile long swath of destruction that toppled hundreds of trees across two counties.Where many of the stately older trees fell during the storm, Callery pears now thrive. Culley stopped under the canopy of their leafy, green foliage. The understory was covered in Amur honeysuckle, another invasive plant from Asia that has exploded in Eastern forests.UC conducts plant surveys in the preserve every three years. The ongoing study suggests the pear trees may be replacing many of the ash trees that were killed by emerald ash borers, another invasive species."In the past, pears would be found along forest edges like along highways. We're now seeing pears invading the center of forests," Culley said. "Once they're established, it's really difficult to remove them. Their roots are deep so you have to cut them and spray them with glyphosate. A lot of land managers simply can't afford to get rid of them."Invasive species are a huge problem around the world. The United States spends more than $260 million fighting aquatic invaders alone, according to the Government Accountability Office. Nearly 1 in 3 species protected under the federal Endangered Species Act are at risk to invasive species, according to the U.S. Fish and Wildlife Service. Competition and predation from invasives is a leading cause of species extinction."A lot of states are concerned about losing the economic benefit of the Callery pear," Culley said. "So how do we reconcile the economic value of the Callery pear and its expense as an invasive?"Ohio's Department of Agriculture is working with nursery growers to phase out the Callery pear in the Buckeye State. Ohio lawmakers in 2018 passed a bill banning the sale or distribution of Callery pears by 2023 to give growers a chance to plant alternatives.Ohio grower Kyle Natorp of Natorp's Nursery in Mason said homeowners have many alternatives to the pear. Fewer customers are asking for pear trees these days, he said."There are dogwoods, crabapples and cherry trees. As a business, we try to grow what the customer wants rather than try to build a market from scratch," Natorp said.His nursery encourages planting a diversity of trees instead of the same kind, which some builders prefer for consistency."They're all the same shape and color and flower. It looks nice but it's not a good horticultural practice," he said. "One disease can take them all out."Culley said foresters should be vigilant about the proliferation of pear trees before they become established."We're warning people in the northern part of the state that they're spreading," she said. "These trees were introduced with the best of intentions. They've sort of gone crazy now and we need to deal with it and learn from our mistakes."
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Extinction
| 2,019 |
June 28, 2019
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https://www.sciencedaily.com/releases/2019/06/190628120432.htm
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When the dinosaurs died, lichens thrived
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When an asteroid smacked into the Earth 66 million years ago, it triggered mass extinctions all over the planet. The most famous victims were the dinosaurs, but early birds, insects, and other life forms took a hit too. The collision caused clouds of ash to block the sun and cool the planet's temperature, devastating plant life. But a new study in
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"We thought that lichens would be affected negatively, but in the three groups we looked at, they seized the chance and diversified rapidly," says Jen-Pang Huang, the paper's first author, a former postdoctoral researcher at the Field Museum now at Academia Sinica in Taipei. "Some lichens grow sophisticated 3D structures like plant leaves, and these ones filled the niches of plants that died out."The researchers got interested in studying the effects of the mass extinction on lichens after reading a paper about how the asteroid strike also caused many species of early birds to go extinct. "I read it on the train, and I thought, 'My god, the poor lichens, they must have suffered too, how can we trace what happened to them?'" says Thorsten Lumbsch, senior author on the study and the Field Museum's curator of lichenized fungi.You've seen lichens a million times, even if you didn't realize it. "Lichens are everywhere," says Huang. "If you go on a walk in the city, the rough spots or gray spots you see on rocks or walls or trees, those are common crust lichens. On the ground, they sometimes look like chewing gum. And if you go into a more pristine forest, you can find orange, yellow, and vivid violet colors -- lichens are really pretty." They're what scientists call "symbiotic organisms" -- they're made up of two different life forms sharing one body and working together. They're a partnership between a fungus and an organism that can perform photosynthesis, making energy from sunlight -- either a tiny algae plant, or a special kind of blue-green bacterium. Fungi, which include mushrooms and molds, are on their own branch on the tree of life, separate from plants and animals (and actually more closely related to us than to plants). The main role of fungi is to break down decomposing material.During the mass extinction 66 million years ago, plants suffered since ash from the asteroid blocked out sunlight and lowered temperatures. But the mass extinction seemed to be a good thing for fungi -- they don't rely on sunlight for food and just need lots of dead stuff, and the fossil record shows an increase in fungal spores at this time. Since lichens contain a plant and a fungus, scientists wondered whether they were affected negatively like a plant or positively like a fungus."We originally expected lichens to be affected in a negative way, since they contain green things that need light," says Huang.To see how lichens were affected by the mass extinction, the scientists had to get creative -- there aren't many fossil lichens from that time frame. But while the researchers didn't have lichen fossils, they did have lots of modern lichen DNA.From observing fungi growing in lab settings, scientists know generally how often genetic mutations show up in fungal DNA -- how frequently a letter in the DNA sequence accidentally gets switched during the DNA copying process. That's called the mutation rate. And if you know the mutation rate, if you compare the DNA sequences of two different species, you can generally extrapolate how long ago they must have had a common ancestor with the same DNA.The researchers fed DNA sequences of three families of lichens into a software program that compared their DNA and figured out what their family tree must look like, including estimates of how long ago it branched into the groups we see today. They bolstered this information with the few lichen fossils they did have, from 100 and 400 million years ago. And the results pointed to a lichen boom after 66 million years ago, at least for some of the leafier lichen families."Some groups don't show a change, so they didn't suffer or benefit from the changes to the environment," says Lumbsch, who in addition to his work on lichens is the Vice President of Science and Education at the Field. "Some lichens went extinct, and the leafy macrolichens filled those niches. I was really happy when I saw that not all the lichens suffered."The results underline how profoundly the natural world we know today was shaped by this mass extinction. "If you could go back 40 million years, the most prominent groups in vegetation, birds, fungi -- they'd be more similar to what you see now than what you'd see 70 million years ago," says Lumbsch. "Most of what we see around us nowadays in nature originated after the dinosaurs."And since this study shows how lichens responded to mass extinction 66 million years ago, it could shed light on how species will respond to the mass extinction the planet is currently undergoing. "Before we lose the world's biodiversity, we should document it, because we don't know when we'll need it," says Huang. "Lichens are environmental indicators -- by simply doing a biodiversity study, we can infer air quality and pollution levels."Beyond the potential implications in understanding environmental impacts and mass extinctions, the researchers point to the ways the study deepens our understanding of the world around us."For me, it's fascinating because you would not be able to do this without large molecular datasets. This would have been impossible ten years ago," says Lumbsch. "It's another piece to the puzzle to understanding what's around us in nature.""We expect a lot of patterns from studying other organisms, but fungi don't follow the pattern. Fungi are weird," says Huang. "They're really unpredictable, really diverse, really fun."This study was contributed to by researchers from the Field Museum, Kasetsart University, Brigham Young University, and Academia Sinica.
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Extinction
| 2,019 |
June 27, 2019
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https://www.sciencedaily.com/releases/2019/06/190627113958.htm
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Some extinct crocs were vegetarians
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Based on careful study of fossilized teeth, scientists Keegan Melstom and Randall Irmis at the Natural History Museum of Utah at the University of Utah have found that multiple ancient groups of crocodyliforms -- the group including living and extinct relatives of crocodiles and alligators -- were not the carnivores we know today, as reported in the journal Current Biology on June 27. In fact, the evidence suggests that a veggie diet arose in the distant cousins of modern crocodylians at least three times.
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"The most interesting thing we discovered was how frequently it seems extinct crocodyliforms ate plants," said Keegan Melstrom, a doctoral student at the University of Utah. "Our study indicates that complexly-shaped teeth, which we infer to indicate herbivory, appear in the extinct relatives of crocodiles at least three times and maybe as many as six."All living crocodylians possess a similar general body shape and ecology to match their lifestyle as semiaquatic generalist carnivores, which includes relatively simple, conical teeth. It was clear from the start of the study that extinct species showed a different pattern, including species with many specializations not seen today. One such specialization is a feature known as heterodonty: regionalized differences in tooth size or shape."Carnivores possess simple teeth whereas herbivores have much more complex teeth," Melstrom explained. "Omnivores, organisms that eat both plant and animal material, fall somewhere in between. Part of my earlier research showed that this pattern holds in living reptiles that have teeth, such as crocodylians and lizards. So these results told us that the basic pattern between diet and teeth is found in both mammals and reptiles, despite very different tooth shapes, and is applicable to extinct reptiles."To infer what those extinct crocodyliforms most likely ate, Melstrom and his graduate advisor, chief curator Randall Irmis, compared the tooth complexity of extinct crocodyliforms to those of living animals using a method originally developed for use in living mammals. Overall, they measured 146 teeth from 16 different species of extinct crocodyliforms.Using a combination of quantitative dental measurements and other morphological features, the researchers reconstructed the diets of those extinct crocodyliforms. The results show that those animals had a wider range of dental complexities and presumed dietary ecologies than had been appreciated previously.Plant-eating crocodyliforms appeared early in the evolutionary history of the group, the researchers conclude, shortly after the end-Triassic mass extinction, and persisted until the end-Cretaceous mass extinction that killed off all dinosaurs except birds. Their analysis suggests that herbivory arose independently a minimum of three times, and possibly six times, in Mesozoic crocodyliforms."Our work demonstrates that extinct crocodyliforms had an incredibly varied diet," Melstrom said. "Some were similar to living crocodylians and were primarily carnivorous, others were omnivores and still others likely specialized in plants. The herbivores lived on different continents at different times, some alongside mammals and mammal relatives, and others did not. This suggests that an herbivorous crocodyliform was successful in a variety of environments!"Melstrom says they are continuing to reconstruct the diets of extinct crocodyliforms, including in fossilized species that are missing teeth. He also wants to understand why the extinct relatives of crocodiles diversified so radically after one mass extinction but not another, and whether dietary ecology could have played a role.This research was supported by the US National Science Foundation, the Welles Fund from the University of California Museum of Paleontology and the University of Utah Department of Geology & Geophysics Chapman Fund.
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Extinction
| 2,019 |
June 26, 2019
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https://www.sciencedaily.com/releases/2019/06/190626171230.htm
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Some corals can survive in acidified ocean conditions, but have lower density skeletons
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Coral reefs face many challenges to their survival, including the global acidification of seawater as a result of rising carbon dioxide levels in the atmosphere. A new study led by scientists at UC Santa Cruz shows that at least three Caribbean coral species can survive and grow under conditions of ocean acidification more severe than those expected to occur during this century, although the density of their skeletons was lower than normal.
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The study took advantage of the unusual seawater chemistry found naturally at sites along the Caribbean coastline of Mexico's Yucatan Peninsula, where water discharging from submarine springs has lower pH than the surrounding seawater, with reduced availability of the carbonate ions corals need to build their calcium carbonate skeletons.In a two-year field experiment, the international team of researchers transplanted genetically identical fragments of three species of corals to a site affected by the springs and to a nearby control site not influenced by the springs, and then monitored the survival, growth rates, and other physiological traits of the transplants. They reported their findings in a paper published June 26 in "The good news is the corals can survive and deposit calcium carbonate, but the density of their skeletons is reduced, which means the framework of the reef would be less robust and might be more susceptible to storm damage and bioerosion," said Adina Paytan, a research professor at UCSC's Institute of Marine Sciences and corresponding author of the paper.Of the three species tested, the one that performed best in the low-pH conditions was Coauthor Donald Potts, professor of ecology and evolutionary biology at UC Santa Cruz, said the transplanted species are all widespread throughout the Caribbean. "The slow-growing, dome-shaped corals tend to be more tolerant of extreme conditions, and they are important in building up the permanent structure of the reef," he said. "We found that they have the potential for persistence in acidified conditions."Corals will have to cope with more than ocean acidification, however. The increasing carbon dioxide level in the atmosphere is also driving climate change, resulting in warmer ocean temperatures and rising sea levels. Unusually warm temperatures can disrupt the symbiosis between coral polyps and the algae that live in them, leading to coral bleaching. And rapidly rising sea levels could leave slow-growing corals at depths where they would die from insufficient sunlight.Nevertheless, Potts noted that several species of Caribbean corals have long fossil records showing that they have persisted through major changes in Earth's history. "These are species with a history of survival and tolerance," he said.He added that both Both of the slow-growing species that did well under acidified conditions have internal fertilization and brood their larvae, so that their offspring have the potential to settle immediately in the same area, Potts said. "This means there is potential for local genetic adaptation over successive generations to changing environmental conditions," he said.The authors also noted that the differences among coral species in survival and calcification under acidified conditions could be useful information for reef restoration efforts and perhaps even for efforts to genetically modify corals to give them greater stress tolerance.Paytan said she remains "cautiously optimistic," despite the many threats facing coral reefs worldwide."These corals are more robust than we thought," she said. "They have the potential to persist with ocean acidification, but it costs them energy to cope with it, so we have to do all we can to reduce other stressors, such as nutrient pollution and sedimentation."Paytan and Potts said the collaboration with Mexican researchers was essential to the success of the project, enabling frequent monitoring of the transplanted corals throughout the two-year experiment.
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June 26, 2019
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https://www.sciencedaily.com/releases/2019/06/190626160341.htm
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A new normal: Study explains universal pattern in fossil record
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Throughout life's history on earth, biological diversity has gone through ebbs and flows -- periods of rapid evolution and of dramatic extinctions. We know this, at least in part, through the fossil record of marine invertebrates left behind since the Cambrian period. Remarkably, extreme events of diversification and extinction happen more frequently than a typical, Gaussian, distribution would predict. Instead of the typical bell-shaped curve, the fossil record shows a fat-tailed distribution, with extreme, outlier, events occurring with higher-than-expected probability.
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While scientists have long known about this unusual pattern in the fossil record, they have struggled to explain it. Many random processes that occur over a long time with large sample sizes, from processes that produce school grades to height among a population, converge on the common Gaussian distribution. "It's a very reasonable default expectation," says Santa Fe Institute Omidyar Fellow Andy Rominger. So why doesn't the fossil record display this common pattern?In a new paper published in "Within a lineage of closely related organisms, there should be a conserved evolutionary dynamic. Between different lineages, that dynamic can change," says Rominger. That is, within clades, related organisms tend to find an effective adaptive strategy and never stray too far. But between these clade-specific fitness peaks are valleys of metaphorically uninhabited space. "It turns out, just invoking that simple idea, with some very simple mathematics, described the patterns in the fossil record very well."These simple mathematics are tools that Fuentes, in 2009, used to describe another system with an unusual fat-tailed distribution: the stock market. By using superstatistics -- an approach from thermodynamics to describe turbulent flow -- Fuentes could accurately describe the hard-to-predict dramatic crashes and explosions in value."In biology, we see these crashes and explosions too, in terms of biodiversity," says Rominger. "We wondered if Fuentes' elegant approach could also describe the evolutionary dynamics we see in the fossil record."The team writes that their success opens up new research directions to better understand the evolutionary processes that lead to both stable rates of extinction and speciation at the order- and family-levels of life, and to interruptions that allow for new life forms to emerge.
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Extinction
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June 26, 2019
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https://www.sciencedaily.com/releases/2019/06/190626133816.htm
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Former war refugee maps habitat for West African bird
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Growing up in Liberia during that country's brutal 14-year civil war, Benedictus Freeman and his family fled into the rainforest, where they survived for years eating bush meat and foraging. The rainforest provided Freeman sustenance and protection -- but more than that, the experience ignited a passion in him for understanding and preserving nature.
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"At that time, I really didn't know how important the forest would become for me -- I saw the forest as a source of resources like food and shelter," said Freeman, who today is a doctoral student in ecology & evolutionary biology at the University of Kansas and KU Biodiversity Institute. "But I developed an interest in nature there, and eventually I started studying forestry for my undergraduate degree. That actually influenced my decision to get more interested in nature and conservation."The rainforests that once protected Freeman and his family host one of West Africa's flagship bird species -- the White‐breasted Guineafowl (Agelastes meleagrides). Now, Freeman is lead author of a new paper in the peer-reviewed journal Avian Research that projects the geographic distribution of the bird through 2050 as it shifts habitat due to climate change."This bird is endemic to West Africa, but it's not fully understood -- it's poorly studied," Freeman said. "Because of this poor history, there's very little understanding about its range. Our study recharacterizes its distribution and helps us to understand to what extent it's distributed across the region. The bird is threatened, and it's of conservation concern. So that's why it was selected for study."According to Freeman, the vulnerable White-breasted Guineafowl, which has appeared on Liberian postage stamps, serves as an iconic "flagship species," conservation of which could preserve habitat of many lesser-known animals at the same time.The KU researcher said West Africa suffers from extensive deforestation due to increasing populations, urbanization, agriculture expansion (both substance farming and industrial-scale farming of palm oil), logging and mining. Because of its exclusive dependence on the forest for habitat, the White-breasted Guineafowl is particularly susceptible to habitat loss."It occurs within rainforest habitats in West Africa where it feeds like regular birds, like chickens feed, and depends on insects and seeds and things," Freeman said. "The important thing about this bird is that it's a specialist -- it's more restricted to rainforest habitats. There is a sister species (Black Guineafowl, Agelastes niger) of the same bird that occurs on the other side of the Guinean forest, but this one is range-restricted, and it's only found in this region. It's not going to be found anywhere else in the world."Freeman hopes his research predicting the distribution of the bird in coming decades can help inform policymakers about which areas of rainforest should be prioritized for conservation.For the new paper, Freeman and his colleagues -- Daniel Jiménez‐García of Benemérita Universidad Autónoma de Puebla in Mexico, Benjamin Barca of the Royal Society for the Protection of Birds in Sierra Leone and Matthew Grainger of Newcastle University in the United Kingdom -- used occurrence data from the Global Biodiversity Information Facility and datasets about occurrences of the White-breasted Guineafowl in Sapo National Park in Liberia and Gola Rainforest National Park in Sierra Leone, including data collected by Freeman.The authors used environmental datasets from NASA and other open sources to perform ecological niche modeling, which the researchers said "integrates known occurrences of species and environmental variables (e.g., temperature, precipitation) to characterize potential future geographic distributions of species in response to global climate change."The team created maps showing current and likely future habitats where the White‐breasted Guineafowl could migrate in response to a shifting climate. Unexpectedly, there was good news for the iconic bird in the findings: "The projected impacts of climate change on the geographic distribution of White-breasted Guineafowl were minimal, suggesting stability across the species' range for the present and in the future, at least as regards climate change effects," researchers said. "Low sensitivity to climate change in this species does match the general observation for West African birds."However, the team found coastal areas where the White‐breasted Guineafowl is found today would be degraded by sea-level rise and resulting coastal erosion, destroying some of the species' range.As for Freeman, this summer he's back in Liberia conducting more fieldwork on birds in some of the same areas his team found to be suitable for the White-breasted Guineafowl."We were pleased to document populations at the sites where we worked, and then we were able to collect data on other bird species," he said. "We have some interesting records that might be species not yet known to science, but we need to do some detailed studies."Freeman aims to finish his doctorate at KU next year, he said. After that, he'll look for opportunities for postdoctoral work."I don't know exactly where that's going to be," he said. "But I'm hoping that wherever I get a good job, I can have an opportunity to work in West Africa to do more research. There's a huge capacity gap in that area. There's a need to have homegrown scientists involved with this kind of research specifically. So, my passion is to work there."
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Extinction
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June 25, 2019
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https://www.sciencedaily.com/releases/2019/06/190625173438.htm
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Pine woodland restoration creates haven for birds in Midwest
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Millions of acres of pine woodlands once covered a large portion of the Midwest. But as humans logged these trees and suppressed natural fires, the woodlands gave way to dense forests with thick leaf litter and tree species that were less fire-resistant, leading to more intense and unpredictable fires as well as the loss of native bird habitats.
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Now, researchers from the University of Missouri have shown in a new study that restoration of pine woodlands, through the combined use of intentional, managed fires and strategic thinning of tree density, has a strikingly beneficial effect on a diverse array of birds, some of which are facing sharp declines from human-driven impacts like climate change and habitat loss."Some people might hear the words 'fire' and 'thinning' and immediately imagine charred, flattened wastelands, but that isn't the reality," said Melissa Roach, now a researcher with the U.S. Geological Survey's Bird Banding Lab who carried out the study while completing her master's degree at MU. "Researchers are using these management techniques to restore beautiful open woodlands. In this study, we found that birds that have been struggling elsewhere are positively thriving in these restored areas."Frank Thompson, a wildlife biologist with the USDA Forest Service and cooperative professor at MU's College of Agriculture, Food and Natural Resources with more than two decades of experience studying Midwestern bird populations, worked with Roach to survey 16 bird species in varying degrees of pine woodland density. These woodlands were located in parts of Missouri, Arkansas and Oklahoma in the Ozark-Ouachita Mountain Complex. Unlike most studies, Roach returned to the same locations three years in a row to monitor the bird populations over time.The researchers found that the restored pine woodland created an open canopy and a lush ground layer, and was ideal for allowing a balance between species that prefer less tree density and canopy cover with those that prefer more. Several of the birds that were observed thriving in this habitat are in decline elsewhere, including the Red-headed Woodpecker and the Prairie Warbler. Only five species were impacted negatively by restoration, but these remain abundant in the untreated forests that still dominate the Midwest.Researchers also isolated two management practices--controlled fires and tree thinning--to determine their individual effects on bird abundance. Eight of the 16 species of birds, including the Red-headed Woodpecker, were more numerous in areas with a history of fires, while four species benefitted from thinning. Taken together, Thompson said the results suggest that restoring pine woodlands in conjunction with prescribed fires and tree thinning can create suitable habitats for a wide range of birds."Our study shows that restoration using fire and tree-thinning leaves large, widely-spaced trees for canopy-nesting species while allowing the development of grasses and shrubs for ground or shrub-nesting species," Thompson said. "Given that we took care to survey birds with diverse breeding requirements, we can see that restored pine woodlands can support many different birds with different needs, whether they nest on the ground, in shrubs or high in the canopies of mature trees. This is a powerful testament to the need to continue restoring these woodlands, which are also rich in plant diversity and likely more sustainable in many cases than closed forests under climate change."
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Extinction
| 2,019 |
June 19, 2019
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https://www.sciencedaily.com/releases/2019/06/190619174533.htm
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Deep submersible dives shed light on rarely explored coral reefs
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Just beyond where conventional scuba divers can go is an area of the ocean that still is largely unexplored. In waters this deep -- about 100 to at least 500 feet below the surface -- little to no light breaks through.
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Researchers must rely on submersible watercraft or sophisticated diving equipment to be able to study ocean life at these depths, known as the mesophotic zone. These deep areas span the world's oceans and are home to extensive coral reef communities, though little is known about them because it is so hard to get there.A collaborative research team from the University of Washington, College of Charleston, University of California Berkeley, University of Hawaii and other institutions has explored the largest known coral reef in the mesophotic zone, located in the Hawaiian Archipelago, through a series of submersible dives. There, they documented life along the coral reef, finding a surprising amount of coral living in areas where light levels are less than 1% of the light available at the surface.Their findings were published April 8 in the journal "Because mesophotic corals live close to the limits of what is possible, understanding their physiology will give us clues of the extraordinary strategies corals use to adapt to low-light environments," said lead author Jacqueline Padilla-Gamiño, an assistant professor in the UW School of Aquatic and Fishery Sciences.Knowing how these deep coral reefs function is important because they appear to be hotspots for biodiversity, and home to many species found only in those locations, Padilla-Gamiño explained. Additionally, close to half of all corals in the ocean have died in the past 30 years, mostly due to warm water temperatures that stress their bodies, causing them to bleach and eventually die. This has been documented mostly in shallower reefs where more research has occurred. Scientists say that more information about deeper reefs in the mesophotic zone is critical for preserving that habitat."Mesophotic reefs in Hawaii are stunning in their sheer size and abundance," said co-author Heather Spalding at College of Charleston. "Although mesophotic environments are not easily seen, they are still potentially impacted by underwater development, such as cabling and anchoring, and need to be protected for future generations. We are on the tip of the iceberg in terms of understanding what makes these astounding reefs tick."Padilla-Gamiño was on board during two of the team's eight submersible dives off the coast of Maui that took place from 2000 to 2011. Each dive was a harrowing adventure: Researchers spent up to eight hours in cramped quarters in the submersible that was tossed from the back of a larger boat, then disconnected once the submersible reached the water.Once in the mesophotic zone, they collected specimens using a robot arm, and captured video footage and photos of life that has rarely been seen by humans."It's a really unbelievable place," Padilla-Gamiño said. "What is surprising is that, in theory, these corals should not be there because there's so little light. Now we're finally understanding how they function to be able to live there."By collecting coral samples and analyzing their physiology, the researchers found that different corals in the mesophotic zone use different strategies to deal with low amounts of light. For example, some species of corals change the amount of pigments at deeper depths, while other species change the type and size of symbionts, which are microscopic seaweeds living inside the tissue of corals, Padilla-Gamiño explained. These changes allow corals to acquire and maximize the light available to perform photosynthesis and obtain energy.Additionally, the corals at deeper depths are likely eating other organisms like zooplankton to increase their energy intake and survive under very low light levels. They probably do this by filter feeding, Padilla-Gamiño said, but more research is needed to know for sure.The researchers hope to collect more live coral samples from the mesophotic zone to be able to study in the lab how the symbionts, and the corals they live inside, function."The more we can study this, the more information we can have about how life works. This is a remarkable system with enormous potential for discovery," Padilla-Gamiño said. "Our studies provide the foundation to explore physiological ?exibility, identify novel mechanisms to acquire light and challenge current paradigms on the limitations of photosynthetic organisms like corals living in deeper water."Other co-authors are Celia Smith at University of Hawaii at M?noa; Melissa Roth at UC Berkeley; Lisa Rodrigues at Villanova University; Christina Bradley at Salisbury University; and Robert Bidigare and Ruth Gates at Hawaii Institute of Marine Biology.The study was funded by the National Oceanic and Atmospheric Administration and the National Science Foundation.
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Extinction
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June 19, 2019
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https://www.sciencedaily.com/releases/2019/06/190619130251.htm
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Investigating coral and algal 'matchmaking' at the cellular level
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What factors govern algae's success as "tenants" of their coral hosts both under optimal conditions and when oceanic temperatures rise? A Victoria University of Wellington-led team of experts that includes Carnegie's Arthur Grossman investigates this question.
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Corals are marine invertebrates that build large exoskeletons from which colorful reefs are constructed. But this reef-building is only possible because of a mutually beneficial relationship between the coral and various species of single-celled algae called dinoflagellates that live inside the cells of coral polyps.These algae are photosynthetic, which means that like plants they can convert the Sun's energy into chemical energy in the form of food. Many of the photosynthetically derived nutrients synthesized by an alga serve as food for its coral host, while the host in turn provides the alga with essential inorganic nutrients, including carbon dioxide, nitrogen in the form of ammonium, and phosphate. However, ocean warming due to climate change is causing many corals to lose their native algal tenants -- along with the nutrients that they provide -- a phenomenon called bleaching. If the bleached coral is not recolonized with new algal tenants, it can die.Some species of the dinoflagellate algae form these symbiotic relationships with multiple types of coral, others are more specific."We're interested in understanding the cellular processes that maintain those preferential relationships," Grossman said. "We also want to know if it's possible that more heat tolerant, non-preferred algae could revive bleached coral communities even if the relationship is less efficient."Other organisms such as sea anemones are part of the same phylum as coral, called cnidaria; they also host algae but are easier to study. In this paper -- published by "In this study we hoped to elucidate proteins that function to improve nutrient exchange between the anemone and its native algae and why the anemone's success is compromised when it hosts the non-native heat resistant algae," Grossman said.The team found that anemones colonized by native algae expressed elevated levels of proteins associated with the metabolism of organic nitrogen and lipids -- nutrients that can be efficiently synthesized as a consequence of the algae's photosynthetic activity. These anemones also synthesized a protein called NPC2-d which is thought to be key to cnidarian's ability to take up the algae and recognize it as a symbiotic partner.In contrast, anemones with the non-native tenant expressed proteins associated with stress, which likely reflects less optimal integration of the metabolisms of the two organisms."Our findings open doors to future studies to identify key proteins and cellular mechanisms involved in maintaining a robust relationship between the alga and its cnidarian host and the ways in which the metabolism of the organisms are integrated," Grossman concluded.
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Extinction
| 2,019 |
June 18, 2019
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https://www.sciencedaily.com/releases/2019/06/190618070807.htm
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Coral bleaching causes a permanent change in fish life
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Repeat coral bleaching caused by rising sea temperatures has resulted in lasting changes to fish communities, according to a new long-term study in the Seychelles.
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Large predator fish such as snappers and very small fish such as damselfish dramatically reduced in number and were largely replaced by seaweed-loving fish like rabbitfish.Publishing in the journal While some of the coral reefs surveyed, bounced back and recovered following the bleaching event, other reefs shifted to fields of seaweeds.Changes in fish communities were most apparent on these seaweed dominated reefs, but the 'herbivore' fish that feed on seaweeds became a dominant part of the community on all the reefs in the study.Researchers believe these same changes are likely to be found in similarly damaged reefs around the world and could be described as the 'new normal' state for post bleached reefs.The Lancaster University-led research tracked reef recovery in the Seychelles for 16 years, before another major coral-bleaching event impacted the reefs in 2016. Despite the length of time between these two major coral bleaching events, fish populations failed to recover to their pre-bleaching condition.Where previously there were greater numbers of large predator fish such as snappers and groupers and also a large amount of very small fish such as damselfish and butterflyfish, after bleaching a new community, dominated by algal-feeding parrotfish and rabbitfish and invertebrate-feeding fish such as emperors and wrasses, has taken over.These changes occurred because the fish's habitat structure -- corals -- collapsed. Where corals did not recover and seaweeds took over the space, the number and composition of fish changed substantially.Surprisingly, even on the reefs where the corals gradually recovered between the bleaching events, the number of fish species recovered, but did not return to their original species composition.Other studies have shown that the time between bleaching periods is now reducing, and is typically less than 10 years. In this study the time frame from the 1998 coral bleaching event to the next major one was longer -18 years -- yet the fish communities were still unable to recover. This leads researchers to conclude other reefs will suffer similar shifts, especially given bleaching events are becoming more frequent.Dr James Robinson, of Lancaster University, the lead author of the study, said: "Although the 18-year period between major mass bleaching events allowed corals to recover on some reefs, we found evidence that fish populations were not able to return to their pre-bleaching levels, and they were substantially altered on the reefs that become dominated by seaweeds. The Seychelles case study suggests under current levels of ocean warming -- where the average frequency of bleaching events is less than 10 years -- permanent changes to reef fishes are likely on most coral reefs globally."Professor Nick Graham, of Lancaster University, added: "The new normal for coral reefs will be reef fish communities which have fewer species and are dominated by herbivores and invertebrate feeding fish. This will alter the way coral reefs function, and the fishery opportunities for coastal communities adjacent to coral reefs."
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Extinction
| 2,019 |
June 14, 2019
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https://www.sciencedaily.com/releases/2019/06/190614125846.htm
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A shady spot may protect species against rapid climate warming
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Finding a shady refuge to cool off on a hot day could be more than a lifesaver in a warming world. It might save several species that would otherwise go extinct due to global warming, according to an analysis by ecologists at a dozen institutions.
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"Animals are not passive, and there's plenty of evidence that some of them will seek out shade to regulate their body temperature," said Rice University ecologist Volker Rudolf, co-author of a study in Global Change Biology that examined both the behavior and habitats of 39 species. "The big question, for ecologists, is whether we can create a predictive framework that uses what we already know about species' behaviors and habitats to predict whether this behavior might buffer them from rapid climate change and potentially rescue them from otherwise going extinct."Rudolf said he and his colleagues, including study co-lead authors Samuel Fey of Reed College and David Vasseur of Yale University, set out to create such a framework, in part because a number of high-profile studies have ignored behavior in making predictions about the possible impacts of climate warming.Scientists have examined the impact of temperature on the fitness of many species. To control for external factors, almost all such tests are performed in a laboratory, where temperature can be increased while all other factors remain constant, said Rudolf, a professor in Rice's Department of BioSciences. The overall health, or fitness, of individuals often falls off as temperatures increase, especially in insects and other ectothermic animals whose bodies don't self-regulate temperature."Behavior allows for self-regulation of body temperature, even in some cases where physiology doesn't," Rudolf said. "So ignoring this behavior means you're probably making wrong predictions."But behavior only goes so far. If a creature lives where there is no shade or other means to cool off, it's obviously not an option. It may also be impractical, especially if getting to the shady spot requires an enormous expenditure of energy.To examine the consequences of this behavior across a wide range of animals, the scientists created a mathematical framework that accounts for variability in microclimate in the habitat of a species to estimate the cost-benefit trade-off an individual faces when expending energy to seek shade. The framework was first verified on tests with the southern rock agama, a lizard native to South Africa, and was later applied to a database of 38 insect species from Europe, Asia, North America, Africa and Australia.Using International Panel on Climate Change temperature projections for the year 2050, the researchers found that 19 of the insects were likely to be negatively impacted by warming temperatures. They further found that behavior would likely mitigate the ill effects of warming for 17 of the 19 species, including six that were predicted to experience "behavioral rescue," a situation where behavioral adaptation keeps the species from going extinct. In fact, warmer temperatures, in conjunction with behavioral adaptation, were predicted to increase fitness for 10 species."With climate change already increasing temperatures worldwide, it is important to find ways to forecast how this will affect individual species as well as tightly couple ecological communities," Rudolf said.In addition to looking at the direct effects of temperature on one species, he said it will be important for ecologists to consider how rising temperatures will affect a species' predators, competitors and food resources, including prey. Where looking at temperature alone might suggest a species will do better or worse, those predictions could change based on the impacts on closely coupled species.Additional co-authors include Karla Alujević and Susana Clusella-Trullas of Stellenbosch University in South Africa; Kristy Kroeker of the University of California, Santa Cruz; Michael Logan of the University of Nevada, Reno, and the Smithsonian Tropical Research Institution in Panama; Mary O'Connor of the University of British Columbia; John DeLong of the University of Nebraska; Scott Peacor of Michigan State University; Rebecca Selden of Rutgers University; and Andy Sih of the University of California, Davis. The research was supported by CapeNature and initiated by conversations at the 2016 Gordon Research Conference on Predator-Prey Interactions.
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Extinction
| 2,019 |
June 13, 2019
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https://www.sciencedaily.com/releases/2019/06/190613143520.htm
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Migratory hoverflies 'key' as many insects decline
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Migratory hoverflies are "key" to pollination and controlling crop pests amid the decline of many other insect species, new research shows.
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University of Exeter scientists studied the movements of migratory hoverflies and were surprised to find up to four billion migrate to and from Britain each year.The study shows these numbers have been relatively stable over the last decade, and such abundance means migratory hoverflies pollinate many billions of flowers and produce larvae that eat up to ten trillion aphids.Recent research has suggested more than 40% of insect species worldwide are "threatened with extinction," creating a major threat to "ecosystem services" (benefits to humans from the natural environment, such as pollination of crops)."The number of migrating hoverflies coming and going over Britain was much higher than we had expected," said Dr Karl Wotton, Royal Society research fellow at the University of Exeter."They are widely considered to be the second most important pollinators, after bees."They are especially important pollinators of wildflowers, soft fruits and brassica crops, and their larvae prey on various species of aphids -- which are the key crop pest in Europe."This dual role makes them uniquely beneficial to humans."Migrating hoverflies arrive in Britain in spring and, with a month-long life cycle, those that leave are descendants of the spring arrivals."We are net exporters of hoverflies," said Dr Jason Chapman, of the Centre for Ecology and Conservation on the University of Exeter's Penryn Campus in Cornwall."Each female can lay up to 400 eggs and, though many die as eggs or larvae, the departing population in autumn is larger than that arriving in spring."As well as their vital pollinating and aphid-eating roles, migrating hoverflies provide food for a range of predators including birds."The study, supported by colleagues at Nanjing Agricultural University, Rothamsted Research, the University of Greenwich and the Max Planck Institute, used radar data on insects flying between 150m and 1km above the ground.The hoverflies wait for favourable winds before migrating between Britain and mainland Europe.Dr Chapman added: "Migrating insects are generally bucking the trend of decline that we're seeing with many other insects."Their mobility is probably a key part of this, as it allows them to move on to find the best habitats."Hoverflies are also generalists -- the adults feed on many kinds of pollen and the larvae eat many aphid species."Considering that many beneficial insects are seriously declining, our results demonstrate that migrant hoverflies are key to maintaining essential ecosystem services."
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Extinction
| 2,019 |
June 12, 2019
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https://www.sciencedaily.com/releases/2019/06/190612141356.htm
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Protecting coral reefs in a deteriorating environment
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Coral reefs around the world face growing danger from a changing climate, on top of the historic threats from local pollution and habitat destruction. In response, scientists are researching new interventions that have the potential to slow coral reef damage from warming and acidifying oceans. The interventions span a wide range of physical and biological approaches for increasing the stability of coral reefs, but they have only been tested at small scales.
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A new report from the National Academies of Sciences, Engineering, and Medicine examines these resilience tools and provides decision-makers with a process they can follow in considering whether to use one or more of the novel approaches.Many of the new interventions seek to amplify natural resilience, such as laboratory breeding of corals that show greater heat resistance. Other methods, some merely on the horizon such as genetic manipulation of corals, might one day introduce new levels of stress tolerance. Ultimately, all interventions alter the reef in some way. These changes will result in benefits that differ across sites, and they may have varying unintended consequences -- meaning that the risks and benefits need to be weighed locally, the report says."Maintaining the stability of coral reefs in the face of local and climate stressors is a key goal for supporting human well-being around the world," said Stephen Palumbi, chair of the 12-member committee that wrote the report, and Jane and Marshall Steel Jr. Professor in Marine Sciences at Stanford University. "Many new interventions have promise for these efforts, but they differ widely in their readiness levels, and implementing them will require careful attention to regional contexts."Since the 1980s, tropical coral reef coverage around the world has declined by about 30% to 50%. Pollution, habitat destruction, and overfishing have long been among the culprits in many places, but increasingly, coral reef loss can be attributed to a changing climate. Rising water temperatures are increasing the frequency of mass bleaching events and are making disease outbreaks more common. And as ocean waters become more acidic from absorbing carbon dioxide, it will become harder for corals to grow and maintain their skeletons.Coral reefs' destruction has serious human costs, because many coastal communities depend on local reefs for fishing and tourism. Coral reefs also absorb energy from the waves that pass over them, buffering shore communities against destructive storms.In response to these threats, researchers are developing new ways to improve corals' persistence in a changing climate -- 23 of which were described in the first report released by the committee last November.The committee's new, final report includes an assessment of the technical readiness of various interventions. Some are possible to use now -- for example, pre-exposing corals to mild warming in order to improve their tolerance of greater heat levels. With more research and testing, others may be available for use in the next two to five years, such as using antibiotics to treat disease, mixing cool water into reef habitats, or shading corals from sunlight and heat. Still other proposed interventions -- for example, using tools such as CRISPR/Cas9 to genetically manipulate corals to make them more threat-resistant -- need significantly more research and development, and are at least a decade away."Though all of these interventions entail some risk, the risk from doing nothing is increasing year by year," said committee member Nancy Knowlton, former holder of the Sant Chair in Marine Science at the Smithsonian Institution.Whether a specific intervention (or a combination of interventions) is suitable depends not just on its technical readiness, but on each particular ecological and social setting, the report stresses. Local factors such as the level of reef degradation, the quality of the water, and the resources and infrastructure available will determine if an intervention is needed or beneficial.Equally important is whether the intervention is acceptable to a community, the report says. Throughout the decision-making process, it is important to engage a broad set of stakeholders -- both to establish objectives and to choose a course of action that reflects community values. "Stakeholder engagement enables choosing interventions with expected outcomes that align with the goals of the community," said committee member Marissa Baskett, professor of environmental science and policy at the University of California, Davis.The report also recommends that coral reef managers follow an "adaptive management" approach in making decisions about interventions -- an approach that recognizes uncertainty and incorporates learning to adjust and improve strategies over time. "The science of coral reef interventions is still young, and particular environments may respond to them in different ways. So using a structured and adaptive decision-making approach allows managers to make decisions even when there is uncertainty," said Palumbi.The first step of the adaptive management cycle is setting goals and objectives along with stakeholders, against which interventions' effects can be compared, and outlining acceptable courses of action. Locally-tailored models of coral reef dynamics, and how they change with different interventions, are a necessary tool to evaluate and compare the impact of different intervention strategies on coral reef outcomes. Developing a successful modeling framework requires substantial effort, the report concludes, but it pays off in the ability to assess the risks of new interventions compared to the risks posed by taking no action.As strategies are implemented, efforts must be invested in monitoring the effects of interventions to increase knowledge about their impacts, evaluating their results, and communicating with stakeholders. Based on the observed effects, managers can then continue or alter their approach as needed.The ability to make informed decisions and effectively implement novel interventions could be improved if remaining gaps in research -- both on the interventions and on corals themselves -- were filled, the report says. It identifies priority areas for research in basic coral biology, site-based assessments, improvement of interventions, and improvements in risk assessment and modeling. Increasing the ease of use and scale of use of different interventions, so communities have a larger toolbox to choose from, are important research goals."We must also grapple with and solve the key problem of greenhouse gas emissions," Palumbi said. "But the wealth of intervention options gives us some hope that we can help coral reefs successfully survive the next century as diverse, productive, and beautiful places in the sea."Report:
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Extinction
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June 12, 2019
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https://www.sciencedaily.com/releases/2019/06/190612092945.htm
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Baby pterodactyls could fly from birth
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A breakthrough discovery has found that pterodactyls, extinct flying reptiles also known as pterosaurs, had a remarkable ability -- they could fly from birth. This discovery's importance is highlighted by the fact that no other living vertebrates today, or in the history of life as we know it, have been able to replicate this. This revelation has a profound impact on our understanding of how pterodactyls lived, which is critical to understanding how the dinosaur world worked as a whole.
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Previously, pterodactyls were thought to only be able to take to the air once they had grown to almost full size, just like birds or bats. This assumption was based on fossilised embryos of the creatures found in China that had poorly developed wings.However, Dr David Unwin, a University of Leicester palaeobiologist who specialises in the study of pterodactyls and Dr Charles Deeming, a University of Lincoln zoologist who researches avian and reptilian reproduction, were able to disprove this hypothesis. They compared these embryos with data on prenatal growth in birds and crocodiles, finding that they were still at an early stage of development and a long way from hatching. The discovery of more advanced embryos in China and Argentina that died just before they hatched provided the evidence that pterodactyls had the ability to fly from birth. Dr David Unwin said: "Theoretically what pterosaurs did, growing and flying, is impossible, but they didn't know this, so they did it anyway."Another fundamental difference between baby pterodactyls, also known as flaplings, and baby birds or bats, is that they had no parental care and had to feed and look after themselves from birth. Their ability to fly gave them a lifesaving survival mechanism which they used to evade carnivorous dinosaurs. This ability also proved to be one of their biggest killers, as the demanding and dangerous process of flight led to many of them dying at a very early age.The research has also challenged the current view that pterodactyls behaved in a similar way to birds and bats and has provided possible answers to some key questions surrounding these animals. Since flaplings were able to both fly and grow from birth, this provides a possible explanation as to why they were able to reach enormous wingspans, far larger than any historic or current species of bird or bat. How they were able to carry out this process will require further research, but it is a question that wouldn't have been posed without these recent developments in our understanding.Dr Deeming added: "Our technique shows that pterosaurs were different from birds and bats and so comparative anatomy can reveal novel developmental modes in extinct species."
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Extinction
| 2,019 |
June 12, 2019
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https://www.sciencedaily.com/releases/2019/06/190612084337.htm
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Why Noah's Ark won't work
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A Noah's Ark strategy will fail. In the roughest sense, that's the conclusion of a first-of-its-kind study that illuminates which marine species may have the ability to survive in a world where temperatures are rising and oceans are becoming acidic.
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Two-by-two, or even moderately sized, remnants may have little chance to persist on a climate-changed planet. Instead, for many species, "we'll need large populations," says Melissa Pespeni a biologist at the University of Vermont who led the new research examining how hundreds of thousands of sea urchin larvae responded to experiments where their seawater was made either moderately or extremely acidic.The study was published on June 11, 2019, in the Pespeni and her team were surprised to discover that rare variation in the DNA of a small minority of the urchins were highly useful for survival. These rare genetic variants are "a bit like having one winter coat among fifty lightweight jackets when the weather hits twenty below in Vermont," Pespeni says. "It's that coat that lets you survive." When the water conditions were made extremely acidic, these rare variants increased in frequency in the larvae. These are the genes that let the next generation of urchins alter how various proteins function--like the ones they use to make their hard-but-easily-dissolved shells and manage the acidity in their cells.But to maintain these rare variants in the population--plus other needed genetic variation that is more common and allows for response to a range of acid levels in the water--requires many individuals."The bigger the population, the more rare variation you'll have," says Reid Brennan, a post-doctoral researcher in Pespeni's UVM lab and lead author on the new study. "If we reduce population sizes, then we're going to have less fodder for evolution--and less chance to have the rare genetic variation that might be beneficial."In other words, some organisms might persist in a climate-changed world because they're able to change their physiology--think of sweating more; some will be able to migrate, perhaps farther north or upslope. But for many others, their only hope is to evolve--rescued by the potential for change that lies waiting in rare stretches of DNA.The purple sea urchins the UVM team studied in their Vermont lab are part of natural populations that stretch from Baja, California to Alaska. Found in rocky reefs and kelp forests, these prickly creatures are a favorite snack of sea otters--and a key species in shaping life in the intertidal and subtidal zones. Because of their huge numbers, geographic range, and the varying conditions they live in, the urchins have high "standing genetic variation," the scientists note. This makes purple urchins likely survivors in the harsh future of an acidified ocean--and good candidates for understanding how marine creatures may adapt to rapidly changing conditions.It is well understood that rising average global temperatures are a fundamental driver of the imminent extinction faced by a million or more species--as a recent UN biodiversity report notes. But it's not just rising averages that matter. It may be the hottest--or most acidic--moments that test an organism's limits and control its survival. And, as the UVM team writes, "the genetic mechanisms that allow rapid adaptation to extreme conditions have been rarely explored."The new study used an innovative "single-generation selection" experiment that began with twenty-five wild-caught adult urchins. Each female produced about 200,000 eggs from which the scientists were able extract DNA out of pools of about 20,000 surviving larvae that were living in differing water conditions. This very large number of individuals gave the scientists a clear view that purple urchins possess a genetic heritage that lets them adapt to extremely acidic ocean water. "This species of sea urchin is going to be okay in the short term. They can respond to these low pH conditions and have the needed genetic variation to evolve," says UVM's Reid Brennan. "So long as we do our part to protect their habitats and keep their populations large."But coming through the ferocious challenge of rapid climate change may come at a high cost. "It's hopeful that evolution happens--and it's surprising and exciting that these rare variants play such a powerful role," says Melissa Pespeni, an assistant professor in UVM's biology department and expert on ocean ecosystems. "This discovery has important implications for long-term species persistence. These rare variants are a kind of currency that urchins have to spend," she says. "But they can only spend it once."
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Extinction
| 2,019 |
June 10, 2019
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https://www.sciencedaily.com/releases/2019/06/190610151740.htm
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Past climate change pushed birds from the northern hemisphere to the tropics
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Researchers have shown how millions of years of climate change affected the range and habitat of modern birds, suggesting that many groups of tropical birds may be relatively recent arrivals in their equatorial homes.
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The researchers, from the Universities of Cambridge and Oxford, applied climate and ecological modelling to illustrate how the distribution of major bird groups is linked to climate change over millions of years. However, while past climate change often occurred slowly enough to allow species to adapt or shift habitats, current rates of climate change may be too fast for many species, putting them at risk of extinction. The results are reported in "Palaeontologists have documented long-term links between climate and the geographic distributions of major bird groups, but the computer models needed to quantify this link had not been applied to this question until now," said Dr Daniel Field from Cambridge's Department of Earth Sciences, the paper's co-lead author.For the current study, the researchers looked at ten bird groups currently limited to the tropics, predominantly in areas that were once part of the ancient supercontinent of Gondwana (Africa, South America and Australasia). However, early fossil representatives of each of these groups have been found on northern continents, well outside their current ranges.For example, one such group, the turacos ('banana eaters') are fruit-eating birds which are only found in the forests and savannahs of sub-Saharan Africa, but fossils of an early turaco relative have been found in modern-day Wyoming, in the northern United States.Today, Wyoming is much too cold for turacos for most of the year, but during the early Palaeogene period, which began with the extinction of non-avian dinosaurs 66 million years ago, the Earth was much warmer. Over time, global climates have cooled considerably, and the ancestors of modern turacos gradually shifted their range to more suitable areas."We modelled the habitable area for each group of birds and found that their estimated habitable ranges in the past were very different from their geographic distributions today, in all cases shifting towards the equator over geological time," said Dr Erin Saupe from the University of Oxford, the paper's other lead author.Saupe, Field and their collaborators mapped information such as average temperature and rainfall and linked it to where each of the bird groups is found today. They used this climatic information to build an 'ecological niche model' to map suitable and unsuitable regions for each bird group. They then projected these ecological niche models onto palaeoclimate reconstructions to map potentially-suitable habitats over millions of years.The researchers were able to predict the geographic occurrences of fossil representatives of these groups at different points in Earth's history. These fossils provide direct evidence that these groups were formerly distributed in very different parts of the world to where they are presently found."We've illustrated the extent to which suitable climate has dictated where these groups of animals were in the past, and where they are now," said Field. "Depending on the predictions of climate change forecasts, this approach may also allow us to estimate where they might end up in the future.""Many of these groups don't contain a large number of living species, but each lineage represents millions of years of unique evolutionary history," said Saupe. "In the past, climate change happened slowly enough that groups were able to track suitable habitats as these moved around the globe, but now that climate change is occurring at a much faster rate, it could lead to entire branches of the tree of life going extinct in the near future."The research was funded in part by the Natural Environment Research Council (NERC).
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Extinction
| 2,019 |
June 10, 2019
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https://www.sciencedaily.com/releases/2019/06/190610111459.htm
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2019 'Dead Zone' may be the second largest on record
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A recent forecast of the size of the "Dead Zone" in the northern Gulf of Mexico for late July 2019 is that it will cover 8,717-square-miles of the bottom of the continental shelf off Louisiana and Texas. The unusually high Mississippi River discharge in May controls the size of this zone, which will likely be the second largest zone since systematic measurements began in 1985. The water mass with oxygen concentrations less than 2 parts per million forms in bottom waters each year primarily as a result of nitrogen and phosphorus loading from the Mississippi River watershed, which fertilizes the Gulf of Mexico's surface waters to create excessive amounts of algal biomass. The decomposition of this plant material in the bottom layer leads to oxygen loss.
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The low oxygen conditions in the gulf's most productive waters stresses organisms and may even cause their death, threatening living resources, including fish, shrimp and crabs caught there. Low oxygen conditions started to appear 50 years ago when agricultural practices intensified in the Midwest. No reductions in the nitrate loading from the Mississippi River to the Gulf of Mexico have occurred in the last few decades.The predicted hypoxic area is about the size of the land area of New Hampshire and about 4.5 times the size of the Hypoxia Action Plan goal. This estimate assumes that there are no significant tropical storms in the two weeks before the monitoring cruise or during the cruise. The estimate is made each year by LSU scientists Eugene Turner and Nancy Rabalais.The report is posted at
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Extinction
| 2,019 |
June 7, 2019
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https://www.sciencedaily.com/releases/2019/06/190607110458.htm
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Rapid change in coral reefs prompts global calls for a rethink
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Coral reef experts from around the world are calling for an urgent re-evaluation of our climate goals in the light of increasing evidence of unprecedented speed of change to these fragile ecosystems. Coral reefs, which have functioned relatively unchanged for some 24 million years, are now going through profound changes in their make-up.
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Writing in a special feature of The scientists address issues such as how we should actually define what comprises a functioning coral reef in the Anthropocene, an era where humans are the dominant force of planetary change.As the world's climate changes, tropical temperatures shift towards the poles, enabling corals to grow in new places. As corals are lost to warming oceans in some places and growing in previously inhospitable cooler waters, how are environmental scientists to react?This shifting picture requires fresh responses from the scientific community if we are to preserve coral ecosystems along with the services and benefits they provide from food to tourism, coastal protection and ecosystem support.Professor Nick Graham of Lancaster University said: "Coral reefs have been with us in some form since the dinosaurs and today they are at the frontline in terms of responses to climate change and a range of other human pressures. Our special feature captures an emerging realisation within the coral reef science community that the rules of how coral reefs function, their species configurations, geographic distributions, and the benefits derived by people, are all changing. The scientific community, managers, and resource users are having to rapidly understand and adapt to this changing ecosystem and learn how to sustain it. This will only be possible if carbon emissions are rapidly reduced."Bangor University's Dr Gareth Williams said: "This special feature on the functional ecology of coral reefs is necessary and timely. Within one generation we are already observing changes which were not foreseen. This pace of change is so fast that it requires us to revisit and question whether our understanding of how these ecosystems function, built up over the many decades of research, is still relevant. The works call for the scientific community to revisit many classic questions and theories surrounding the ecology, management and conservation of coral reefs, asking provocative questions such as: what makes for a functioning coral reef in this new climate scenario and human-dominated world? Answering these questions has important implications for how we study, describe and manage these ecosystems moving forward."
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Extinction
| 2,019 |
June 6, 2019
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https://www.sciencedaily.com/releases/2019/06/190606150310.htm
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Argentine fossils take oak and beech family history far into Southern Hemisphere
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One of the world's most important plant families has a history extending much farther south than any live or fossil specimen previously recorded, as shown by chinquapin fruit and leaf fossils unearthed in Patagonia, Argentina, according to researchers.
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"The oak and beech family is recognized everywhere as one of the most important plant groups and has always been considered northern," said Peter Wilf, professor of geosciences and associate in the Earth and Environmental Systems Institute, Penn State. "We're adding a huge spatial dimension to the history of the Fagaceae family, and that's exciting." The plant family also includes chestnuts and the closely related chinquapins.Common in the Northern Hemisphere and Asian tropics, Fagaceae cross the equator only in Southeast Asia, and even there just barely. The latest study, published today (June 7) in The researchers first found fossils resembling some oak leaves, with straight secondary veins and one tooth per secondary vein, at Laguna del Hunco, Chubut province. The leaves comprise about 10 percent of the thousands of 52-million-year-old leaf fossils, representing almost 200 species, found at the site over two decades in a long-term project between Penn State, Cornell University and Museo Paleontológico Egidio Feruglio (MEF), Trelew, Argentina.For years the researchers hesitated to classify the leaves, because paleobotanist Edward Berry had assigned similar fossils to another family, and any claim of Fagaceae at so remote a location would require much more supporting evidence.Later, the team unearthed rare fruit fossils -- two fruit clusters, one with more than 110 immature fruits -- at the site and compared them to living relatives. They found that these were fossils of ancient Castanopsis, an Asian chinquapin that today dominates the biodiverse, lower elevation mountain rainforests of Southeast Asia."One of the first clues was a little lip where the fruit is splitting open," Wilf said. "I recognized this lip as being similar to the fruit of the Japanese chinquapin. Then I realized there's a nut inside."The nuts are fully encased in a scaly outer covering, or cupule, that splits open when the fruits mature. The cupules are arranged on a spike-like fruiting axis, and the young nuts retain delicate parts from their flowering stage. Their features are just like the living Castanopsis, Wilf said, and the fruits confirm that the leaves are Fagaceae."This is the first confirmed evidence that Fagaceae, considered restricted to the Northern Hemisphere, was in the Southern Hemisphere," said Maria Gandolfo, associate professor, Cornell University. "This is remarkable and allows us to rethink the origins of the fossil flora."The fossils date to the early Eocene 52.2 million years ago. They are the only fossilized or living Fagaceae ever found south of the Malay Archipelago, the island chain just north of Australia.During the globally warm early Eocene there was no polar ice, and South America, Antarctica and Australia had not completely separated, comprising the final stage of the Gondwanan supercontinent. The researchers think animals had helped disperse the chinquapin's ancestors from North to South America at an earlier time. The plants thrived in the wet Patagonian rainforest, whose closest modern analog is the mountain rainforests of New Guinea."Before the current semi-desert conditions, trees covered Patagonia," said Rubén Cúneo, director of MEF. "Changes in climatic conditions turned it into a shrubland, and the trees were displaced."The chinquapins may have also ranged into then-adjacent Antarctica and on to Australia, said Wilf. Castanopsis may have survived in Australia until the continent collided with Southeast Asia, where today chinquapins are keystone species, providing forest structure and food and habitat for birds, insects and mammals."We're finding, in the same rocks as Castanopsis, fossils of many other plants that live with it today in New Guinea and elsewhere, including ferns, conifers and flowering plants," said Wilf. "You can trace some of the associations with Castanopsis seen in Eocene Argentina to southern China and beyond."Today, Castanopsis plays an important role in intercepting year-round mountain precipitation that delivers clean water for drinking, fishing and agriculture to more than half a billion people and sustains diverse freshwater and coastal ecosystems. However, humans are clearing these rainforests for timber, development and crop cultivation, and modern climate change is increasing droughts and fire frequency."These plants are adaptable if given time and space," Wilf said, adding Castanopsis' trek from Patagonia to Southeast Asia occurred over millions of years and thousands of miles. "But the pace of change today is hundreds of times faster than in geologic time. The animals that depend on these plants are adaptable only to the extent that the plants are, and we are one of the animals that depend on this system. If we lose mountain rainforests, really fast we lose reliable water flows for agriculture, clean coral reefs offshore, biodiversity and much more."This study has implications for extinction in the face of climate change, according to Kevin Nixon, professor and L.H. Bailey Hortorium curator, Cornell University. He said Castanopsis went extinct in Patagonia due to a major extinction caused by the slow cooling and drying of the climate that occurred with the glaciation of Antarctica and the rise of the Andes."Those kinds of climate changes can have massive effects on biodiversity," Nixon said. "The relevance of understanding this is we can start to look at extinction processes. The better we can understand what causes extinction, the better we can deal with it."The National Science Foundation, National Geographic Society and David and Lucile Packard Foundation funded this research.
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Extinction
| 2,019 |
June 5, 2019
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https://www.sciencedaily.com/releases/2019/06/190605150655.htm
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To see how invading predators change an ecosystem, watch the prey, say researchers
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Invading predators can devastate an ecosystem. In fact, a leading cause of extinction is the introduction of predators into an isolated system like an island or a lake. The destruction is usually blamed on the predator's eating choices, but sometimes the key lies in the prey animals' responses, according to an international team of researchers led by Princeton's Robert Pringle.
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"You really can't understand predator-prey interactions -- or how predators will affect biodiversity and ecosystems -- without understanding the behavior of the prey," said Pringle, an associate professor of ecology and evolutionary biology. "The ways in which prey change their behavior to avoid getting eaten is a hard thing to predict, but without understanding that, you can't predict anything else. Most theory in ecology simply assumes that predators eat prey, end of story. The real world is more complicated. But it's not so complicated that we can't get to the bottom of it."The question is rapidly becoming more pressing, noted co-author Rowan Barrett, the Canada Research Chair of Biodiversity Science at McGill University in Montreal, Quebec. "Human activity is increasing the occurrence of new predators being introduced to formerly isolated ecosystems," he said. "Our work shows that the consequences of these predator invasions for biodiversity can depend strongly on changes in prey behavior that alter the way prey species use their environments."To tackle the question, the team used three lizard species: one predator, the curly-tailed lizard The researchers traveled to 16 small islands in the Bahamas that they used as experimental ecosystems. The brown anoles were established on all 16, and the researchers introduced the other two lizards separately or in combination."It's so rare in ecology to be able to manipulate whole ecosystems -- these little islands are kind of like big oceanic petri dishes that enable us to run really tight and compelling experiments," Pringle said. "It's just not possible to do that in most places."The researchers found that in the absence of predators, the two anole species coexisted just fine, with green anoles in trees and brown anoles living closer to the ground. The two species competed for insects, but the competition was "not severe," Pringle said. But when the team introduced the curly-tailed predators, the brown anoles fled to the trees, where the chunky ground-dwelling lizard couldn't follow. This intensified the competition between the two prey species for space and food, which undermined their ability to coexist. The results suggest that when prey can respond rapidly to the presence of a predator by changing their behavior, predators might typically reduce the ability of prey species to coexist."One of the key implications of our study is that the size of the refuges that prey have from predators can be really important for ensuring that prey don't go extinct," said Todd Palmer, a co-first-author at the University of Florida. "When there's not enough room for prey to hang out without the constant risk of being eaten, something's got to give, and that's when we see species disappearing. Some of the more recent examples of catastrophic species extinction, such as the collapse of a really diverse group of fish species in the African great lakes, may have occurred in part because there simply wasn't enough safe space in those ecosystems. So our findings not only give us some clues about how to manage future predator introductions, but also a better understanding of how past extinctions may have arisen as well."This research "provides a beautiful counterexample to a classic ecology theory," said Gaku Takimoto, a theoretical ecologist at the University of Tokyo who was not involved in the research. "In theory, predation promotes the coexistence of competing prey species by crushing superior competitors and siding with inferior competitors, but their experiment showed that risk of predation caused a superior competitor to shift its habitat to usurp that of weaker competitors and destroy their coexistence."Scientists have long known how important "keystone predators" can be for healthy ecosystems. According to the keystone predator theory, top predators can prevent any one prey species from becoming too abundant and outcompeting all the other prey species, which should generally increase the diversity of the species at low levels of the food chain. While this study does not overturn this concept, it does highlight that an ecosystem with a top predator will not necessarily be more diverse than one without a top predator."Predators can reduce the diversity of prey species," said Pringle. "That's not 'good,' and it's not 'bad' -- it is what it is. The important thing to me is that we understand how and why predators have the effects that they do, so that we can predict what will happen when ecosystems gain new predators through invasions or when they lose existing predators through extinctions. That is really what our study was aiming to do. It's not a morality play. There's no good and no evil. We're just trying to get a clear understanding of the biology."Scientists still don't fully understand all the ways introduced predators affect resident prey species. In some cases, of course, an introduced predator can devastate prey populations by simply eating them up. But prey can also respond to predators in ways that reduce their likelihood of getting eaten -- like hiding in trees, as the brown anoles did. There, the risk of predation is low, but then these areas become crowded, and competition becomes intense. This leads to the opposite outcome from the classical keystone predation scenario; Pringle's team called it "refuge competition.""After six years of population monitoring, we found that curly-tailed lizards destabilized coexistence of the competing prey species by forcing brown and green anoles to share the same predator-free refuges and intensifying competition between them, leading to the extinction of some populations," said McGill's Barrett. Their results therefore challenge the generality of the keystone-predation hypothesis and support the refuge-competition hypothesis in this environment, he said.The researchers wanted to dig deeper than simple population surveys, so they conducted DNA metabarcoding on fecal samples from each lizard species, to analyze their diets. DNA metabarcoding, a powerful tool that uses short fragments of fecal DNA to identify the prey species eaten by a predator, showed how the lizard species were competing for food on the islands. The researchers also used stable-isotope analysis to analyze how the experimental treatments affected the length of the food chains on the islands and the position of each species in the food chain.Taken together, these techniques allowed the researchers to understand their results much more deeply, said Pringle. "A lot of times, you'll run an experiment in the field and get some results, but you won't necessarily understand why you got those results -- you might have a best guess or a favored hypothesis, but it's often a bit ambiguous," he said. "It's been a goal of mine for a long time to integrate new techniques like DNA metabarcoding with established techniques like muddy-boots field experiments to try to get more insight into mechanism. In this study, we really wove all these elements together over the course of the six-year experiment, and that is very satisfying."Pringle shares co-first-authorship with Tyler Kartzinel, a former postdoc in his lab who is now at Brown University, and with Todd Palmer of the University of Florida. Other Princeton co-authors are graduate student Matthew Hutchinson and graduate alumni Tyler Coverdale (Ph.D. 2018) and Josh Dakin (Ph.D. 2017). Undergraduate Lauren Wyman (Class of 2014) contributed to the fieldwork, and she and Annie Ferlmann (Class of 2016) both did senior theses using data from this project."Dr. Pringle was able to mimic naturally occurring introductions of new competitors and predators and then track what happens in real time," said Jodie Jawor, a program director at the National Science Foundation, which funded this research. "This is a rare and valuable test of what happens to communities when new species are introduced. ... Habitats and the composition of animal communities can change for various reasons -- natural disasters, development, construction -- so this work helps us understand the ecological impacts and potentially address them proactively and more fully informed."The research was supported by the United States National Science Foundation (grant DEB-1457697), the Princeton Environmental Institute, a Canada Research Chair, and a Vanier Canada Scholarship from the Natural Sciences and Engineering Research Council of Canada.
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Extinction
| 2,019 |
June 4, 2019
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https://www.sciencedaily.com/releases/2019/06/190604131203.htm
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Rare fossils provide more detailed picture of biodiversity during Middle Ordovician
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A clutch of marine fossil specimens unearthed in northern Portugal that lived between 470 and 459 million years ago is filling a gap in understanding evolution during the Middle Ordovician period.
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The discovery, explained in a new paper just published in "The paper describes the first soft-body fossils preserved as carbonaceous films from Portugal," said lead author Julien Kimmig, collections manager at the University of Kansas Biodiversity Institute and Natural History Museum. "But what makes this even more important is that it's one of the few deposits that are actually from the Ordovician period -- and even more importantly, they're from the Middle Ordovician, a time were very few soft-bodied fossils are known."Kimmig and his KU Biodiversity Institute colleagues, undergraduate researcher Wade Leibach and senior curator Bruce Lieberman, along with Helena Couto of the University of Porto in Portugal (who discovered the fossils), describe three marine fossil specimens: a medusoid (jellyfish), possible wiwaxiid sclerites and an arthropod carapace."Before this, there had been nothing found on the Iberian Peninsula in the Ordovician that even resembled these," Kimmig said. "They close a gap in time and space. And what's very interesting is the kind of fossils. We find Medusozoa -- a jellyfish -- as well as animals which appear to be wiwaxiids, which are sluglike armored mollusks that have big spines. We found these lateral sclerites of animals which were actually thought to have gone extinct in the late Cambrian. There might have been some that survived into the Ordovician in a Morocco deposit, but nothing concrete has been ever published on those. And here we have evidence for the first ones actually in the middle of the Ordovician, so it extends the range of these animals incredibly."Kimmig said the discovery of uncommon wiwaxiids fossils in this time frame suggests the animals lived on Earth for a far greater span of time than previously understood."Especially with animals that are fairly rare that we don't have nowadays like wiwaxiids, it's quite nice to see they lived longer than we ever thought," he said. "Closely after this deposit, in the Upper Ordovician, we actually get a big extinction event. So, it's likely the wiwaxiids survived up to that big extinction event and didn't go extinct earlier due to other circumstances. But it might have been whatever caused the big Ordovician extinction event killed them off, too."According to the researchers, the soft-bodied specimens fill a gap in the fossil record for the Middle Ordovician and suggest "many soft-bodied fossils in the Ordovician remain to be discovered, and a new look at deep-water shales and slates of this time period is warranted.""It's a very interesting thing with these discoveries -- we're actually getting a lot of information about the distribution of animals chronologically and geographically," Kimmig said. "Also, this gives us a lot of information on how animals adapted to different environments and where they actually managed to live. With these soft-body deposits, we get a much better idea of how many animals there were and how their environment changed over time. It's something that applies to modern days, with changing climate and changing water temperatures, because we can see how animals over longer periods of time in the geologic record have actually adapted to these things."Co-author Couto discovered the fossils in the Valongo Formation in northern Portugal, an area famed for containing trilobites. When the animals were alive, the Valongo Formation was part of a shallow sea on the margin of northern Gondwana, the primeval supercontinent."Based on the shelly fossils, the deposit looks like it was a fairly common Ordovician community," Kimmig said. "And now we know that in addition to those common fossils jellyfish were floating around, we had sluglike mollusks roaming on the ground, too, and we had bigger arthropods, which might have been predatory animals. So, in that regard, we're getting a far better image with these soft-bodied fossils of what these communities actually looked like."According to the KU researcher, scientists didn't grasp until recently that deposits from this period could preserve soft-bodied specimens."For a long time, it was just not known that these kinds of deposits survived in to the Ordovician," Kimmig said. "So, it is likely these deposits are more common in the Ordovician than we know of, it's just that people were never looking for them."Kimmig led analysis of the fossils at KU's Microscopy and Analytical Imaging Laboratory to ensure the fossils were made of organic material. Leibach, the KU undergraduate researcher, conducted much of the lab work."We analyzed the material and looked at the composition because sometimes you can get pseudo fossils -- minerals that create something that looks like a fossil," Kimmig said. "We had to make sure that these fossils actually had an organic origin. And what we found is that they contain carbon, which was the big indication they would actually be organic."
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Extinction
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June 4, 2019
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https://www.sciencedaily.com/releases/2019/06/190604131131.htm
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Ant reactions to natural habitat disruptions tell us a lot about their evolution
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A Concordia biology professor is calling on ant experts to develop a set of common principles that influence the way the insects respond when their habitat undergoes severe disruption.
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Writing in the Lessard writes that Andersen's system of grouping ant communities along certain criteria is a helpful start, particularly when it comes to how different species respond to disturbances to their environment. But much more work is needed before ant ecologists -- known formally as myrmecologists -- have an agreed-upon standard framework.Andersen's groupings provide a base from which researchers can compare changes in the makeup of ant communities around the world. Ants are a highly diverse group of organisms: there are more than 12,000 separate species, found on all continents except Antarctica and in almost all ecosystems, from arctic taiga to arid desert. This makes them easy to sample and identify, says Lessard, and easy to monitor when measuring recovery efforts and response to disturbance.He writes that comparing those responses offers several important insights. For instance, all ant communities around the globe react strongly to habitat openness, or how much vegetation covers the ground, regardless of how that openness comes about."Ant communities will not respond so differently to a fire versus the cutting down of a forest versus an outbreak of herbivores eating up biomass," explains Lessard, Concordia University Research Chair in Biodiversity and Ecosystem Functioning."They will respond to the openness that these create. It doesn't matter what the actual source of the disturbance is, what matters is whether the canopy is open or closed."He notes that ant communities' response to disturbance can also be quite heterogeneous. An ant community in the Brazilian savanna, for instance, will react differently to a change in its ecosystem than a colony in the Australian savanna.This is thanks to millions of years of biogeographic and evolutionary history. Most ant communities in Brazil are evolutionarily adapted to forest habitats, and so the loss of canopy to events like forest fires will have a greater effect on them than a similar event would have on a species adapted to the hot, dry Australian ecosystem.As Lessard writes, these findings show that their presence over the eons of so-called deep time "has left a signature on contemporary structure of ant communities."As useful and interesting as he finds them, however, Lessard believes Andersen's functional groupings are at least somewhat arbitrary."If someone else decided which ants would belong to which groups, how meaningful would that be?" he asks.Without an existing common framework, ant ecologists are "out of sync" in what functional traits they measure to assess the consequences of human-made disturbances, he argues."If someone is trying to measure one trait and someone else is measuring a different trait, we'll never be able to compare how they might facilitate or prevent extinction in the face of a disturbance," Lessard says."In the ant world, we really don't have much widespread agreement on which traits would be most useful when it comes to measuring how communities respond to disturbance and understanding the fundamental process of how species come together in one place."
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Extinction
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June 3, 2019
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https://www.sciencedaily.com/releases/2019/06/190603124542.htm
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Feathers came first, then birds
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New research, led by the University of Bristol, suggests that feathers arose 100 million years before birds -- changing how we look at dinosaurs, birds, and pterosaurs, the flying reptiles.
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It also changes our understanding of feathers themselves, their functions and their role in some of the largest events in evolution.The new work, published in the journal The key discovery came earlier in 2019, when feathers were reported in pterosaurs -- if the pterosaurs really carried feathers, then it means these structures arose deep in the evolutionary tree, much deeper than at the point when birds originated.Lead author, Professor Mike Benton, from the University of Bristol's School of Earth Sciences, said: "The oldest bird is still Archaeopteryx first found in the Late Jurassic of southern Germany in 1861, although some species from China are a little older."Those fossils all show a diversity of feathers -- down feathers over the body and long, vaned feathers on the wings. But, since 1994, palaeontologists have been contending with the perturbing discovery, based on hundreds of amazing specimens from China, that many dinosaurs also had feathers."Co-author, Baoyu Jiang from the University of Nanjing, added: "At first, the dinosaurs with feathers were close to the origin of birds in the evolutionary tree."This was not so hard to believe. So, the origin of feathers was pushed back at least to the origin of those bird-like dinosaurs, maybe 200 million years ago."Dr Maria McNamara, co-author from University College Cork, said: "Then, we had the good fortune to work on a new dinosaur from Russia, Kulindadromeus."This dinosaur showed amazingly well-preserved skin covered with scales on the legs and tail, and strange whiskery feathers all over its body."What surprised people was that this was a dinosaur that was as far from birds in the evolutionary tree as could be imagined. Perhaps feathers were present in the very first dinosaurs."Danielle Dhouailly from the University of Grenoble, also a co-author, works on the development of feathers in baby birds, especially their genomic control. She said: "Modern birds like chickens often have scales on their legs or necks, and we showed these were reversals: what had once been feathers had reversed to be scales."In fact, we have shown that the same genome regulatory network drives the development of reptile scales, bird feathers, and mammal hairs. Feathers could have evolved very early."Baoyu Jiang continued: "The breakthrough came when we were studying two new pterosaurs from China."We saw that many of their whiskers were branched. We expected single strands -- monofilaments -- but what we saw were tufts and down feathers. Pterosaurs had feathers."Professor Benton added: "This drives the origin of feathers back to 250 million years ago at least."The point of origin of pterosaurs, dinosaurs and their relatives. The Early Triassic world then was recovering from the most devastating mass extinction ever, and life on land had come back from near-total wipe-out."Palaeontologists had already noted that the new reptiles walked upright instead of sprawling, that their bone structure suggested fast growth and maybe even warm-bloodedness, and the mammal ancestors probably had hair by then."So, the dinosaurs, pterosaurs and their ancestors had feathers too. Feathers then probably arose to aid this speeding up of physiology and ecology, purely for insulation. The other functions of feathers, for display and of course for flight, came much later."
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Extinction
| 2,019 |
June 3, 2019
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https://www.sciencedaily.com/releases/2019/05/190530101136.htm
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Edible insects? Lab-grown meat? The real future food is lab-grown insect meat
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Livestock farming is destroying our planet. It is a major cause of land and water degradation, biodiversity loss, acid rain, coral reef degeneration, deforestation -- and of course, climate change. Plant-based diets, insect farming, lab-grown meat and genetically modified animals have all been proposed as potential solutions. Which is best?
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All of these combined, say researchers at Tufts University.Writing in "Due to the environmental, public health and animal welfare concerns associated with our current livestock system, it is vital to develop more sustainable food production methods," says lead author Natalie Rubio.Genetically modified livestock, for example that produce less methane or resist disease, can do little to relieve issues like land and water degradation, deforestation and biodiversity loss.But for meat-lovers, soy- or mushroom-based substitutes just don't hit the spot -- and some plant crops are as thirsty as livestock.Insect farming has a much lower water and space requirement -- think vertical farming -- and twice as much of a cricket is edible than of a big-boned, big-bellied cow. Unsurprisingly though, creepy crawlies are proving even harder for consumers to swallow.Finally, lab-grown meat could squeeze water and space savings furthest of all, without compromising on taste. Culturing beef, pork or chicken cells might require even more energy and resources than livestock farming, however -- leaving us trading farts for fossil fuels. (Or is that burps?)A better solution, says Rubio, may lie at the intersection of all these options: lab-grown insect meat -- fed on plants, and genetically modified for maximum growth, nutrition and flavor."Compared to cultured mammalian, avian and other vertebrate cells, insect cell cultures require fewer resources and less energy-intensive environmental control, as they have lower glucose requirements and can thrive in a wider range of temperature, pH, oxygen and osmolarity conditions," reports Rubio."Alterations necessary for large-scale production are also simpler to achieve with insect cells, which are currently used for biomanufacture of insecticides, drugs and vaccines."Research for these applications has led already to inexpensive, animal-free growth media for insect cells -- including soy- and yeast-based formulas -- as well as successful 'suspension culture'."In most mammalian muscle cell culture systems, the cells have to be fixed in a single layer to a growth surface -- which is complex to scale up for mass food production. Many insect cells, however, can be grown free-floating in a suspension of growth media to allow cost-effective, high-density cell generation," Rubio explains.Technology developed to stimulate movement of insect tissue for bio-robotics could also be applied to food production, since regular contraction may be required for cultured insect muscle to develop a 'meaty' texture. A particularly efficient method is optogenetic engineering, whereby cells are made to contract in response to light by introducing a new gene -- another advantage of insect cells, which more readily accept genetic modifications than do other animal cells.So, future food production could be a sight to behold: silent discos of insect muscles, flexing to the pulse of lasers in vast pools of soy juice. But how will it taste?The short answer, says Rubio, is that nobody knows."Despite this immense potential, cultured insect meat isn't ready for consumption. Research is ongoing to master two key processes: controlling development of insect cells into muscle and fat, and combining these in 3D cultures with a meat-like texture. For the latter, sponges made from chitosan -- a mushroom-derived fiber that is also present in the invertebrate exoskeleton -- are a promising option."Eventually, insect labriculture could turn up some altogether more familiar flavors."Advances in insect cell culture and tissue engineering can potentially be translated to lobster, crab and shrimp, due to the evolutionary proximity of insects and crustaceans," suggests Rubio.
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Extinction
| 2,019 |
May 31, 2019
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https://www.sciencedaily.com/releases/2019/05/190531100554.htm
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In hot pursuit of dinosaurs: Tracking extinct species on ancient Earth via biogeography
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One researcher at the University of Tokyo is in hot pursuit of dinosaurs, tracking extinct species around ancient Earth. Identifying the movements of extinct species from millions of years ago can provide insights into ancient migration routes, interaction between species, and the movement of continents.
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"If we find fossils on different continents from closely related species, then we can guess that at some point there must have been a connection between those continents," said Tai Kubo, Ph.D., a postdoctoral researcher affiliated with the University Museum at the University of Tokyo.Previous studies in biogeography -- the geographic distribution of plants and animals -- had not considered the evolutionary relationships between ancient species. The new method that Kubo designed, called biogeographical network analysis, converts evolutionary relationships into geographical relationships.For example, cats and dogs are more closely related to each other than to kangaroos. Therefore, a geographical barrier must have separated the ancestors of kangaroos from the ancestors of cats and dogs well before cats and dogs became separate species.Most fossils are found in just a few hot-spot locations around the world and many ancient species with backbones (vertebrates) are known from just one fossil of that species. These limitations mean that a species' fossils cannot reveal the full area of where it was distributed around the world."Including evolutionary relationships allows us to make higher resolution maps for where species may have migrated," said Kubo.The analysis used details from evolutionary studies, the location of fossil dig sites, and the age of the fossils. Computer simulations calculated the most likely scenarios for the migration of species between continents on the Cretaceous-era Earth, 145 to 66 million years ago.This new analysis verified what earlier studies suggested: nonavian dinosaurs were divided into a group that lived in the Northern Hemisphere and another that lived in the Southern Hemisphere, and that those two groups could still move back and forth between Europe and Africa during the Early Cretaceous period (145 to 100 million years ago), but became isolated in the Late Cretaceous period (100 to 66 million years ago).During the Early Cretaceous period, there were three major supercontinents: North America-Europe-Asia, South America-Africa, and Antarctica-India-Australia.By the Late Cretaceous period, only the North America-Europe-Asia supercontinent remained. The other supercontinents had separated into the continents we know today, although they had not yet drifted to their current locations."During the Late Cretaceous period, high sea levels meant that Europe was a series of isolated islands. It makes sense that nonavian dinosaur species differentiated between Africa and Europe during that time," said Kubo.Kubo plans to complete additional biogeographical analyses for different time periods to continue tracking extinct species around the world and through time.
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Extinction
| 2,019 |
May 29, 2019
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https://www.sciencedaily.com/releases/2019/05/190529113055.htm
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Coral reefs can't return from acid trip
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A new study published in
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The study was led by researchers from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE). Their results suggest some corals and coralline algae -- the 'glue' that holds reefs together -- cannot survive the expected more acidic oceans caused by climate change."The results validate previous research on ocean acidification threats to coral reefs," said lead author Dr Steeve Comeau, who is now based at the Sorbonne Université CNRS Laboratoire d'Océanographie de Villefranche sur Mer in France.Co-author Prof Malcolm McCulloch, from Coral CoE at the University of Western Australia, said the researchers examined the calcifying fluid of four species of coral and two types of coralline algae under a year-long simulation."The effects on the calcifying fluid were rapid and persisted for the whole year," Prof McCulloch said.Co-author Dr Chris Cornwall, now at the Victoria University of Wellington in New Zealand, explained coralline algae cements reefs together by acting as a foundation species and breeding ground for many species from the poles to the tropics."Declines in coralline algae could lead to the loss of important marine species that use the algae as a nursery," he explained."The results also confirm that ocean acidification could have repercussions on the competition between species. This can affect the ecological function of reefs," Dr Comeau added.He said the team did find two coral species were resistant to ocean acidification. However, these are corals that were resistant from the start."This indicates they already had an in-built mechanism that made them resistant," he explained, "whereas sensitive corals were affected from the start and were not actually able to acclimatise."The study suggests the composition and function of future reefs -- if they can survive climate change -- will be very different to what we see today.
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Extinction
| 2,019 |
May 24, 2019
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https://www.sciencedaily.com/releases/2019/05/190524130239.htm
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Soil communities threatened by destruction, instability of Amazon forests
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The clearing and subsequent instability of Amazonian forests are among the greatest threats to tropical biodiversity conservation today.
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Although the devastating consequences of deforestation to plants and animal species living above the ground are well-documented, scientists and others need to better understand how soil communities respond to this deforestation to create interventions that protect biodiversity and the ecosystem. But that information has been lacking.A team of researchers led by Colorado State University's André Franco, a research scientist in the Department of Biology, conducted a meta-analysis of nearly 300 studies of soil biodiversity in Amazonian forests and sites in various stages of deforestation and land-use.The new study, "Amazonian deforestation and soil biodiversity," is published in the June issue of Overall, the researchers found that the abundance, biomass, richness and diversity of soil fauna and microbes were all reduced following deforestation. Soil fauna or animals that were studied include earthworms, millipedes, dung beetles, nematodes, mites, spiders and scorpions.Franco, who hails from Brazil, said that this is the first time that all of the available scientific data related to soil biodiversity in Amazonian forests has been synthesized.The research team also found that the way the land is used after the forest is cleared matters to soil biodiversity. Species of invertebrates such as earthworms, ants and termites -- which are described as soil engineers -- were more vulnerable to the displacement of forests with pastures than by crops, while microbes showed the opposite pattern.Franco said the highest biodiversity losses were found on the side of the Amazon with the highest mean annual precipitation and in areas where the soil was very acidic."That means these areas should be higher priorities for conservation efforts," he said.Scientists also uncovered gaps in existing research."Very few studies looked at the impact of disturbances like wildfires and selective logging on these forests," Franco said. "Yet logging is an official management strategy in the Amazon forest."In addition, the team found a lack of data from seven of the nine countries that the Amazon biome covers parts of, including Bolivia, Peru, Ecuador, Venezuela, Guyana, Suriname and French Guiana.Sobral noted that biodiversity is a hot topic and was elevated recently with the release of a report from the United Nations, which found that nature is declining globally at unprecedented rates. But most of the scientific knowledge in the world about biodiversity relates to birds and mammals, he said.The team is continuing this research in the Amazon, working with farmers' associations and two research institutes in Brazil to collect and analyze soil samples with the goal of studying the consequences of this loss of biodiversity.Zaid Abdo, a bioinformatics expert and associate professor in the Department of Microbiology, Immunology and Pathology, has joined the CSU-based research team.Sobral said it's extremely important that the scientists work with local farmers and others who are impacted by the deforestation."We're very focused on making sure the research isn't disconnected from local communities' needs and aspirations," he said. "Our work is guided by what the farmers want to know and how scientific knowledge could shape their future sustainable development."
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Extinction
| 2,019 |
May 23, 2019
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https://www.sciencedaily.com/releases/2019/05/190523143058.htm
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Live fast, die young: Study shows tiny fishes fuel coral reefs
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Scientists have long sought to understand how coral reefs support such an abundance of fish life despite their location in nutrient-poor waters. According to a new study published May 23 in the journal
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The study shows that these fishes perform a critical role on coral reefs, supplying almost 60% of consumed fish food by constantly replenishing their populations in a rapid cycle of life and death."Scientists have puzzled over coral reefs for centuries, wondering how such productive, diverse ecosystems survive in what is essentially a marine desert," said lead author Simon Brandl, formerly with the Smithsonian's Tennenbaum Marine Observatories Network and currently a postdoctoral research fellow with Simon Fraser University. "It's remarkable to find that these tiny, almost universally overlooked fishes actually serve as the cornerstone of coral-reef fish communities."Cryptobenthic reef fishes, such as gobies, blennies or cardinalfishes, are the smallest of all marine vertebrates. Although they vary in size, the tiniest cryptobenthics will never reach 1 inch and weigh almost nothing. Other coral-reef dwellers eat these fishes in large quantities, most within the first few weeks of their existence.Instead of disappearing, however, cryptobenthic fish populations somehow flourish in the face of constant predation. The researchers solved this paradox by studying the larvae of reef fishes. While the larvae of most fish species disperse into the open ocean, where only a few survive, cryptobenthics behave differently. Brandl and his team found that most cryptobenthic larvae appear to remain close to their parents' reefs, yielding many more survivors among their babies. These larvae then rapidly replace cryptobenthic adults eaten on the reef, sustaining the growth of larger reef fishes."We found that cryptobenthic fish larvae absolutely dominate the larval-fish communities near reefs, which provides a continuous stream of new generations of tiny fish as a food source for other reef creatures," said Carole Baldwin, co-author on the study and curator of fishes at the Smithsonian's National Museum of Natural History. "It's incredible that these fishes contribute so much to coral reefs. They're so small that historically we haven't recognized their enormous significance."Scientists from Australia, Canada, France and the United States contributed to this research. The team studied cryptobenthics in Belize, French Polynesia and Australia, combed decades of data on coral-reef fish larvae and developed a population model to better understand how cryptobenthics contribute to the diet of coral-reef dwellers.The study began in 2015, when Brandl was a postdoctoral fellow at the Smithsonian's Marine Global Earth Observatory (MarineGEO), but these tiny fishes are more relevant today than ever. As coral reefs undergo dramatic declines, their fish communities -- and the people who depend on them -- may be in jeopardy. The researchers hope that the vast diversity of cryptobenthics and their unique way of life can make them a resilient foundation for coral reefs.
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Extinction
| 2,019 |
May 23, 2019
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https://www.sciencedaily.com/releases/2019/05/190523130206.htm
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Ecologists find bush dog, native of South America, in remote central Costa Rica
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Wildlife ecologists at the University of Massachusetts Amherst who are studying different conservation practices in the forests of Costa Rica recently made a startling discovery on a wildlife camera trap -- wild bush dogs documented farther north than ever before and at the highest elevation.
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Doctoral student Carolina Saenz-Bolaños is in Costa Rica comparing land use, management techniques, their effects on species presence and abundance, and human attitudes in four different areas in the rugged Talamanca Mountains: a national park, an adjacent forest reserve, an indigenous territory and nearby unprotected areas.She and her advisor, professor of environmental conservation Todd Fuller at UMass Amherst, with others, report in an article today in Fuller says, "They aren't supposed to be there, but Carolina's work shows they really are, and they seem to be doing well. Not only is this wild dog rare wherever it is found, but this mountain range is very remote, with very little access. They could have been there before and we wouldn't know it. So we're documenting them with this report."Saenz-Bolaños says that because the roadless area is so huge, she and colleagues are not sure if the dogs are expanding their range, returning to a former range, or if they've been there all along but eluded detection. She works with Victor Montalvo, a fellow UMass Amherst doctoral student, and Eduardo Carrillo of the Universidad Nacional de Costa Rica and UMass Amherst adjunct professor of environmental conservation.Once the dogs were spotted on camera, the researchers contacted Michael Mooring of San Diego's Point Loma Nazarene University who, with Junior Porras of Costa Rica's National System of Conservation Areas (SINAC), also had obtained new bush dog photos from southern Costa Rica.Saenz-Bolaños, who has been operating trap cameras in the area since 2012, says, "I know most of the things that live here, so when I saw them on the camera I said 'Wow, what is that -- bush dogs here?' I was very excited and thrilled to see them." She adds, "The native people have a name for these dogs and their oral tradition says the dogs have been there in the past, but people living there now have never seen one."Bush dogs have been spotted north of the Panama Canal near the Costa Rica border in the past 10 years, she adds, but they are completely unexpected in the northern parts of the Talamanca Mountains.Fuller says that bush dogs have lived in South America for thousands of years, and no one knows why they have not moved farther north into Central America, where the habitat is similar, but they are so rare that studying them is quite difficult. "There are still definitely interesting things to find out about them, especially if they're expanding their range," he says.Curious about what it would take to collect more sightings of bush dogs in Costa Rica, he and Saenz-Bolaños worked with Paul Sievert of the U.S. Geological Survey and UMass Amherst to calculate how many camera-trap hours it might take to have even a 50-50 chance of seeing the animals again in an area of roughly 2,000 square miles (5,000 sq. km). Fuller says they estimate that it would require at least 25 camera traps set out for 100 nights, a difficult task in such remote, mountainous and tropical terrain.The ecologists hope that their report will spark the imaginations of other wildlife ecologists, park managers and rangers in the region, who might set up their own camera traps in promising areas. Saenz-Bolaños plans to continue monitoring her study area and plans to try to talk to more local people about the dogs. Fuller adds, "At this point the mountain range looks like good bush dog habitat, but we just don't know if they are getting started there or are already at home."The Stone Zoo in Stoneham, Mass., part of Zoo New England, has a family of bush dogs on exhibit where visitors can see these small wild dogs. The zoo participates in species survival planning for the bush dog to manage and conserve threatened or endangered animals.
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Extinction
| 2,019 |
May 22, 2019
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https://www.sciencedaily.com/releases/2019/05/190522120509.htm
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Mapping the global distribution of phytoplankton
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With some 10,000 to 20,000 different species in the world's oceans, the diversity of phytoplankton (phyto from the Greek for plant) species is extremely rich. These phytoplankton form a key element of ocean ecosystems and life on this planet, producing more oxygen than all the world's rainforests combined. They also serve as the fundamental basis of the marine food chain.
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To date, however, very little has been known about the geographic and seasonal diversity of phytoplankton. Although many species of phytoplankton have been identified, the question of when and where they occur is largely unexplored; in light of the current biodiversity crisis, this represents a serious knowledge gap.In early May, the Intergovernmental Platform on Biodiversity and Ecosystem Services stated in its latest report that a million of all known species on earth are under threat of extinction as a result of human activity and climate change. However, for many important species, especially species of the world's smallest form of marine life, plankton, our knowledge of their distribution and diversity remains inadequate or non-existent to this day.Now, a team of researchers from ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL have filled in some of this knowledge gap. In a study published recently in the Their study reveals that tropical waters hold the richest diversity of species at all times of the year. Phytoplankton diversity is particularly high in the seas of the Indonesian-Australian archipelago, in parts of the Indian Ocean and in the equatorial Pacific Ocean. In the subtropics, biodiversity drops off markedly beyond 30 degrees latitude North and South, reaching its lowest values around a latitude of 55 degrees. Diversity then picks up again slightly towards the poles."We were surprised to find that on a monthly basis, the polar seas present greater diversity than the mid-latitudes," says Damiano Righetti, the lead author of the study. He is a PhD student with ETH professor Nicolas Gruber and senior scientist Meike Vogt. "It's remarkable because global species distribution and diversity are normally closely linked to environmental temperature trends."Species diversity typically decreases continuously towards the poles, where it is normally at its lowest. Temperature could plausibly be the direct driver of this decline. According to metabolic theory, higher temperatures accelerate metabolism, mutations of genetic material and speciation. This explains why the tropics are richer in species than the mid-latitudes and the polar regions, as would be expected.The study reveals that phytoplankton does not always behave in line with this theory. "Evidently, there are factors other than temperature affecting plankton diversity," Righetti says. Two of these might be the strong currents and turbulence, which are prevalent in the mid-latitudes, but less so in polar or tropical seas. "The seasonal fluctuations and ocean turbulence in these latitudes might suppress the development of biodiversity, even though the temperatures here are higher than in the polar oceans," the ecologist says.Righetti and colleagues also found that phytoplankton diversity in the mid-latitudes, unlike in the tropics, varies greatly from season to season. Righetti explains that although the number of species in the mid-latitudes is constant over time, the species composition changes over the course of the year: "In contrast to tropical seas, the diversity here is dynamic throughout the year, but hardly any research has been done on this."Working with ETH adjunct professor Niklaus Zimmermann and other colleagues from the WSL, Righetti developed a computer model to map the diversity distribution of phytoplankton. They fed this model with observational data and used it to project where each species occurs -- with a temporal resolution of one month.The observational data came from water samples collected during research trips as well as from normal shipping routes. Phytoplankton specialists subsequently studied the samples under the microscope to determine which species they contained. Over time, these research cruises amassed huge amounts of observational data on several thousand different species. Righetti and colleagues then gathered the data available into a database and analyzed it.It must be noted, however, that sampling has not been evenly distributed across the oceans and, in many regions, has not spanned all seasons. Thanks to British researchers, the North Atlantic is very well represented, but very little data exist for large parts of the other oceans. The ETH researchers compensated for this distortion in their models.Their work is significant in a number of respects. Not only are their distribution maps the first to chart phytoplankton; their models can also be used to predict how the diversity of phytoplankton could develop under changing temperature conditions. Warmer waters as a result of climate change could alter the distribution of phytoplankton. "In turn, this could have a serious impact on the entire marine food chain," Righetti says.
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Extinction
| 2,019 |
May 17, 2019
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https://www.sciencedaily.com/releases/2019/05/190517115129.htm
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Opposite pathways in forest recovery
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Tropical forests are being deforested at an alarming rate to make way for agriculture and pastureland; the good news is that they can regrow naturally when the fields are abandoned. An international research team including participation from the University of Göttingen has found that regenerating wet and dry forests actually show opposite pathways. This implies a fundamental change in our understanding of how tropical forests change over time, with consequences for forest restoration, biodiversity, and ecology. Their results were published in
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Eighty-five researchers from 16 different countries collected original data from 50 sites, 1,400 plots and more than 16,000 trees in tropical forests across Latin America. The scientists tracked the recovery of tropical forests to understand how the regrowing process works.They found that tree species that produce expensive and durable wood can persist for a very long time, especially under adverse climatic conditions but this strategy comes at the expense of a reduced and slow growth. Early in regeneration, light and water resources are in abundant supply, which leads to the dominance of "fast" pioneer species with soft wood. Whereas late in succession, the availability of resources declines, leading to the dominance of "slow" late-successional species with hard wood. This information is crucial to improving initiatives to restore forests and to select the best species for planting. "Our study shows how tropical forests regenerate on cattle pastures and agricultural fields," says Dr Dylan Craven from Göttingen University, who measured wood density in central Panama. "It is extraordinarily variable, mostly due to differences in climate. Understanding how tropical forests regenerate in different contexts will be essential for developing effective native species reforestation programmes and conservation areas for biodiversity and climate mitigation across Latin America. Hopefully similar studies from the African and Asian tropics will be forthcoming, and will strengthen similar programmes with a data-driven approach."
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Extinction
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May 15, 2019
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https://www.sciencedaily.com/releases/2019/05/190515175435.htm
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Hunting responsible for mammal declines in half of intact tropical forests
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Defaunation -- the loss of species or decline of animal populations -- is reaching even the most remote and pristine tropical forests. Within the tropics, only 20% of the remaining area is considered intact, where no logging or deforestation has been detected by remote sensing. However, a new study publishing May 14 in the open-access journal
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Overhunting, as opposed to deforestation, is undetectable by remote-sensing techniques, and to date, there were vast understudied areas in the tropics where hunting impacts on mammal communities were unknown. In this study, the authors have projected for the first time the spatial patterns of hunting-induced mammal defaunation in the tropics and have identified areas where hunting impacts on mammal communities are expected to be high.Predicted hotspots of hunting-induced defaunation are located in West and Central Africa, particularly Cameroon, and in Central America, NW South America and areas in SE Asia (Thailand, Malaysia and SW China). Predictions were based on a newly developed hunting regression model, based upon socio-economic drivers, such as human population density and hunters' access points, and species traits, such as body size. The model relies on more than 3,200 abundance data estimates from the last 40 years and included more than 160 studies and hundreds of authors studying approximately 300 mammal species across the tropics.These defaunation maps are expected to become an important input for large-scale biodiversity assessments, which have routinely ignored hunting impacts due to data paucity, and may inform species extinction risk assessments, conservation planning and progress evaluations to achieve global biodiversity targets.
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Extinction
| 2,019 |
May 15, 2019
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https://www.sciencedaily.com/releases/2019/05/190515085438.htm
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Dolphin ancestor's hearing was more like hoofed mammals than today's sea creatures
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Vanderbilt University paleontologists are looking into the evolutionary origins of the whistles and squeaks that dolphins and porpoises make -- part of the rare echolocation ability that allows them to effectively navigate their dark environment.
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The team, one of the first in the world to examine the ability's origins, used a small CT scanner to look inside a 30-million-year-old ear bone fossil from a specimen resembling Olympicetus avitus. This member of the toothed whale family, in a branch that died out before modern dolphins and porpoises appeared, lived in what is now the state of Washington. The CT scan revealed cochlear coiling with more turns than in animals with echolocation, indicating hearing more similar to the cloven-hoofed, terrestrial mammals dolphins came from than the sleek sea creatures they are today."The simple theory is that there was one origin for echolocation in dolphins, and we'd find it in their 30-million-year-old ancestor," said Rachel A. Racicot, who completed the research as a visiting scholar at Vanderbilt. "Now, we believe it didn't evolve just once in this lineage, but more than once and in more than one lineage -- at least in xenorophids, which are extinct, and somewhere along the line to the Odontoceti crown group that still survives."Because echolocation is useful for navigating dark waters, natural selection likely came into play with its development in the branch that survived, she said. The findings appear May 15 in The Royal Society journal Racicot will join Vanderbilt's Earth and Environmental Sciences Department after spending a year working in Germany. Her co-author, Assistant Professor of Earth and Environmental Sciences Simon A.F. Darroch, installed the CT scanner, which works the same way as those used in medicine and allows for internal examination of fossils without damaging them.Learning echolocation's origins also can help preserve modern creatures that use it, Darroch said, by understanding how they're perceiving sound from ship engines, oil drills and other machinery. Confusion over those sounds may be causing mass stranding events, and solving the mystery could lead to methods of discouraging species such as the vaquita, a small porpoise on the brink of extinction in the Gulf of California, away from boats and nets."If we develop correlates for the shapes of the inner ear and how that corresponds to hearing frequencies, we can extrapolate those methods without capturing animals and bombarding them with sounds that don't work," Darroch said.First, according to Racicot and Darroch, paleontologists will have to find and scan a much larger sampling of all the toothed whale group's ancestors and those of rare modern species.Other authors were Robert W. Boessenecker of the College of Charleston, who identified, described and prepared the specimen, and Jonathan H. Geisler of the New York Institute of Technology, who coded characters and explored its evolutionary tree.This work was supported by Vanderbilt University and National Science Foundation grant EAR 1349607.
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Extinction
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May 14, 2019
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https://www.sciencedaily.com/releases/2019/05/190514171415.htm
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Species facing climate change could find help in odd place: Urban environments
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When it comes to wildlife conservation efforts, urban environments could be far more helpful than we think, according to new research. A study published today in
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For landscapes to facilitate range expansion, there is a balance to be struck between promoting movement with low-quality habitat (places where a species can survive, but does not have all the resources it needs to complete its life cycle) and promoting population growth with high-quality habitat. They conclude that low-quality habitats that meet a minimum standard could actually provide a benefit as conduits for movement.The underlying behaviour that explains this surprising result is that when animals find themselves in an inhospitable area they tend to make longer and straighter movements. As long as they do not die in this area, their arrival at another breeding area will tend to be quicker. The researchers used data from 78 species in 70 studies to show that in 73 percent of cases, animals moved faster through 'lower-quality' habitats. To illustrate what this principle means on the ground, the team used mathematical models to calculate rates of range expansion across a variety of landscapes for an exemplar species -- the Baltimore checkerspot butterfly. They showed that range expansion is fastest through landscapes composed of around 15 percent high-quality habitat and 85 percent unsuitable habitat."At landscape scales, 15% high-quality habitat is still more than currently exists in most ecosystems. Nonetheless, our findings point to the potential of using suburban and even urban greenspace as underappreciated areas that could facilitate range shifts, if green spaces such as lawns were converted to native plant gardens, which have high conservation potential for insects and other wildlife species," said lead author Elizabeth Crone, a professor of biology at Tufts University.Jenny Hodgson, co-author of the study and lecturer in evolution, ecology and behaviour at the University of Liverpool added: "This could offer a new perspective of flexibility for landscape planners: they needn't worry if they can't create unbroken tracts of high-quality wildlife habitat, instead they can create strategic 'stepping stones' in urban and agricultural areas. However, the stepping stones need to provide resources for breeding, not just temporary food resources."The researchers hope their study will make designers of city and suburban environments start to think differently about their approach, by providing a starting point to assess the consequences of landscape structure in the management of wildlife, regardless of whether the goal is to enhance or restrict the potential for range expansion."Nearly all high-profile studies about biodiversity conservation have focused on documenting the patterns of species habitat use and movement. We feel that more insights are gained by considering the mechanisms behind these patterns," said co-author Cheryl Schultz, professor of conservation biology at Washington State University. "In this case, our discovery that lower quality habitats assist species movement to better habitats sets up a more realistic and achievable objective for urban landscapers, and provides an important complement to conservation efforts focused on preserving large tracts of natural areas and high-quality habitat."Also contributing to the study were Frithjof Lutscher, professor at University of Ottawa, who provided the population dynamics model and its analysis, and Leone Brown, research associate at Tufts University.This work was funded by a Department of Defense Strategic Environmental Research and Development Program Award to EEC and CBS (RC-2119) and by an NSERC Discovery Grant to FL (RGPIN-2016-04795).
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Extinction
| 2,019 |
May 13, 2019
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https://www.sciencedaily.com/releases/2019/05/190513100546.htm
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Understanding relationship break-ups to protect the reef
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Unravelling the secrets of the relationship between coral and the algae living inside it will help prevent coral bleaching, University of Queensland researchers believe.
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Bleaching occurs when the symbiotic relationship between coral and algae breaks down -- corals under environmental stress disconnect from their algae partners, which means they lose their energy source.Institute for Molecular Bioscience (IMB) researcher Dr Cheong Xin Chan said most studies to date have been about the corals rather than the algae."Little is known about the molecular mechanisms underlying their symbiotic relationship -- how can we understand the break-up if we don't understand the relationship in the first place?" he said.Dr Chan's team is using genomic data to look for genes that enhance resilience in the algae and help coral adapt to the environmental shifts created by climate change.The algae that live within coral are dinoflagellates, a type of phytoplankton -- tiny photosynthetic organisms that manufacture their own food harvesting energy from sunlight."This algae family is very diverse," Dr Chan said."Some are toxic, causing the harmful algal blooms known as 'red tides', while others provide bioluminescence or grow in sea ice, and many are free-living."IMB researcher Mr Raul González-Pech said the algal genome is about half the size of the human genome."Nothing is straightforward with these algae as they have some of the weirdest genomes we've ever seen," he said."In a human cell, the DNA is organised into 23 pairs of chromosomes but the DNA of these algal cells is so tightly packed that we still don't know exactly how many chromosomes they have."Previous studies were based on bacteria or parasites, with researchers predicting these algae would have a similar evolutionary path, but genetic data shows they operate very differently to other intracellular inhabitants."In our earlier analysis of the genomes, we found that these algae may be capable of sexual reproduction, which may enhance their capacity to adapt to the environment," Mr González-Pech said.The researchers now want to compare the genomics of the symbiotic and free-living species to understand how the differences in their genomes correspond to differences in their lifestyles.That would provide more clues about their symbiotic relationship with coral."Dinoflagellates are vital for the survival of Australia's Great Barrier Reef," Dr Chan said."We can use genomic information to address fundamental questions of what makes these algae successful symbiotic partners in the coral reefs, for example, how they contribute to heat-resistance in certain corals more than others."We have sequenced nine of these algal genomes in four years -- the sequencing technology has come so far and allowed us to be the most prolific lab for generating dinoflagellate genomic data.""Understanding this relationship between algae and coral is one of the most challenging problems."Here at IMB, we are motivated by the most complex puzzles."
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Extinction
| 2,019 |
May 10, 2019
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https://www.sciencedaily.com/releases/2019/05/190510091342.htm
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How whales defy the cancer odds: Good genes
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Scientists know that age and weight are risk factors in the development of cancer. That should mean that whales, which include some of the largest and longest-lived animals on Earth, have an outsized risk of developing cancer.
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But they don't. Instead, they are less likely to develop or die of this enigmatic disease. The same is true of elephants and dinosaurs' living relatives, birds. Marc Tollis, an assistant professor in the School of Informatics, Computing, and Cyber Systems at Northern Arizona University, wants to know why.Tollis led a team of scientists from Arizona State University, the University of Groningen in the Netherlands, the Center for Coastal Studies in Massachusetts and nine other institutions worldwide to study potential cancer suppression mechanisms in cetaceans, the mammalian group that includes whales, dolphins and porpoises. Their findings, which picked apart the genome of the humpback whale, as well as the genomes of nine other cetaceans, in order to determine how their cancer defenses are so effective, were published today in The study is the first major contribution from the newly formed Arizona Cancer and Evolution Center or ACE, directed by Carlo Maley under an $8.5 million award from the National Cancer Institute. Maley, an evolutionary biologist, is a researcher at ASU's Biodesign Virginia G. Piper Center for Personalized Diagnostics and professor in the School of Life Sciences. He is a senior co-author of the new study.The study found that nature has beaten cancer in countless ways across the tree of life, Tollis said, and researchers can use that information to help find potential new targets for preventing cancer in humans, like using the whale version of a protein that can stop cell proliferation to develop drugs that shrink tumors in humans."Our goal is not only to get nature to inform us about better cancer therapies, but to give the public a new perspective of cancer," Tollis said. "The fact that whales and elephants evolved to beat cancer, and that dinosaurs suffered from it as well, suggests that cancer has been a selective pressure across many millions of years of evolution, and it has always been with us. Our hope is that this may change people's relationship with the disease, which can be painful and personal. It also helps provide even better appreciation for biodiversity. In our current sixth mass extinction, we need all the reasons for conservation that we can get."At its most basic, cancer occurs when body cells divide and mutate. Cell division is normal in living creatures, as are body cell, or somatic, mutations. Most of the time, somatic mutations are either harmless or the body is able to fix those mutations. When it doesn't, that can lead to cancer.Beyond that foundation, cancer gets much more complicated. For all of the research being done on all types of cancer and all types of organisms, there are still more questions than answers. However, age and body size are well-known risk factors in people. Tollis said one explanation for this is that cancer risk overall is a function of the number of cell divisions that occur over the lifetime of an organism."This is driven by somatic evolution -- genetic changes that occur when body cells copy their genomes, divide and produce daughter cells," he said. "The longer you live, the more cell divisions you have and the higher chance that a cancer-causing mutation will occur in the genome of the descendent cells. Similarly, larger individuals are made of more cells, which also increases the chance of cancer-causing mutations."Knowing this, it's worth looking at whether whales, which live longer than most mammals on the planet and have a much higher percentage of body fat, are more likely to develop cancer. They aren't. This phenomenon, known as Peto's Paradox, is what Tollis and his team studied. How do whales defy these well-known risk factors? In earlier research, ASU's Carlo Maley investigated alternate mechanisms responsible for cancer suppression in elephants.The team worked under a federal research permit to obtain skin samples from an adult female humpback whale off the coast of Massachusetts. This whale, named Salt, is well-known to researchers and whale watchers alike. She was cataloged by the Center for Coastal Studies in the mid-1970s and selected for this study because her life history is among the most well-documented of any individual humpback whale. The team sequenced and assembled Salt's genome, which requires extracting DNA from skin tissue, fractioning it into smaller bits and put through a DNA sequencer that produces almost 2 billion short sequences. Then they put those sequences back together into a genome assembly that spans about 2.7 billion base pairs. (By contrast, the human genome is about 3.1 billion base pairs long.) They also sequenced RNA, which helps in the process of finding the precise coordinates where genes lie in the genome.The team then compared the humpback whale genome to those of other mammals including other ocean giants like the blue whale, fin whale, bowhead whale and sperm whale. They expected to see a lot of differences, but also a few similarities, particularly with the parts of the genome that perform important functions. They also looked for parts of the genome that had evolved to help whales adapt to their environment.What they found was that some parts of the whale genome have evolved faster than in other mammals. These parts of the whale genome contain genes that control the cell cycle, cell proliferation and DNA repair, which are essential for normal cell function. In human cancers, many of these genes are mutated. The whale genome also evolved many duplications in tumor suppressor genes."Nature is showing us that these changes to cancer genes are compatible with life. The next questions are, which of these changes is preventing cancer, and can we translate those discoveries into preventing cancer in humans?" said Carlo Maley, a cancer evolutionary biologist from ASU's Biodesign Institute and one of the two senior authors, who started this project in 2011 with Per Palsbøll, a marine mammal conservation geneticist from the Groningen Institute for Evolutionary Life Sciences at University of Groningen, in collaboration with Jooke Robbins from the Center for Coastal Studies."This suggests that whales are unique among mammals in that in order to evolve their gigantic sizes, these important 'housekeeping' genes, that are evolutionarily conserved and normally prevent cancer, had to keep up in order to maintain the species' fitness," Tollis said. "We also found that despite these cancer-related parts of whale genomes evolving faster than other mammals, on average whales have accumulated far fewer DNA mutations in their genomes over time compared to other mammals, which suggests they have slower mutation rates."This slow rate of change may also limit whales' exposure to cancer-causing somatic mutations.This study builds on research that the ASU team has done finding lower rates of cancer in elephants, another mammal that is large and can live a long time but doesn't have much in common genetically with whales. Both species arrived at the same result -- cancer suppression -- through different mechanisms. The same is likely true of extinct giant dinosaurs; although scientists have found evidence of cancer in dinosaur fossils, this group of organisms includes the largest animals ever to walk the earth and thus they probably had efficient cancer suppression as well.Next steps for Tollis and his team will be to better understand the cancer suppression phenotype using experiments with whale cell lines, which will provide important functional validation of the team's genomic results. That will be the first step in generating whale-derived human cancer drugs. They also are looking at other animals, such as bats, tortoises and crocodilians, to see how these varied long-lived species suppress cancer. The humpback whale genome also will serve as the basis for studies by other team members on whale mutation rates and other adaptations taking advantage of a collection of the 9,000-plus DNA samples collected from free-ranging humpback whales curated by Palsbøll's team.This research is supported by the Arizona Cancer Evolution Center, which is funded through a five-year grant from the National Institutes of Health, with additional funding by the University of Groningen.
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Extinction
| 2,019 |
May 9, 2019
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https://www.sciencedaily.com/releases/2019/05/190509101916.htm
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The bird that came back from the dead
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New research has shown that the last surviving flightless species of bird, a type of rail, in the Indian Ocean had previously gone extinct but rose from the dead thanks to a rare process called 'iterative evolution'.
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The research, from the University of Portsmouth and Natural History Museum, found that on two occasions, separated by tens of thousands of years, a rail species was able to successfully colonise an isolated atoll called Aldabra and subsequently became flightless on both occasions. The last surviving colony of flightless rails is still found on the island today.This is the first time that iterative evolution (the repeated evolution of similar or parallel structures from the same ancestor but at different times) has been seen in rails and one of the most significant in bird records.The white-throated rail is a chicken-sized bird, indigenous to Madagascar in the south-western Indian Ocean. They are persistent colonisers of isolated islands, who would have frequent population explosions and migrate in great numbers from Madagascar. Many of those that went north or south drowned in the expanse of ocean and those that went west landed in Africa, where predators ate them. Of those that went east, some landed on the many ocean islands such as Mauritius, Reunion and Aldabra, the last-named is a ring-shaped coral atoll that formed around 400,000 years ago.With the absence of predators on the atoll, and just like the Dodo of Mauritius, the rails evolved so that they lost the ability to fly. However, Aldabra disappeared when it was completely covered by the sea during a major inundation event around 136,000 years ago, wiping out all fauna and flora including the flightless rail.The researchers studied fossil evidence from 100,000 years ago when the sea-levels fell during the subsequent ice age and the atoll was recolonised by flightless rails. The researchers compared the bones of a fossilised rail from before the inundation event with bones from a rail after the inundation event. They found that the wing bone showed an advanced state of flightlessness and the ankle bones showed distinct properties that it was evolving toward flightlessness.This means that one species from Madagascar gave rise to two different species of flightless rail on Aldabra in the space of a few thousand years.Lead researcher Dr Julian Hume, avian paleontologist and Research Associate at the Natural History Museum, said: "These unique fossils provide irrefutable evidence that a member of the rail family colonised the atoll, most likely from Madagascar, and became flightless independently on each occasion. Fossil evidence presented here is unique for rails, and epitomises the ability of these birds to successfully colonise isolated islands and evolve flightlessness on multiple occasions."Co-author Professor David Martill, from the School of Earth and Environmental Sciences at the University of Portsmouth, said: "We know of no other example in rails, or of birds in general, that demonstrates this phenomenon so evidently. Only on Aldabra, which has the oldest palaeontological record of any oceanic island within the Indian Ocean region, is fossil evidence available that demonstrates the effects of changing sea levels on extinction and recolonisation events."Conditions were such on Aldabra, the most important being the absence of terrestrial predators and competing mammals, that a rail was able to evolve flightlessness independently on each occasion."The study is published in the latest issue of the
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Extinction
| 2,019 |
May 6, 2019
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https://www.sciencedaily.com/releases/2019/05/190506150049.htm
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Shipwrecks off North Carolina, U.S. coast harbor tropical migrants
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Tropical and subtropical fish are taking up residence on shipwrecks and other sunken structures off the North Carolina coast. This pattern may continue or even accelerate in coming years given predictions of warming oceans under climate change, a new study co-led by Duke University scientists suggests.
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"The artificial reefs created by these structures may be acting as stepping stones for fish that are moving northward and living at the edge of their geographic range, or beyond it, in search of suitable habitat," said Avery B. Paxton, a visiting scholar at the Duke University Marine Laboratory, who was lead author of the study."Globally, there is broad evidence that many tropical fish species are shifting their ranges poleward and to deeper waters in response to changing ocean conditions, and what we see on these reefs seems to fit that pattern," she said.One of the most surprising findings of the study is that the tropical and subtropical fish observed off North Carolina exhibit a strong preference for hanging out on human-made structures versus natural rocky reefs found nearby, noted J. Christopher Taylor, a research ecologist at NOAA's National Centers for Coastal Ocean Science and a co-author of the study."It could be that the zooplankton and smaller fish these species eat are more plentiful on artificial reefs. Or it could be that human-made reefs' complex structures give the fish more nooks and crannies where they can evade predators. We're still trying to figure it out," Taylor said.The fishes' preference for artificial habitats suggests networks of the human-made structures -- which are already commonly found up and down the East Coast and in other waters worldwide -- could act as underwater corridors the fish use to reach the habitats they need to survive, said Paxton, who also works with CSS Inc. under contract to NOAA's National Centers for Coastal Ocean Science.Paxton, Taylor and their colleagues published their peer-reviewed paper May 6 in To do the study, teams of scuba-diving scientists conducted population and species counts at 30 artificial and natural reefs off the N.C. coast between 2013 and 2015. To track seasonal differences in fish populations, most of the reefs were visited four times a year.Analysis of the data confirmed that the number and diversity of tropical and subtropical fish on deep artificial reefs was far greater than on nearby natural reefs.Common tropical species spotted on the artificial reefs included blue chromis, purple reef fish and bluehead wrasse. Common subtropical species spotted there included vermilion snapper, greater amberjack and bar jack.Temperate fish species such as black sea bass and tautog, on the other hand, were far more prevalent on the area's natural rocky reefs.The depth of the artificial reef mattered hugely, Paxton noted."We didn't see these patterns on artificial reefs at shallow or intermediate depths, we only saw them on deep reefs, located between 80 to 115 feet below the surface, where water temperatures often experience less seasonal change," she said.
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Extinction
| 2,019 |
May 6, 2019
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https://www.sciencedaily.com/releases/2019/05/190506111436.htm
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Oxygen linked with the boom and bust of early animal evolution
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Extreme fluctuations in atmospheric oxygen levels corresponded with evolutionary surges and extinctions in animal biodiversity during the Cambrian explosion, finds new study led by UCL and the University of Leeds.
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The Cambrian explosion was a crucial period of rapid evolution in complex animals that began roughly 540 million years ago. The trigger for this fundamental phase in the early history of animal life is a subject of ongoing biological debate.The study, published today in The study is the first to show that during the Cambrian explosion there was significant correlation between surges in oxygen levels and bursts in animal evolution and biodiversity, as well as extinction events during periods of low oxygen.Dr Tianchen He, study lead author and postdoctoral researcher at the University of Leeds, began this research while at UCL. He said: "The complex creatures that came about during the Cambrian explosion were the precursors to many of the modern animals we see today. But because there is no direct record of atmospheric oxygen during this time period it has been difficult to determine what factors might have kick started this crucial point in evolution."By analysing the carbon and sulphur isotopes found in ancient rocks, we are able to trace oxygen variations in Earth's atmosphere and shallow oceans during the Cambrian Explosion. When compared to fossilised animals from the same time we can clearly see that evolutionary radiations follow a pattern of 'boom and bust' in tandem with the oxygen levels."This strongly suggests oxygen played a vital role in the emergence of early animal life."Study co-author Professor Graham Shields from UCL Earth Sciences, said: "This is the first study to show clearly that our earliest animal ancestors experienced a series of evolutionary radiations and bottlenecks caused by extreme changes in atmospheric oxygen levels."The result was a veritable explosion of new animal forms during more than 13 million years of the Cambrian Period. In that time, Earth went from being populated by simple, single-celled and immobile organisms to hosting the wonderful variety of intricate, energetic life forms we see today."The team analysed the carbon and sulphur isotopes from marine carbonate samples collected from sections along the Aldan and Lena rivers in Siberia. During the time of the Cambrian explosion this area would have been a shallow sea and the home for the majority of animal life on Earth.The lower Cambrian strata in Siberia are composed of continuous limestone with rich fossil records and reliable age constraints, providing suitable samples for the geochemical analyses. The isotope signatures in the rocks relate to the global production of oxygen, allowing the team to determine oxygen levels present in the shallow ocean and atmosphere during the Cambrian Period.Study co-author Dr Benjamin Mills, from the School of Earth and Environment at Leeds, said: "The Siberian Platform gives us a unique window into early marine ecosystems. This area contains over half of all currently known fossilised diversity from the Cambrian explosion."Combining our isotope measurements with a mathematical model lets us track the pulses of carbon and sulphur entering the sediments in this critical evolutionary cradle. Our model uses this information to estimate the global balance of oxygen production and destruction, giving us new insight into how oxygen shaped the life we have on the planet today."Study co-author Maoyan Zhu from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, said: "Understanding what triggered the Cambrian explosion requires multidisciplinary study. That's why with Graham Shields we organized together such a multidisciplinary team funded by NERC and NSFC in past years. I am so excited about the results through this collaborative project.""On the other hand, it took a long time to get this result. We already got samples from Siberia in 2008. The sections in Siberia are difficult to access. It took time for us to organize the expedition and collect the samples there. Without support from Russian colleagues, we could not do the project."Study co-author Andrey Yu Zhuravlev from Lomonosov Moscow State University said: "This has been an incredibly successful and exciting joint study. The question of the Cambrian Explosion trigger has puzzled scientists for years. Now, the results give us convincing evidence to link the rapid appearance of animals as well as mass extinction during the early Cambrian with oxygen."
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Extinction
| 2,019 |
May 6, 2019
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https://www.sciencedaily.com/releases/2019/05/190506093610.htm
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Nature's dangerous decline 'unprecedented,' species extinction rates 'accelerating'
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Nature is declining globally at rates unprecedented in human history -- and the rate of species extinctions is accelerating, with grave impacts on people around the world now likely, warns a landmark new report from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the summary of which was approved at the 7th session of the IPBES Plenary, meeting last week (29 April -- 4 May) in Paris.
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"The overwhelming evidence of the IPBES Global Assessment, from a wide range of different fields of knowledge, presents an ominous picture," said IPBES Chair, Sir Robert Watson. "The health of ecosystems on which we and all other species depend is deteriorating more rapidly than ever. We are eroding the very foundations of our economies, livelihoods, food security, health and quality of life worldwide.""The Report also tells us that it is not too late to make a difference, but only if we start now at every level from local to global," he said. "Through 'transformative change', nature can still be conserved, restored and used sustainably -- this is also key to meeting most other global goals. By transformative change, we mean a fundamental, system-wide reorganization across technological, economic and social factors, including paradigms, goals and values.""The member States of IPBES Plenary have now acknowledged that, by its very nature, transformative change can expect opposition from those with interests vested in the status quo, but also that such opposition can be overcome for the broader public good," Watson said.The IPBES Global Assessment Report on Biodiversity and Ecosystem Services is the most comprehensive ever completed. It is the first intergovernmental Report of its kind and builds on the landmark Millennium Ecosystem Assessment of 2005, introducing innovative ways of evaluating evidence.Compiled by 145 expert authors from 50 countries over the past three years, with inputs from another 310 contributing authors, the Report assesses changes over the past five decades, providing a comprehensive picture of the relationship between economic development pathways and their impacts on nature. It also offers a range of possible scenarios for the coming decades.Based on the systematic review of about 15,000 scientific and government sources, the Report also draws (for the first time ever at this scale) on indigenous and local knowledge, particularly addressing issues relevant to Indigenous Peoples and Local Communities."Biodiversity and nature's contributions to people are our common heritage and humanity's most important life-supporting 'safety net'. But our safety net is stretched almost to breaking point," said Prof. Sandra Díaz (Argentina), who co-chaired the Assessment with Prof. Josef Settele (Germany) and Prof. Eduardo S. Brondízio (Brazil and USA)."The diversity within species, between species and of ecosystems, as well as many fundamental contributions we derive from nature, are declining fast, although we still have the means to ensure a sustainable future for people and the planet."The Report finds that around 1 million animal and plant species are now threatened with extinction, many within decades, more than ever before in human history.The average abundance of native species in most major land-based habitats has fallen by at least 20%, mostly since 1900. More than 40% of amphibian species, almost 33% of reef-forming corals and more than a third of all marine mammals are threatened. The picture is less clear for insect species, but available evidence supports a tentative estimate of 10% being threatened. At least 680 vertebrate species had been driven to extinction since the 16th century and more than 9% of all domesticated breeds of mammals used for food and agriculture had become extinct by 2016, with at least 1,000 more breeds still threatened."Ecosystems, species, wild populations, local varieties and breeds of domesticated plants and animals are shrinking, deteriorating or vanishing. The essential, interconnected web of life on Earth is getting smaller and increasingly frayed," said Prof. Settele. "This loss is a direct result of human activity and constitutes a direct threat to human well-being in all regions of the world."To increase the policy-relevance of the Report, the assessment's authors have ranked, for the first time at this scale and based on a thorough analysis of the available evidence, the five direct drivers of change in nature with the largest relative global impacts so far. These culprits are, in descending order: (1) changes in land and sea use; (2) direct exploitation of organisms; (3) climate change; (4) pollution and (5) invasive alien species.The Report notes that, since 1980, greenhouse gas emissions have doubled, raising average global temperatures by at least 0.7 degrees Celsius -- with climate change already impacting nature from the level of ecosystems to that of genetics -- impacts expected to increase over the coming decades, in some cases surpassing the impact of land and sea use change and other drivers.Despite progress to conserve nature and implement policies, the Report also finds that global goals for conserving and sustainably using nature and achieving sustainability cannot be met by current trajectories, and goals for 2030 and beyond may only be achieved through transformative changes across economic, social, political and technological factors. With good progress on components of only four of the 20 Aichi Biodiversity Targets, it is likely that most will be missed by the 2020 deadline. Current negative trends in biodiversity and ecosystems will undermine progress towards 80% (35 out of 44) of the assessed targets of the Sustainable Development Goals, related to poverty, hunger, health, water, cities, climate, oceans and land (SDGs 1, 2, 3, 6, 11, 13, 14 and 15). Loss of biodiversity is therefore shown to be not only an environmental issue, but also a developmental, economic, security, social and moral issue as well."To better understand and, more importantly, to address the main causes of damage to biodiversity and nature's contributions to people, we need to understand the history and global interconnection of complex demographic and economic indirect drivers of change, as well as the social values that underpin them," said Prof. Brondízio. "Key indirect drivers include increased population and per capita consumption; technological innovation, which in some cases has lowered and in other cases increased the damage to nature; and, critically, issues of governance and accountability. A pattern that emerges is one of global interconnectivity and 'telecoupling' -- with resource extraction and production often occurring in one part of the world to satisfy the needs of distant consumers in other regions."The Report also presents a wide range of illustrative actions for sustainability and pathways for achieving them across and between sectors such as agriculture, forestry, marine systems, freshwater systems, urban areas, energy, finance and many others. It highlights the importance of, among others, adopting integrated management and cross-sectoral approaches that take into account the trade-offs of food and energy production, infrastructure, freshwater and coastal management, and biodiversity conservation.Also identified as a key element of more sustainable future policies is the evolution of global financial and economic systems to build a global sustainable economy, steering away from the current limited paradigm of economic growth."IPBES presents the authoritative science, knowledge and the policy options to decision-makers for their consideration," said IPBES Executive Secretary, Dr. Anne Larigauderie. "We thank the hundreds of experts, from around the world, who have volunteered their time and knowledge to help address the loss of species, ecosystems and genetic diversity -- a truly global and generational threat to human well-being."
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Extinction
| 2,019 |
May 3, 2019
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https://www.sciencedaily.com/releases/2019/05/190503080558.htm
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Breaking bread with rivals leads to more fish on coral reefs
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Cooperation is key to most successful endeavours. And, scientists find, when fishermen and women cooperate with other fishers, this can boost fish stocks on coral reefs.
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Dr Michele Barnes, a senior research fellow from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU), is the lead author of a study published today that looks at the relationships between competing fishers, the fish species they hunt, and their local reefs."Relationships between people have important consequences for the long-term availability of the natural resources we depend on," Dr Barnes says."Our results suggest that when fishers -- specifically those in competition with one another -- communicate and cooperate over local environmental problems, they can improve the quality and quantity of fish on coral reefs."Co-author Prof Nick Graham, from Lancaster University (previously at JCU), adds: "Coral reefs across the world are severely degraded by climate change, the pervasive impacts of poor water quality, and heavy fishing pressure. Our findings provide important insights on how fish communities can be improved, even on the reefs where they are sought."Dr Barnes and her team interviewed 648 fishers and gathered underwater visual data of reef conditions across five coral reef fishing communities in Kenya.They found that in the places where fishers communicated with their competitors about the fishing gear they use, hunting locations, and fishing rules, there were more fish in the sea -- and of higher quality.Co-author Dr Jack Kittinger, Senior Director at Conservation International's Center for Oceans, says this is likely because such cooperative relationships among those who compete for a shared resource -- such as fish -- create opportunities to engage in mutually beneficial activities. These relationships also help build trust, which enables people to develop a shared commitment to managing resources sustainably."This is why communication is so critical," says Dr Kittinger. "Developing sustained commitments, such as agreements on rules, and setting up conflict resolution mechanisms, are key to the local management of reefs.""The study demonstrates that the positive effect of communication does not necessarily appear when just anyone in a fishing community communicates -- this only applies to fishers competing over the same fish species," adds co-author Dr Örjan Bodin, from the Stockholm Resilience Centre at Stockholm University.The study advances a framework that can be applied to other complex environmental problems where environmental conditions depend on the relationships between people and nature.Co-author Dr Orou Gaoue, from the University of Tennessee Knoxville, emphasises this broad appeal."Although this study is on coral reefs, the results are also relevant for terrestrial ecosystems where, in the absence of cooperation, competition for non-timber forest products can quickly lead to depletion even when locals have detailed ecological knowledge of their environment.""Environmental problems are messy," explains Dr Barnes. "They often involve multiple, interconnected resources and a lot of different people -- each with their own unique relationship to nature.""Understanding who should cooperate with whom in different contexts and to address different types of environmental problems is thus becoming increasingly important," she concludes.
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Extinction
| 2,019 |
May 1, 2019
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https://www.sciencedaily.com/releases/2019/05/190501114623.htm
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Flowering plants, new teeth and no dinosaurs: New study sheds light on the rise of mammals
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A new study published April 30 in the
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Previously, mammals in the Age of Dinosaurs were thought to be a relatively small part of their ecosystems and considered to be small-bodied, nocturnal, ground-dwelling insectivores. According to this long-standing theory, it wasn't until the K-Pg mass extinction event about 66 million years ago, which wiped out all non-avian dinosaurs, that mammals were then able to flourish and diversify. An astounding number of fossil discoveries over the past 30 years has challenged this theory, but most studies looked only at individual species and none has quantified community-scale patterns of the rise of mammals in the Mesozoic Era.Co-authors are Meng Chen, a University of Washington alumnus and current postdoctoral researcher at Nanjing University; Caroline Strömberg, a University of Washington biology professor and curator of paleobotany at the UW's Burke Museum of Natural History & Culture; and Gregory Wilson, a UW associate professor of biology and Burke Museum curator of vertebrate paleontology. The team created a Rubik's Cube-like structure identifying 240 "eco-cells" representing possible ecological roles of mammals in a given ecospace. These 240 eco-cells cover a broad range of body size, dietary preferences, and ways of moving of small-bodied mammals. When a given mammal filled a certain type of role or eco-cell, it filled a spot in the 'Rubik's Cube.' This method provides the first comprehensive analysis of evolutionary and ecological changes of fossil mammal communities before and after K-Pg mass extinction."We cannot directly observe the ecology of extinct species, but body size, dietary preferences and locomotion are three aspects of their ecology that can be relatively easily inferred from well-preserved fossils," said Chen. "By constructing the ecospace using these three ecological aspects, we can visually identify the spots filled by species and calculate the distance among them. This allows us to compare the ecological structure of extinct and extant communities even though they don't share any of the same species."The team analyzed living mammals to infer how fossil mammals filled roles in their ecosystems. They examined 98 small-bodied mammal communities from diverse biomes around the world, an approach that has not been attempted at this scale. They then used this modern-day reference dataset to analyze five exceptionally preserved mammal paleocommunities -- two Jurassic Period and two Cretaceous Period communities from northeastern China, and one Eocene Epoch community from Germany. Usually Mesozoic Era mammal fossils are incomplete and consist of fragmentary bones or teeth. Using these remarkably preserved fossils enabled the team to infer ecology of these extinct mammal species, and look at changes in mammal community structure during the last 165 million years.The team found that, in current communities of present-day mammals, ecological richness is primarily driven by vegetation type, with 41 percent of small mammals filling eco-cells compared to 16 percent in the paleocommunities. The five mammal paleocommunities were also ecologically distinct from modern communities and pointed to important changes through evolutionary time. Locomotor diversification occurred first during the Mesozoic, possibly due to the diversity of microhabitats, such as trees, soils, lakes and other substrates to occupy in local environments. It wasn't until the Eocene that mammals grew larger and expanded their diets from mostly carnivory, insectivory and omnivory to include more species with diets dominated by plants, including fruit. The team determined that the rise of flowering plants, new types of teeth and the extinction of dinosaurs likely drove these changes.Before the rise of flowering plants, mammals likely relied on conifers and other seed plants for habitat, and their leaves and possibly seeds for food. By the Eocene, flowering plants were both diverse and dominant across forest ecosystems. Flowering plants provide more readily available nutrients through their fast-growing leaves, fleshy fruits, seeds and tubers. When becoming dominant in forests, they fundamentally changed terrestrial ecosystems by allowing for new modes of life for a diversity of mammals and other forest-dwelling animals, such as birds."Flowering plants really revolutionized terrestrial ecosystems," said Strömberg. "They have a broader range of growth forms than all other plant groups -- from giant trees to tiny annual herbs -- and can produce nutrient-rich tissues at a faster rate than other plants. So when they started dominating ecosystems, they allowed for a wider variety of life modes and also for much higher 'packing' of species with similar ecological roles, especially in tropical forests."Tribosphenic molars -- complex multi-functional cheek teeth -- became prevalent in mammals in the late Cretaceous Period. Mutations and natural selection drastically changed the shapes of these molars, allowing them to do new things like grinding. In turn, this allowed small mammals with these types of teeth to eat new kinds of foods and diversify their diets.Lastly, the K-Pg mass extinction event that wiped out all dinosaurs except birds 66 million years ago provided an evolutionary and ecological opportunity for mammals. Small body size is a way to avoid being eaten by dinosaurs and other large vertebrates. The mass extinction event not only removed the main predators of mammals, but also removed small dinosaurs that competed with mammals for resources. This ecological release allowed mammals to grow into larger sizes and fill the roles the dinosaurs once had."The old theory that early mammals were held in check by dinosaurs has some truth to it," said Wilson. "But our study also shows that the rise of modern mammal communities was multifaceted and depended on dental evolution and the rise of flowering plants."
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Extinction
| 2,019 |
April 30, 2019
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https://www.sciencedaily.com/releases/2019/04/190430141628.htm
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Marine scientists investigate the relationship between bumphead parrotfish and their coral reef habitat on a molecular level
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The next time you find yourself luxuriating in some exotic, Instagrammable vacation spot, thank a parrotfish. That white sand slithering between your toes? It consists mostly of their excrement.
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But here's another thing for which we can be grateful: our enhanced understanding of their environment's system chemistry and system ecology.In a study focused on the chemistry of the consumption and excretion of the bumphead parrotfish (Bolbometopon muricatum), UC Santa Barbara marine scientists sought to understand the relationship between the the massive, coral mega-consumers and the reef environments that serve as the fishes' habitats as well as their sources of sustenance."They're underwater elephants," said Grace Goldberg, lead author of a paper published in the journal "We think about coral reef systems as these stressed systems under climate change," Goldberg said. "And these fish, because they're so big, drive a lot of reef processes through their interaction with the coral and the physical reef environment." To understand how they forage is to get a better picture of the complex dynamics that shape the reefs and the communities they support.But while it's common knowledge that environments and the species therein influence each other to some degree, the extent of this relationship can now be defined at a molecular level, with results that add new perspective to the study of coral reef ecology."What do we know about the raw materials of what they're ingesting and what they're pooping out?" Goldberg said.To find out, the researchers collected fecal samples while swimming behind B. muricatum at the Palmyra Atoll in the heart of the Pacific Ocean. Bumphead parrotfish, unlike their fellow corallivorous cousins, dine almost exclusively on coral polyps and their calcium carbonate skeletons. Live coral (with polyps) and coral rock (just the hard skeleton) bites were also sampled in the process. The researchers used a chisel and calipers to remove a bite-sized chunk for analysis.Then they turned to materials science. Using a differential scanning calorimeter, they probed their samples for their energy content, the same way chemists and materials scientists might investigate the energy content of coal and other fuels. They also used an elemental analyzer to determine the presence of nutrients and other elements relevant to the fish and the reefs.The results? Coral rock, it turns out, contains about three times as many calories than live coral does. While the coral rock is considered "dead," Goldberg said, other organisms colonize and recolonize the stony structures."It actually carries more nutrition and is full of life and full of calories," she said. More work is necessary to understand what quantity of the nutrients the fish actually absorb into their tissues, Goldberg added, which may shed light on their foraging habits.At the other end, bumphead parrotfish feces, unlike that of other fish and marine organisms, was not shown to generate any significant impacts on the chemistry of their coral reef environment.The researchers' findings contribute to a growing body of knowledge of coral reef ecology. The role of bumphead parrotfish in particular is complex. Their feeding habits contribute to the health of the reefs by consuming algae that compete with coral polyps for surface area. The fish also aid in the corals' reproduction by opening up space and fragmenting the corals, which allows polyps to spread and colonize other sections of reef. But, their consumption of large amounts of coral and the potential of their prodigious amount of feces to smother parts of the reef could also be cause for concern, especially in an era of shrinking coral reefs. Because the bumpheads exert such a huge effect on the reefs they live in and feed on, they present an ecological puzzle to those who work to conserve the vulnerable fish and their sensitive, shrinking environment."We wanted to understand why it eats what it eats and what the implications of it might be for their environment," Goldberg said of the multidisciplinary approach to studying the foraging habits of the bumphead parrotfish. "We're trying to understand it in a really holistic way."
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Extinction
| 2,019 |
April 29, 2019
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https://www.sciencedaily.com/releases/2019/04/190429154554.htm
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Are coffee farms for the birds? Yes and no
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Over 11 field seasons, between 1999 and 2010, ornithologist Cagan Sekercioglu trekked through the forests and coffee fields of Costa Rica to study how tropical birds were faring in a changing agricultural landscape. Through painstaking banding of individual birds, Sekercioglu asked whether the expansion of coffee plantations is reducing tropical bird biodiversity.
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The answer, published this week in "It's two sides of a coin," Sekercioglu says. "These tropical agricultural habitats that are mostly deforested still maintain large numbers of tropical species. Even small patches of trees can make a difference and help some species. But the flip side of the coin is, in the long term, most of these species are still declining."The seeds of this project were planted in 1996 when Sekercioglu, then an undergraduate at Harvard University, was studying the effects of logging on tropical bird communities in Uganda. "I wanted to continue that research in grad school," he says, "but I wanted something long term. Not just a quick snapshot, but a multiyear study where I could look at long-term population change."Such long-term studies are rare, partially because of the research timeline of a typical graduate student. Doctoral students in biology may be able to collect four years of data before compiling their research into a dissertation to complete their degree. But Sekercioglu wanted more than four years. To get the long-term trends he wanted, he needed at least six years. Ten would be even better.With the blessing of his doctoral advisory committee at Stanford University, Sekercioglu set out for Costa Rica in 1999 for the first of 11 field seasons. Between 1999 and 2010, he and his team set up stations in both protected forests and in coffee plantations where he and colleagues would extend nearly invisible nets. The "mist nets" allowed the researchers to temporarily capture birds and affix an ankle band, or check for an existing band, before releasing the bird. Banding allows each bird to be individually identifiable -- an essential element of fine-grained population surveys. "These are small, often secretive songbirds we're talking about," Sekercioglu says. "You need the bird banding. It's labor intensive, but there's really no substitute."After earning his doctorate in 2003, Sekercioglu remained at Stanford, first as a postdoctoral scholar and then as a senior research scientist, to keep the Costa Rica project going. Over the years, with the support of his co-authors Gretchen Daily, Paul Ehrlich, Chase Mendenhall and Federico Oviedo-Brenes, he and his colleagues mist netted 57,307 birds from 265 species in 19 different study sites -- all by hand. In 2009, after securing a position at the University of Utah, he wrapped up his field work in Costa Rica before moving to his current lab in Salt Lake City in 2010.In Sekercioglu's new paper, he and his co-authors present their results. First, some definitions of the land types in the study:The results of the study are a mix of Over the study period, 61% more bird populations declined as remained stable or grew, and this trend held in all study sites except those in the large La Amistad International Park. "If you really want to conserve the native tropical forest bird community," Sekercioglu says, "there's really no replacement for big forest reserves like La Amistad. You really need at least 1,000 hectares (3.86 square miles) native primary forest. So, there's no replacement for that."Now some But just looking at the number of species can hide some The coffee plantations redeem themselves, somewhat, with a little bit of Are shaded coffee plantations an answer to the threat of deforestation? "No" Sekercioglu says. "In the long term, by themselves, they are not enough to preserve tropical biodiversity. We need a combination of agricultural areas with as much tree cover as possible and extensive primary forest reserves."Despite the labor-intensive nature of a bird banding study and the relative rarity of such a long-term project, an undertaking like this is necessary to get a more accurate picture of bird population compositions and trends. "These days it would be very hard to do a study like this," Sekercioglu says. A "snapshot study" might have concluded, for example, that the number of bird species in the Las Cruces Forest Reserve indicated a healthy forest, when in fact Sekercioglu's study found more than three-fifths of the bird species in decline."Short-term studies that focus just on species richness are likely to provide a rosier picture of the community health and the conservation status of these species than the reality," he says.Sekercioglu's co-authors were Chase D. Mendenhall of the Carnegie Museum of Natural History, Federico Oviedo-Brenes of the Organization for Tropical Studies, Joshua J. Horns of the University of Utah and Paul R. Ehrlich and Gretchen C. Daily of Stanford University.The study was supported by grants from the Moore Family Foundation, the National Geographic Society, the Wildlife Conservation Society and the Winslow Foundation.Sekercioglu says that certified shade-grown coffee plantations are the best for bird biodiversity and species health. He can say that with authority -- he's traveled to the Kaffa province in Ethiopia from which coffee got its name, where he discovered the world's bird friendliest coffee. There, where indigenous coffee plants grow beneath canopies of native trees, Sekercioglu and his team recorded all the same species in traditional shade coffee plantations that they had also mist netted in large forest reserves. Shade-grown coffee plantations produce smaller yields than sun coffee plantations, but shade-grown coffee farms are the "gold standard" for friendliness to birds. Several programs exist for certifying shade-grown coffee, with the Bird-Friendly Coffee certification from the Smithsonian Migratory Bird Center maintaining the highest standards.
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Extinction
| 2,019 |
April 25, 2019
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https://www.sciencedaily.com/releases/2019/04/190425162351.htm
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Preventing collapse after catastrophe
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As the impacts of climate change escalate, ecosystems will likely undergo events that will disrupt entire populations. In marine ecosystems, anthropogenic warming has subjected organisms to elevated temperatures, oxygen loss, and acidification. The increased frequency and severity of catastrophic events may inhibit a population's ability to recover and, in turn, may spur collapse.
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Mass mortality events can exacerbate the risk of extinction for species that are prone to Allee effects, particularly species harvested commercially. When species experience Allee effects, they exhibit diminished reproductive success at decreased population density. Managed fisheries frequently keep populations at low densities.In "Catastrophic Mortality, Allee Effects, and Marine Protected Areas," published in While recent hypoxic events led to significant abalone decreases at Isla Natividad, the "no-take reserves" in the region sustained a higher density of abalones and produced higher recruitment levels after the disruption in comparison to the areas where fishing occurs.The authors propose that the implementation of marine protected areas (MPAs) that incorporate "no-take reserves" offers a spatial management strategy that ensures available resources to restore depleted populations and encourage recruitment in low-density areas after a disaster.When a fishery is devastated by a mass mortality event, there are also nonspatial strategies that can be employed. A fishery, in response, could temporarily close to give the population a recovery period. The authors refer to this strategy as a "dynamic post-catastrophe fishery closure," or the DC strategy. Another option is for the fishery to forgo closing down entirely. The authors refer to this strategy as the "no-closure (NC) management strategy."Utilizing a spatially explicit integral projection model (IPM), the authors ran simulations to determine how each of these three management strategies would influence recovery after a mass mortality event. The simulations measured the number of instances where a catch was able to return to a level above the threshold of collapse. The authors also conducted sensitivity analyses to determine how other factors, such as dispersal distance, MPA size, and catastrophe severity, impacted population recovery.Results indicate that the implementation of MPAs significantly aids in preventing population collapse."Our model predicts that a network of protected areas that reduce or possibly eliminate anthropogenic disturbances can minimize the risk of population collapse caused by large-scale extreme climatic events for species whose dynamics at low density are characterized by an Allee effect. Networks of protected areas can effectively increase resilience if their size and spatial layout are able to maintain a breeding population sufficient to rebuild the reproductive potential despite the presence of Allee effects," the authors write.
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Extinction
| 2,019 |
April 24, 2019
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https://www.sciencedaily.com/releases/2019/04/190424153732.htm
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Meet Callichimaera perplexa, the platypus of crabs
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The crab family just got a bunch of new cousins -- including a 95-million-year-old chimera species that will force scientists to rethink the definition of a crab.
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An international team of researchers led by Yale paleontologist Javier Luque announced the discovery of hundreds of exceptionally well-preserved specimens from Colombia and the United States that date back to the mid-Cretaceous period of 90-95 million years ago. The cache includes hundreds of tiny comma shrimp fossils, several true shrimp, and an entirely new branch of the evolutionary tree for crabs.The most intriguing discovery, according to the researchers, is Luque noted that "A study about the discovery appears in the April 24 online edition of the journal "It is very exciting that today we keep finding completely new branches in the tree of life from a distant past, especially from regions like the tropics, which despite being hotspots of diversity today, are places we know the least about in terms of their past diversity," Luque said.
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Extinction
| 2,019 |
April 23, 2019
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https://www.sciencedaily.com/releases/2019/04/190423133705.htm
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Largest collection of coral reef maps ever made
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A study from scientists at the Khaled bin Sultan Living Oceans Foundation and the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science offers a new way to accurately map coral reefs using a combination of Earth-orbiting satellites and field observations. This first-ever global coral reef atlas contains maps of over 65,000 square kilometers (25,097 square miles) of coral reefs and surrounding habitats.
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The maps, published today in the journal The high-resolution coral reef maps contain information on shallow water marine habitat such as fore and back reefs as well as information on the size of seagrass beds and mangrove forests for key locations visited on the expedition. All of these coastal habitats are key components of tropical coastal ecosystems and help to filter water, protect the coast from storms, and provide key nursery habitat for commercial and subsistence fisheries. They also face increasing threats from coastal development, overfishing, and climate change.To develop the new model to accurately map coral reef and other tropical shallow-water marine habitats, scientists took data collected from extensive SCUBA surveys conducted on the Global Reef Expedition and extrapolate that information across the entire reef using ultra-high-resolution satellite imagery. By comparing the maps with video footage from cameras dropped at precise coordinates along the reef, the scientists were able to verify the accuracy of their new mapping method."In order to conserve something, it's imperative to know where it is located and how much of it you have," said Sam Purkis, professor and chair of the UM Rosenstiel School Department of Marine Geosciences. "Developing such an understanding for coral reefs is especially challenging because they are submerged underwater and therefore obscured from casual view. With this study, we demonstrate the potential to use satellite images to make coral reef maps at global scale."Scientists now have a way to peer beneath the waves to accurately map large areas of coral reefs at greatly reduced cost. Traditional coral reef surveys are expensive to conduct and limited in scope, requiring hours of underwater surveys conducted by highly-trained scientific divers. Using this new model, scientists can create detailed coral reef habitat maps at a regional scale without having to survey the entire reef in person."Satellite, aircraft, and drone imaging will become an increasingly important tool for addressing the coral reef crisis at the global scale at which it's occurring." said Purkis, also the interim chief scientist for the Living Oceans Foundation.The high-resolution coral reef maps made for this study can be found on the World Reef Map, an interactive coral reef atlas where users can explore all of the coral reefs and shallow water marine habitats mapped on the Global Reef Expedition.Although they by no means cover every reef worldwide, this new atlas covers a meaningful portion of key reef provinces around the world. It also provides much-needed baseline data of coral reef health prior to the 2017 mass bleaching event. This digital resource has been made available to the public so that governments and conservation organizations can use these maps to protect and restore their coral reefs for generations to come.Scientists estimate that over 50 percent of coral reefs worldwide have been lost in the past 40 years due to climate change and other human pressures. These new detailed habitat maps can help local resource managers identify areas that may be in greatest need of conservation action."Benthic habitat maps are an essential tool in coral reef conservation as they provide a snapshot of where reefs are located and the status of their health," said Alexandra Dempsey, the director of science management for the Khaled bin Sultan Living Oceans Foundation and a co-author of the paper. "Scientists will use these habitat maps as baseline data to help track changes in reef composition and structure over time."
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Extinction
| 2,019 |
April 23, 2019
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https://www.sciencedaily.com/releases/2019/04/190423133651.htm
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Soft tissue makes coral tougher in the face of climate change
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Climate change and ocean warming threaten coral reefs and disrupt the harmonious relationship between corals and their symbiotic algae, a process known as "coral bleaching." However, a new study conducted by scientists at the University of Hawai'i (UH) at Mānoa and the California Academy of Sciences revealed soft tissues that cover the rocky coral skeleton promote the recovery of corals following a bleaching event.
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These soft tissues, which are home to beneficial algae, represent a source of energy for corals. The study, led by Chris Wall, a graduate student at the Hawai'i Institute of Marine Biology (HIMB) in the UH Mānoa School of Ocean and Earth Science and Technology (SOEST), showed corals with thicker tissue may be better equipped to survive bleaching in a warming ocean.Coral reefs are a vital resource to the people of Hawai'i and the state's economy in the form of tourism, diving, and recreational fisheries, in addition to protecting shorelines from storms and coastal erosion.When corals are stressed, they lose the colorful algae living in their tissues, resulting in bleaching and sometimes death of the corals. These events have been historically rare in the Hawaiian Islands, but heat stress is becoming more widespread as a result of climate change. Repeated bleaching events in 2014 and 2015 show that Hawai'i is not immune to the effects of ocean warming."While we know a great deal about thermal stress and its effects on corals, we know comparatively little about how corals recover from bleaching in the real world, or how local factors, such as light or nutrients in seawater, can influence recovery from bleaching," said Wall.In the fall of 2014, Wall and colleagues studied colonies of two species of corals, rice coral and finger coral, in Kāne'ohe Bay, O'ahu, Hawai'i, when seawater in the bay reached unusually high temperatures of 86F, which is near the maximum temperature Hawaiian corals can tolerate. The team was interested in how colonies that were sensitive to thermal stress responded to and recovered from bleaching compared to adjacent coral colonies that remained pigmented and did not bleach.During the warming event and three months later, the team assessed the coral animals and their symbiotic algae, and throughout the study measured environmental factors including light levels, water temperatures, sedimentation rates, and seawater nutrients to better understand how environmental factors influenced the severity of coral bleaching and rates of recovery. The researchers also used naturally-occurring chemical signatures in coral tissues to test how corals were performing and what they were eating during and after stress."A coral's diet is based on food from their symbionts and the consumption of small organisms in seawater known as plankton, and these two sources supply the building blocks for coral tissues. But under bleaching, corals are left without their symbionts and are in effect starving. We wanted to know how corals overcome this nutritional dilemma -- were they relying on stored energy in their tissues (much like a bear in hibernation) or were they eating more plankton?"The bleached colonies did not die and showed remarkable resilience, recovering from losses in both their symbionts and soft tissues within three months. This recovery was hastened by environmental factors, such as cooler water temperatures and water with low nutrient concentrations, which influenced coral tissues.The researchers determined that coral tissues are very important in the bleaching recovery process and corals with abundant or thick tissues may be able to better survive and recover from bleaching stress. The stored energy in coral tissues, and not greater plankton feeding, served as food for corals during thermal stress and helped corals recover."Kāne'ohe Bay is a unique coral ecosystem that has rebounded from decades of human impacts. Therefore, corals in Kāne'ohe Bay may hold valuable lessons for science as we work to understand the basis for coral tolerance to the environmental challenges experienced today and those to come in the future as humans continue to change our global climate," said Wall.In the future, the researchers will work to better understand what mechanisms underpin the coral animals' and their microbes' tolerance and vulnerability to ocean warming.
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Extinction
| 2,019 |
April 22, 2019
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https://www.sciencedaily.com/releases/2019/04/190422090855.htm
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How does wildlife fare after fires?
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Fire ecologists and wildlife specialists at La Trobe University have made key discoveries in how wildlife restores itself after bushfires, and what Australian conservationists can do to assist the process.
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The study, published this week in Wildlife Research journal, looks at various reserves in the Australian state of Victoria after bushfires had taken place. It finds that the surrounding area of any fire dictates what species survived and went onto thrive.Key findings of the study included:To minimise damage of large bushfires and to protect important species and vegetation, strategic burns create firebreaks -- vital in slowing the spread of fire.La Trobe honours student Angela Simms, author of the study, said the study opens up an important discussion on how conservationists can make informed decisions on planned and strategic burning."With our dry climate, Australia has seen more than its fair share of destructive bushfires. This, in conjunction with increasing habitat loss more generally, means that it's not uncommon to see localized extinctions of species after a fire."We can conclude that the surrounding habitat and vegetation to a fire directly determines the species that will recolonize that area."From this, we know the wider landscape context -- particularly surrounding species and vegetation -- should be a key consideration for conservation programs when planning locations for strategic burns."But it also tells us a lot about what to expect when a bushfire does take place, and what preparations they can undertake to restore native wildlife that could be vulnerable when needed."There is still much to learn about post-fire fauna communities but this study marks the start of a journey to better understand how we can protect important wildlife before, during and after fires."
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Extinction
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April 18, 2019
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https://www.sciencedaily.com/releases/2019/04/190418131256.htm
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Ocean currents bring good news for reef fish
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Researchers have discovered some good news for fish populations living on coral reefs hit by climate change.
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Renato Morais is a PhD candidate from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU). He led a study that looked at how fish on a bleached coral reef get their food."We already knew that coral reef fish rely on food drifting in from the sea, such as plankton," Mr Morais said."But, we didn't know exactly how important this was," he said.Mr Morais and Professor David Bellwood, also from Coral CoE at JCU, combined high-resolution surveys and individual biomass production estimates to generate the first map of where the energy comes from for all fish on a coral reef."We looked at everything from gobies to coral trout and large jacks, assessing more than 18,000 fish from over 300 species," said Mr Morais."We found that various transport mechanisms, such as currents and tides, interact with the reef and bring in vast amounts of plankton."The pair found that for every kilogram of fish produced on the reef more than 400 grams of that kilogram relied on food derived from the open ocean, rather than the reef itself. This rises to almost 600 grams on the side of the reef facing the open ocean."This means, that for many reefs, food from outside can sustain fish populations, even when the coral is badly damaged," Prof Bellwood said.The scientists found that areas of the reef that were more exposed to the open ocean produced the largest quantities of fish -- with reef slopes being the most fruitful."The discovery that reef fish get so much of their food from off-reef sources was encouraging, especially because many species that feed on oceanic material have a history of disappearing after coral loss," said Mr Morais."This is the first time we have been able to put all species in perspective," said Prof Bellwood. "Our study offers hope that reefs subject to coral loss can still be productive.""The reefs may be damaged but they are still incredibly valuable."
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| 2,019 |
April 18, 2019
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https://www.sciencedaily.com/releases/2019/04/190418080758.htm
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Fossils found in museum drawer in Kenya belong to gigantic carnivore
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Paleontologists at Ohio University have discovered a new species of meat-eating mammal larger than any big cat stalking the world today. Larger than a polar bear, with a skull as large as that of a rhinoceros and enormous piercing canine teeth, this massive carnivore would have been an intimidating part of the eastern African ecosystems occupied by early apes and monkeys.
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In a new study published in the "Opening a museum drawer, we saw a row of gigantic meat-eating teeth, clearly belonging to a species new to science," says study lead author Borths. Borths was a National Science Foundation Postdoctoral Research Fellow with Stevens in the Department of Biomedical Sciences at Ohio University when the research was conducted, and is now Curator of the Division of Fossil Primates at the Duke Lemur Center at Duke University.Simbakubwa is Swahili for "big lion" because the animal was likely at the top of the food chain in Africa, as lions are in modern African ecosystems. Yet Simbakubwa was not closely related to big cats or any other mammalian carnivore alive today. Instead, the creature belonged to an extinct group of mammals called hyaenodonts.Hyaenodonts were the first mammalian carnivores in Africa. For about 45 million years after the extinction of the non-avian dinosaurs, hyaenodonts were the apex predators in Africa. Then, after millions of years of near-isolation, tectonic movements of the Earth's plates connected Africa with the northern continents, allowing floral and faunal exchange between landmasses. Around the time of Simbakubwa, the relatives of cats, hyenas, and dogs began to arrive in Africa from Eurasia.As the relatives of cats and dogs were going south, the relatives of Simbakubwa were going north. "It's a fascinating time in biological history," Borths says. "Lineages that had never encountered each other begin to appear together in the fossil record."The species name, kutokaafrika, is Swahili for "coming from Africa" because Simbakubwa is the oldest of the gigantic hyaenodonts, suggesting this lineage of giant carnivores likely originated on the African continent and moved northward to flourish for millions of years.Ultimately, hyaenodonts worldwide went extinct. Global ecosystems were changing between 18 and 15 million years ago as grasslands replaced forests and new mammalian lineages diversified. "We don't know exactly what drove hyaenodonts to extinction, but ecosystems were changing quickly as the global climate became drier. The gigantic relatives of Simbakubwa were among the last hyaenodonts on the planet," remarks Borths."This is a pivotal fossil, demonstrating the significance of museum collections for understanding evolutionary history," notes Stevens, Professor in the Heritage College of Osteopathic Medicine at Ohio University and co-author of the study. "Simbakubwa is a window into a bygone era. As ecosystems shifted, a key predator disappeared, heralding Cenozoic faunal transitions that eventually led to the evolution of the modern African fauna."This study was funded by grants from the National Science Foundation (EAR/IF-0933619; BCS-1127164; BCS-1313679; EAR-1349825; BCS-1638796; DBI-1612062), The Leakey Foundation, National Geographic Society (CRE), Ohio University Research Council, Ohio University Heritage College of Osteopathic Medicine, SICB and The Explorers Club.This discovery underscores both the importance of supporting innovative uses of fossil collections, as well as the importance of supporting the research and professional development of talented young postdoctoral scientists like Dr. Borths," said Daniel Marenda, a program director at the National Science Foundation, which funded this research. "This work has the potential to help us understand how species adapt -- or fail to adapt in this case -- to a rapidly changing global climate."
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Extinction
| 2,019 |
April 17, 2019
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https://www.sciencedaily.com/releases/2019/04/190417171033.htm
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New eDNA technology used to quickly assess coral reefs
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Scientists at the University of Hawai`i at Mānoa Department of Biology have developed a technique for measuring the amount of living coral on a reef by analyzing DNA in small samples of seawater. The new research by Patrick Nichols, a graduate student in the marine biology graduate program, and Peter Marko, an associate professor in the Department of Biology, was published in
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Underwater visual surveys are used widely in coral reef ecology and are an important part of any coral reef monitoring program. However, visual surveys are typically conducted using SCUBA, which can be both time-consuming and logistically challenging.As an efficient complement to visual surveys, the analysis of environmental DNA (eDNA), DNA sloughed or expelled from organisms into the environment, has been used to assess species diversity, primarily in aquatic environments. The technique takes advantage of the fact that all organisms constantly shed DNA into the environment, leaving behind a genetic residue that can be detected and analyzed with molecular biology tools.Despite the growing use of eDNA to catalog the presence and absence of species, a reliable link between the abundance of organisms and the quantity of DNA has remained elusive. In their paper, Nichols and Marko demonstrate that this new method tested on coral reefs in Hawai?i is a quick and cost-effective way to measure live coral "cover," the amount of a coral reef occupied by living corals. Because corals facilitate the presence of many other species on a reef, coral cover is one of several important measuring sticks that scientists use to characterize the status of a reef, an urgent task on reefs that are declining worldwide as a consequence of global climate change."It still amazes me that in a tiny tube of water, there is enough information to track the relative abundance of entire communities," said Nichols. "Increasing the breadth and scope of surveys is exactly what makes the future of eDNA so exciting!"The project used "metabarcoding," a technique in which all of the DNA in a water sample is analyzed in one step with DNA sequencing. Coral DNA sequences are then identified and counted to determine the abundances of different types of corals at each reef. Degraded reefs have very little coral eDNA whereas reefs with more living corals have a much stronger coral eDNA signature.The authors explain in their paper that this new technique can be used to track changes in coral reef health and community composition over time, as well as detect rare species that can otherwise be missed by traditional visual-based survey methods."If you asked me 10 years ago if this was possible, I would have said, 'No way,'" said Marko. "But advances in technology and falling costs of highly-sensitive DNA sequencing methods have opened the door to all kinds of important ecological questions."The researchers are currently applying what they learned from the project to the most compelling applications of eDNA monitoring in communities that are much more difficult to visually assess, such as deep reefs that provide potential refuge from climate change for temperature-sensitive species.
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Extinction
| 2,019 |
April 17, 2019
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https://www.sciencedaily.com/releases/2019/04/190417153809.htm
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These beetles have successfully freeloaded for 100 million years
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Almost 100 million years ago, a tiny and misfortunate beetle died after wandering into a sticky glob of resin leaking from a tree in a region near present-day Southeast Asia. Fossilized in amber, this beetle eventually made its way to the desk of entomologist Joe Parker, assistant professor of biology and biological engineering at Caltech. Parker and his colleagues have now determined that the perfectly preserved beetle fossil is the oldest-known example of an animal in a behaviorally symbiotic relationship.
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A paper describing the work appears on April 16 in the journal Symbiotic relationships between two species have arisen repeatedly during animal evolution. These relationships range from mutually beneficial associations, like humans and their pet dogs, to the parasitic, like a tapeworm and its host.Some of the most complex examples of behavioral symbiosis occur between ants and other types of small insects called myrmecophiles -- meaning "ant lovers." Thanks to ants' abilities to form complex social colonies, they are able to repel predators and amass food resources, making ant nests a highly desirable habitat. Myrmecophiles display elaborate social behaviors and chemical adaptations to deceive ants and live among them, reaping the benefits of a safe environment and plentiful food.Ants' social behaviors first appear in the fossil record 99 million years ago, during the Cretaceous period of the Mesozoic era, and are believed to have evolved not long before, in the Early Cretaceous. Now, the discovery of a Cretaceous myrmecophile fossil implies that the freeloading insects were already taking advantage of ants' earliest societies. The finding means that myrmecophiles have been a constant presence among ant colonies from their earliest origins and that this socially parasitic lifestyle can persist over vast expanses of evolutionary time."This beetle-ant relationship is the most ancient behavioral symbiosis now known in the animal kingdom," says Parker. "This fossil shows us that symbiosis can be a very successful long-term survival strategy for animal lineages."The fossilized beetle, named Promyrmister kistneri, belongs to a subfamily of "clown" beetles (Haeteriinae), all modern species of which are myrmecophiles. These modern beetles are so specialized for life among ants that they will die without their ant hosts and have evolved extreme adaptations for infiltrating colonies. The beetles are physically well protected by a thick tank-like body plan and robust appendages, and they can mimic their host ants' nest pheromones, allowing them to disguise themselves in the colony. They also secrete compounds that are thought to be pacifying or attractive to ants, helping the beetles gain the acceptance of their aggressive hosts. The fossilized Promyrmister is a similarly sturdy insect, with thick legs, a shielded head, and glandular orifices that the researchers theorize exuded chemicals to appease its primitive ant hosts.Depending on another species so heavily for survival has its risks; indeed, an extinction of the host species would be catastrophic for the symbiont. The similarities between the fossilized beetle and its modern relatives suggest that the particular adaptations of myrmecophile clown beetles first evolved inside colonies of early "stem group" ants, which are long extinct. Due to Promyrmister's remarkable similarity to modern clown beetles, Parker and his collaborators infer that the beetles must have "host switched" to colonies of modern ants to avoid undergoing extinction themselves. This adaptability of symbiotic organisms to move between partner species during evolution may be essential for the long-term stability of these intricate interspecies relationships.
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Extinction
| 2,019 |
April 15, 2019
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https://www.sciencedaily.com/releases/2019/04/190415122249.htm
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New evidence suggests volcanoes caused biggest mass extinction ever
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Researchers say mercury buried in ancient rock provides the strongest evidence yet that volcanoes caused the biggest mass extinction in the history of the Earth.
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The extinction 252 million years ago was so dramatic and widespread that scientists call it "the Great Dying." The catastrophe killed off more than 95 percent of life on Earth over the course of hundreds of thousands of years.Paleontologists with the University of Cincinnati and the China University of Geosciences said they found a spike in mercury in the geologic record at nearly a dozen sites around the world, which provides persuasive evidence that volcanic eruptions were to blame for this global cataclysm.The study was published this month in the journal The eruptions ignited vast deposits of coal, releasing mercury vapor high into the atmosphere. Eventually, it rained down into the marine sediment around the planet, creating an elemental signature of a catastrophe that would herald the age of dinosaurs."Volcanic activities, including emissions of volcanic gases and combustion of organic matter, released abundant mercury to the surface of the Earth," said lead author Jun Shen, an associate professor at the China University of Geosciences.The mass extinction occurred at what scientists call the Permian-Triassic Boundary. The mass extinction killed off much of the terrestrial and marine life before the rise of dinosaurs. Some were prehistoric monsters in their own right, such as the ferocious gorgonopsids that looked like a cross between a sabre-toothed tiger and a Komodo dragon.The eruptions occurred in a volcanic system called the Siberian Traps in what is now central Russia. Many of the eruptions occurred not in cone-shaped volcanoes but through gaping fissures in the ground. The eruptions were frequent and long-lasting and their fury spanned a period of hundreds of thousands of years."Typically, when you have large, explosive volcanic eruptions, a lot of mercury is released into the atmosphere," said Thomas Algeo, a professor of geology in UC's McMicken College of Arts and Sciences."Mercury is a relatively new indicator for researchers. It has become a hot topic for investigating volcanic influences on major events in Earth's history," Algeo said.Researchers use the sharp fossilized teeth of lamprey-like creatures called conodonts to date the rock in which the mercury was deposited. Like most other creatures on the planet, conodonts were decimated by the catastrophe.The eruptions propelled as much as 3 million cubic kilometers of ash high into the air over this extended period. To put that in perspective, the 1980 eruption of Mount St. Helens in Washington sent just 1 cubic kilometer of ash into the atmosphere, even though ash fell on car windshields as far away as Oklahoma.In fact, Algeo said, the Siberian Traps eruptions spewed so much material in the air, particularly greenhouse gases, that it warmed the planet by an average of about 10 degrees centigrade.The warming climate likely would have been one of the biggest culprits in the mass extinction, he said. But acid rain would have spoiled many bodies of water and raised the acidity of the global oceans. And the warmer water would have had more dead zones from a lack of dissolved oxygen."We're often left scratching our heads about what exactly was most harmful. Creatures adapted to colder environments would have been out of luck," Algeo said. "So my guess is temperature change would be the No. 1 killer. Effects would exacerbated by acidification and other toxins in the environment."Stretching over an extended period, eruption after eruption prevented the Earth's food chain from recovering."It's not necessarily the intensity but the duration that matters," Algeo said. "The longer this went on, the more pressure was placed on the environment."Likewise, the Earth was slow to recover from the disaster because the ongoing disturbances continued to wipe out biodiversity, he said.Earth has witnessed five known mass extinctions over its 4.5 billion years.Scientists used another elemental signature -- iridium -- to pin down the likely cause of the global mass extinction that wiped out the dinosaurs 65 million years ago. They believe an enormous meteor struck what is now Mexico.The resulting plume of superheated earth blown into the atmosphere rained down material containing iridium that is found in the geologic record around the world.Shen said the mercury signature provides convincing evidence that the Siberian Traps eruptions were responsible for the catastrophe. Now researchers are trying to pin down the extent of the eruptions and which environmental effects in particular were most responsible for the mass die-off, particularly for land animals and plants.Shen said the Permian extinction could shed light on how global warming today might lead to the next mass extinction. If global warming, indeed, was responsible for the Permian die-off, what does warming portend for humans and wildlife today?"The release of carbon into the atmosphere by human beings is similar to the situation in the Late Permian, where abundant carbon was released by the Siberian eruptions," Shen said.Algeo said it is cause for concern."A majority of biologists believe we're at the cusp of another mass extinction -- the sixth big one. I share that view, too," Algeo said. "What we should learn is this will be serious business that will harm human interests so we should work to minimize the damage."People living in marginal environments such as arid deserts will suffer first. This will lead to more climate refugees around the world."We're likely to see more famine and mass migration in the hardest hit places. It's a global issue and one we should recognize and proactively deal with. It's much easier to address these problems before they reach a crisis."
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Extinction
| 2,019 |
April 11, 2019
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https://www.sciencedaily.com/releases/2019/04/190411154731.htm
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Advanced virtual technology captures how coral reefs recover after bleaching
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Researchers at Scripps Institution of Oceanography and engineers at UC San Diego have used new imaging software to detect dramatic recovery after a bleaching event on the reefs surrounding remote Palmyra Atoll in the tropical Pacific. The research was published April 5 in
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In 2015, Palmyra experienced its warmest water in recorded history, prompting a widespread bleaching event that affected over 90 percent of the corals surrounding the island. Researchers found that despite the widespread bleaching, most of the corals recovered, with less than 10 percent dying.The conclusions are based on comprehensive monitoring of the reefs and is providing for more precise observations of how reefs are changing over time. The researchers used a long-term data set of thousands of pictures of the same reef area collected over eight years. These images were stitched together using custom software to create 3D photo mosaics of the ecosystem -- a virtual representation of the corals. The technology was developed by the 100 Island Challenge team, a collaborative group of marine ecologists and engineers using the latest technology to monitor coral reefs around the world."This imaging provides a way of getting back into the environment in a virtual world," said Mike Fox, lead author and postdoc at Woods Hole Oceanographic Institution, who completed the research as a Ph.D. student at Scripps. "It allows us to bring the reef back into the lab."The researchers combined this imaging technology with a new custom visualization software, VisCore, that allows users to re-examine the thousands of photographs that comprise the mosaics. VisCore took more than 15,000 images for every 10 square-meter area of coral reef and then processed the data to turn the images into a 3D map that users can dive into in virtual reality.The 100 Island Challenge literally unlocked another dimension to Viscore by bringing a highly interdisciplinary research team together, to create the data, algorithms and tools that are now allowing scientists to virtually explore reefs in the lab; to time-travel virtually from year to year; to track the growth and decline of individual colonies; and to study spatial and temporal relationships across the reef.The project was made possible by bringing together researchers from Scripps and the Jacobs School of Engineering at UC San Diego with a deep commitment to the project, said Falko Kuester, a professor of computer science and structural engineering at UC San Diego."We want to give coral reefs a voice, to tell their stories and engage stakeholders to safeguard them," he said.Hundreds of videos the researchers generated are available on YouTube for public viewing."The program gave us the unique opportunity to virtually re-visit each of our dives and to examine the reef with a new focus," said Fox. "When we 'dove' back into the images, we realized that the bleaching was even worse than we remembered when we were actually diving on the reef collecting the data."Along with documenting the bleaching, the researchers were able to closely monitor coral recovery. Looking at photomosaics of the reef after the bleaching event, Fox and team documented growth in an important reef-building species, crustose coralline algae. This alga helps hold reefs together and can encourage the settlement of juvenile corals.In areas where coral did die and was covered with reef-smothering algae, researchers saw that in about a year this algae was replaced by the pink crustose coralline. This is partly due to the health of the larger ecosystem, as Palmyra has robust populations of herbivorous fish that can control destructive algae growth.Tracking these recovery processes at specific coral colonies over time gives researchers a deeper understanding of how individual corals -- and the larger reef they are a part of -- are coping with environmental stresses in the era of human-influenced climate change.Traditionally, changes in coral reefs were measured with transect sampling, in which divers record observations along one specific line across the reef."It's like trying to measure national population growth by going to one random U.S. city and asking people if they had a child," said Stuart Sandin, a Scripps researcher who co-authored the paper and is co-founder of the 100 Island Challenge. "You're not going to show the larger picture."With the reef mosaics and the pinpoint accuracy of VisCore, coral scientists can look at demographic cues in a vast area. The colony-specific nature of the data gives more precision, and like tracking population growth in a country, can show regional and national trends."Using a combination of novel technology and more traditional approaches, our team was able to show that the reefs of Palmyra did not suffer the same fate as many other reefs during the recent global bleaching event," said Jen Smith, a Scripps researcher and senior author on the paper, and co-founder of the 100 Island Challenge. "Despite extreme heating, corals were able to recover without experiencing widespread mortality. These findings certainly provide an important counterpoint to the general decline in reef health being reported globally."This research was funded by generous donations from the Scripps Family Foundation, the Bohn Family, the Wilson family, Marcia Grand and several other anonymous donors to the Smith and Sandin labs between 2009-2018.
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Extinction
| 2,019 |
April 10, 2019
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https://www.sciencedaily.com/releases/2019/04/190410095939.htm
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How much nature is lost due to higher yields?
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The exploitation of farmland is being intensified with a focus to raising yields. The degree to which yields actually increase as a result and the extent of the simultaneous loss of biological diversity have to date been under-researched factors. An international team of scientists has now evaluated data from worldwide research in which both yield and biodiversity were examined before and after intensification measures.
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Around 80 percent of land area in Europe is used for settlement, agriculture and forestry. In order to increase yields even further than current levels, exploitation is being intensified. Areas are being consolidated in order to cultivate them more efficiently using larger machines. Pesticides and fertilisers are increasingly being used and a larger number of animals being kept on grazing land. "Such measures increase yield but, overall, they also have negative impacts on biodiversity," says UFZ biologist Dr. Michael Beckmann. "This is because even agricultural areas offer fauna and flora a valuable habitat -- which is something that is frequently not sufficiently taken into consideration." In addition, previous studies have mostly examined the effects of intensified land use only from one perspective: either with regard to the increase in yield or the loss of biodiversity. "We unfortunately still know far too little about the relationship between the two and what price nature ultimately has to pay for increases in yield," says Beckmann. In the recent study, the team of scientists aimed to address this knowledge gap.To this end, the researchers sifted through some 10,000 topically relevant studies looking for those that collected measurement data for yield and biodiversity both before and after intensification measures. "The majority of the studies fell through the net in this respect. A mere 115 studies actually measured both parameters for the same areas, making them relevant for our purposes," says Beckmann. The 449 agricultural areas examined in these studies are, however, distributed around the globe, are located in different climatic zones and the time they have been in use varies greatly. To be able to use these studies for their analysis, the researchers developed a mathematical model that takes account of these differences and renders the data comparable. They then summarised the respective yield increases and biodiversity losses. "We were able to demonstrate that, on average, intensification of land use gave rise to an increase in yield of 20 percent but this is, at the same time, associated with a nine percent loss of species," says Beckmann.To obtain a more detailed insight into the impact of intensification measures, the researchers divided the agricultural areas into three classes of intensity -- low, medium and high. Proceeding in this way made it possible to compare the results of all three agricultural production systems -- arable land, grasslands and forest -- with each other. Areas of medium intensity of use demonstrated the highest increase (85 percent) in yield following intensification measures. But they also had the greatest loss of species (23 percent). In contrast, areas that already had high intensity of use did not reveal any significant loss of species but still showed an increase in yield of 15 percent. "Initially, this sounds excellent: greater yield without loss of species," says Beckmann. "But where there was not much biodiversity left to start with due to highly intense usage, there is, of course, also not much that can be lost. In such cases, the critical point may have already been passed." In a comparison of the effects of intensification measures on arable land, grasslands and forests, forests performed best with regard to lower species loss. The study findings indicate that intensified land use may, in individual cases such as timber production, also lead to greater yields without any detrimental effect on biodiversity.The study makes clear how great the impact of the intensity of agricultural production can be for the protection of biodiversity. It reveals general trends and identifies gaps in our knowledge. Concrete recommendations for action in specific regions cannot be derived from the study, however. "Further research is necessary in order to understand the conditions under which land usage is linked to a low or an especially high risk to biodiversity," says Michael Beckmann. "This is the only way to ensure that we are able to apply intense land use practices and protect biodiversity at the same time. After all, species conservation can and must also take place in our cultivated landscapes."
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Extinction
| 2,019 |
April 8, 2019
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https://www.sciencedaily.com/releases/2019/04/190408091304.htm
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Official stats mask shark and ray species caught in the Mediterranean and Black seas
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Shark and ray species commonly caught in the Mediterranean and Black seas are not being reported in official statistics, new research from the
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A new study published in "The Mediterranean and Black Seas have historically harboured a high diversity and abundance of sharks and rays, but now between between 53 per cent and 71 per cent of them face an elevated risk of extinction," said Madeline Cashion, lead author of the study, who carried out the research at the By not keeping track of the different species of sharks and rays that they are bringing to port, countries may be further threatening those already at risk."Part of the problem is that many sharks and rays in the region are caught as bycatch in fisheries targeting other species and are brought to port either because there is a small market for them or because, by law, they cannot be thrown back at sea," Cashion said. "If neither fishers nor authorities keep detailed records of what is being caught, then it's very difficult to detect declines and design effective measures to protect threatened species."Despite the lack of reporting, Cashion found in her research that sharks and rays have become increasingly rare following centuries of exploitation and the more recent expansion and intensification of fisheries in the Mediterranean, in particular of the non-European ones. In many cases, catch data is the only source of information to know if species still exist where they were historically found."The problem is that detailed catch data is hard to come by because species identification can be very tricky," Cashion said. "Good reporting relies on the financial and logistical support of governments and fisheries management organizations. Fishers can't be expected to take it on alone."Given the threats posed by the fishing industry to at-risk sharks and rays due to the lack of specific information, the researchers call for a better implementation of existing data collection and reporting policies.They also call for official statistics to start accounting for fish that are caught and thrown back into the ocean and those that are caught incidentally."To understand the real trends of shark and ray exploitation and abundance, we need to know what is discarded at sea because not all species survive after being pulled up by a net," said Daniel Pauly, co-author of the study and the
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Extinction
| 2,019 |
April 3, 2019
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https://www.sciencedaily.com/releases/2019/04/190403155411.htm
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Think the tick threat grows with the grass? Not necessarily!
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When Susannah Lerman talked with fellow researchers and friends about her study of the effects of less frequent lawn mowing to improve habitat for native bees, the response she heard most had nothing to do with bees. "The first thing people said was that letting the grass get longer would invite ticks," said Lerman, a research ecologist with the USDA Forest Service's Northern Research Station. "It was clear that before we could make the case for promoting lawns as bee habitat, we had to understand the tick risk."
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In a study published today in the journal "There are obvious limitations to this study in terms of establishing the risk of ticks," Lerman said. "We sampled for a single species of tick, and our study was limited to 16 residential lawns in a single city. Still, our study has two significant take-aways: you do not necessarily invite ticks if you mow the lawn every other week instead of every week, and common assumptions about nature are always worth investigating; scientists may be surprised by what we find."Blacklegged ticks are notorious as carriers of Lyme disease, a tick-borne infection with significant human health risks that is prevalent in the Northeast. While blacklegged ticks are no doubt lurking in people's yards, D'Amico said that the grassy part of a property is probably too dry for the tick. "This species needs near 100 percent humidity for at least part of the day," D'Amico said. "Where we have leaf litter, the ticks do very well."In the United States, an estimated 40 million acres of residential lawn managed by homeowners, businesses, government agencies and cemeteries have the potential to become habitat for beleaguered native bee species, if people can put aside a very reasonable fear and loathing of ticks. In this study, Lerman and her team found good reason to do so.
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Extinction
| 2,019 |
April 3, 2019
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https://www.sciencedaily.com/releases/2019/04/190403135052.htm
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Global warming disrupts recovery of coral reefs
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The damage caused to the Great Barrier Reef by global warming has compromised the capacity of its corals to recover, according to new research published today in
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"Dead corals don't make babies," said lead author Professor Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies at James Cook University (JCU). "The number of new corals settling on the Great Barrier Reef declined by 89 percent following the unprecedented loss of adult corals from global warming in 2016 and 2017."The unique study measured how many adult corals survived along the length of the world's largest reef system following extreme heat stress, and how many new corals they produced to replenish the Great Barrier Reef in 2018. The loss of adults resulted in a crash in coral replenishment compared to levels measured in previous years before mass coral bleaching."The number of coral larvae that are produced each year, and where they travel to before settling on a reef, are vital components of the resilience of the Great Barrier Reef. Our study shows that reef resilience is now severely compromised by global warming," said co-author Professor Andrew Baird."The biggest decline in replenishment, a 93% drop compared to previous years, occurred in the dominant branching and table coral, Acropora. As adults these corals provide most of the three-dimensional coral habitat that support thousands of other species," he said."The mix of baby coral species has shifted, and that in turn will affect the future mix of adults, as a slower than normal recovery unfolds over the next decade or longer.""The decline in coral recruitment matches the extent of mortality of the adult brood stock in different parts of the Reef," added Professor Hughes. "Areas that lost the most corals had the greatest declines in replenishment.""We expect coral recruitment will gradually recover over the next five to ten years, as surviving corals grow and more of them reach sexual maturity, assuming of course that we don't see another mass bleaching event in the coming decade," he said.So far, the Great Barrier Reef has experienced four mass bleaching events due to global warming, in 1998, 2002, and back-to-back in 2016 and 2017. Scientists predict that the gap between pairs of coral bleaching events will continue to shrink as global warming intensifies."It's highly unlikely that we could escape a fifth or sixth event in the coming decade," said co-author Professor Morgan Pratchett."We used to think that the Great Barrier Reef was too big to fail -- until now," he said."For example, when one part was damaged by a cyclone, the surrounding reefs provided the larvae for recovery. But now, the scale of severe damage from heat extremes in 2016 and 2017 was nearly 1500km -- vastly larger than a cyclone track."Professor Pratchett added that the southern reefs that escaped the bleaching are still in very good condition, but they are too far away to replenish reefs further north."There's only one way to fix this problem," says Hughes, "and that's to tackle the root cause of global heating by reducing net greenhouse gas emissions to zero as quickly as possible."
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Extinction
| 2,019 |
April 3, 2019
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https://www.sciencedaily.com/releases/2019/04/190403095507.htm
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Global eradication of 'fly of death' not ethically justified, researchers conclude
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The tsetse fly, also known as the "fly of death" and the "poverty fly," is the primary means of transmission for the parasite that causes trypanosomosis.
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Known as sleeping sickness in humans, trypanosomosis is a serious disease that threatens millions of people across 36 African countries and causes billions of dollars of livestock and crop losses.Without a vaccine to treat the disease, health officials have begun an eradication campaign that if successful would result in the extinction of the entire tsetse fly family. They are using new, more effective technologies including releasing irradiated male flies that sterilize females, and impregnating cattle and pigs with pesticides, effectively using them as live bait.In a paper just published in the journal "A basic rule of ethics is that just because you can do something -- in this case, eradicate a harmful species through advanced technologies -- doesn't automatically mean you should do it," said study co-author Michael Paul Nelson, professor and the Ruth H. Spaniol Chair of Renewable Resources in OSU's College of Forestry. "A project like this requires rational ethical discourse."Most at risk of contracting sleeping sickness, which is nearly always fatal if not treated, are those in remote rural areas dependent on agriculture, hunting and fishing -- areas with limited access to adequate health care. Without a vaccine, officials are focused on controlling the tsetse fly."Numerous elimination programs have been established across Africa, many under the umbrella of PATTEC: the Pan African Tsetse and Trypanosomosis Eradication Campaign," Nelson said. "Recently, Ghana, Burkina Faso, Mali, Uganda, Kenya and Ethiopia were involved in the first phase of PATTEC. Other countries, including Senegal, Zimbabwe and Botswana, have also successfully eliminated tsetse flies from part of or their full territory using sources of funding other than PATTEC."Nelson and study co-author Chelsea Batavia, who recently completed a Ph.D. in the College of Forestry at Oregon State, say the ethical aspects of intentionally wiping out the family's 31 species must be considered despite the significant harm the flies cause to humans."You really need to weigh arguments built around two different types of values of the species at local and global scales: instrumental values and intrinsic values," Nelson said.A species' instrumental value refers to its "utility or function as a means to an end." It can also refer to "disvalues," aspects that detract from human well-being, such as the tsetse fly's role as a disease transmitter.Intrinsic value refers to value beyond and/or regardless of any utility or disutility a species gives to humans."In practical terms, we can compare instrumental values and disvalues by calculating the relative benefits and costs associated with a species," said Batavia. "Strict utilitarian logic would suggest it's appropriate to pursue elimination programs whose total benefit exceeds total costs."But these utilitarian calculations aren't so simple.Along with monetary costs and benefits, there are other values and disvalues that need to be factored in as well, such as:And those are just questions dealing with the instrumental values. The ethics become more complex when the tsetse flies' intrinsic value is brought into the equation."It is important to consider intrinsic value as a separate type of value rather than attempting to weigh it against instrumental values," Batavia said. "And complete and intentional eradication of a species is pretty tough to justify, once we recognize that species as a bearer of intrinsic value."Rather than global eradication of the species, targeted elimination of certain populations of tsetse fly would minimally harm the species but greatly benefit human and animal health and well-being, the researchers say."We suggest localized elimination represents a defensible compromise as long as it's enacted with due restraint and harm to tsetse flies is minimized," Batavia said. "We suggest tsetse flies have intrinsic value, and certain obligations follow from that proposition; but we definitely don't want to forget that human beings have intrinsic value as well. So we propose elimination techniques that are diligently, cautiously and selectively applied to those fly populations actively compromising human communities can appropriately promote the welfare of human beings, who are bearers of intrinsic value, while also acknowledging the intrinsic value of tsetse fly species."
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Extinction
| 2,019 |
April 1, 2019
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https://www.sciencedaily.com/releases/2019/04/190401171407.htm
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Farming for natural profits in China
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A new strategy being rolled out in China relies on the idea that farmers can harvest much more than crops. The idea is that well-managed, diverse agricultural lands can provide flood control, water purification and climate stabilization, among other valuable services.
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A recent case-study by researchers at Stanford, McGill University and the Chinese Academy of Sciences provide a promising demonstration of this approach -- farmers who took environmental concerns into account doubled their incomes and reduced reliance on a single harvest while also gaining environmental benefits from the land. The group said the approach could help farmers worldwide protect both the environment and their livelihoods."Twentieth century monoculture farms greatly increased agricultural production, but at a huge price," said Gretchen Daily, cofounder and faculty director of the Stanford Natural Capital Project."Conventional thinking says that monoculture farming is the only way to feed the world, but today there is a lot of rethinking, as billions of people are exposed to heightened flood risk, water pollution, climate risk and other serious vulnerabilities." Daily was senior author on a paper describing the results, published April 1 in the Working with government authorities, the researchers looked at how their proposed approach, called the "Ecological Development Strategy" could work in Hainan Island, a rural, tropical region where expanding rubber plantations have driven extensive loss of natural forest and its vital benefits, such as soil retention and flood mitigation. Although the economy grew due to the plantations, intensive monocropping practices increased sediment runoff and channeled agricultural chemicals into surface waters. Forest recreation and tourism disappeared. Flooding was exacerbated by the area's loss of trees.The researchers looked at land use and land cover changes in Hainan Island over a 19-year period of steady rubber plantation growth. Pairing that information with survey data from households, the team used the Natural Capital Project's InVEST modeling software to understand how changes in land use management could have garnered different results in natural forest or economic prosperity. Alongside the historical land data of almost two decades, the models helped researchers understand what could have happened if the land had never been developed for rubber plantations or if the plantations had been managed differently.In particular, the researchers looked at one key land management change: a technique called intercropping that involves cultivating other valuable plants in the understory of a main crop. They found that rubber farmers who did this maintained the same production levels as monoculture plantations while significantly increasing soil retention, flood mitigation and nutrient retention. Perhaps most strikingly, farmers who took this approach doubled their incomes due to revenue from the additional crops. By diversifying their land, farmers also insured themselves against the risk of a single-crop's harvest failing or losing market value; key vulnerabilities of the monoculture system.Central to the Chinese Ecological Development Strategy is a focus on targeted investments in nature. Identifying places like Hainan where policy and management decisions can support both the economy and environment is crucial to achieve the widespread impacts that China is looking for. According to the researchers, this study illustrates how regions can leverage natural resources to support economic growth without sacrificing ecosystem health or human well-being.The challenges that Hainan rubber plantation farmers face in terms of relying on single crops are magnified at a global scale, where monocultures, such as soy, beef and palm oil, drive the vast majority of the global food market. Global climate insecurity, water contamination and species mass extinction are the result. The study's authors emphasize that the science and practices exist to help drive a shift away from monoculture systems worldwide, and economic incentives await those who do."There doesn't necessarily need to be a trade-off," Daily said. "You can have high value, high yielding production that secures farmers' livelihoods and supports the vital functioning of the natural ecosystem."
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Extinction
| 2,019 |
April 1, 2019
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https://www.sciencedaily.com/releases/2019/04/190401121805.htm
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New study measures UV-filter chemicals in seawater and corals from Hawaii
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Scientists have completed the first comprehensive assessment of UV-filters in surface seawater, sediment, and coral tissue from multiple coral reefs around the island of Oahu, Hawaii. UV-filters are active ingredients in sunscreens, but are also added to many other products, including textile, plastics, and paint to prevent photo degradation. The UV-filters oxybenzone and octinoxate have received attention by policy makers regarding their potential impact on corals. The research will help provide a baseline for future risk assessments.
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Globally corals are in serious decline with major threats from increasing temperatures due to climate change and disease. New threats from chemical contaminants in seawater are an emerging area of concern, particularly near coral reef areas with high-density population, tourism, or recreational activities.The detection of sunscreen active ingredients (i.e., UV-filters) in the aquatic environment has raised concerns over potential adverse impacts on coral reefs. However, there is very limited scientific data on their environmental concentrations in seawater near coral reefs in Hawaii. To help address these data deficiencies, University of Maryland Center for Environmental Science and University of Maryland, Baltimore County researchers measured the concentration of 13 UV filters, including oxybenzone and octinoxate, in seawater, sediment, and coral tissues. Other organic chemicals (e.g., sucralose and surfactants, synthetic hormones and polycyclic aromatic hydrocarbons [PAHs]) were also analyzed in the study."Our study vastly expands the current body of scientific data needed to assess the environmental risk of these chemicals to corals. This data can be used in conjunction with future toxicological studies to estimate environmental risk to corals and other species," said study lead Carys Mitchelmore of the University of Maryland Center for Environmental Science. Her research expertise focuses on understanding how contaminants and other environmental stressors interact with and impact organisms, especially sensitive species like corals.Study locations were chosen to represent different hypothesized loadings of UV-filters from municipal, recreational, and tourism activities, and included the tourist hot-spot Waikiki Beach and Kaneohe Bay, a popular location for water-based recreational activities. The study is the first to present on the concentration of UV-filters in coral tissue from the U.S.A. and reports the presence of at least 8 different UV-filters in coastal waters, sediment, and coral tissue from Hawaii.The study found low, parts per trillion, seawater concentrations of oxybenzone at the 19 sites studied, with most sites (12 of 19) reporting less than 10 parts per trillion (or 10 ng/L). (One part per trillion is the equivalent of adding 10 drops to a football stadium similar to the Rose Bowl filled with water.) The highest concentrations were found at the places where more people were, with up to 136 parts per trillion found at a Waikiki Beach site. No measured levels of octinoxate were found in any of the seawater samples."Overall, the impacts of oxybenzone and octinoxate to intact corals occur at much higher concentrations than this study found in seawater near coral reefs. Currently, there are only five studies that have looked at the toxicity of oxybenzone and/or octinoxate to corals, so much more research on the toxicity to corals is needed," said Mitchelmore.The study also shows that surfactant (i.e. detergent) degradation products are in seawater around the reefs, especially at Waikiki Beach, which may also impact corals. "Corals are faced with multiple stressors, and it is challenging to determine which chemicals are at concentrations in the environment that cause harm to the reefs," she said."We currently face huge challenges to protect our coastal and oceanic ecosystems," said Mitchelmore. "Much more research is needed to determine the risk of UV-filters to corals. Scientists from academia, government, and industry need to work together to conduct additional monitoring and toxicology studies so that management and policy decisions can determine what are the priority stressors and contaminants of concern most damaging to reefs."The paper "Occurrence and distribution of UV-filters and other anthropogenic contaminants in coastal surface water, sediment, and coral tissue from Hawaii" was recently published in
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Extinction
| 2,019 |
March 28, 2019
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https://www.sciencedaily.com/releases/2019/03/190328150846.htm
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Novel insights into soil biodiversity, Earth's global engine
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A Virginia Tech professor was part of an international team of researchers that discovered new advances about the major ecological patterns driving the changes in soil biodiversity that occur over millions of years.
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The study published in the journal for the "This research provides a new framework for understanding soil and ecosystem biodiversity, which is fundamental to maintaining our global biosphere and managing for future global change" said Mark A. Williams, an associate professor in the School of Plant and Environmental Sciences in the Virginia Tech College of Agriculture and Life Sciences.Soil microbes and animals, from tiny soil bacteria to earthworms, are unsung heroes in our environment, providing hundreds of billions of dollars in ecosystem services. These organisms are critical to maintaining the global biosphere and human existence. As a thought experiment during classes, Williams often asks his students what would happen if all of these diverse organisms were to become extinct. "Humans would die, too," is the typical answer.These soil organisms provide clean drinking water, regulation of the atmosphere, and nutrients that allow for productive and sustainable crop and natural ecosystems. Soil animals and microbes are by far the most abundant and diverse organisms on Earth. Still, little is known about their relationships to ecosystem change and natural history."We sought to understand how soil biodiversity changes over millions of years, and whether ecological patterns would help explain aspects of ecosystem and global ecology," Williams said.Two major ecological patterns explain the changes in soil biodiversity from centuries to many millennia.In less productive ecosystems, increases in soil biodiversity followed increases in plant cover, which provide food for soil microbes and animals. In more productive ecosystems, however, where resource availability is more abundant, acidification during soil development was often associated with declines in soil biodiversity. Interestingly, these patterns, which had not yet been observed, are different from those reported for other communities, such as plants and large fauna.
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Extinction
| 2,019 |
March 28, 2019
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https://www.sciencedaily.com/releases/2019/03/190328102628.htm
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In ancient oceans that resembled our own, oxygen loss triggered mass extinction
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Roughly 430 million years ago, during the Earth's Silurian Period, global oceans were experiencing changes that would seem eerily familiar today. Melting polar ice sheets meant sea levels were steadily rising, and ocean oxygen was falling fast around the world.
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At around the same time, a global die-off known among scientists as the Ireviken extinction event devastated scores of ancient species. Eighty percent of conodonts, which resembled small eels, were wiped out, along with half of all trilobites, which scuttled along the seafloor like their distant, modern-day relative the horseshoe crab.Now, for the first time, a Florida State University team of researchers has uncovered conclusive evidence linking the period's sea level rise and ocean oxygen depletion to the widespread decimation of marine species. Their work highlights a dramatic story about the urgent threat posed by reduced oxygen conditions to the rich tapestry of ocean life.The findings from their study were published in the journal Although other researchers had produced reams of data on the Ireviken event, none had been able to definitively establish a link between the mass extinction and the chemical and climatic changes in the oceans."The connection between these changes in the carbon cycle and the marine extinction event had always been a mystery," said lead author Seth Young, an assistant professor in FSU's Department of Earth, Ocean and Atmospheric Science.To address this old and obstinate question, Young and his co-authors deployed new and innovative strategies. They developed an advanced multiproxy experimental approach using stable carbon isotopes, stable sulfur isotopes and iodine geochemical signatures to produce detailed, first-of-their-kind measurements for local and global marine oxygen fluctuation during the Ireviken event."Those are three separate, independent geochemical proxies, but when you combine them together you have a very powerful data set to unravel phenomena from local to global scales," Young said. "That's the utility and uniqueness of combining these proxies."Young and his team applied their multiproxy approach to samples from two geologically important field sites in Nevada and Tennessee, both of which were submerged under ancient oceans during the time of the extinction event. After analyzing their samples at the FSU-based National High Magnetic Field Laboratory, the connections between changes in ocean oxygen levels and mass extinction of marine organisms became clear.The experiments revealed significant global oxygen depletion contemporaneous with the Ireviken event. Compounded with the rising sea level, which brought deoxygenated waters into shallower and more habitable areas, the reduced oxygen conditions were more than enough to play a central role in the mass extinction. This was the first direct evidence of a credible link between expansive oxygen loss and the Ireviken extinction event.But, Young found, that oxygen loss wasn't universal. Only about 8 percent or less of the global oceans experienced significantly reducing conditions with very little to no oxygen and high levels of toxic sulfide, suggesting that these conditions didn't need to advance to whole-ocean scale to have an outsized, destructive effect."Our study finds that you don't necessarily need the entire ocean to be reducing to generate these kind of geochemical signatures and to provide a kill mechanism for this significant extinction event," Young said.Today, like 430 million years ago, sea level is on the rise and ocean oxygen is hemorrhaging at an alarming rate. As parallels continue to emerge between today's changes and past calamities, peering into the Earth's distant past could be a critical tool in preparing for the future."There are common threads with other climatic and extinction events throughout Earth's history, and future work will continue to help us understand the similarities and differences of these events to constrain future climate predictions," said co-author Jeremy Owens, an assistant professor in FSU's Department of Earth, Ocean and Atmospheric Science who has worked on other extinction events in the Jurassic and Cretaceous periods."I think it's important to see how these events played out all the way from extinction interval through recovery period, how severe they were and their connections to the ancient environment along the way," added Young. "That could help us figure out what's in store for our future and how we can potentially mitigate some of the negative outcomes."This study was funded by the National Science Foundation and the Geological Society of America.
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Extinction
| 2,019 |
March 27, 2019
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https://www.sciencedaily.com/releases/2019/03/190327112649.htm
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New medication gives mice bigger muscles
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It is common knowledge that as people grow older they lose a large part of their muscle mass -- and neither are their bones what they once were. Researchers from Aarhus University, Denmark, working together with researchers at Erasmus Medical Center in Rotterdam have now studied a new group of medication which could prove beneficial for the elderly and the chronically ill who suffer a loss of bone- and muscle mass.
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They have named the group of medicinal products IASPs, Inhibitors of the Activin-receptor Signaling Pathway."IASPs inhibit a signal pathway which is found in virtually all cells. The difference between the various medications in the group is that they inhibit different routes into the pathway," explains PhD student Andreas Lodberg from the Department of Biomedicine at Aarhus University.The researchers have shown that it is possible to achieve an effect on different tissues such as muscle tissue, bone tissue or blood cells depending on the IASP they used."We found an increased muscle mass of 19 per cent in mice after just one week. At the same time as an effect on the muscle mass, we saw that the drugs also counteracted osteoporosis," says Andreas Lodberg.However, there is an Achilles heel. The effect on the blood cells has presented the researchers with a challenge. Thus far the drugs in the group of medicinal products have stimulated the formation of red blood cells as vigorously as EPO."This isn't bad if we're dealing with someone suffering from anemia, low muscle mass and osteoporosis all at once, as is the case for some. But for the majority of patients with a normal blood per cent, this increases the risk of blood clots," he says.The researchers have therefore been working on a solution. They have succeeded in creating a molecule in the IASP group which for the first time works on bones and muscles but does not affect the blood.The results have just been published in the international journal Andreas Lodberg and his colleagues have now begun investigating how IASPs specifically act when building up bone. They use different models in mice to create a loss of muscle mass before examining the tensile strength of the bones and the activity in the cells which break down and build up bones."Our earlier results could indicate that IASPs inhibit cells which break down bone tissue while at the same time the cells which build up bone tissue are stimulated, a phenomenon known as 'dual-action'," he explains.A different IASP that the researchers tested led to a 48 per cent increase in the bone strength of the neck of the femur after three weeks compared to the group that did not receive treatment."If the results of the clinical studies continue to show such promise it may make sense to treat frail elderly patients suffering muscle loss as a result of chronic diseases with an IASP. Both for the individual patient and for the national economy as falls and broken bones in elderly patients are a costly affair with high mortality and also because the loss of muscle mass due to chronic diseases impacts on quality of life and mortality rates," says Andreas Lodberg.
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Extinction
| 2,019 |
March 26, 2019
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https://www.sciencedaily.com/releases/2019/03/190326160455.htm
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In the tree of life, youth has its advantages
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It's a question that has captivated naturalists for centuries: Why have some groups of organisms enjoyed incredibly diversity -- like fish, birds, insects -- while others have contained only a few species -- like humans.
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Researchers trying to explain why the Tree of Life is so unbalanced have agreed on a few explanations -- a species' ability to change colour, its body size, and how it interacts with its environment all influence how quickly it can form new species compared to other organisms.Geological age has also been a major explanation -- older groups of organisms have had more time to accumulate more species.But new research in the "If you look at rates of macroevolutionary diversification across 3.8 billion years, it's younger groups of organisms, on average, that accumulate diversity much more quickly than older groups," says Matthew Pennell, an evolutionary biologist at the University of British Columbia and senior author on the paper."This suggest that there are some time-dependant, hidden general principles governing how life diversifies on Earth -- operating underneath all the other factors we typically think determine how quickly species diversify or go extinct."The researchers estimated specification and extinction rates across almost 25,000 branches of multicellular organisms, using data from studies of over 100 groups of species and an independent data set of fossil time series. That enabled them to compare rates of diversification broadly over time. For example cichlids (a species of fish) from African rift lakes are diversifying incredibly fast, while whales are an example of a group that appear to be far past their prime in terms of diversity."If groups of species were simply reaching equilibrium and slowing down over time, we'd expect a more consistent pattern of slowing within every group we look at," says Pennell. "But our results aren't showing that."When the researchers looked at individual groups, rates of diversification varied dramatically. What they did find at the macro-level was a strong pattern of faster growth of diversity in younger groups of species."This really throws a wrench in how we interpret how life diversified on Earth," says Pennell.Evolutionary biologists have tended to look at particular features that have helped particular groups of animals diversify -- or not."The far less explored, and potentially more interesting question, is why, despite all the complexity involved in the evolution of new species, that process looks so similar across the Tree of Life."
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Extinction
| 2,019 |
March 26, 2019
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https://www.sciencedaily.com/releases/2019/03/190326122147.htm
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Widespread losses of pollinating insects in Britain
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Many insect pollinator species are disappearing from areas of Great Britain, a new study has found.
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The research, led by the Centre for Ecology & Hydrology, measured the presence of 353 wild bee and hoverfly species across the country, from 1980 to 2013. It showed one third of species experienced declines in terms of areas in which they were found, while one tenth increased. For the remainder of species, their distribution was either stable or the trend was inconclusive.A positive but unexpected finding of the study was the increase in key bee species responsible for pollinating flowering crops, such as oil-seed rape. This could be in response to the large increases of mass-flowering crops grown during the study period and government-subsidised schemes that encourage farmers to plant more of the wildflowers they feed on.The research, published in the journal Overall losses were more notable for pollinator species found in northern Britain. This may be a result of climate change, with species that prefer cooler temperatures reducing their geographical spread in response to less climatically suitable landscapes.Dr Gary Powney of the Centre for Ecology & Hydrology, who led the research, says: "We used cutting-edge statistical methods to analyse a vast number of species observations, revealing widespread differences in distribution change across pollinating insects. There is no one single cause for these differences, but habitat loss is a likely key driver of the declines."While the increase in key crop pollinators is good news, they are still a relatively small group of species. Therefore, with species having declined overall, it would be risky to rely on this group to support the long-term food security for our country. If anything happens to them in the future there will be fewer other species to 'step up' and fulfil the essential role of crop pollination.He adds: "Non-crop pollinators are also vital for a healthy countryside rich in biodiversity; not only because of their crucial role in pollinating wildflowers, but as a key food resource for other wildlife."Wildflowers and pollinators rely on each other for survival. Losses in either are a major cause for concern when we consider the health and beauty of our natural environment."Dr Claire Carvell of the Centre for Ecology & Hydrology, a co-author of the study, points out there are multiple environmental pressures leading to changing patterns of occurrence in bees and hoverflies across the country.She says: "There is an urgent need for more robust data on the patterns and causes of pollinator declines. While this analysis sends us a warning, the findings support previous studies suggesting that conservation actions, such as wildlife-friendly farming and gardening, can have a lasting, positive impact on wild pollinators in rural and urban landscapes. However, these need further refining to benefit a wider range of species."Dr Carvell adds: "In addition to recording species sightings, more standardised monitoring of pollinator numbers is required at a national level and a new UK Pollinator Monitoring Scheme has been set up to do just this."Over 700,000 records were analysed for this study. Most were collected by expert naturalists in the Bees, Wasps and Ants Recording Society (BWARS) and the UK Hoverfly Recording Scheme, in more than 19,000 1km by 1km squares across Great Britain. It's thought to be the first study of its kind, since there have been no previous large-scale, long-term, species-specific estimates of distribution change for pollinating insects in Britain. #Mike Edwards of BWARS said: "All important studies of animal population trends, such as this latest research, rely entirely on the wildlife recorders who go out and record sightings of different species in their area. Therefore, we would encourage more people to take part in wildlife recording, so we can increase our understanding of how wildlife is responding to environmental change."
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Extinction
| 2,019 |
March 25, 2019
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https://www.sciencedaily.com/releases/2019/03/190325120347.htm
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A varied menu for the carnivorous waterwheel plant
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The Freiburg biologists Dr. Simon Poppinga, Anna Westermeier and Prof. Dr. Thomas Speck, working in cooperation with researchers from the Ruhr University Bochum and the Institute of Botany of the Czech Academy of Sciences in T?ebo? (Czech Republic), have for the first time reconstructed in detail the "menu" of the carnivorous waterwheel plant (
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Using its snap traps, which are only a few millimeters in size, the waterwheel plant catches prey animals that live underwater. The traps snap shut within about 20 milliseconds of mechanical stimulation. The basic trapping principle of the waterwheel plant is the same as the terrestrial Venus flytrap (The scientists undertook comparative analyses of the prey composition of a total of eight different populations of the waterwheel plant in Germany and the Czech Republic. This showed that the prey's mode of locomotion is irrelevant to Aldrovanda, because besides fast swimming prey, the researchers also often found slow crawling animals such as snails in the traps. The 43 prey taxa identified ranged from tiny water mites to comparatively large mosquito larvae and back swimmers that barely fit into the traps. Likewise, the trap size does not act as a morphological filter for certain prey sizes, as large traps also contained small prey animals (and vice versa). Since the waterwheel plant occurs in highly fragmented habitats, which may be very different in terms of the composition of their animal inhabitants, the diverse diet of Aldrovanda could be an advantage over a stricter prey specialization, the researchers speculate.The Plant Biomechanics Group at the Botanical Garden of the University of Freiburg has a research focus into the investigation of plant movement principles, especially the fast traps of carnivorous plants. The team has already investigated the Aldrovanda traps in respect to their biomechanics and functional morphology as part of an international research cooperation and have transferred their deformation principle into a biomimetic facade shading, the Flectofold.
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Extinction
| 2,019 |
March 21, 2019
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https://www.sciencedaily.com/releases/2019/03/190321125957.htm
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Bacteria bide their time when antibiotics attack
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If an antibiotic doesn't kill all the bacteria that infects a patient, the surviving bugs may be particularly adept at timing their resurgence.
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Theoretical scientists at Rice University have proposed a better way to understand how to prescribe antibiotics to kill every last bacterium or at least discourage them from developing resistanceAnatoly Kolomeisky, a Rice professor of chemistry and chemical and biomolecular engineering, considers antibiotic resistance "the most serious problem of the 21st century."A new study by Kolomeisky and postdoctoral researcher Hamid Teimouri shows that fluctuating growth rates of bacteria can increase the time it takes for a bacterial colony to die out and give it a better shot at developing resistance."Our calculations suggest this fluctuation, which bacteria can easily do, might help them bide their time and try different mutations," Kolomeisky said. "We think this is the possible first step in antibiotic resistance."Their theory appears in the Royal Society journal The researchers show that there is no correlation between the bacterial extinction probabilities widely used to determine antibiotic doses and actual extinction times."There is huge abuse of antibiotics in the world, and especially in this country," Kolomeisky said. "In the last five years, there's been a 4 percent increase in antibiotic prescriptions. Essentially, a huge amount of antibiotics is given to people when it's not needed."The researchers argued it should someday be possible to prescribe a more accurate dose by knowing the size of an infecting colony and the average time it will take to completely eradicate it. They present a preliminary model, from which the pharmaceutical companies might learn how to develop better strategies to improve treatment of infections.Bacterial population dynamics are key to the study, Kolomeisky said."Now, when doctors calculate how much antibiotic you should get, they treat everyone equally," he said. "That's already a huge mistake: They assume you have a huge amount of bacteria in your body and use a very simple deterministic model to prescribe the minimal concentration of antibiotic. Below that threshold, they say you will not be cured, and above it, you will always be cured."So everyone is getting exactly one tablet per day, and it doesn't matter whether you're a kid or an adult," he said.That one-size-fits-all strategy doesn't account for fluctuations in the growth rate of bacteria, Kolomeisky said. The new model incorporates these random fluctuations when averaging the amount of time it takes a population to die."The problem comes when the antibiotics are working and you come to where there's almost no bacteria," he said. "When there's almost none or the numbers are relatively small, so-called stochastic (random) effects become important. We know that it's enough to have as few as 10 salmonella or shigella bacteria for the infection to start again."Kolomeisky said current models only tell doctors the probability that a course of antibiotics will cure a patient."We care much more about the average time to be cured, not the probability," he said. "This will give doctors a much clearer description of what should be done."The study has implications for agriculture, Kolomeisky said."Food supplies 75 percent of antibiotics," he said. "We need to optimize antibiotic activities there as well, to lower the levels of antibiotics getting to people."This is a very long way from real applications, but it should give industry some ideas of what to do next and how to couple it with biochemical studies," Kolomeisky said. "It's not enough to investigate only the biochemical and genetic parts of bacterial infection. Knowing the population dynamics aspects of the antibiotic action can clarify a lot of issues."The Welch Foundation, the National Science Foundation and the Center for Theoretical Biological Physics at Rice supported the research.
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Extinction
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March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320141030.htm
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Predicted deforestation in Brazil could lead to local temperature increase up to 1.45°C
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A new model quantifies how forest change affects local surface temperatures by altering sunlight-reflection and evapotranspiration properties, and predicts that Brazilian deforestation could result in a 1.45°C increase by 2050, in a study published March 20, 2019 in the open-access journal
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Forests are known to reflect less sunlight and have higher evapotranspiration than open vegetation, meaning that deforestation and forestation could affect local land surface temperature. However, until recently there were limited high-resolution global data. The authors of the present study used a global dataset from 2000-2010 to quantify impacts of forest change on local temperatures. They used newly-released data on forest cover, evapotranspiration rates, sunlight-reflection and land surface temperature and built a model to quantify the relationship between these variables for tropical, temperate, and boreal regions.The authors found that deforestation and forestation generally appeared to have opposite effects of similar magnitude on local temperature. However, the nature of the effect and the magnitude of the temperature change depended on latitude: in tropical and temperate regions, deforestation led to warming, while forestation had cooling effects. In boreal regions, deforestation led to slight cooling, though the magnitude of the effect was smaller. The magnitude of the forest change effects was greatest in tropical regions, with, for example, deforestation of approximately 50 percent leading to local warming of over 1°C.The authors used their model to predict local temperature change in Brazil between 2010 and 2050. Assuming the current rate of illegal deforestation is maintained, this predicted an annual land surface temperature rise of up to 1.45°C in some areas by 2050. However, if no further illegal deforestation occurred, the temperature rise could be far more limited.This new model quantifies the effect of forest change on local surface temperatures, through changes in sunlight-reflection and evapotranspiration. The authors note that their Brazil case study "illustrates that current land use policies can impact future local climate."The authors add: "Forestation has the potential to reverse deforestation impacts on local climate, especially in tropical and temperate regions."
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| 2,019 |
March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320120603.htm
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Butterfly numbers down by two thirds, German scientists find
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Meadows adjacent to high-intensity agricultural areas are home to less than half the number of butterfly species than areas in nature preserves. The number of individuals is even down to one-third of that number. These are results of a research team led by Jan Christian Habel at the Technical University of Munich (TUM) and Thomas Schmitt at the Senckenberg Nature Research Society.
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Germany is home to roughly 33,500 species of insects -- but their numbers are decreasing dramatically. Of the 189 species of butterflies currently known from Germany, 99 species are on the Red List, 5 have already become extinct, and 12 additional species are threatened with extinction.Now a team led by Prof. Jan-Christian Habel of the Department of Terrestrial Ecology of the Technical University of Munich and Prof. Thomas Schmitt, Director of the Senckenberg German Entomological Institute in Muencheberg in Brandenburg, has examined the specific effects of the intensity of agricultural use on the butterfly fauna.The research team recorded the occurrence of butterfly species in 21 meadow sites east of Munich. Of these study sites, 17 are surrounded by agriculturally used areas, and four are in nature preserves with near-natural cultivation.They recorded a total of 24 butterfly species and 864 individuals in all study sites. Specialists among the butterflies were particularly dependent on near-natural habitats, while the more adaptable "generalists" were also found in other grassland sites."In the meadows that are surrounded by agriculturally used areas we encountered an average of 2.7 butterfly species per visit; in the four study sites within the protected areas 'Dietersheimer Brenne' and 'Garchinger Heide' near Munich we found an average of 6.6 species," adds Prof. Werner Ulrich of the Copernicus University in Thorn, Poland."Our results show an obvious trend: in the vicinity of intensively cultivated fields that are regularly sprayed with pesticides, the diversity and numbers of butterflies are significantly lower than in meadows near less used or unused areas," explains the study's lead author, Prof. Jan Christian Habel."Our study emphasizes the negative impact of the conventional, industrialized agriculture on the butterfly diversity and shows the urgent need for ecologically sustainable cultivation methods. Additional field studies may aid in identifying individual factors responsible for the insect die-back and in implementing appropriate countermeasures," adds Schmitt in closing.
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| 2,019 |
March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320110624.htm
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Coral reefs near equator less affected by ocean warming
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Ocean warming is threatening coral reefs globally, with persistent thermal stress events degrading coral reefs worldwide, but a new study has found that corals at or near the equator are affected less than corals elsewhere.
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The findings from Florida Institute of Technology Ph.D. student Shannon Sully and professor Rob van Woesik, along with colleagues at the University of California at Santa Barbara and Reef Check, were published March 20 in the journal The work, which was supported by the National Science Foundation and the Zegar Family Foundation, was based on analysis of field observations from a 20-year global survey of over 3,500 coral study sites led by Reef Check founder and former director Gregor Hodgson.As expected, coral bleaching was most common in localities experiencing high-temperature stress, but it was significantly less common in those places with high monthly variation in temperatures."We found that it took higher temperatures to bleach corals this past decade than it did 20 years ago," Florida Tech's Shannon Sully said.The authors suggest that bleaching at higher temperatures this decade is likely a consequence of the decline in temperature-sensitive corals during previous bleaching events and that the remaining populations now have a higher thermal threshold for bleaching."We found that the reefs near the Equator were less affected by bleaching than elsewhere, despite similar thermal-stress levels at equatorial sites," said Deron Burkepile, a co-author from UCSB.Rob van Woesik, professor and director of the Institute for Global Ecology at Florida Tech, said even with the new analysis, some questions remain."We are uncertain why equatorial reefs are more tolerant of recent temperature stress, but we do know that we must protect these equatorial reefs -- and reefs everywhere -- from other disturbances, lest we lose coral reefs that protect coastal inhabitants from storm waves and help feed millions of people worldwide," he said.Jan Freiwald, Reef Check's executive director, added that he was glad to see Reef Check's data put to good use."Reef Check's citizen science divers work hard to survey reefs all over the world so that we have the data we need to understand our reefs and make effective management decisions in a changing planet," he said.
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Extinction
| 2,019 |
March 20, 2019
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https://www.sciencedaily.com/releases/2019/03/190320102158.htm
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Local extinction of Southern California mountain lions possible within 50 years
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Two isolated mountain lion populations in southern California's Santa Ana and Santa Monica Mountains are at risk of local extinction, perhaps as soon as within 50 years, according to a study published in the journal
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The study showed the extinction risk is due to low genetic diversity and mortality that affects the stability of the population. Mountain lion mortality is often caused by humans, but can also result from changes in the environment, such as wildfire and fluctuations in prey density.The two mountain lion populations in the human-dominated landscape of southern California are isolated by freeways and development. For the study, lead author John Benson of the University of Nebraska and co-authors at UCLA, the University of California, Davis, the National Park Service, the University of Washington, Northern Arizona University, and the University of Wyoming used population viability modeling to predict the possibilities of extinction from genetic and demographic risk factors."It's easy to read our paper as yet another pessimistic story about wildlife threatened by human actions -- and in a sense that is true," said Benson. "However, there is also a more optimistic message in that our model predicted that these populations can persist with relatively modest increases in landscape connectivity. If we can maintain healthy populations of mountain lions -- a species that roams widely and requires such large spaces -- here in greater Los Angeles, that bodes well for our ability to conserve large carnivores anywhere."Both mountain lion populations have very low genetic diversity as a result of inbreeding, which is inevitable given the lack of connectivity between the mountain ranges and surrounding areas.Genetic diversity in these two populations is expected to rapidly decline over the next 50 years, which raises concern about inbreeding depression -- a phenomenon in which survival and reproduction of animals decline due to low genetic diversity. When the researchers simulated the effects of inbreeding depression in the two populations, the model predicted that rapid extinction was almost certain.The model predicted generally similar dynamics in the two populations, but the research also revealed differences driven by greater population size and higher mortality in the Santa Ana Mountains."Our research has shown that the mountain lions in the coastal Santa Ana Mountain Range are primarily put at risk by restriction of their movement across Interstate 15, and their high mortality rates from vehicle collisions and being killed after they have killed unprotected pets or livestock," said T. Winston Vickers, report co-author and associate veterinarian at the University of California, Davis' Karen C. Drayer Wildlife Health Center. "Efforts are underway with highway engineers to improve wildlife crossing structures or build new ones on both the I-15 and 101 freeways to enhance movement into and out of both mountain ranges."The research highlighted that conservation of large carnivores, including mountain lions, is achievable within urbanized landscapes. But this requires effort. Land protection, connection between the lands and strategies to promote coexistence with humans are necessary to prevent the extinction of these top predators."It was interesting to see the differences between the two populations, such as the higher mortality rates in the Santa Anas, and sobering to see the fast rates of extinction predicted for both populations if serious inbreeding depression sets in," said co-author and National Park Service Wildlife Ecologist Seth Riley, who has been studying mountain lions in the Santa Monica mountains since 2002. "However, it's also really heartening to see how much of a difference increasing connectivity can make for these isolated populations."Research in the Santa Ana Mountains was supported by California State Department of Parks and Recreation, California Department of Fish and Game, The Nature Conservancy, McBeth Foundation, Anza Borrego Foundation, Nature Reserve of Orange County, National Science Foundation, Foothill/Eastern Transportation Corridor Agency, San Diego County Association of Governments Environmental Mitigation Program, San Diego Foundation, Felidae Conservation Fund, Mountain Lion Foundation, Santa Rosa Plateau Foundation, Institute for Wildlife Studies, and private donors.Major funding for John Benson's work on this project was provided by the La Kretz Center for California Conservation Science at UCLA and the National Park Service.
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Extinction
| 2,019 |
March 19, 2019
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https://www.sciencedaily.com/releases/2019/03/190319112211.htm
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'Insectageddon' is 'alarmist by bad design': Scientists point out the study's major flaws
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Amidst worldwide publicity and talks about 'Insectageddon': the extinction of 40% of the world's insects, as estimated in a recent scientific review, a critical response was published in the open-access journal
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Query- and geographically-biased summaries; mismatch between objectives and cited literature; and misuse of existing conservation data have all been identified in the alarming study, according to Drs Atte Komonen, Panu Halme and Janne Kotiaho of the University of Jyväskylä (Finland). Despite the claims of the review paper's authors that their work serves as a wake-up call for the wider community, the Finnish team explain that it could rather compromise the credibility of conservation science.The first problem about the paper, titled "Worldwide decline of the entomofauna: A review of its drivers" and published in the journal "If you search for declines, you will find declines. We are not questioning the conclusion that insects are declining," Komonen and his team point out, "but we do question the rate and extent of declines."The Finnish research team also note that there are mismatches between methods and literature, and misuse of IUCN Red List categories. The review is criticised for grouping together species, whose conservation status according to the International Union for Conservation of Nature (IUCN) is Data Deficient with those deemed Vulnerable. By definition, there are no data for Data Deficient species to assess their declines.In addition, the review paper is seen to use "unusually forceful terms for a peer-reviewed scientific paper," as the Finnish researchers quote a recent news story published in The Guardian. Having given the words dramatic, compelling, extensive, shocking, drastic, dreadful, devastating as examples, they add that that such strong intensifiers "should not be acceptable" in research articles."As actively popularising conservation scientists, we are concerned that such development is eroding the importance of the biodiversity crisis, making the work of conservationists harder, and undermining the credibility of conservation science," the researchers explain the motivation behind their response.
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Extinction
| 2,019 |
March 18, 2019
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https://www.sciencedaily.com/releases/2019/03/190318132644.htm
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Alligator study reveals insight into dinosaur hearing
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To determine where a sound is coming from, animal brains analyze the minute difference in time it takes a sound to reach each ear -- a cue known as interaural time difference. What happens to the cue once the signals get to the brain depends on what kind of animal is doing the hearing.
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Scientists have known that birds are exceptionally good at creating neural maps to chart the location of sounds, and that the strategy differs in mammals. Little was known, however, about how alligators process interaural time difference.A new study of American alligators found that the reptiles form neural maps of sound in the same way birds do. The research by Catherine Carr, a Distinguished University Professor of Biology at the University of Maryland, and her colleague Lutz Kettler from the Technische Universität München, was published in the Most research into how animals analyze interaural time difference has focused on physical features such as skull size and shape, but Carr and Kettler believed it was important to look at evolutionary relationships.Birds have very small head sizes compared with alligators, but the two groups share a common ancestor -- the archosaur -- which predates dinosaurs. Archosaurs began to emerge around 246 million years ago and split into two lineages; one that led to alligators and one that led to dinosaurs. Although most dinosaurs died out during the mass extinction event 66 million years ago, some survived to evolve into modern birds.Carr and Kettler's findings indicate that the hearing strategy birds and alligators share may have less to do with head size and more to do with common ancestry."Our research strongly suggests that this particular hearing strategy first evolved in their common ancestor," Carr said. "The other option, that they independently evolved the same complex strategy, seems very unlikely."To study how alligators identify where sound comes from, the researchers anesthetized 40 American Alligators and fitted them with earphones. They played tones for the sleepy reptiles and measured the response of a structure in their brain stems called the nucleus laminaris. This structure is the seat of auditory signal processing. Their results showed that alligators create neural maps very similar to those previously measured in barn owls and chickens. The same maps have not been recorded in the equivalent structure in mammal brains."We know so little about dinosaurs," Carr said. "Comparative studies such as this one, which identify common traits extending back through evolutionary time add to our understanding of their biology."
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Extinction
| 2,019 |
March 14, 2019
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https://www.sciencedaily.com/releases/2019/03/190314151619.htm
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Researchers uncover new clues to surviving extinction
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Scientists are peeking into ancient oceans to unravel the complexities of mass extinctions, past and future. A new examination of Earth's largest extinction by scientists at the California Academy of Sciences and the University of Wisconsin-Milwaukee sheds light on how ecosystems are changed by such transformative events.
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The study, published today in "We're interested in understanding why certain species and communities survived and recovered better than others," says Dr. Ashley Dineen, a former Academy postdoctoral researcher and current Museum Scientist of Invertebrate Paleontology at the UC Museum of Paleontology at Berkeley. "For a long time biology has focused on the number of species that survive extinction events, but we need to also ask what those species did and how they reacted to stresses -- these insights are important as we push our planet into an increasingly uncertain future."The massive extinction event, often referred to as the "Great Dying," took place 252 million years ago and frequently serves as a proxy for the modern era. Similar to today, the climate regime was transitioning from a cooler period to a warmer period. This climatic fluctuation, driven by massive volcanic eruptions that spewed noxious gases, increased the temperature and acidity of the oceans, decreased oxygen concentrations, interrupted mighty ocean currents, and turned the ocean system on its head.The researchers examined fossils of ocean-dwelling invertebrate creatures like clams, snails, corals, and sponges from Utah, Nevada, and Texas. This region once comprised the shallow outskirts of the ancient and vast Panthalassa Ocean. Using numerical methods, the team grouped marine survivor species into functional groups with similar traits, like mobile bottom-dwelling omnivores such as sea urchins, to better understand the ecological transformation in the wake of the Great Dying."We learned from our analysis that beyond documenting the number of species that arise during an ecological recovery, we need to know what they were actually doing -- what scientists call their functional diversity," says Dr. Peter Roopnarine, Academy Curator of Geology. "This helps us understand if the system has shifted toward favoring species with a variety of responses to stress."One surprising revelation: the study results showed significant ecological continuity among species -- where species that were wiped out during the extinction event shared the same traits as those that originated in its aftermath. During recovery, however, there was a significant shift in numbers toward bigger and more active survivors that are strikingly similar to the inhabitants of our modern oceans. This shift in functional emphasis may be the the hallmark of an ecosystem set on the road to recovery."Our next step is to determine what kinds of species you want on the frontlines of recovery," says Dineen. "For example, if you have a reef with twenty different species of corals but they all react the same to stressors, then they will all be similarly impacted when hit with a disturbance. But on a separate reef, if you have twenty coral species and each reacts differently to stress, the chance of losing the entire reef is lower. Having diverse coping mechanisms is critical for a future marked by increasing environmental stressors."The study team hopes their findings about species survivors will help scientists identify our modern -- and urgently needed -- conservation priorities."We're often focused on estimating the number of species in an ecosystem, but we should also be learning about how -- and how well -- these species survive, and concentrate conservation efforts accordingly," says Dineen. "When you consider the mass extinction we face today, it's clear we have to take entire systems into account before it's too late to correct course."
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Extinction
| 2,019 |
March 13, 2019
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https://www.sciencedaily.com/releases/2019/03/190313140558.htm
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Protected areas could help large herbivores bounce back after war
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Large herbivore populations can substantially recover after war-induced declines, given that protected area management is provided, according to a study published March 13 in the open-access journal
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To date, it has not been clear how large mammal communities reassemble after being pushed to the brink of extinction. Few data are available to answer this question, as it is rarely possible to document both the decline and recovery of wildlife populations. In the new study, Stalmans and colleagues present the first in-depth quantitative account of war-induced collapse and postwar recovery in a diverse assemblage of large herbivores. In Gorongosa National Park, the researchers assembled data from 15 aerial wildlife counts of nine large herbivores conducted before (1968-1972) and after (1994-2018) the Mozambican Civil War of 1977-1992.The results showed that large herbivore populations declined by more than 90% during the war. Total biomass has substantially recovered since 1994 and most herbivore populations have increased postwar, but species composition has shifted dramatically. Formerly dominant large herbivores -- including elephant, hippo, buffalo, zebra, and wildebeest -- are now outnumbered by waterbuck and other small- to mid-sized antelopes. Waterbuck abundance has increased by an order of magnitude, whereas elephant, hippo, and buffalo, which totaled 89% of prewar biomass, now comprise just 23%. These trends mostly reflect natural population growth following the resumption of protection under the Gorongosa Restoration Project, which was initiated in 2004.According to the authors, the results demonstrate the potential for rapid postwar recovery of large herbivore biomass, given sound protected area management, but also suggest that restoration of community structure takes longer and may require active intervention.The authors add: "How do large-mammal communities reassemble after being pushed to the brink of extinction? This article presents the first in-depth quantitative account of war-induced collapse and postwar recovery in a diverse assemblage of large herbivores."
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Extinction
| 2,019 |
March 12, 2019
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https://www.sciencedaily.com/releases/2019/03/190312170815.htm
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Desert plants provided by homeowners offer habitat for desert bird species
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A persistent question among urban ecology researchers has been the long-term impact of urbanization on bird species biodiversity. Specifically, they wonder whether the portions of cities with higher diversity are simply exhibiting an "extinction debt" -- populations doomed to extinction but not yet disappeared -- or if other factors such as range shifts or local environmental changes play a role in changes in diversity.
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Now, researchers led by co-first authors Paige S. Warren at UMass Amherst and Susannah B. Lerman of the USDA Forest Service, with Riley Andrade, Kelli Larson and Heather Bateman of Arizona State University, report on results from their long-term monitoring of birds in the Phoenix metropolitan area. Details appear in the current online issue of The study looked at bird communities over time in relation to habitat, societal factors, human responses and bird populations. Findings suggest that although the presence of bird species, bird abundance and the number of bird species all decreased over time, in areas where homeowners provided desert landscaping -- fine gravel and drought-tolerant, desert-adapted vegetation -- some desert specialist birds such as verdin and cactus wren could still be found.The researchers also report observing socio-economic factors associated with species diversity. For example, the desert-like landscaping types and desert specialist bird species occurred more frequently in neighborhoods with higher per-capita incomes and lower percentages of renters and Hispanic/Latinx residents. Warren notes that including socioeconomic factors has become more common recently, but it's still unusual. Their earlier work "was truly ground-breaking with respect to including socioeconomic factors," she says."The fact that all kinds of species were declining is particularly surprising and troubling to us," says Lerman. However, Warren adds, "Our results suggest that if we could find ways to encourage homeowners to provide more areas with desert-like plantings, there are opportunities to retain the richness of bird species, even in people's back yards."Doug Levey, an NSF Long-Term Ecological Research (LTER) program director, says, "It's surprising and worrisome that birds are declining in neighborhoods that appear otherwise unchanged. Something is going on and these scientists are well on the way to figuring it out."As noted, this study built upon an earlier investigation in the same area by Warren and Lerman, who found positive associations between certain bird species and landscaping arrangements such that desert birds were found associated with desert-like landscaping. They also found greater resident satisfaction in neighborhoods with greater bird diversity, and neighborhoods with wealthier residents had more localized bird species.Five years after the first study, the researchers revisited the same sites to evaluate changes in bird species composition in the context of bird population trends, plus local environmental changes in habitat and land use, to see what species persisted over time, whether desert birds continue to associate with desert-like landscapes, whether socio-economic inequalities in access to bird diversity persist and whether these affect resident satisfaction with bird variety.Warren, Lerman and colleagues conducted the investigation in the National Science Foundation's (NSF) Central Arizona-Phoenix (CAP) LTER site in the same 39 neighborhoods sampled five years earlier. They and colleagues surveyed birds twice per year, characterized landscape type and administered a household survey to gauge neighborhood satisfaction with local birds. They used census data to characterize neighborhood socio-economic features and local maps to identify land use changes. Dan Childers, CAP LTER director, says, "This excellent paper demonstrates that inter-disciplinary socio-ecological analysis of long-term data is critical to helping us better understand urban ecosystem dynamics."The authors report that average bird occupancy -- the proportion of places where a species is found -- decreased between the two periods by 9 percent, from 46.7 to 37.8 percent, and note that six of 11 desert specialist species declined. Also, there were fewer desert bird species recorded during the second time period. However, half of the generalist bird species and half of the invader species remained stable.Landscape types showed little change; in particular the number of desert-like landscapes was the same between periods, they note. Census data showed a shift toward more Hispanic/Latinx residents and fewer Anglo residents, while income and education levels did not change. Similarly, associations between desert birds in higher income neighborhoods and more exotic species found in Hispanic/Latinx neighborhoods remained consistent through the two sampling periods, even though the types of birds shifted over time.Overall, the authors report, "the decline in bird species/change in composition is driven by factors other than changing demographics or landscapes." They add, "We documented significant losses in species richness and abundance, particularly for desert specialist species across a five-year period. However, some of the obvious mechanisms of regional population trends or local-scale environmental change do not appear to account for these losses, raising the possibility of an extinction debt."Warren says, "The declines we found here mirror similar declines found over a 12-year period in riparian habitats in Phoenix, suggesting this is not just a five-year dip." Lerman adds that a loss of species in residential yards could significantly affect residents' access to a vibrant and unique desert fauna, and she hopes that this information "will inspire residents and local gardening organizations to landscape with birds in mind."Childers points out, "Cities are designed, built and managed as human habitat, and these findings demonstrate how our decisions about that affect other species that share our urban ecosystems with us. These 'lessons learned' also provide valuable input as we work with urban practitioners to help move our cities towards more sustainable futures."
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Extinction
| 2,019 |
March 11, 2019
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https://www.sciencedaily.com/releases/2019/03/190311081931.htm
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New species of stiletto snake capable of sideways strikes discovered in West Africa
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Following a series of recent surveys in north-western Liberia and south-eastern Guinea, an international team of researchers found three stiletto snakes which were later identified as a species previously unknown to science.
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The discovery, published in the open-access journal Curiously, stiletto snakes have unusual skulls and venom delivery system, allowing them to attack and stab sideways with a fang sticking out of the corner of their mouths. While most of these burrowing snakes are not venomous enough to kill a human -- even though some are able to inflict serious tissue necrosis -- this behaviour makes them impossible to handle using the standard approach of holding them with fingers behind the head. In fact, they can even stab with their mouths closed.The new species, called The new species lives in primary rainforest and rainforest edges in the western part of the Upper Guinea forests. Branch's Stiletto Snake is most likely endemic to this area, a threatened biogeographic region already known for its unique and diverse fauna.The first specimen of the new species was collected at night from a steep bank of a small rocky creek in a lowland evergreen rainforest in Liberia. Upon picking it up, the snake tried to hide its head under body loops, bending it at an almost right angle, so that its fangs were partly visible on the sides. Then, it repeatedly stroke. It is also reported to have jumped distances almost as long as its entire body. The other two specimens used for the description of the species were collected from banana, manioc and coffee plantations in south-eastern Guinea, about 27 km apart."The discovery of a new and presumably endemic species of fossorial snake from the western Upper Guinea forests thus is not very surprising," conclude the researchers. "However, further surveys are needed to resolve the range of the new snake species, and to gather more information about its ecological needs and biological properties."
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Extinction
| 2,019 |
March 8, 2019
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https://www.sciencedaily.com/releases/2019/03/190308180302.htm
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Horseshoe crabs are really relatives of spiders, scorpions
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Blue-blooded and armored with 10 spindly legs, horseshoe crabs have perhaps always seemed a bit out of place.
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First thought to be closely related to crabs, lobsters and other crustaceans, in 1881 evolutionary biologist E. Ray Lankester placed them solidly in a group more similar to spiders and scorpions. Horseshoe crabs have since been thought to be ancestors of the arachnids, but molecular sequence data have always been sparse enough to cast doubt.University of Wisconsin-Madison evolutionary biologists Jesús Ballesteros and Prashant Sharma hope, then, that their recent study published in the journal By analyzing troves of genetic data and considering a vast number of possible ways to examine it, the scientists now have a high degree of confidence that horseshoe crabs do indeed belong within the arachnids."By showing that horseshoe crabs are part of the arachnid radiation, instead of a lineage closely related to but independent of arachnids, all previous hypotheses on the evolution of arachnids need to be revised," says Ballesteros, a postdoctoral researcher in Sharma's lab. "It's a major shift in our understanding of arthropod evolution."Arthropods are often considered the most successful animals on the planet since they occupy land, water and sky and include more than a million species. This grouping includes insects, crustaceans and arachnids.Horseshoe crabs have been challenging to classify within the arthropods because analysis of the animals' genome has repeatedly shown them to be related to arachnids like spiders, scorpions, mites, ticks and lesser-known creatures such as vinegaroons. Yet, "scientists assumed it was an error, that there was a problem with the data," says Ballesteros.Moreover, horseshoe crabs possess a mix of physical characteristics observed among a variety of arthropods. They are hard-shelled like crabs but are the only marine animals known to breathe with book gills, which resemble the book lungs spiders and scorpions use to survive on land.Only four species of horseshoe crabs are alive today, but the group first appeared in the fossil record about 450 million years ago, together with mysterious, extinct lineages like sea scorpions. These living fossils have survived major mass extinction events and today their blood is used by the biomedical industry to test for bacterial contamination.Age is just one of the problems inherent in tracing their evolution, say Ballesteros and Sharma, since searching back through time to find a common ancestor is not easy to accomplish. And evidence from the fossil record and genetics indicates evolution happened quickly among these groups of animals, convoluting their relationships to one another."One of the most challenging aspects of building the tree of life is differentiating old radiations, these ancient bursts of speciation," says Sharma, a professor of integrative biology. "It is difficult to resolve without large amounts of genetic data."Even then, genetic comparisons become tricky when looking at the histories of genes that can either unite or separate species. Some genetic changes can be misleading, suggesting relationships where none exist or dismissing connections that do. This is owed to phenomena such as incomplete lineage sorting or lateral gene transfer, by which assortments of genes aren't cleanly made across the evolution of species.Ballesteros tested the complicated relationships between the trickiest genes by comparing the complete genomes of three out of the four living horseshoe crab species against the genome sequences of 50 other arthropod species, including water fleas, centipedes and harvestmen.Using a complex set of matrices, taking care not to introduce biases in his analysis, he painstakingly teased the data apart. Still, no matter which way Ballesteros conducted his analysis, he found horseshoe crabs nested within the arachnid family tree.He says his approach serves as a cautionary tale to other evolutionary biologists who may be inclined to cherry-pick the data that seem most reliable, or to toss out data that don't seem to fit. Researchers could, for example, "force" their data to place horseshoe crabs among crustaceans, says Sharma, but it wouldn't be accurate. The research team tried this and found hundreds of genes supporting incorrect trees.Ballesteros encourages others to subject their evolutionary data to this kind of rigorous methodology, because "evolution is complicated."Why horseshoe crabs are water dwellers while other arachnids colonized land remains an open question. These animals belong to a group called Chelicerata, which also includes sea spiders. Sea spiders are marine arthropods like horseshoe crabs, but they are not arachnids."What the study concludes is that the conquest of the land by arachnids is more complex than a single tradition event," says Ballesteros.It's possible the common ancestor of arachnids evolved in water and only groups like spiders and scorpions made it to land. Or, a common ancestor may have evolved on land and then horseshoe crabs recolonized the sea."The big question we are after is the history of terrestrialization," says Sharma.For Ballesteros, who is now studying the evolution of blindness in spiders living deep within caves in Israel, his motivations get to the heart of human nature itself."I get to look with childish curiosity and ask: 'How did all this diversity come to be?'" he says. "It's incredible what exists, and I never thought I would have the privilege to be able to do this."The study was funded by the M. Guyer postdoctoral fellowship and supported by National Science Foundation grant IOS-1552610.
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Extinction
| 2,019 |
March 7, 2019
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https://www.sciencedaily.com/releases/2019/03/190307172219.htm
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Coral reef parks protecting only 40 percent of fish biomass potential
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Marine scientists from WCS (Wildlife Conservation Society) and other groups examining the ecological status of coral reefs across the Indian and Pacific oceans have uncovered an unsettling fact: even the best coral reef marine parks contain less than half of the fish biomass found in the most remote reefs that lie far from human settlements.
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The study titled "Global baselines and benchmarks for fish biomass: comparing remote reefs and fisheries closures" appears in the new edition of the journal "Searching for healthy reef fish communities to act as benchmarks required going far from shore to provide the ultimate control for human impacts. What we uncovered is that fishing has long-lasting seascape impacts, even when fishing has stopped in parks for decades," said Dr. Tim McClanahan, WCS Senior Conservationist and lead author of the study.The researchers gathered data from a number of reef fish studies conducted between 2005 and 2016 on nearly 1,000 coral reefs to evaluate the effectiveness of remote reef baselines and nearshore benchmarks, management or access systems that are often used to evaluate the ecological status of marine ecosystems.The coral reefs examined included both fishing closures (ranging from more than 15 years to 48 years in duration) and reef systems in sites that were more than 9 hours travel time from land-based markets. The mean distance to markets for remote areas was 39 hours of travel time compared to 2 hours for nearshore fisheries closures. Fish species from 28 families commonly found in coral reefs were included in the analysis. Sharks, generally wide-ranging species that are not always effectively protected through fishing closures, were excluded from the analysis. Thus, the finding could not be attributed to losses of sharks, species known to be highly vulnerable to fishing.The analysis found that there was no significant change in a reef's biomass between those fish communities found in fishing closures that were approximately 15 years old and those that were nearly 50 years old. They did find that fishing closures had only 40 percent of the fish biomass contained in more remote reefs that had not experienced significant levels of fishing. Specifically, fishing closures used in the study had an average biomass of 740 kilograms per hectare, as opposed to 1,870 kilograms per hectare found in offshore reef sites. Remote reefs in tropical latitudes also contained more biomass than remote sites in subtropical locations; the authors also found that variables such as coral cover and light levels (related to depth) influenced reef's biomass of fish but in different ways for nearshore closure and remote reefs -- indicating very different ecologies for coral parks and remote reefs.The authors maintain that, while fishing closures are still an important tool for marine management in heavily fished seascapes, the new findings underline the difficulties of simulating wilderness in small marine parks.McClanahan added: "We can see the important role that marine wilderness plays in protecting fish communities, a role that marine parks in nearshore locations are not able to simulate. Now, when we calculate fish baselines and biomass, we know what is truly being compared and lost in terms of conditions prior to human impacts."The authors of the paper are: Tim McClanahan and Remy M. Oddenyo of WCS; Robert E. Schroeder of NOAA (National Oceanic and Atmospheric Administration) Fisheries; Alan M. Friedlander of the National Geographic Society and University of Hawaii; Laurent Vigliola of Institut de Recherche pour le Développement, France; Laurent Wantiez of Institut de Sciences Exactes et Appliquées, France; Jennifer E. Caselle of the University of California; Nicholas A.J. Graham of Lancaster University, United Kingdom; Shaun Wilson of the Department of Biodiversity Conservation and Attractions and University of Western Australia; Graham J. Edgar and Rick D. Stuart-Smith of the University of Tasmania, Australia;, and J. Cinner of James Cook University.This work was supported by the John D. and Catherine T. MacArthur Foundation, the Marine Science for Management program of the Western Indian Ocean Marine Science Association, and the United States Agency for International Development.
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Extinction
| 2,019 |
March 7, 2019
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https://www.sciencedaily.com/releases/2019/03/190307131404.htm
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When coral reefs change, researchers and local communities may not see eye to eye
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Disturbances in coral reefs can trigger significant ecosystem shifts, but ecologists and local fishing populations may perceive those shifts in fundamentally different ways, according to a study from Florida State University researchers.
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This apparent disconnect between data-driven scientists and experience-driven fishing communities could have major implications for the management and resilience of coral reefs and other sensitive marine ecosystems.Study author Andrew Rassweiler, an assistant professor in FSU's Department of Biological Science, worked with collaborators from University of California, Santa Barbara and San Diego State University to administer a suite of surveys and fish population assessments on the French Polynesian island of Moorea"Our study emphasizes that different groups have different perceptions of change and ecosystem health," Rassweiler said.The findings were published in the journal Coral reefs around the world are experiencing considerable pressure from human activity. As ecosystems succumb to these pressures, biodiversity declines and coastal communities -- which depend on the vitality of coral reefs -- become less economically and culturally secure.In Moorea, this process has historically taken on a patchwork quality, with some areas of the island's lagoons supporting robust coral communities and other areas giving way to overgrowth by seaweed. But after an outbreak of coral-devouring crown-of-thorns sea stars in 2009 and a destructive cyclone in 2010, live coral cover in many locations around the island was reduced by upward of 95 percent.These destabilizing events threw the ecosystem into disarray. In addition to widespread coral loss, fish abundances changed abruptly, with herbivorous fish swarming the area to graze on seaweed growing on the skeletons of dead coral.This influx of seaweed-feeding fish wasn't necessarily a surprise. Long-term ecological research on the island had identified the role of herbivorous fish in keeping seaweed forests in check. But less was known about how Moorea's local fishing communities, where more than three-quarters of households contain a member who actively fishes the reef, reacted to this rapid and radical shift in fish abundances."Everyone around the island is fishing, but we know very little about how fishers decide where to fish and what fish to target," Rassweiler said. "This paper was a first step in looking at how people's fishing behavior changed following a big change in the fish community."By comparing the fish caught and sold around the island to the fish observed by researchers on the reef, Rassweiler's team determined that the shifting abundances of reef-dwelling fish communities were reflected in shifting compositions of the fish people caught. Most notable was a decrease in Naso, or unicornfish, which islanders would eat multiple times a week before the 2009 and 2010 disturbances, and an increase in algae-eating parrotfish, which began to appear in higher concentrations on the reef after the mass coral die-off.These changes, however, were not perceived by the locals to be especially significant. Surveys indicated that while residents of the island were aware of shifts in the reef, the disturbances did not prompt appreciable changes in fishing behavior. Even more puzzling, the islanders did not report changes in the composition of fish they caught, sold and ate, despite the scientific evidence."Fish consumers can have very different perceptions than scientists and resource managers, even in a place where locals are closely connected to reefs," said Dan Thornhill, a program director in the National Science Foundation's Division of Ocean Sciences, which funded the study along with NSF's Dynamics of Coupled Natural and Human Systems program. "That will be an important consideration going forward in the sustainable management of reefs and the fisheries they support."As both unicornfish and parrotfish were prized by fishers before the ecological disturbances, researchers said that the shifting abundances of the two types of fish may not have registered to Moorea's fishing communities as a particularly important event."Moorea's fishers view the environment as naturally variable, and the changes in the abundances of fishes on the reef resulting from the environmental disturbances are a normal occurrence for them," said study co-author and U.C. Santa Barbara ecologist Sally Holbrook.These changes were, however, of major concern to scientists, for whom seemingly small changes in population abundances could be portents of deeper ecological dysfunction."Scientists have demonstrated that these shifts are ecologically very important, but for fishers they were not as significant," Rassweiler said. "This is part of a bigger project where we're working with the fishers to think about reef health and management. It's been enlightening because they have unique insight about the status of different species."Added San Diego State anthropologist Matthew Lauer: "It's fascinating that scientists and Polynesian fishers, both of whom spend a huge amount of time on these reefs, have such radically differing standpoints about ecosystem change. Getting a handle on their differing views about marine health and change will not only help us learn more about these reefs but can also contribute to more effective and collaborative resource management."
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Extinction
| 2,019 |
March 6, 2019
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https://www.sciencedaily.com/releases/2019/03/190306143025.htm
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Fish diversity linked to Caribbean coral reef health
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The health of coral reefs can be impacted as much by the diversity of fish that graze on them as by the amount of fish that do so, according to a new study by scientists at Bigelow Laboratory for Ocean Sciences. In the
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"Scientists have long known that reefs are healthier when a large number, or a 'high biomass,' of plant-eating fish graze their surfaces," said Doug Rasher, senior author of the study and a senior research scientist at Bigelow Laboratory. "However, this study revealed that having a diverse portfolio of those fish species on the reef is equally important to keeping reefs well grazed and hospitable to baby corals."The findings have significant implications for the management of tropical fisheries. Many herbivores, such as parrotfish and surgeonfish, are eaten by people across the Caribbean. Management plans often focus on sustaining a given number of herbivores on a reef, and not necessarily promoting species diversity within the herbivore community.As these fish graze, they scrape tiny turf algae and seaweeds from the reef, keeping spaces free of algae and primed for the settlement of baby corals. This grazing is especially important following reef disturbances, such as hurricanes and coral bleaching events. In these decisive moments, considerable space on the reef suddenly becomes available. If seaweeds take hold, they prevent corals from re-establishing and can take over in their place. Shifts to seaweed beds are difficult to reverse and have become common in the Caribbean, where corals have declined on average by 80 percent over the last 40 years.Scientists previously determined that different fish species favor consuming different algae. This means that diverse groups of herbivores keep algae at bay more effectively. However, these localized benefits of biodiversity have typically been studied on individual reefs, so it has been unclear whether such "biodiversity effects" are common throughout the ocean. To address this question, the research team studied 10 reefs spread across more than 1,000 kilometers of coastline in the Dominican Republic. By studying this vast area, they were able to quantify the influence of herbivore biomass and diversity across many reefs, as well as identify new biodiversity effects that might operate across the entire region."Looking at reefs in isolation is like studying individual pieces of the puzzle," said Rasher, who completed the analysis with Jon Lefcheck, a former postdoctoral scientist in his lab and the lead study author. "It is only by studying multiple reefs across an entire region that we could see the much larger role that biodiversity plays in supporting the process of grazing."The fieldwork was carried out by Rasher in collaboration with Bob Steneck, scientist at University of Maine, and Ruben Torres, president of Reef Check Dominican Republic. Using remote underwater cameras, Rasher captured extensive video of fish grazing at each reef site. In these same places, the team measured the abundance of algae on the reef and how well the herbivores had trimmed it down. They also counted the number of baby corals present on the reef.Back at the lab, Anne Innes-Gold, intern in the Research Experience for Undergraduates program at Bigelow Laboratory, analyzed the video footage to observe the amount, diversity, and sizes of the fish that had grazed the reef. Lefcheck then designed a statistical model to process the data and disentangle the impact of fish biomass and diversity on grazing. The model also enabled them to make more accurate comparisons among reefs by accounting for the influence of environmental differences that exist from site to site."Our research helps bring coral reefs in line with what we know from many other ecosystems -- from seagrass beds to forests and grasslands," said Lefcheck, now Tennenbaum Coordinating Scientist for the Smithsonian's MarineGEO program. "It appears more and more likely that biodiversity is the lynchpin that holds nature together."This study, which was funded by philanthropic gifts from Bigelow Laboratory donors, shows the importance of considering the influence of biodiversity at multiple spatial scales when studying an ecosystem or managing natural resources."Fisheries are typically managed at the level of country or region, not the reef," Rasher said. "This research shows that fostering fish diversity -- both at the local and regional scale -- is more important than we realized to the health of coral reefs."
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Extinction
| 2,019 |
March 4, 2019
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https://www.sciencedaily.com/releases/2019/03/190304145423.htm
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Research provides insight on survivability of rare Wyoming plant
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A rare plant found only at two sites in central Wyoming has persisted, in part, because it can recover from relatively low densities and grows at different rates within each location, according to new research led by a University of Wyoming scientist.
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The desert yellowhead, which grows on fewer than 55 acres in the Beaver Rim area of Fremont County, has been listed as a threatened species under the Endangered Species Act since 2002. The new research, published by lead author Reilly Dibner, a postdoctoral researcher formerly at UW's Haub School of Environment and Natural Resources, provides insights into how the plant has managed to survive in small, stable numbers. But the scientists say its long-term future is difficult to predict because of increasingly variable rainfall patterns and warming.The research paper appears today in "A small, isolated population like this generally is thought to have a high probability for extinction, but several mechanisms have allowed the desert yellowhead to persist so far," says Dibner, who received her Ph.D. from UW's Program in Ecology. "While this plant has shown remarkable stability over its short known history, we lack the ability to confidently predict its future chances of survival."The plant, also known as "yermo" -- which comes from its scientific name, Yermo xanthocephalus -- was discovered in 1990 by botanist Robert Dorn in the Sand Draw area southeast of Riverton. That population was monitored closely for a decade by Central Wyoming College faculty member Richard Scott and his wife, Beverly, along with other volunteers. In 2010, as a result of extensive searches by UW's Natural Diversity Database and the Bureau of Land Management, a second, smaller population of desert yellowhead was discovered by UW scientists Bonnie Heidel and Joy Handley about five miles away at Cedar Rim.The desert yellowhead has attracted attention because of its unusual geographic distribution, uniqueness and extreme rarity. It's not known if the desert yellowhead has always had such a limited range or if it once was distributed more broadly.Dibner and the other researchers used detailed population data collected by the Scotts, along with five years of data from their own study, to assess the factors that allow the desert yellowhead to survive in such small numbers. They concluded that several mechanisms are in place to keep the plant from disappearing.The research found that despite the low density of the desert yellowhead -- there are fewer than 15,000 individual plants scattered across the 55 acres -- these populations survive partly because of a principle called negative density dependence. This means that the populations tend to grow fastest when at low numbers, allowing them to bounce back from low numbers."In particular, negative density dependence is an important mechanism allowing subpopulations to recover from unfavorable environmental conditions," the researchers wrote.Additionally, diversity in the plant's responses to precipitation, soils and other environmental factors has served as a stabilizing mechanism for the desert yellowhead. For example, some of the plants growing below steep slopes respond relatively poorly during wet years, while dry years are harder on plants located in flatter areas. That makes the desert yellowhead more likely to persist in a variable climate, the scientists say.The researchers used computer simulations to attempt to predict the future population of the desert yellowhead. Simulations based on historical numbers estimated a substantially greater chance of long-term survival than simulations based on the more recent five-year study, but the scientists say that's likely because of drier-than-average climate conditions during the more recent study."We found that longer-term census data gave more realistic, higher estimates of population stability than did our shorter-term demographic study," they wrote."What remains unclear is whether or not central Wyoming will face wetter or drier conditions with climate change, or how increasing temperatures will mediate effects of moisture for yermo," they added. "Thus, as with most other species, we still lack the ability to predict confidently the dynamics with changing abiotic (nonbiological) conditions."
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Extinction
| 2,019 |
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