Date
stringlengths 11
18
| Link
stringlengths 62
62
| Title
stringlengths 16
148
| Summary
stringlengths 1
2.68k
| Body
stringlengths 22
13k
⌀ | Category
stringclasses 20
values | Year
int64 2k
2.02k
|
|---|---|---|---|---|---|---|
October 1, 2020
|
https://www.sciencedaily.com/releases/2020/10/201001113623.htm
|
Mud-slurping chinless ancestors had all the moves
|
A team of researchers, led by the University of Bristol, has revealed our most ancient ancestors were ecologically diverse, despite lacking jaws and paired fins.
|
Long before they evolved out of the water, our ancient ancestors were simple fish-like creatures, but without fins or chins, who survived by filtering nutrients from sediment.They have long been thought of as the lazy lumps who spent most of their lives resting on or near to the sea floor. The belief was that everything changed with the evolution of jawed vertebrates whose paired fins made them the super-swimmers and active predators, driving their jawless relatives to extinction.However, a new study published in the journal Researchers from the University of Bristol used computer simulations to explore how avatars of our extinct ancestors interacted with water currents. These experiments revealed the bizarre spikes and spines that ornamented the heads of these jawless vertebrates were actually hydrodynamic adaptations, passively generating lift from water currents flowing over the body. The varying head shapes of different species allowed them to adapt to different positions, some high, others low, within the water. Our ancient ancestors were already ecologically diverse, long before the evolution of their jawed vertebrate relatives.Dr Humberto G. Ferron, a postdoctoral researcher from the University of Bristol and one of the paper's co-authors, said: "The evolution of jaws and fins have classically been seen as the key evolutionary inventions that allowed vertebrates to diversify their lifestyles."In this context, jawless ancestors, characterized by the presence of heavy rigid headshields, were assumed to be cumbersome fish-like creatures, living on the bottom of rivers and seas, with poor manoeuvrability."The question of how our ancient ancestors made a living has long been a mystery because there are no animals like them alive today. The 'osteostracans' (their latin name, meaning bony shells) were heavily armoured, encased in thick bone from snout to tail. They lacked a rear pair of legs and some had none at all; many possessed bizarre horn-like extensions from the front of their heads.Ferrón and colleagues tackled this problem using state-of-the-art computational engineering techniques that simulate the behaviour of fossil avatars in water currents.Dr Imran Rahman, from the Oxford University Museum of Natural History, said: "The application of computational fluid dynamics, has allowed us to study the swimming performance of ancient vertebrates and learn more about their position in evolutionary history.Dr Carlos Martinez Perez, from the University of Valencia (Spain), added: "Our simulations reveal that the different species of osteostracans show equally different hydrodynamic efficiencies. Some of them performed better when moving close to the sea floor or riverbed while others performed better when swimming freely in the water."Professor Phil Donoghue, another Bristol co-author, concluded: "The different species' body shapes are adapted to different environments, revealing distinct lifestyles among these groups of jawless early vertebrates."Our results calls into question the prevailing view that these extinct groups of jawless vertebrates were ecologically constrained, and reveals the main evolutionary hypothesis for the origin of jawed vertebrates is more complex than previously thought."
|
Extinction
| 2,020 |
September 23, 2020
|
https://www.sciencedaily.com/releases/2020/09/200923124751.htm
|
Halt post-disturbance logging in forests, experts urge
|
Storms, fires, bark beetles: Many forests around the world are increasingly affected by these and other natural disturbances. It is common practice to eliminate the consequences of these disturbances -- in other words, to harvest damaged trees as quickly as possible. Spruce trees attacked by bark beetles are removed from the forest, as are dryed beeches or trees thrown to the ground by storms.
|
"However, this practice is an additional disturbance that has a negative impact on biodiversity," says Dr. Simon Thorn, forest ecologist from Julius-Maximilians-Universität (JMU) Würzburg in Bavaria, Germany. During such logging operations, soil is damaged, most dead wood is removed and structures such as folded up root plates are lost. "That is why a certain proportion of such disturbed forests should be excluded from overall logging operations," Thorn says.Forests in which natural disturbances are preserved without human intervention are among the most threatened habitats in the world. "Up to now, there have been no evidence-based benchmarks on what proportion of land in a naturally disturbed forest should be left in order to promote the biodiversity of plants, birds, insects and fungal species " says the JMU scientist.To close this gap, an international research team led by Simon Thorn has analyzed data global dataset on natural forest disturbances. In the journal
|
Extinction
| 2,020 |
September 16, 2020
|
https://www.sciencedaily.com/releases/2020/09/200916131036.htm
|
Biologists developing global citizen network to monitor insect abundance
|
A U of A biologist is part of an international team of researchers building a volunteer network of citizen scientists to help monitor the abundance of dragonflies and damselflies.
|
Recent studies have indicated that insect species in general are declining throughout the world and could be headed toward collapse due to intensive agricultural practices, climate change and habitat loss. For many species, however, there isn't enough baseline data to determine trends in insect abundance.Adam Siepielski, associate professor of biology, is part of a team working on a solution -- establishing a volunteer network that will collect data on odonata, the scientific name for dragonflies and damselflies. Odonata are easy to spot, often vividly colored and an important indicator group of species reflecting environmental changes in freshwater biodiversity."Volunteer nature enthusiasts can greatly help to monitor the abundance of dragonflies and damselflies, iconic freshwater sentinels and one of the few nonpollinator insect groups appreciated by the public and amenable to citizen science," the scientists wrote in a paper published in the journal Researchers propose modeling the volunteer network on a similar collection of projects, organizations and individuals dedicated to butterflies. "The network has improved knowledge of not only butterfly geographical distributions but also their relative population sizes across years and the effects of large-scale environmental change," researchers wrote."We are hopeful that with similar efforts dedicated to odonata, great strides can be made in our understanding of changes in their abundances and distributions too. They really are amazing animals and fascinating to observe," said Siepielski.An odonata network would fill in gaps from areas of the world with little information, and incorporate existing data-collection efforts. Ideally, volunteers would collect data at a fixed location for 10 to 15 years, and have a standardized portal to report their findings."An army of amateur naturalists may contribute far more data than a small cadre of professional observers," the researchers wrote. "Citizen science promotes biophilia while contributing enormously to understanding large-scale biodiversity loss and environmental change, especially in developing or transitioning regions."
|
Extinction
| 2,020 |
September 3, 2020
|
https://www.sciencedaily.com/releases/2020/09/200903095637.htm
|
True size of prehistoric mega-shark finally revealed
|
To date only the length of the legendary giant shark Megalodon had been estimated. But now, a new study led by the University of Bristol and Swansea University has revealed the size of the rest of its body, including fins that are as large as an adult human.
|
There is a grim fascination in determining the size of the largest sharks, but this can be difficult for fossil forms where teeth are often all that remain.Today, the most fearsome living shark is the Great White, at over six metres (20 feet) long, which bites with a force of two tonnes.Its fossil relative, the big tooth shark Megalodon, star of Hollywood movies, lived from 23 to around three million years ago, was over twice the length of a Great White and had a bite force of more than ten tonnes.The fossils of the Megalodon are mostly huge triangular cutting teeth bigger than a human hand.Jack Cooper, who has just completed the MSc in Palaeobiology at the University of Bristol's School of Earth Sciences, and colleagues from Bristol and Swansea used a number of mathematical methods to pin down the size and proportions of this monster, by making close comparisons to a diversity of living relatives with ecological and physiological similarities to Megalodon.The project was supervised by shark expert Dr Catalina Pimiento from Swansea University and Professor Mike Benton, a palaeontologist at Bristol. Dr Humberto Ferrón of Bristol also collaborated.Their findings are published today in the journal Jack Cooper said: "I have always been mad about sharks. As an undergraduate, I have worked and dived with Great whites in South Africa -- protected by a steel cage of course. It's that sense of danger, but also that sharks are such beautiful and well-adapted animals, that makes them so attractive to study."Megalodon was actually the very animal that inspired me to pursue palaeontology in the first place at just six years old, so I was over the moon to get a chance to study it."This was my dream project. But to study the whole animal is difficult considering that all we really have are lots of isolated teeth."Previously the fossil shark, known formally as Dr Pimiento said: "Megalodon is not a direct ancestor of the Great White but is equally related to other macropredatory sharks such as the Makos, Salmon shark and Porbeagle shark, as well as the Great white. We pooled detailed measurements of all five to make predictions about Megalodon."Professor Benton added: "Before we could do anything, we had to test whether these five modern sharks changed proportions as they grew up. If, for example, they had been like humans, where babies have big heads and short legs, we would have had some difficulties in projecting the adult proportions for such a huge extinct shark."But we were surprised, and relieved, to discover that in fact that the babies of all these modern predatory sharks start out as little adults, and they don't change in proportion as they get larger."Jack Cooper said: "This means we could simply take the growth curves of the five modern forms and project the overall shape as they get larger and larger -- right up to a body length of 16 metres."The results suggest that a 16-metre-long This means an adult human could stand on the back of this shark and would be about the same height as the dorsal fin.The reconstruction of the size of Megalodon body parts represents a fundamental step towards a better understanding of the physiology of this giant, and the intrinsic factors that may have made it prone to extinction.
|
Extinction
| 2,020 |
August 27, 2020
|
https://www.sciencedaily.com/releases/2020/08/200826200709.htm
|
How vitamin C could help over 50s retain muscle mass
|
Vitamin C could be the key to better muscles in later life, according to new research from the University of East Anglia (UEA).
|
A study published today shows that older people who eat plenty of vitamin C -- commonly found in citrus fruits, berries and vegetables -- have the best skeletal muscle mass.This is important because people tend to lose skeletal muscle mass as they get older -- leading to sarcopenia (a condition characterised by loss of skeletal muscle mass and function), frailty and reduced quality of life.Lead researcher Prof Ailsa Welch, from UEA's Norwich Medical School said: "As people age, they lose skeletal muscle mass and strength."People over 50 lose up to one per cent of their skeletal muscle mass each year, and this loss is thought to affect more than 50 million people worldwide.""It's a big problem, because it can lead to frailty and other poor outcomes such as sarcopenia, physical disability, type-2 diabetes, reduced quality of life and death.""We know that Vitamin C consumption is linked with skeletal muscle mass. It helps defend the cells and tissues that make up the body from potentially harmful free radical substances. Unopposed these free radicals can contribute to the destruction of muscle, thus speeding up age-related decline.""But until now, few studies have investigated the importance of Vitamin C intake for older people. We wanted to find out whether people eating more Vitamin C had more muscle mass than other people."The research team studied data from more than 13,000 people aged between 42-82 years, who are taking part in the EPIC (European Prospective Investigation into Cancer and Nutrition) Norfolk Study.They calculated their skeletal muscle mass and analysed their vitamin C intakes from a seven-day food diary. They also examined the amount of vitamin C in their blood.Dr Richard Hayhoe, also from UEA's Norwich Medical School, said: "We studied a large sample of older Norfolk residents and found that people with the highest amounts of vitamin C in their diet or blood had the greatest estimated skeletal muscle mass, compared to those with the lowest amounts."We are very excited by our findings as they suggest that dietary vitamin C is important for muscle health in older men and women and may be useful for preventing age-related muscle loss."This is particularly significant as Vitamin C is readily available in fruits and vegetables, or supplements, so improving intake of this vitamin is relatively straightforward."We found that nearly 60 per cent of men and 50 per cent of women participants were not consuming as much Vitamin C as they should, according to the European Food Safety Agency recommendations."We're not talking about people needing mega-doses. Eating a citrus fruit, such as an orange, each day and having a vegetable side to a meal will be sufficient for most people."The research was led by the University of East Anglia, in collaboration with the University of Cambridge and Strangeways Research Laboratory in Cambridge, and developed from a UEA medical student project by Lucy Lewis.The EPIC-Norfolk study was supported by grant funding from the Medical Research Council and Cancer Research UK.
|
Extinction
| 2,020 |
August 25, 2020
|
https://www.sciencedaily.com/releases/2020/08/200825124631.htm
|
New tool for identifying endangered corals could aid conservation efforts
|
Coral conservation efforts could get a boost from a newly developed genotyping "chip" -- the first of its kind for corals. The chip allows researchers to genetically identify corals and the symbiotic algae that live within the coral's cells, a vital step for establishing and maintaining genetic diversity in reef restoration efforts. The chip and its accompanying online analysis pipeline help to democratize the genetic identification of coral biodiversity, making it accessible to conservation biologists who might not have access to the laboratory and computational resources needed to extract DNA and analyze the data.
|
A paper describing the new chip appears in the journal "Corals around the world are endangered due to warming oceans," said Iliana Baums, professor of biology at Penn State and leader of the research team. "We designed this genotyping chip to help restoration and conservation efforts. There is very little overhead needed to use the chip, so small restoration operations can access coral genetic identification to help them maximize reef health by ensuring coral populations are genetically diverse."The chip, also called a microarray, uses more than 30,000 single nucleotide polymorphisms (SNPs) -- locations in the coral genome where at each of the locations a single letter in the DNA alphabet can vary among different corals in the Acroporid family. The Acroporid family of corals contains the largest number of different species of any coral family and are common in the Caribbean Sea and the Pacific Ocean. The chip was designed using Caribbean corals but can also be used to analyze Pacific species and allows researchers to identify the symbiotic algae that reside in the coral cells.Corals can reproduce asexually by fragmentation, so Caribbean reefs are often dominated by corals that all can be traced back to a single origin and are therefore genetically nearly identical -- researchers refer to these related corals as a "genet." The chip is sensitive enough to allow researchers to reliably distinguish members of different genets within the same coral species."One way to increase genetic diversity in a reef is to make sure it is built by individuals of more than one genet," said Baums. "Because all of the corals on a reef could be members of the same genet, it is vital to have a reliable way to identify them and our chip provides this to researchers in the field."To use the SNP chip, which was developed at Penn State and licensed to Thermo Fisher Scientific who produces the Affymetrix microarrays, researchers can simply send a sample of coral to a commercial laboratory. At the lab, DNA is extracted and run on the chip and the resulting data is returned to the researcher. The researcher can then upload the data files into the online analysis pipeline called the Standard Tools for Acroporid Genotyping (STAG). The analysis is performed and data maintained in a customized "Science Gateway" in the open-source web-based Galaxy platform, a resource for data-rich biomedical research also developed at Penn State."With the SNP chip and STAG pipeline we can help ensure that researchers around the world can genetically identify corals in a standardized way," said Baums. "The database maintained in the Science Gateway allows researchers to compare samples, identify novel strains, and track coral diversity through time."In addition to Baums, the research team includes Sheila A. Kitchen, who designed the chip, Greg Von Kuster, Kate L. Vasquez Kuntz, Hannah G. Reich, and Webb Miller at Penn State; Sean Griffin at the NOAA Restoration Center; and Nicole D. Fogarty at the University of North Carolina Wilmington. The research was funded by the NOAA Office for Coastal Management and the U.S. National Science Foundation.
|
Extinction
| 2,020 |
August 18, 2020
|
https://www.sciencedaily.com/releases/2020/08/200818142141.htm
|
Bird skull evolution slowed after the extinction of the dinosaurs
|
From emus to woodpeckers, modern birds show remarkable diversity in skull shape and size, often hypothesized to be the result of a sudden hastening of evolution following the mass extinction that killed their non-avian dinosaur cousins at the end of the Cretaceous 66 million years ago. But this is not the case according to a study by Ryan Nicholas Felice at University College London, publishing August 18, 2020 in the open-access journal
|
The researchers used high-dimensional 3D geometric morphometrics to map the shape of 354 living and 37 extinct avian and non-avian dinosaurs in unprecedented detail and performed phylogenetic analyses to test for a shift in the pace of evolution after the origin of birds. They found that all regions of the skull evolved more rapidly in non-avian dinosaurs than in birds, but certain regions showed rapid pulses of evolution in particular lineages.For example, in non-avian dinosaurs, rapid evolutionary changes in the jaw joint were associated with changes in diet, while accelerated evolution of the roof of the skull occurred in lineages that sported bony ornaments such as horns or crests. In birds, the most rapidly evolving part of the skull was the beak, which the authors attribute to adaptation to different food sources and feeding strategies.The authors say that overall slower pace of evolution in birds compared to non-avian dinosaurs calls into question a long-standing hypothesis that the diversity seen in modern birds resulted from rapid evolution as part of an adaptive radiation following the end-Cretaceous extinction event.
|
Extinction
| 2,020 |
August 6, 2020
|
https://www.sciencedaily.com/releases/2020/08/200806111852.htm
|
Researchers hope to save seabirds by calculating the value of their excrement
|
Seabird species such as gulls and pelicans are often overlooked when it comes to conservation and can struggle to capture the public eye. To raise awareness of their importance to people and the ecosystems we depend on, a Science & Society article appearing August 6 in the journal
|
"Guano production is an ecosystem service made by seabirds at no cost to us -- I can go to an island, collect the guano, and sell it at market price as fertilizer," says co-author Marcus V. Cianciaruso, ecology professor at the Federal University of Goiás in Brazil. While few seabird species produce guano that is currently commercialized, the rest provide important nutrients to the ecosystems where their guano is deposited. "Because there is this scientific and biological importance, it's possible to quantify seabird ecosystem services in a language that the general public and policymakers can begin to understand," he says.To do this, Cianciaruso and Daniel Plazas-Jiménez, a PhD student at the Federal University of Goiás, began by gathering data about global seabird populations producing commodifiable guano. "Because guano is a commodity, we used its market price to estimate the added value of guano produced by seabirds each year," says Plazas-Jiménez.For the species that do not produce commodifiable guano, the researchers then estimated the value of nitrogen and phosphorus deposited every year in their colonies by calculating the cost to replace these nutrients with inorganic versions. The result is staggering: when combined, the nutrient deposition and the commodifiable guano could be worth an estimated $473.83 million per year.Although not all guano can be commodified, these nutrients that it deposits are important to ecosystems such as coral reefs, where guano's presence can increase reef fish biomass by up to 48%. "We made a very conservative estimate that 10% of coral reef fish stocks depend on seabird nutrients," says Plazas-Jiménez. "According to the United Nations and the Australian government, the annual economic returns of commercial fisheries on coral reefs is over $6 billion. So, 10% of this value is around $600 million per year." When added to the previous figure, the value of nutrients deposited by seabirds increases to an estimated $1 billion.Much of this value comes from threatened or endangered species. "The example of coral reefs is just for a little group of seabirds," says Plazas-Jiménez. "A huge amount of nutrient deposition happens in Antarctic ecosystems: penguins contribute half of the nitrogen and phosphorus deposited by seabirds every year. However, 60% of this contribution is made by penguin species with declining populations, and these contributions will decrease in the future if no conservation activity is taken."The researchers hope this paper will shed light on how valuable these species are at a global scale. "Seabirds have a lot of importance to people," says Plazas-Jiménez. "Being able to calculate a monetary value of an ecological function made by a particular species is just another tool in the conservation toolbox."Only a fraction of the value of seabirds to ecosystems and to people is represented by this estimate -- among other functions, they contribute to vast birdwatching and tourism industries around the world. "If you start to look into every function that seabirds have and try to monetize this, the value is going to be much, much higher," says Cianciaruso.Their estimate also doesn't account for the local importance of the birds. For many coastal communities, the direct and indirect benefits of living with them are essential. "In some areas, fishermen follow seabirds to find places to fish," says Plazas-Jiménez. "To that fisherman, seabirds are everything."
|
Extinction
| 2,020 |
August 5, 2020
|
https://www.sciencedaily.com/releases/2020/08/200805160944.htm
|
Long-term human impacts on reef fish
|
Resource fishes -- species targeted for human consumption -- play a key role in reef ecosystems long before they end up on the dinner table. In Hawai?i, subsistence and recreational fishing of local resource fish represent more than half of the share of annual reef seafood consumption, while also playing a vital role in indigenous cultural life.
|
These same fishes also help reefs to stay healthy by removing algae from coral surfaces, which in turn, help coral recover from bleaching. Given the beneficial relationship between resource fishes and corals, determining how local pressures impact resource fish biomass is necessary for improving reef conservation and management.In a new study investigating human impacts on resource fish biomass on the Island of Hawai?i, researchers from the Arizona State University Center for Global Discovery and Conservation Science (GDCS) and Hawai'i Division of Aquatic Resources (DAR) observed an alarming 45% decrease in fish biomass over a decade of surveys. The scientists proposed actionable solutions to mitigate future losses. The study was published today in The researchers investigated the influence of local factors on the nearshore resource fisheries of West Hawai'i Island and compared the impact of distinct types of marine protections. They considered a range of factors including commercial and non-commercial fishing as well as nitrogen pollution from sewage disposal systems and golf courses. They also used ASU's Global Airborne Observatory to map the 3-D reef habitat to assess how it affects fish diversity, abundance, and biomass. The researchers analyzed extensive fish survey data collected by DAR between 2008 and 2018 at more than 300 sites spanning 180 km of coastline."Resource fish have been greatly reduced over the past decade in West Hawai'i. We see that negative impacts of nitrogen pollution can outweigh other habitat and land-use stresses on resource fish," said Dr. Shawna Foo, a postdoctoral researcher at GDCS and lead author of the study. Nitrogen effluent from sewage and golf courses contaminates nearshore waters, creating stress for corals and were a major driver of resource fish declines documented in the study.Despite the long-term decline, the researchers also found that different types of management resulted in different levels of fish biomass. They found significantly greater fish abundance and biomass in areas that banned spearfishing compared to areas that did not, likely due to the fact that four of the five most common species from the surveys are primarily caught by spears. This finding was particularly true for ?scrapers' such as parrotfish.The researchers also found that marine management areas with multiple bans on spearfishing, aquarium collection, and lay nets had the highest overall fish biomass compared to other managed or unmanaged areas, especially for herbivorous fish. Their findings are supported by a recent global analysis of marine management led by the University of Leeds, which reported higher fish biomass in areas where gear was limited to pole and line fishing. Those researchers recommended specific gear restrictions as a relevant management strategy to attain the dual objectives of supporting resource fish biomass recovery and satisfying stakeholders.Greg Asner, GDCS director and co-author of the study noted, "These results are among the clearest to emerge for Hawaii. Based on the long-term monitoring efforts of our Hawai?i DAR partners, we were able to ascertain unequivocal evidence for a decline in shallow reef fish populations along the famous Kona coast of Hawai?i Island. We were also able to connect both the decline and the remaining fish stocks to specific actions that can be taken now to enhance the fishery and protect reefs. This is a triple win for science, management, and the fisher community."The study reinforces the urgent need to protect reef ecosystems from increasing threats of habitat degradation and climate change. Last year alone, ocean temperatures reached near-record levels, ushering in a coral bleaching event that resulted in coral loss across the Hawaiian archipelago. To protect resource fish biomass and aid reef resilience and recovery, regional management of multiple stressors is greatly needed. The researchers proposed to mitigate such future losses by banning and/or restricting specific fishing gear types and more aggressive management of land-based pollution."The collaboration with our partners at GDCS provides an incredible opportunity to combine state-of-the-art seascape level mapping with DAR's long-term coral reef monitoring to understand the links between marine and land management and coral reef health.," noted Brian Neilson, Administrator in charge of the Hawai?i Division of Aquatic Resources. "This study is critical for informing statewide management strategies to maintain important resource fish stocks and resilient reefs, as we face unprecedented climate-driven threats."This study was supported by grants from the Lenfest Ocean Program, The Battery Foundation, and the John D. and Catherine T. MacArthur Foundation.
|
Extinction
| 2,020 |
August 4, 2020
|
https://www.sciencedaily.com/releases/2020/08/200804190708.htm
|
Angels in disguise: Angelfishes hybridize more than any other coral reef species
|
Renowned journal
|
Hybridisation refers to the process by which two different species mate and produce hybrid offspring.The research was led by Yi-Kai (Kai) Tea, PhD candidate at the University of Sydney's School of Life and Environmental Sciences.He and his colleagues, Professors Nathan Lo and Simon Ho, Dr Joseph DiBattista from the Australian Museum, Jean-Paul Hobbs from the University of Queensland, and Federico Vitelli from Edith Cowan University, sought to explore why only some fishes create hybrids, and the factors that facilitate this.After deciding to focus on "one of the most charismatic and iconic groups of coral reef fishes," the marine angelfish, they found that 42 species -- nearly half of all known species of marine angelfishes -- create hybrids."This is among the highest incidence of hybridisation in coral reef fishes," Mr Tea said."We also found that hybrids are frequently produced even between angelfish species that are distantly related to each other; some separated by over 10 million years in evolutionary time."Other hybrids were found between species with over 12 percent pairwise distance in mitochondrial DNA. Pairwise distance is a measurement of differences in pairs of DNA sequences."This genetic separation is quite astounding, considering that hybrids are rarely reported between species that share more than 2 percent in genetic distance," Mr Tea said. "Though coral reef fish hybrids are common; they are usually formed by closely-related species."A third key finding was that angelfish hybridise wherever different species exist. This contrasts with other coral reef fishes, which tend to only hybridise within certain zones of their shared habitats."In terms of coral reef fish hybridisation, much remains unanswered, particularly in the context of why, and how hybrids are formed. We still don't know why some species hybridise and others don't. For example, the regal angelfish, Pygoplites diacanthus, is found throughout the Indian and Pacific Oceans, yet no hybrids have ever been reported for this species," Mr Tea said. "In terms of cracking the secrets to hybridisation in coral reefs, we've only just scratched the surface."
|
Extinction
| 2,020 |
August 4, 2020
|
https://www.sciencedaily.com/releases/2020/08/200804111528.htm
|
Between shark and ray: The evolutionary advantage of the sea angels
|
The general picture of a shark is that of a fast and large ocean predator. Some species, however, question this image -- for example angel sharks. They have adapted to a life on the bottom of the oceans, where they lie in wait for their prey. In order to be able to hide on or in the sediment, the body of angel sharks became flattened in the course of their evolution, making them very similar to rays, which are closely related to sharks.
|
The oldest known complete fossils of angel sharks are about 160 million years old and demonstrate that the flattened body was established early in their evolution. This also indicates that these extinct angel sharks already had a similar lifestyle as their extant relatives -- and that this lifestyle obviously was very successful.Angel sharks are found all over the world today, ranging from temperate to tropical seas, but most of these species are threatened. In order to understand the patterns and processes that led to their present low diversity and the possible consequences of their particular anatomy, the team has studied the body shapes of angel sharks since their origins using modern methods.For this purpose, the skulls of extinct species from the late Jurassic period (about 160 million years ago) and of present-day species were quantitatively analysed using X-ray and CT images and prepared skulls employing geometric-morphometric approaches. In doing so, the evolution of body shapes could be explained comparatively, independent of body size.The results show that early angel sharks were different in their external shape, whereas modern species show a comparably lower variation in shape. "Many of the living species are difficult to identify on the basis of their skeletal anatomy and shape, which could be problematic for species recognition," explains Faviel A. López-Romero.It has been shown that in living species the individual parts of the skull skeleton are more closely integrated than in their extinct relatives. This led to a reduced variability in appearance during the evolution of angel sharks. "The effect of integrating different parts of the skull into individual, highly interdependent modules can lead to a limited ability to evolve in different forms, but at the same time increases the ability to successfully adapt to specific environmental conditions," explains Jürgen Kriwet.In the case of the angel sharks, increasing geographical isolation resulted in the development of different species with very similar adaptations. "But modular integration also means that such animals are no longer able to react quickly to environmental changes, which increases their risk of extinction," concludes Jürgen Kriwet.
|
Extinction
| 2,020 |
July 31, 2020
|
https://www.sciencedaily.com/releases/2020/07/200731085637.htm
|
Reduced coral reef fish biodiversity under temperatures that mirror climate predictions
|
Biologists recently studied cryptobenthic reef fishes in the Arabian Gulf and the Sea of Oman and found that the more thermally extreme coral reef habitat in the Arabian Gulf adversely impacted the diversity and productivity of these important fishes.
|
As global warming continues to escalate, there are lasting implications to consider, including the changes to biological communities in vital habitats such as coral reefs. A team of researchers, led by Simon Brandl (currently at the Centre de Recherches Insulaires et Observatoire de l'Environnement, CRIOBE, France) and Jacob Johansen, an Assistant Research Professor at Hawai'i Institute of Marine Biology (and previously a research scientist at NYU Abu Dhabi's Marine Biology Lab), recently studied cryptobenthic reef fishes (small, bottom-dwelling fish that are at the base of coral reef food webs) in the Arabian Gulf and the Sea of Oman and found that the more thermally extreme coral reef habitat in the Arabian Gulf adversely impacted the diversity and productivity of these important fishes.In the paper, "The Arabian Gulf is the world's hottest sea each summer with temperatures well beyond those experienced by fishes elsewhere in the tropics, while the adjacent Sea of Oman is considerably more benign. This makes this region a useful natural laboratory for understanding how climate extremes affect fish function and diversity," said senior author Associate Professor of Biology at NYU Abu Dhabi John Burt.Fish communities in the Arabian Gulf were found to be half as diverse and less than 25 percent as abundant as those in the Gulf of Oman, despite broad similarities in the amount of live coral. Surprisingly, this does not seem to be related to absolute temperature tolerances of cryptobenthic fishes."We expected to see much lower temperature tolerances in species that occur in the Sea of Oman, but not in the southern Arabian Gulf," said Johansen. "Yet, the critical thermal tolerances of all species found in the Sea of Oman were, in theory, sufficient to survive even the maximum summer temperatures of 36°C in the southern Arabian Gulf."Instead, differences in prey eaten and body condition in the species present at both locations suggest that the thermal extremes of the Arabian Gulf are an energetically challenging environment for these smallest marine vertebrates. While hotter waters require more energy, a distinct, less diverse set of prey items in the Arabian Gulf may make it difficult for these small-bodied fishes to satisfy their energetic demands.Importantly, the reduced diversity and abundance of cryptobenthic fishes greatly impairs the unique functional role of these animals. "These tiny fishes normally feed a lot of the larger, predatory animals on coral reefs by growing and dying rapidly, while constantly replenishing their populations," explains Brandl, "But on reefs in the southern Arabian Gulf, cryptobenthic fish communities provide only a fraction of the fish flesh that they can produce in more benign environments.""Our findings highlight an imminent threat to cryptobenthic reef fishes and their essential role for coral reef functioning. These smallest marine ectotherms may struggle to compensate for increasing costs of growth and maintenance as they adapt to more extreme temperatures," said Johansen. "Extreme environmental conditions, as predicted for the end of the 21st century, could, therefore, disrupt the community structure and productivity of coral reefs in the Arabian Gulf and beyond."
|
Extinction
| 2,020 |
July 27, 2020
|
https://www.sciencedaily.com/releases/2020/07/200727114703.htm
|
Cycad plants provide an important 'ecosystem service'
|
A study published in the June 2020 edition of the peer-reviewed journal
|
"The new knowledge from this study shows how loss of cycad plants from natural habitats may create detrimental ripple effects that negatively influence the other organisms that evolved to depend on their ecosystem services," said Patrick Griffith, executive director of the Montgomery Botanical Center.Cycad plants host nitrogen-fixing cyanobacteria within specialized roots. The tiny microbes willingly share the newly acquired nitrogen with their hosts as their contribution to a symbiosis that benefits both organisms.Research teams at the University of Guam have long been studying the nutrient relations of Cycas micronesica throughout its endemic range, according to Adrian Ares, associate director of the Western Pacific Tropical Research Center."This unique arborescent cycad species is of cultural and ecological importance, and the findings illuminate new knowledge about the ecosystem services that are provided by the plant," Ares said.The study focused on the concentrations in soil of three elements that impact the growth and development of living organisms. In soils nearby the cycad plants, nitrogen and carbon increased to concentrations that exceeded those of soils that were distant from the plants. In contrast, phosphorus concentrations were depleted in the soils nearby the cycad plants when compared to the distant soils."In addition to the direct contributions of carbon and nitrogen to the bulk soils, the chemical changes imposed by the cycad plants created niche habitats that increased spatial heterogeneity in the native forests," Ares said, adding that ecosystems with high biodiversity are generally more resistant to damage by threats and more resilient after the negative impacts.The niche spaces created by the cycad plants provide the soil food web with a microhabitat that differs from the surrounding forest soils. These soils imprinted by the cycad plants benefit the organisms that exploit spaces characterized by greater nitrogen levels relative to phosphorus and greater carbon levels relative to phosphorus. Scientists call these elemental relationships "stoichiometry," and much has been studied about the importance of these relationships to organismal health and productivity.The model cycad plants that were employed for the study included two of the cycad species that are native to the United States."This study was apropos because the Montgomery Botanical Center is positioned within Zamia integrifolia habitat in Miami, Fla., and the Western Pacific Tropical Research Center is within Cycas micronesica habitat in Mangilao, Guam," Griffith said.The Florida species is the only cycad species that is native to the continental United States, and the Guam species is the only Cycas species native to the United States."Both research teams were gratified to successfully answer questions that were asked of the botanical denizens that have long resided in the respective local forests," Griffith said.
|
Extinction
| 2,020 |
July 21, 2020
|
https://www.sciencedaily.com/releases/2020/07/200721114739.htm
|
New study takes closer look at how environment affects daily life of sloths
|
Scientists studying brown-throated three-toed sloths, where predators are extinct and food is more accessible, have found that the animals adapt to have a primarily diurnal, or daytime, schedule.
|
The study was conducted in a highly disturbed section of the Atlantic forest, in Northeastern Brazil. Researchers recorded the sloths' behaviors and circadian rhythm during the course of 29 days. The results, published in the journal "These environmental disturbances are in no way an ideal scenario from a conservation perspective but the results -- fewer predators, easier access to primary food sources -- clearly had a positive impact based on our observations," said Giles Duffield, associate professor in the Department of Biological Sciences at the University of Notre Dame, and a co-author of the study. "With less competition for food and fewer predators these animals developed a more synchronous pattern of activity."Previous studies have focused sloth activity in undisturbed forests. The research, led by Antonio Rossano Mendes Pontes at the National Institute of Amazonian Research, is unique in that researchers not only monitored sloths in a highly disturbed setting but their behavior -- rest, travel, movement, feeding and grooming -- was observed over a complete 24-hour cycle."In all other studies, sloths have been found to be nocturnal or cathemeral," Duffield said. "We did not expect to see such clear and distinct diurnal behavior."Sloths spend a majority of their time at rest -- up to 90 percent in some cases. A number of factors can influence a sloth's tendency toward diurnal or nocturnal activity, including temperature, competition and the threat of predators. Rest was still the dominant activity, even in a highly disturbed environment. The sloths spent an average of 75 percent of their time resting. Females rested significantly more than the males and infants rested 79 percent of the time on average. Peak activity took place in the early morning and late afternoon hours.There is no preserved land left within the Atlantic forest, according to the study. An estimated 98 percent of its woodland has been lost, so researchers can't compare activity between highly disturbed and undisturbed sections of the forest. For the same reason, the study asserts the assumption that the daytime activity observed by this group of sloths is an adaptive response to changes in their environment.While found in a few unique cases in nature, "it's generally rare to observe such flexibility in an organism that allows it to switch from predominately nocturnal to daytime active," Duffield said. "These results highlight that a more variable or nocturnal activity pattern might be a strategy that improves chances of survival in a more challenging environment, one with predators such as eagles and large snakes, heavier competition for food sources produced by other herbivores, and where the sloth has to move around more to find its preferred food. It's ironic, but these results suggest that when conditions are 'easier' for the iconic slow-moving sloth, as we find in this disturbed forest habitat, it reverses the time of its preferred activity within the 24-hour day.
|
Extinction
| 2,020 |
July 20, 2020
|
https://www.sciencedaily.com/releases/2020/07/200720102058.htm
|
Arizona rock core sheds light on Triassic dark ages
|
A rock core from Petrified Forest National Park, Arizona, has given scientists a powerful new tool to understand how catastrophic events shaped Earth's ecosystems before the rise of the dinosaurs.
|
The quarter-mile core is from an important part of the Triassic Period when life on Earth endured a series of cataclysmic events: Our planet was struck at least three times by mountain-sized asteroids, chains of volcanoes erupted to choke the sky with greenhouse gases, and tectonic movement tore apart Earth's single supercontinent, Pangea.Among the chaos, many plants and animals, including some of the long-snouted and armored reptiles that ruled Pangea throughout the Triassic, vanished in a possible shake-up of life on Earth that scientists have yet to explain.The study, published July 20 in By determining the age of the rock core, researchers were able to piece together a continuous, unbroken stretch of Earth's history from 225 million to 209 million years ago. The timeline offers insight into what has been a geologic dark age and will help scientists investigate abrupt environmental changes from the peak of the Late Triassic and how they affected the plants and animals of the time."The core lets us wind the clock back 225 million years when Petrified Forest National Park was a tropical hothouse populated by crocodile-like reptiles and turkey-size early dinosaurs," said Cornelia Rasmussen, a postdoctoral researcher at the University of Texas Institute for Geophysics (UTIG), who led the analysis that determined the age of the core."We can now begin to interpret changes in the fossil record, such as whether changes in the plant and animal world at the time were caused by an asteroid impact or rather by slow geographic changes of the supercontinent drifting apart," she said.Petrified Forest National Park's paleontologist Adam Marsh said that despite a rich collection of fossils from the period in North America, until now there was little information on the Late Triassic's timeline because most of what scientists knew came from studying outcrops of exposed rock pushed to the surface by tectonic movements."Outcrops are like broken pieces of a puzzle," said Marsh, who earned his Ph.D. from The University of Texas at Austin's Jackson School of Geosciences. "It is incredibly difficult to piece together a continuous timeline from their exposed and weathered faces."Marsh was not an author of the study but is part of the larger scientific coring project. UTIG is a unit of the Jackson School.The Petrified Forest National Park core overcomes the broken puzzle problem by recovering every layer in the order it was deposited. Like tree rings, scientists can then match those layers with the fossil and climate record.To find the age of each layer, the researchers searched the rock core for tiny crystals of the mineral zircon, which are spewed into the sky during volcanic eruptions. Zircons are a date stamp for the sediments with which they are buried. Researchers then compared the age of the crystals with traces of ancient magnetism stored in the rocks to help develop a precise geologic timeline.Geoscience is rarely so simple, however, and according to Rasmussen, the analysis of the core gave them two slightly different stories. One shows evidence that a shake-up in the species might not be connected to any single catastrophic event and could simply be part of the ordinary course of gradual evolution. The other shows a possible correlation between the change in the fossil record and a powerful asteroid impact, which left behind a crater in Canada over 62 miles wide.For Marsh, the different findings are just part of the process to reach the truth."The two age models are not problematic and will help guide future studies," he said.The research is the latest outcome of the Colorado Plateau Coring Project. The research and the coring project were funded by the National Science Foundation and International Continental Drilling Program.
|
Extinction
| 2,020 |
July 17, 2020
|
https://www.sciencedaily.com/releases/2020/07/200717133233.htm
|
Uplifting of Columbia River basalts opens window on how region was sculpted
|
Uplifting of Columbia River basalts has allowed University of Oregon researchers to better understand of how magma 14-16 million years ago shaped the region and why greenhouse gases released during a series of volcanic eruptions did not trigger a global extinction event.
|
The insights, published in The Columbia River Flood Basalts represent the youngest continental flood basalt province on Earth and one of the best preserved. It covers roughly 210,000 square kilometers, extending from eastern Oregon and Washington to western Idaho and part of northern Nevada.Pivotal to the research were 27 samples from 22 different dikes -- wall-like bodies of magma that cut through the sheeted lava flow landscape during the eruptions. A 10-meter-thick feeder dike into the Wallowa batholith, formed from a mix of basaltic magma and granite 16 million years ago, for example, likely acted as a magma conduit for up to seven years. It formed one of the largest surface lava flows and chemically altered about 100 meters of surrounding bedrock."We found that when hot basaltic magma intruded into the crust it boiled groundwater and volatilized everything in and near its path, causing chemical and isotopic changes in the rocks and the release of greenhouse gases," said Ilya Bindeman, a professor in the Department of Earth Sciences, who led the study.Collectively, the effects of the heating throughout the flood-basalt region may have lasted about 150 years after magma stopped flowing, building the landscape that is visible today across the region, the seven-member research team from three countries concluded."The Columbia River basalts that are so dear to us in the Pacific Northwest," Bindeman said. "They are now uplifted and eroded to the level that allows us to sample the contacts of these basalts with the previous rocks. The same process today is happening every hour and everywhere under midocean ridges and also on continents. By studying these not-so-ancient rocks we have learned what is going on under our feet."Computer modeling done with the chemical data suggests that the hydrothermal heating of the region's original metasedimentary rocks -- a metamorphic rock formed through the deposition and solidification of sediment -- and relatively low levels of organic matter affected by the eruptions would have generated the release of about 18 gigatons of carbon dioxide and methane. One gigaton equals a billion metric tons.The individual Columbia River basalt eruptions were each 10 to 100 times larger than the largest historically experienced eruptions of Iceland's Eldgja and Laki volcanic eruptions in the years 934 and 1783, respectively, noted study co-author Leif Karlstrom, a professor of earth sciences, who along with Bindeman is a member of the Oregon Center for Volcanology.The Laki eruption, which killed thousands of people, released volcanically derived greenhouse gases that generated a year without summer followed by a warm year across Europe and North America, Karlstrom said.While the Columbia River eruptions released 210,000 cubic kilometers of basaltic magma over 1.5 million years, leading to global climate impacts, the researchers concluded, they did not cause mass extinctions such as the one triggered by eruptions over a similar timescale about 250 million years ago that formed the Siberian Traps.The difference, the research team theorized, is in the geology of the regions. The Columbia River basalt eruptions occurred in igneous crust that contained low levels of organic matter that could be released by hydrothermal heating. Eruptions in the Siberian Traps occurred in organics-rich sedimentary rocks.While the new findings suggest that similar regional-scale groundwater circulation around dikes is a signature of flood basalt volcanism globally, the researchers noted, the consequences may not always be catastrophic on a broad scale.In the Columbia River basalts and the likely related Yellowstone hotspot, hydrothermal circulation is manifested as subtle isotopic signals, a depletion of oxygen isotopes, in the rocks, the research team found.The research, primarily completed in Bindeman's Stable Isotope Laboratory, was funded by the U.S., Russian and Swiss National Science Foundations.
|
Extinction
| 2,020 |
July 16, 2020
|
https://www.sciencedaily.com/releases/2020/07/200716144731.htm
|
Genetics could help protect coral reefs from global warming
|
Coral reefs are dying at an alarming rate as water temperatures rise worldwide as a result of global warming, pollution and human activities. In the last three decades, half of Australia's Great Barrier Reef has lost its coral cover.
|
A new study from Columbia University provides more evidence that genetic-sequencing can reveal evolutionary differences in reef-building corals that one day could help scientists identify which strains could adapt to warmer seas.The findings, published in "We need to use as many tools as possible to intervene or we will continue to see coral reefs vanish," said Zachary Fuller a postdoctoral researcher in biology at Columbia and first author on the study. "Using genomics can help identify which corals have the capacity to live at higher temperatures and reveal genetic variants associated with climate resilience."Coral reefs, found throughout the world in tropical oceans, are one of the most diverse and valuable ecosystems on Earth. They are actually living animal colonies and important for many reasons. Reefs provide a habitat for a large variety of marine species; protect coastlines from storms, floods and erosion; and help sustain the fishing and tourism industries.In the late 1990s, reefs worldwide experienced their first wave of mass bleaching, which occurs when high water temperatures destroy the symbiotic relationship with a colony's colorful algae, causing the corals to turn white. The loss effectively starves them, as corals are dependent on the photosynthetic algae that lives within their tissues for nutrients. Reefs can recover from bleaching, but prolonged periods of environmental stress can eventually kill them.The Columbia research predicts, to some degree, which corals are likely to withstand unusually high temperatures and resist bleaching events."Genomics allows us to examine the genetic differences that could influence survival and bleaching tolerance, helping us work out how we might support coral health," said Molly Przeworski, professor in the Departments of Biological Sciences and Systems Biology at Columbia and senior study author.To collect their genetic data, Fuller, Przeworski and their collaborators from the Australian Institute of Marine Science analyzed 237 samples collected at 12 locations along the Great Barrier Reef, generating the highest quality sequences of any corals to date. The sequencing allowed the researchers to look across the genome for signatures where adaptation occurred and to find genetically distinct variations associated with bleaching tolerance."What we discovered is that no single gene was responsible for differences in a coral's response to bleaching, but instead many genetic variants influence the trait," Fuller said. "On their own, each has a very small effect, but when taken together we can use all these variants to predict which corals may be able to survive in the face of hotter seas."Fuller and Przeworski said the findings offer a pathway for coral biologists to further search for strains that can better cope with ocean warming and enables similar approaches that can be used in other species most at risk from climate change."The best chance we have to save what's left of the Earth's coral reefs is to mitigate the effects of climate change by rapidly reducing greenhouse gas emissions," Fuller said. "In the meantime, genetic approaches may be able to buy us time."Collaborators on the study includeAustralian Institute of Marine Science (AIMS), The Agouron Institute, Gencove Inc., and The University of Texas at Austin.
|
Extinction
| 2,020 |
July 16, 2020
|
https://www.sciencedaily.com/releases/2020/07/200716101539.htm
|
Fish reef domes a boon for environment, recreational fishing
|
In a boost for both recreational fishing and the environment, new UNSW research shows that artificial reefs can increase fish abundance in estuaries with little natural reef.
|
Researchers installed six humanmade reefs per estuary studied and found overall fish abundance increased up to 20 times in each reef across a two-year period.The study, published in the The research was a collaboration between UNSW Sydney, NSW Department of Primary Industries (DPI) Fisheries and the Sydney Institute of Marine Science (SIMS).Professor Iain Suthers, of UNSW and SIMS, led the research, while UNSW alumnus Dr Heath Folpp, of NSW DPI Fisheries, was lead author.Co-author Dr Hayden Schilling, SIMS researcher and Conjoint Associate Lecturer at UNSW, said the study was part of a larger investigation into the use of artificial reefs for recreational fisheries improvement in estuaries along Australia's southeast coast."Lake Macquarie, Botany Bay and St Georges Basin were chosen to install the artificial reefs because they had commercial fishing removed in 2002 and are designated specifically as recreational fishing havens," Dr Schilling said."Also, these estuaries don't have much natural reef because they are created from sand. So, we wanted to find out what would happen to fish abundance if we installed new reef habitat on bare sand."Previous research has been inconclusive about whether artificial reefs increased the amount of fish in an area, or if they simply attracted fish from other areas nearby."In each estuary, the scientists installed 180 "Mini-Bay Reef Balls" -- commercially made concrete domes with holes -- divided into six artificial reefs with 30 units each.Each unit measures 0.7m in diameter and is 0.5m tall, and rests on top of bare sand.Professor Suthers said artificial reefs were becoming more common around the world and many were tailored to specific locations.Since the study was completed, many more larger units -- up to 1.5m in diameter -- have been installed in NSW estuaries."Fish find the reef balls attractive compared to the bare sand: the holes provide protection for fish and help with water flowing around the reefs," Prof Suthers said."We monitored fish populations for about three months before installing the reefs and then we monitored each reef one year and then two years afterwards."We also monitored three representative natural reef control sites in each estuary."Prof Suthers said the researchers observed a wide variety of fish using the artificial reefs."But the ones we were specifically monitoring for were the species popular with recreational fishermen: snapper, bream and tarwhine," he said."These species increased up to five times and, compared to the bare sand habitat before the reefs were installed, we found up to 20 times more fish overall in those locations."What was really exciting was to see that on the nearby natural reefs, fish abundance went up two to five times overall."Dr Schilling said that importantly, their study found no evidence that fish had been attracted from neighbouring natural reefs to the artificial reefs."There was no evidence of declines in abundance at nearby natural reefs. To the contrary, we found abundance increased in the natural reefs and at the reef balls, suggesting that fish numbers were actually increasing in the estuary overall," he said."The artificial reefs create ideal rocky habitat for juveniles -- so, the fish reproduce in the ocean and then the juveniles come into the estuaries, where there is now more habitat than there used to be, enabling more fish to survive."The researchers acknowledged, however, that while the artificial reefs had an overall positive influence on fish abundance in estuaries with limited natural reef, there might also be species-specific effects.For example, they cited research on yellowfin bream which showed the species favoured artificial reefs while also foraging in nearby seagrass beds in Lake Macquarie, one of the estuaries in the current study.NSW DPI Fisheries conducted an impact assessment prior to installation to account for potential issues with using artificial reefs, including the possibility of attracting non-native species or removing soft substrate.Dr Schilling said their findings provided strong evidence that purpose-built artificial reefs could be used in conjunction with the restoration or protection of existing natural habitat to increase fish abundance, for the benefit of recreational fishing and estuarine restoration of urbanised estuaries."Our results validate NSW Fisheries' artificial reef program to enhance recreational fishing, which includes artificial reefs in estuarine and offshore locations," he said."The artificial reefs in our study became permanent and NSW Fisheries rolled out many more in the years since we completed the study."About 90 per cent of the artificial reefs are still sitting there and we now have an Honours student researching the reefs' 10-year impact." Dr Schilling said the artificial reefs were installed between 2005 and 2007, but the research was only peer-reviewed recently.
|
Extinction
| 2,020 |
July 16, 2020
|
https://www.sciencedaily.com/releases/2020/07/200710100942.htm
|
Revealing winners and losers in projected future climates
|
New research reveals how winners and losers from climate change can be identified based on their ability to adapt to rising future temperatures.
|
In the first study of its kind published in the The study compared thermal tolerance and gene expression (which genes are activated within a cell) in subtropical, desert and temperate Australian rainbowfishes.Evolutionary biologist Professor Luciano Beheregaray says subtropical species were the winners in future climates because evolution suits their local conditions given these fish have the ability to turn on and off a larger number of heat stress genes in hotter climates.The study shows that subtropical species have greater capacity to adapt to future climates than desert species, and that temperate species are the most vulnerable.By looking at how all the genes are expressed in current temperatures and in temperatures projected for 2070, the researchers produced a catalogue of genes that informs about the adaptive capacity to climate change."Resilience or vulnerability to climate change is expected to be influenced by the thermal conditions where species are found, but we knew very little about this, and hardly anything about how this might vary across different climatic regions," says co-author Dr Jonathan Sandoval-Castillo."Our results suggest that the vulnerability of species to climate change will be highly influenced by geographic factors, emphasising the value of assessments of climate traits for more accurate estimates of population impacts and the way ecosystems will ultimately respond," says co-author and PhD student Katie Gates.The findings can also be extended to many non-migratory species, aquatic or terrestrial, under pressure due to climate change."This information is important for identifying biodiversity at high risk of extinction and to develop ways to help them to adapt and persist. This includes restoring lost habitat and actively moving populations to more favourable climatic locations, while we still have time," says Professor Beheregaray."Adaptation of plasticity to projected maximum temperatures and across climatically defined bioregions" by Flinders University evolutionary biologists Professor Luciano Beheregaray, Dr Jonathan Sandoval-Castillo, Katie Gates and Dr Chris Brauer and by collaborators Prof Louis Bernatchez (Université Laval, Canada) and Dr Steve Smith (University of Vienna, Austria) is published in the
|
Extinction
| 2,020 |
July 6, 2020
|
https://www.sciencedaily.com/releases/2020/07/200706140833.htm
|
Plant study challenges tropics' reputation as site of modern evolutionary innovation
|
In a surprise twist, a major group of flowering plants is evolving twice as quickly in temperate zones as the tropics. The finding runs counter to a long-held hypothesis that tropical regions, home to the planet's richest biological diversity, outpace their temperate counterparts in producing new species.
|
The tropics are the birthplace of most species of rosids, a group that makes up more than a quarter of flowering plants, ranging from mangroves to roses to oaks. But in an analysis of about 20,000 rosid species, researchers found the speed of tropical rosid evolution lags far behind that of younger communities in temperate habitats.Although rosids originated 93-115 million years ago, the rate at which the group diversified, or formed new species, dramatically increased over the last 15 million years, a period of global cooling and expanding temperate habitats. Today, rosids are diversifying far faster in places such as the southeastern U.S. than in equatorial rainforests, said study co-lead author Ryan Folk, assistant professor of biological sciences and herbarium curator at Mississippi State University."Everyone knows about the diversity of tropical rainforests. You would assume all the action in evolution is happening in them," said Folk, formerly a postdoctoral researcher at the Florida Museum of Natural History. "But we found out that it is really the temperate regions of the Earth -- really our own backyards -- where a lot of the recent action is taking place."Charles Darwin once described the speed with which the earliest flowering plants evolved and spread across the planet as an "abominable mystery." Scientists are still tracing the driving forces behind these plants' runaway evolutionary success, with temperature emerging as a complex factor: Some studies have shown that flower evolution accelerates in warmer regions while others point to cooler climates. Research on higher and lower latitudes' influence on plant diversification produced similarly conflicting findings.A team of evolutionary biologists selected rosids as the candidates for a closer look at the relationship between temperature and plant diversity in the first large-scale assessment of the group's evolution. Comprising an estimated 90,000-120,000 species, rosids live in nearly all land-based habitats, with rosid trees shaping most temperate and many tropical forests, said study co-author Douglas Soltis, Florida Museum curator and University of Florida distinguished professor."To me that was one of the biggest terrestrial evolutionary events -- the rise of the rosid-dominated forests," he said. "Other lineages, such as amphibians, insects and ferns, diversified in the shadow of rosids."The team's study shows rosids evolved by leaps and bounds after the Earth's hothouse climate began to cool and dry and as many tropical and subtropical habitats transformed into temperate ones -- offering new real estate for evolutionarily enterprising organisms.The diversity of tropical regions, in contrast, is not due to evolutionary mechanisms, but rather stability: Folk said tropical plant communities have "simply failed to go extinct, so to speak."The findings echo a similar pattern the team uncovered in another group of plants known as Saxifragales, but the researchers are cautious about making conjectures on whether the pattern holds true for other plants or animals."It's difficult to say there is a universal pattern for how life responds to temperature," said study co-lead author Miao Sun, a postdoctoral researcher at Denmark's Aarhus University and a former Florida Museum postdoctoral researcher. "On the other hand, there seems to be a trend forming that, together with our study, shows a lower diversification rate in tropical regions compared with temperate zones. But it's still hard to tell to what extent this pattern is true across the tree of life."If cooling temperature spurred rosid diversification, how might the group fare on a warming planet? The prognosis is not promising, the researchers said.Rosids were able to fill cool ecological niches and now may not be able to adapt to a temperature hike, especially at the current rate of change, said study co-author Pamela Soltis, Florida Museum curator and UF distinguished professor."Warming temperatures will likely slow the rate of diversification, but even worse, we don't expect species currently living in arctic or alpine areas to be able to respond to quickly warming temperatures," she said. "The change is happening too rapidly, and we are already seeing species moving northward in the Northern Hemisphere or up mountains, with many more species facing extinction or already lost."The team used genetic data from GenBank and natural history databases such as iDigBio and the Global Biodiversity Information Facility to assemble DNA data for 20,000 species and 3 million plant occurrence records -- one of the largest investigations of this nature to date."This work would have been impossible without natural history collections data," said study co-lead and senior author Robert Guralnick, Florida Museum curator of bioinformatics. "Rosids are an enormously successful group of flowering plants. Look out your window, and you will see rosids. Those plants are there because of processes occurring over millions of years, and now we know something essential about why."
|
Extinction
| 2,020 |
July 6, 2020
|
https://www.sciencedaily.com/releases/2020/07/200706094138.htm
|
Palm trees most abundant in American rainforests
|
Characteristics of palm trees differ from those of other tropical trees in many ways. In a major new study led by scientists at Uppsala University, Sweden, and University of Campinas, Brazil, they have surveyed the actual numbers of palms in tropical rainforests around the globe. The proportion of palm trees is important to include in calculations of forests' potential carbon storage and in estimates of forested areas' sensitivity to climate change.
|
Palm trees are iconic tropical forest plants. However, postcard images of coconut palms leaning over white sandy beaches do not capture the stunning diversity of palms and their importance to humans and ecosystems. There are over 2,500 palm species and many are used by humans for food, shelter, medicine and crafts. In some areas, palms are also entirely dominant and form natural monocultures. Palms are among the most common tree species in the Amazon rainforest, but in some tropical areas they are unusual, or conspicuously absent.Before, variation in numbers of palm trees among tropical regions had not been quantified. Now a study led by Bob Muscarella at Uppsala University in Sweden and Thaise Emilio at University of Campinas in Brazil has made the first global assessment of their numbers. Over 200 co-authors from 48 countries contributed to the scientific article."To get a better understanding of tropical forests and reduce uncertainty about carbon balance in these ecosystems during climate change, we summarised data to show how the number of palms vary around the world compared with other tree species," Muscarella says.Drawing from existing networks of forest plots (including forestplots.net, PPBio, Rainfor, AfriTRON), the researchers compiled a huge database of 2,548 plots and then quantified palm numbers relative to other tree species in the sample plots.The study results show that in the Neotropical rainforests (such as Amazonia), palms are more than five times more numerous than in comparable Asian and African forests. Many palms were already known to prefer land with a good groundwater supply, and the new study confirmed that palm trees were more plentiful in wetter areas with less fertile soils and shallower groundwater.Tropical rainforests are often seen as synonymous with biodiversity. However, this diversity is not evenly distributed, and most plants in a given area belong to only a handful of species. More than half of the total biomass in the Amazon rainforest is distributed among fewer than 300 tree species -- including several species of palms."Understanding the dominant species in tropical forests is crucial to recognising how these forests function and how vulnerable they're going to be to disturbances and climate change in the future," Muscarella says.Being monocotyledons (the seed produces only one first leaf, or cotyledon) palms are more closely related to grasses than to the deciduous trees of the tropics, for instance. Palms therefore differ in many fundamental ways, in anatomy and physiology, from other tropical trees. These differences may have far-reaching implications when it comes to estimating uptake and storage (sequestration) of carbon in tropical forests, as well as their resilience to climate change. The new study provides knowledge with a vital bearing on further research into both of these aspects."Impressive levels of palm abundance do not come as a surprise to many tropical forest researchers. Days of work may be necessary to measure all the palms of a single hectare in some places in the middle of Amazon. However, a fair representation of palms in studies of tropical forests functioning is yet to come. Showing where and when palms must be considered is a major contribution of our new study," Emilio says.
|
Extinction
| 2,020 |
July 2, 2020
|
https://www.sciencedaily.com/releases/2020/07/200702100414.htm
|
Climate change threat to tropical plants
|
Tropical plants closer to the equator are most at risk from climate change because it is expected to become too hot for many species to germinate in the next 50 years, UNSW researchers have found.
|
Their study analysed almost 10,000 records for more than 1300 species from the Kew Gardens' global seed germination database.The research, published in the journal Lead author Alex Sentinella, UNSW PhD researcher, said past research had found that animal species closer to the equator would be more at risk from climate change."The thought was that because tropical species come from a stable climate where it's always warm, they can only cope with a narrow range of temperatures -- whereas species from higher latitudes can cope with a larger range of temperatures because they come from places where the weather varies widely," Mr Sentinella said."However, this idea had never been tested for plants."Because climate change is a huge issue globally, we wanted to understand these patterns on a global scale and build upon the many studies on plants at an individual level in their environment."The researchers examined seed germination data from the Millennium Seed Bank Partnership Data Warehouse, hosted by Kew Royal Botanic Gardens in London, to quantify global patterns in germination temperature.They analysed 9737 records for 1312 plant species from every continent except Antarctica and excluded agricultural crops.Mr Sentinella said they chose seed data because it was widely available and relevant to the ability of a species to cope with different temperatures."With seeds, you can experiment on them quickly, there are a lot of studies about them and importantly, germination directly relates to how a species will survive, because if the seed doesn't germinate the plant won't live," he said."So, we collated the data from the Kew Gardens database, examined all experiments on the same species from the same locations, and then determined the range of temperatures each species could tolerate in order to survive."The researchers also examined climate data for the same locations as the plant species used in the study.They looked at current temperature -- the average temperature of the warmest three months from 1970 to 2000 -- and predicted temperature for 2070.The researchers then compared the temperatures the plants were experiencing now with the forecasted 2070 temperatures.The study discovered tropical plants do not have narrower temperature tolerances but were more at risk from global warming, because it would bring them close to their maximum seed germination temperatures.Mr Sentinella said, on average, the closer a plant was to the equator, the more at risk it would be of exceeding its temperature ceiling by 2070."These plants could be more at risk because they are near their upper limits. So, even a small increase in temperature from climate change could push them over the edge," he said."The figures are quite shocking because by 2070, more than 20 per cent of tropical plant species, we predict, will face temperatures above their upper limit, which means they won't germinate, and so can't survive."Mr Sentinella said the researchers also found that more than half of tropical species are expected to experience temperatures exceeding their optimum germination temperatures."That's even worse because if those plants can survive it would be at a reduced rate of germination and therefore, they might not be as successful," he said."If a seed's germination rate is 100 per cent at its optimum temperature, then it might only manage 50 or 60 per cent, for example, if the temperature is higher than what's ideal."Mr Sentinella said he was surprised to find that climate change would threaten so many tropical species."But our most unexpected discovery was that the hypothesis often used for animals -- that those near the equator would struggle to survive the impact of climate change because they have narrower temperature tolerances -- was not true for plants," he said."We found that regardless of latitude, plant species can germinate at roughly the same breadth of temperatures, which does not align with the animal studies."The researchers also found 95 per cent of plant species at latitudes above 45 degrees are predicted to benefit from warming, because environmental temperatures are expected to shift closer to the species' optimal germination temperatures.Mr Sentinella said it was possible for some plants to slowly evolve to increasing temperatures, but it was difficult to predict which ones would survive."The problem with the quick change in temperatures forecasted, is that some species won't be able to adapt fast enough," he said."Sometimes plants can migrate by starting to grow further away from the equator or, up a mountain slope where it's cooler. But if a species can't do that it will become extinct."There are almost 400,000 plant species worldwide -- so, we would expect a number of them to fail to germinate between now and 2070."Mr Sentinella hopes the researchers' findings will help to conserve plant species under threat from climate change."Ideally, we would be able to conserve all ecosystems, but the funding is simply not there. So, our findings could help conservation efforts target resources towards areas which are more vulnerable," he said."We also hope our findings further strengthen the global body of research about the risks of climate change."Humans have known about dangers of climate change for decades and we already have the answers to tackle it. So, hopefully our study will help encourage people and policy makers to take action now."
|
Extinction
| 2,020 |
June 30, 2020
|
https://www.sciencedaily.com/releases/2020/06/200630161548.htm
|
Microscope allows gentle, continuous imaging of light-sensitive corals
|
Corals are "part animal, part plant, and part rock -- and difficult to figure out, despite being studied for centuries," says Philippe Laissue of University of Essex, a Whitman Scientist at the Marine Biological Laboratory. Many corals are sensitive to bright light, so capturing their dynamics with traditional microscopes is a challenge.
|
To work around their photosensitivity, Laissue developed a custom light-sheet microscope (the L-SPI) that allows gentle, non-invasive observation of corals and their polyps in detail over eight continuous hours, at high resolution. He and his colleagues, including MBL Associate Scientist and coral biologist Loretta Roberson, published their findings this week in Coral reefs, made up of millions of tiny units called polyps, are extremely important ecosystems, both for marine life and for humans. They harbor thousands of marine species, providing food and economic support for hundreds of millions of people. They also protect coasts from waves and floods, and hold great potential for pharmaceutical and biotechnological discovery.But more than half of the world's coral reefs are in severe decline. Climate change and other human influences are gravely threatening their survival. As ocean temperatures rise, coral bleaching is afflicting reefs worldwide. In coral bleaching, corals expel their symbiotic algae and become more susceptible to death."The L-SPI opens a window on the interactions and relationship between the coral host, the symbiotic algae living in their tissues, and the calcium carbonate skeleton they build in real time," Roberson says. "We can now track the fate of the algae during [coral] bleaching as well as during initiation of the symbiosis."Roberson is also using Laissue's imaging technology to measure damage to corals from "bioeroders" -- biological agents like algae and sponges that break down a coral's skeleton, a problem exacerbated by ocean acidification and increasing water temperatures.
|
Extinction
| 2,020 |
June 29, 2020
|
https://www.sciencedaily.com/releases/2020/06/200629150544.htm
|
Asteroid impact, not volcanoes, made the Earth uninhabitable for dinosaurs
|
Modelling of the Chicxulub asteroid impact 66 million years ago shows it created a world largely unsuitable for dinosaurs to live in.
|
The asteroid, which struck the Earth off the coast of Mexico at the end of the Cretaceous era 66 million years ago, has long been believed to be the cause of the demise of all dinosaur species except those that became birds.However, some researchers have suggested that tens of thousands of years of large volcanic eruptions may have been the actual cause of the extinction event, which also killed off almost 75% of life on Earth.Now, a research team from Imperial College London, the University of Bristol and University College London has shown that only the asteroid impact could have created conditions that were unfavourable for dinosaurs across the globe.They also show that the massive volcanism could also have helped life recover from the asteroid strike in the long term. Their results are published today in Lead researcher Dr Alessandro Chiarenza, who conducted this work whilst studying for his PhD in the Department of Earth Science and Engineering at Imperial, said: "We show that the asteroid caused an impact winter for decades, and that these environmental effects decimated suitable environments for dinosaurs. In contrast, the effects of the intense volcanic eruptions were not strong enough to substantially disrupt global ecosystems."Our study confirms, for the first time quantitatively, that the only plausible explanation for the extinction is the impact winter that eradicated dinosaur habitats worldwide."The asteroid strike would have released particles and gases high into the atmosphere, blocking out the Sun for years and causing permanent winters. Volcanic eruptions also produce particles and gases with Sun-blocking effects, and around the time of the mass extinction there were tens of thousands of years of eruptions at the Deccan Traps, in present-day India.To determine which factor, the asteroid or the volcanism, had more climate-changing power, researchers have traditionally used geological markers of climate and powerful mathematical models. In the new paper, the team combined these methods with information about what kinds of environmental factors, such as rainfall and temperature, each species of dinosaur needed to thrive.They were then able to map where these conditions would still exist in a world after either an asteroid strike or massive volcanism. They found that only the asteroid strike wiped out all potential dinosaur habitats, while volcanism left some viable regions around the equator.Co-lead author of the study Dr Alex Farnsworth, from the University of Bristol, said: "Instead of only using the geologic record to model the effect on climate that the asteroid or volcanism might have caused worldwide, we pushed this approach a step forward, adding an ecological dimension to the study to reveal how these climatic fluctuations severely affected ecosystems."Co-author Dr Philip Mannion, from University College London, added: "In this study we add a modelling approach to key geological and climate data that shows the devastating effect of the asteroid impact on global habitats. Essentially, it produces a blue screen of death for dinosaurs."Although volcanoes release Sun-blocking gases and particles, they also release carbon dioxide, a greenhouse gas. In the short term after an eruption, the Sun-blockers have a larger effect, causing a 'volcanic winter'. However, in the longer term these particles and gases drop out of the atmosphere, while carbon dioxide stays around and builds up, warming the planet.After the initial drastic global winter caused by the asteroid, the team's model suggests that in the longer term, volcanic warming could have helped restore many habitats, helping new life that evolved after the disaster to thrive.Dr Chiarenza said: "We provide new evidence to suggest that the volcanic eruptions happening around the same time might have reduced the effects on the environment caused by the impact, particularly in quickening the rise of temperatures after the impact winter. This volcanic-induced warming helped boost the survival and recovery of the animals and plants that made through the extinction, with many groups expanding in its immediate aftermath, including birds and mammals."
|
Extinction
| 2,020 |
June 29, 2020
|
https://www.sciencedaily.com/releases/2020/06/200629120131.htm
|
Bleaching affects aquarium corals, too
|
A new study illustrates the potential impact of recurrent heatwaves on coral species collected by the Australian aquarium coral industry.
|
The study's lead author, Professor Morgan Pratchett from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU), says there are active and expanding aquarium coral fisheries operating across the country in Western Australia, the Northern Territory and Queensland."With widespread coral bleaching again affecting the Great Barrier Reef, and also occurring on coral reefs in Western Australia, there is inevitable concern regarding the sustainability and defensibility of ongoing coral harvesting," Prof Pratchett said.Prior to the study, scientists didn't know much about the temperature sensitivity and bleaching susceptibility of Australian aquarium corals.The researchers tested these parameters on six of the most important exported coral species from Australia."We found two of the most striking species were particularly susceptible and died at the temperatures you would expect when bleaching occurs," Prof Pratchett said."These corals are most abundant within the nearshore habitats of the southern Great Barrier Reef -- an area that bleached earlier this year."One of these species is the Australian saucer coral (Homophyllia australis), found just off the coast of Mackay.With the worldwide demand for Australian aquarium corals increasing, a single aquarium specimen of Homophyllia australis fetched more than $8,000 AUD in Japan in 2017.The study found the other, more widespread, aquarium corals were able to cope with higher temperatures. They bleached but didn't die -- the corals are already regularly exposed to extreme temperatures in a wide variety of different environments, including shallow tidal pools in north Western Australia."Understanding the differential susceptibilities of different coral species to environmental change is a very important aspect of managing coral fisheries," Prof Pratchett said.Australian coral fisheries are often the first to provide reports of coral bleaching across diverse reef environments, as they need to respond to changes in coral health."Those in the industry don't collect bleached corals and actively avoid areas where there has been recent and severe mass bleaching," Prof Pratchett said.He said the study, which was supported by the Fisheries Research and Development Corporation, highlights the need for more specific and targeted in-situ monitoring for these popular aquarium corals.This is especially crucial with the increasing threat posed by ongoing environmental change.
|
Extinction
| 2,020 |
June 23, 2020
|
https://www.sciencedaily.com/releases/2020/06/200623104242.htm
|
Dimethylsulfoniopropionate concentration in coral reef invertebrates
|
New research highlights the effect of benthic assemblages on the sulfur metabolism of coral and giant clam species. The research was conducted at CRIOBE and ENTROPIE research units, with the collaboration of the Swire institute of Marine Science of The University of Hong Kong (SWIMS, HKU), Paris-Saclay UVSQ University, The Cawthron Institute (New Zealand) and The University of French Polynesia. The findings were recently published in the journal
|
To better understand how benthic species assemblages could influence their respective fitness, the researchers created artificial benthic assemblages using two coral species (Pocillopora damicornis and Acropora cytherea) and one giant clam species (Tridacna maxima) and measured the dimethylsulfoniopropionate (DMSP) concentration in each species using Nuclear Magnetic Resonance (NMR) spectroscopy. DMSP, produced in large quantities in coral reefs, is a key compound that plays a central role in the marine sulfur cycle and climate regulation as major precursor of the volatile compound Dimethylsulfide (DMS). While DMSP has been found in terrestrial and marine organisms, only few species are able to produce it, among them marine algae such as dinoflagellates and corals. Numerous ecological studies have focused on DMSP concentrations in corals, which led to the hypothesis that increases in DMSP levels might be a general response to stress."We submitted our different assemblages of one, two or three co-occurring species to a thermal stress and measured the DMSP concentration in each species. Interestingly, we demonstrated that the concentration of DMSP in A. cytherea and T. maxima is modulated according to the complexity of species assemblages," explains Dr Isis Guibert.Coral and giant clams are holobionts living in association with symbiotic algae, Symbiodiniaceae, as well as a large bacterial community. Both, Symbiodiniaceae and bacteria are able to produce DMSP. To determine whether giant clams might also contribute to DMSP production, the team explored transcriptomes of T. maxima for genes encoding enzymes involved in the DMSP biosynthesis. "For the first time, we revealed the existence of homologous genes involved in DMSP production in giant clam genome" said Dr Gaël Lecellier, who supervised the study. "Taken together, our results suggest that DMSP concentration in the holobiont is influenced by their neighboring species, modifying the metabolism of the sulfur pathway." The findings of this study offer new perspectives for future global sulfur cycling research.
|
Extinction
| 2,020 |
June 17, 2020
|
https://www.sciencedaily.com/releases/2020/06/200617150019.htm
|
Knock-knock? Who's there? How coral let symbiotic algae in
|
New work from a team of Carnegie cell, genomic and developmental biologists solves a longstanding marine science mystery that could aid coral conservation. The researchers identified the type of cell that enables a soft coral to recognize and take up the photosynthetic algae with which it maintains a symbiotic relationship, as well as the genes responsible for this transaction.
|
Their breakthrough research is published in Corals are marine invertebrates that build large exoskeletons from which reefs are constructed. But this architecture is only possible because of a mutually beneficial relationship between the coral and various species of single-celled algae called dinoflagellates that live inside individual coral cells."For years, researchers have been trying to determine the mechanism by which the coral host is able to recognize the algal species with which is compatible -- as well as to reject other, less-desirable species -- and then to ingest and maintain them in a symbiotic arrangement," explained Carnegie Embryology Director Yixian Zheng who, with colleagues Chen-ming Fan, Minjie Hu, and Xiaobin Zheng, conducted this research.These dinoflagellates are photosynthetic, which means that, like plants, they can convert the Sun's energy into chemical energy. An alga will share the sugars it synthesizes with its coral host, which in turn provides the alga with the inorganic carbon building blocks it needs, as well as phosphorus, nitrate, and sulfur."However, ocean warming due to climate change is causing many coral hosts to lose their algal tenants -- along with the nutrients that they provide -- a phenomenon called bleaching," explained lead author Hu. "Without algae there to increase its food supply, the coral can die. This makes it particularly critical to understand the symbiotic mechanism now, as coral communities are increasingly jeopardized."Building on Carnegie biologists' longstanding tradition of using a model organism approach to study complicated biological processes, the research team set out to use the pulsing, feathery, lavender-colored, soft coral Xenia to reveal the cell types and pathways that orchestrate the symbiotic relationship between a coral and its algae. This knowledge can then be applied to increase our understanding of other coral species and allow for further research into how these fragile ecosystems are threatened by warming oceans.Applying a wide range of genomic, bioinformatic, and developmental biology tools, the researchers identified the type of cell that is required for the symbiotic relationship to occur. They discovered that it expresses a distinct set of genes, which enable it to identify, "swallow," and maintain an alga in a specialized compartment, as well as to prevent the alga from being attacked by its immune system as a foreign invader. Furthermore, the researchers showed that the uptake process occurs over five stages, with stage three representing mature, alga-hosting cells, and stage one being pre-symbiotic-relationship and stage five being post-alga-expulsion.Looking ahead, the team wants to understand how environmental stress affects progression through the five stages, and which stage is most crucial for recovery after a bleaching event, and the genes that function at each stage.Earlier this year, Zheng was selected as one of 15 scientists awarded a grant from the Gordon and Betty Moore Foundation to support research on symbiosis in aquatic systems. The foundation launched its Symbiosis in Aquatic Systems Initiative last year. Current and emerging leaders in aquatic symbiosis research -- as well as scientists who will apply their deep expertise from other areas of science to aquatic symbiosis -- were selected from a competitive pool."Dr. Zheng's work using the soft coral, Xenia, is an exemplar of how model systems research can advance our understanding of fundamental processes in nature. We look forward to continued discovery as part of her Symbiosis in Aquatic Systems Initiative investigator award," Said Dr. Sara J. Bender, program officer, Science Program, Gordon and Betty Moore Foundation.
|
Extinction
| 2,020 |
June 9, 2020
|
https://www.sciencedaily.com/releases/2020/06/200609095032.htm
|
Nature's 'slow lanes' offer hope for species feeling heat of climate change
|
Pockets of landscape less prone than adjacent areas to disturbances like fire and drought may hold the key for scientists, conservationists and land managers seeking to preserve vulnerable species in a changing climate.
|
These areas, categorized as "disturbance refugia," are becoming a focal point for ecologists trying to learn why change doesn't occur as quickly in some landscapes as it does in others nearby."In the Pacific Northwest, the iconic northern spotted owl relies on refugia in the form of old-growth forests," said Oregon State University forest ecologist Meg Krawchuk. "These forests are refugia from previous stand-replacing disturbances -- that's how they got to be old -- but they're slowly being nibbled away by recent high-severity fires."Known informally as the "lifeboats" or "slow lanes" of biodiversity, refugia have spawned the new field of refugia science, which is the theme of the June issue of Krawchuk, who contributed to the issue with a study of forest refugia in the combined context of fire, drought and insect outbreaks, says research shows that some locations have inherent characteristics -- such as terrain, vegetation, proximity to bodies of water, and slope-face direction -- that buffer them from disturbances in a predictable manner."Scientists and land managers working together on refugia science and implementation will help to conserve forest landscapes, and biodiversity, here in the Pacific Northwest and around the globe that are dear to our hearts," Krawchuk said. "Some disturbances are important ecosystem processes that support biodiversity; however, there is increasing worry about the erosion of biodiversity due to the increased frequency, severity and/or types of forest disturbances, and how they overlap."Natural disturbances can create mosaics across a landscape that support biodiversity, but disturbances outside the historical range of frequency and severity can do short- and long-term ecosystem damage.Recent studies of disturbance refugia in forest ecosystems have focused mainly on fire, Krawchuk said, but the wide range of disturbances in forests necessitates developing a broader understanding of refugia, particularly against the backdrop of climate change."With climate change, forest disturbances like wildfire, drought and insect outbreaks are expected to become more frequent or severe, changing the recipe of these natural disturbances that historically contributed important variety and flavor to ecosystems," she said.The study jointly led by Krawchuk and College of Forestry colleague Garrett Meigs shows how the overlap of disturbances generates a multitude of complex feedbacks, both positive and negative, that affect the structure of refugia and how they work."Detecting refugia in multiple places and at different times and understanding what's behind their occurrence, persistence and value in sustaining biodiversity are important frontiers in science and land management," Krawchuk said. "Developing a disturbance refugia framework that recognizes multiple types of forest disturbance under one banner is an important step for research and management of forest ecosystems that are changing as the planet warms."Thinking in terms of only two types of land categories -- refugia and non-refugia -- is tempting but an oversimplification that scientists and land managers should avoid, she said."The people who study forests and manage them need to recognize there are varying types and qualities of refugia, and the variance will only grow as climate and disturbance regimes continue to change," Krawchuk said. "Considering a broad palette of disturbance refugia together will be critical to management strategies that create and protect refugia. And continued research is necessary to fill out the framework."Disturbance refugia figure to play an increasingly important role in the ability of climate change refugia to help save species from extinction, she said."Identifying disturbance refugia locations within climate change refugia spots would lead to a deeper understanding of refugia," Krawchuk said. "In this era of rapid environmental change, disturbance refugia within mosaics of fire, drought and insect outbreaks will shape the patterns of persistence of forest biodiversity and ecosystem function around the world. There are many iconic and special forest landscapes being confronted with increasing disturbance pressures, including harvest and conversion to agriculture or other uses."Disturbance refugia science is broadly applicable, she added, because many disturbance processes are global -- including pressure from climate change. And the ideas underpinning refugia science go beyond forests and disturbance refugia."We're increasingly realizing that refugia science might provide theory and analysis of the critical role of refugia in social and ecological resilience," Krawchuk said. "For example, as resistance to diseases that can be transmitted from animals to humans, pandemics like COVID-19, political turmoil, violence and land use issues, particularly in the context of extreme events. Refugia are areas of resistance that contribute to system-level resilience."Collaborating with Krawchuk and Meigs were researchers from the University of Idaho, Portland State University, Western Colorado University, the United States Forest Service and the U.S. Geological Survey.Supporting this research were the Forest Service, the USGS and the National Science Foundation.
|
Extinction
| 2,020 |
June 3, 2020
|
https://www.sciencedaily.com/releases/2020/06/200603100500.htm
|
Genetic outcomes of great gray owl population in four states
|
A University of Wyoming researcher led a study of great gray owls in a four-state region, showing that range discontinuity could lead to genetic drift and subsequent loss of genetic diversity in these birds.
|
Lower genetic diversity in these owls means they are more susceptible to changes in their environment and, thus, less able to adapt quickly."With lower genetic diversity, such owls have less ability to adapt to changes that include extreme fire effects on their habitats; human developments; stresses caused by diseases such as West Nile virus and trichomonas, a nasty parasite that damages their oral cavity and can lead to starvation; and other diseases," says Holly Ernest, a UW professor of wildlife genomics and disease ecology, and the Wyoming Excellence Chair in Disease Ecology in UW's Department of Veterinary Sciences and the Program in Ecology. "Another stress can be overzealous photographers who get too near nesting sites and scare great gray owl moms and dads off their nests and endanger the nestlings."Ernest was the senior and corresponding author of a paper, titled "Population Genomic Diversity and Structure at the Discontinuous Southern Range of the Great Gray Owl in North America," that was published online May 31 in Beth Mendelsohn, a 2018 UW Master of Science graduate in veterinary sciences and the Haub School of Environment and Natural Resources, from Missoula, Mont., is the paper's lead author. Mendelsohn is now a raptor biologist conducting research to improve owl and hawk conservation in Rocky Mountain ecosystems.Other contributors to the paper are Bryan Bedrosian, research director of the Teton Raptor Center; Sierra Love Stowell, a research genomicist affiliated with Ernest's lab and a UW postdoctoral researcher from 2016-18; Roderick Gagne, a research scientist at Colorado State University and a UW postdoctoral researcher from 2015-17; Melanie LaCava, a UW Ph.D. candidate in the Program in Ecology and Department of Veterinary Sciences, from San Diego, Calif.; Braden Godwin, a 2019 UW Master of Science graduate in veterinary sciences and the Haub School of Environment and Natural Resources; and Joshua Hull, an adjunct associate professor of animal science at the University of California-Davis."This study constitutes the first genomic work on great gray owls and the first genetic analysis that includes Wyoming, which represents the southern extent of the species range in the Rocky Mountains and is impacted by habitat loss," Ernest says."When compared to some other bird species, we found that great gray owls seem to have lower genetic diversity," Mendelsohn says. "However, we have no evidence that the low genetic diversity is currently having a detrimental effect on the species. It may, however, affect the species' future adaptability."Great gray owls studied live in northern and southern Oregon, California, Idaho and Wyoming. The study found that the populations that lacked connectivity to the rest of the breeding range -- those in California and Oregon -- had lower genetic diversity than the Rocky Mountain owl populations in Idaho and Wyoming. The owls in Idaho and Wyoming were connected to the core of the range. Owls in Wyoming showed greater genetic diversity than the other locations studied."We hypothesize that Wyoming owls live in their habitat range that is like a peninsula finger of habitat coming down, from north to south. From the main, larger habitat range to the north (Montana and up into Canada), they have habitat and range that are still connected, albeit a very tenuous connection, to the large main Montana/Canada habitat and range of great gray owls," Ernest says. "Wyoming owls exist on one of the most southern extents of great gray owl range that still has some connection with that larger Montana/Canada habitat."By contrast, the great gray owl habitat in Oregon and California is cut off from the rest of the owls' range, which is mainly in boreal forests in Canada and around the globe in such regions as Russia, Ernest says. The owls' range becomes increasingly fragmented as it extends farther south. The northern boreal forest transitions to montane forest and borders on sagebrush and desert in Oregon and California.As a result, these range-edge owl populations have a heightened susceptibility to disease and human-caused mortality, such as from trees being cut down to build homes; climate change; genetic diversity erosion; and potential extinction. Small, isolated populations of these owls are more likely to experience inbreeding, which results in lower genetic diversity."Conservationists could learn from this that great gray owls in this part of their range may need extra protections and may be vulnerable to environmental change," Mendelsohn says.During the study, 158 DNA samples from unique owl individuals were sequenced, Mendelsohn says. After filtering for quality and marker coverage, the research team retained 123 individuals that had enough high-quality sequencing reads. For some of the analyses, a subset of 78 individuals was used because known related individuals were removed.The genomics part of this work took a little under 2.5 years at UW, Mendelsohn says."Prior to that, I worked as a field technician at the Teton Raptor Center and helped collect DNA samples from owls from 2013-16," she says. "The lead biologist on the project, Bryan Bedrosian, connected me with Holly for my master's work."
|
Extinction
| 2,020 |
May 26, 2020
|
https://www.sciencedaily.com/releases/2020/05/200526111320.htm
|
Dinosaur-dooming asteroid struck Earth at 'deadliest possible' angle
|
New simulations from Imperial College London have revealed the asteroid that doomed the dinosaurs struck Earth at the 'deadliest possible' angle.
|
The simulations show that the asteroid hit Earth at an angle of about 60 degrees, which maximised the amount of climate-changing gases thrust into the upper atmosphere.Such a strike likely unleashed billions of tonnes of sulphur, blocking the sun and triggering the nuclear winter that killed the dinosaurs and 75 per cent of life on Earth 66 million years ago.Drawn from a combination of 3D numerical impact simulations and geophysical data from the site of the impact, the new models are the first ever fully 3D simulations to reproduce the whole event -- from the initial impact to the moment the final crater, now known as Chicxulub, was formed.The simulations were performed on the Science and Technology Facilities Council (STFC) DiRAC High Performance Computing Facility.Lead researcher Professor Gareth Collins, of Imperial's Department of Earth Science and Engineering, said: "For the dinosaurs, the worst-case scenario is exactly what happened. The asteroid strike unleashed an incredible amount of climate-changing gases into the atmosphere, triggering a chain of events that led to the extinction of the dinosaurs. This was likely worsened by the fact that it struck at one of the deadliest possible angles."Our simulations provide compelling evidence that the asteroid struck at a steep angle, perhaps 60 degrees above the horizon, and approached its target from the north-east. We know that this was among the worst-case scenarios for the lethality on impact, because it put more hazardous debris into the upper atmosphere and scattered it everywhere -- the very thing that led to a nuclear winter."The results are published today in The upper layers of earth around the Chicxulub crater in present-day Mexico contain high amounts of water as well as porous carbonate and evaporite rocks. When heated and disturbed by the impact, these rocks would have decomposed, flinging vast amounts of carbon dioxide, sulphur and water vapour into the atmosphere.The sulphur would have been particularly hazardous as it rapidly forms aerosols -- tiny particles that would have blocked the sun's rays, halting photosynthesis in plants and rapidly cooling the climate. This eventually contributed to the mass extinction event that killed 75 per cent of life on Earth.The team of researchers from Imperial, the University of Freiburg, and The University of Texas at Austin, examined the shape and subsurface structure of the crater using geophysical data to feed into the simulations that helped diagnose the impact angle and direction. Their analysis was also informed by recent results from drilling into the 200 km-wide crater, which brought up rocks containing evidence of the extreme forces generated by the impact.Pivotal to diagnosing the angle and direction of impact was the relationship between the centre of the crater, the centre of the peak ring -- a ring of mountains made of heavily fractured rock inside the crater rim -- and the centre of dense uplifted mantle rocks, some 30 km beneath the crater.At Chicxulub, these centres are aligned in a southwest-northeast direction, with the crater centre in between the peak-ring and mantle-uplift centres. The team's 3D Chicxulub crater simulations at an angle of 60 degrees reproduced these observations almost exactly.The simulations reconstructed the crater formation in unprecedented detail and give us more clues as to how the largest craters on Earth are formed. Previous fully 3D simulations of the Chicxulub impact have covered only the early stages of impact, which include the production of a deep bowl-shaped hole in the crust known as the transient crater and the expulsion of rocks, water and sediment into the atmosphere.These simulations are the first to continue beyond this intermediate point in the formation of the crater and reproduce the final stage of the crater's formation, in which the transient crater collapses to form the final structure. This allowed the researchers to make the first comparison between 3D Chicxulub crater simulations and the present-day structure of the crater revealed by geophysical data.Co-author Dr Auriol Rae of the University of Freiburg said: "Despite being buried beneath nearly a kilometre of sedimentary rocks, it is remarkable that geophysical data reveals so much about the crater structure -- enough to describe the direction and angle of the impact."The researchers say that while the study has given us important insights into the dinosaur-dooming impact, it also helps us understand how large craters on other planets form.Co-author Dr Thomas Davison, also of Imperial's Department of Earth Science and Engineering, said: "Large craters like Chicxulub are formed in a matter of minutes, and involve a spectacular rebound of rock beneath the crater. Our findings could help advance our understanding of how this rebound can be used to diagnose details of the impacting asteroid."The work was supported by the International Ocean Discovery Program (IODP), International Continental Scientific Drilling Program (ICDP), (STFC) DiRAC High Performance Computing Facility and the Natural Environment Research Council.
|
Extinction
| 2,020 |
May 22, 2020
|
https://www.sciencedaily.com/releases/2020/05/200522104015.htm
|
First fossil nursery of the great white shark discovered
|
The great white shark is one of the most charismatic, but also one of the most infamous sharks. Despite its importance as top predator in marine ecosystems, it is considered threatened with extinction; its very slow growth and late reproduction with only few offspring are -- in addition to anthropogenic reasons -- responsible for this.
|
Young white sharks are born in designated breeding areas, where they are protected from other predators until they are large enough not to fear competitors any more. Such nurseries are essential for maintaining stable and sustainable breeding population sizes, have a direct influence on the spatial distribution of populations and ensure the survival and evolutionary success of species. Researchers have therefore intensified the search for such nurseries in recent years in order to mitigate current population declines of sharks by suitable protection measures. "Our knowledge about current breeding grounds of the great white shark is still very limited, however, and palaeo-nurseries are completely unknown," explains Jaime Villafaña from the University of Vienna.He and his colleagues analysed statistically 5 to 2 million year old fossil teeth of this fascinating shark, which were found at several sites along the Pacific coast of Chile and Peru, to reconstruct body size distribution patterns of great white shark in the past. The results show that body sizes varied considerably along the South American paleo-Pacific coast. One of these localities in northern Chile, Coquimbo, revealed the highest percentage of young sharks, the lowest percentage of "teenagers." Sexually mature animals were completely absent.This first undoubted paleo-nursery of the Great White Shark is of enormous importance. It comes from a time when the climate was much warmer than today, so that this time can be considered analogous to the expected global warming trends in the future. "If we understand the past, it will enable us to take appropriate protective measures today to ensure the survival of this top predator, which is of utmost importance for ecosystems," explains palaeobiologist Jürgen Kriwet: "Our results indicate that rising sea surface temperatures will change the distribution of fish in temperate zones and shift these important breeding grounds in the future."This would have a direct impact on population dynamics of the great white shark and would also affect its evolutionary success in the future. "Studies of past and present nursery grounds and their response to temperature and paleo-oceanographic changes are essential to protect such ecological key species," concluded Jürgen Kriwet.
|
Extinction
| 2,020 |
May 19, 2020
|
https://www.sciencedaily.com/releases/2020/05/200519140414.htm
|
Ecosystem diversity drives the origin of new shark and ray species
|
What drives the evolution of new species of sharks and rays? Traditionally, scientists thought it required species to be separated by geographic or spatial barriers, however a new study of elasmobranchs (the group of sharks and rays) has challenged this expectation -- and found evolution is happening faster than many think.
|
Flinders University evolutionary biologists Dr Jonathan Sandoval-Castillo and Professor Luciano Beheregaray tested how different oceanographic conditions in the Gulf of California and the Baja California Peninsula (Mexico) influenced the formation of new species of guitarfish (The team discovered four types, or 'young species', of guitarfish that have similar external appearance but are genetically different.Each type of guitarfish appears to have adapted to one of the four separate regions of the Gulf of California. This promotes environmental tolerances which result in those guitarfish having improved odds for survival and reproduction in the region where they were born."We have shown that these four guitarfish species evolved quite quickly from the same common ancestor," says Dr Jonathan Sandoval-Castillo."The process where several new species originate from one ancestor in a relatively short period of time is called adaptive radiation, and this is the first report of such a process in sharks and rays. Our results help changing the false popular belief that sharks and rays do not evolve, or only evolve very slowly," says Prof Luciano Beheregaray.These findings also have important implications for the management of exploited elasmobranch species, such as guitarfish in the Gulf of California which represents an important fishery for Mexico.If these young species adapt and evolve to their local habitat conditions, they cannot be replaced by migrants from other habitats."If such species are incorrectly managed as a single stock, it can result in the over-exploitation and possibly extinction of the entire species."
|
Extinction
| 2,020 |
May 18, 2020
|
https://www.sciencedaily.com/releases/2020/05/200518144953.htm
|
How climate killed corals
|
A squad of climate-related factors is responsible for the massive Australian coral bleaching event of 2016. If we're counting culprits: it's two by sea, one by land.
|
First, El Niño brought warmer water to the Coral Sea in 2016, threatening Australia's Great Barrier Reef's corals. Long-term global warming meant even more heat in the region, according to a new CIRES assessment. And in a final blow that year, a terrestrial heatwave swept over the coast, blanketing the reef system well into the winter, Karnauskas found. The final toll: more than half the coral in some parts of the Great Barrier Reef died."When the Great Barrier Reef bleached severely back in 2016, it earned global attention," said Kris Karnauskas, CIRES Fellow, associate professor of atmospheric and oceanic sciences at the University of Colorado Boulder and author on the study out today in Karnauskas dissected the reasons behind the excessively warm water in Northern Australia's Coral Sea -- water warm enough to "bleach" and kill coral, especially in the northern Great Barrier Reef. Karnauskas used satellite observations and a mathematical technique to fingerprint what phenomena led to what amount of warming, and when. It was the interaction of two key things, he found, that caused the coral-killing heat: A marine heatwave followed by a terrestrial one, both exacerbated by global warming.First came a marine heatwave. It was El Niño that initially caused a spike in sea surface temperature by shifting sun-blocking clouds away from the region, but global warming trends increased its intensity and extended it by several months by raising the background temperature. Then, a landborne heatwave moved across eastern Australia and spilled out over the ocean just as the first phase of the marine heatwave was ending."It turns out that El Niño did play a role, and the eventual warmth was certainly higher because of the long-term trend, but the reason it lasted so long was actually this terrestrial heatwave lurking over eastern Australia until the marine warming event was just finally waning, and then: bang, the heatwave leaked out over the coastline," Karnauskas said. "That warm air over the ocean changed the way heat is exchanged between the ocean and atmosphere, keeping the ocean warm and bleaching for an extra month or so."Increased water temperatures off the northeastern Australian coast triggered mass death of corals on an unprecedented scale. The hot water persisted for months, and caused extensive damage to the ecosystem -- drastically changing the species composition of the region."This new finding reveals that climate variability and change can lead to marine impacts in surprising, compounding ways, including heatwaves both on land and in the ocean," said Karnauskas. "From heatwaves to hurricanes, we need to double down on efforts to understand the complexities of how anthropogenic climate change will influence extreme events in the future."
|
Extinction
| 2,020 |
May 15, 2020
|
https://www.sciencedaily.com/releases/2020/05/200515103920.htm
|
Metagenomics reveals distinct microbiotypes of giant clams
|
New research conducted at CRIOBE and ENTROPIE research units, with the collaboration of the Swire institute of Marine Science of The University of Hong Kong, The Cawthron Institute and James Cook University, highlights the impacts of benthic species assemblages on the giant clams Tridacna maxima. The findings were recently published in the journal
|
The researchers explored for the first time the influence of benthic species-assemblages on giant clams health, with or without increasing temperature. To do so, they created artificial benthic assemblages using two coral species (Pocillopora damicornis and Acropora cytherea) and one giant clam species (Tridacna maxima). The results showed that the health status of giant clams depended on the neighbouring species. Moreover, using cutting-edge DNA multiplexing-metabarcoding technology adapted by Dr. Xavier Pochon, the team studied the microbial community of the giant clams. The researchers newly discovered distinct microbiotypes (group of specific bacteria) in the studied T. maxima population, one of which was linked to clam mortality.Giant clams are less studied by scientists, yet they are important members of coral reefs and play numerous ecological roles. They are the largest living bivalves and serve as food for fish and human. Like coral, they contribute to primary production through photosynthesis by hosting unicellular algae. They also host a large community of bacteria as well as animals such as shrimps or crabs. However, all of the 12 currently recognised species are under threat and more than 50% of the wild population are either locally extinct or severely depleted."For decades we have been focusing on the effect of climate change on single species but this doesn't reflect what could happen within coral reef as a whole. This is why we decided to explore the effect of neighbouring species on the giant clam. We were extremely surprised to discover that the presence of some corals, particularly Acropora cytherea, led to an acute sensitivity of giant clams to increasing temperature which therefore exhibited a high death rate." explains Dr. Isis Guibert.Microbiomes are an integral part of multicellular organisms, contributing to their health and physiological performance. The scientists noted that despite a surge of interest in this research focus, very few invertebrate microbiomes have been studied. The microbiome of giant clams is particularly interesting because clams are exposed to an extreme abundance and diversity of microbes through filter feeding. The discovery of specific microbiome structure, detectable from the genus level, is the first description of microbiotypes in invertebrates. "The results of our study suggest that, similarly to humans, genetic factors might drive the microbiotype of a giant clam." said Dr. Isis Guibert.Interestingly, the clams with compromised health were characterised by a prominence of vibrio and therefore a distinct microbiome. "The relative proportion of Vibrionaceae could be used as an early indicator of clam health in natural populations." explains Dr.Véronique Berteaux-Lecellier, who supervised the study, "We hypothesise that A. cytherea could secrete metabolites that might have weakened the clams' defenses against Vibrio infection; future research should explore this possibility." The findings of this study suggest that the composition of the coral reef benthos, together with increasing water temperatures, could negatively impact the health of giant clams and potentially other reef organisms. Therefore, the findings support the idea that, like terrestrial conservation and restoration, taking account of the entire benthic assemblages should be the goal of marine conservation strategies.
|
Extinction
| 2,020 |
May 21, 2020
|
https://www.sciencedaily.com/releases/2020/05/200521084728.htm
|
'Heat resistant' coral developed to fight bleaching
|
The team included researchers from CSIRO, Australia's national science agency, the Australian Institute of Marine Science (AIMS) and the University of Melbourne.
|
Corals with increased heat tolerance have the potential to reduce the impact of reef bleaching from marine heat waves, which are becoming more common under climate change."Coral reefs are in decline worldwide," CSIRO Synthetic Biology Future Science Platform (SynBio FSP) science lead Dr Patrick Buerger said."Climate change has reduced coral cover, and surviving corals are under increasing pressure as water temperatures rise and the frequency and severity of coral bleaching events increase."The team made the coral more tolerant to temperature-induced bleaching by bolstering the heat tolerance of its microalgal symbionts -- tiny cells of algae that live inside the coral tissue."Our novel approach strengthens the heat resistance of coral by manipulating its microalgae, which is a key factor in the coral's heat tolerance," Dr Buerger said.The team isolated the microalgae from coral and cultured them in the specialist symbiont lab at AIMS. Using a technique called "directed evolution," they then exposed the cultured microalgae to increasingly warmer temperatures over a period of four years.This assisted them to adapt and survive hotter conditions."Once the microalgae were reintroduced into coral larvae, the newly established coral-algal symbiosis was more heat tolerant compared to the original one," Dr Buerger said.The microalgae were exposed to temperatures that are comparable to the ocean temperatures during current summer marine heat waves causing coral bleaching on the Great Barrier Reef.The researchers then unveiled some of the mechanisms responsible for the enhanced coral bleaching tolerance."We found that the heat tolerant microalgae are better at photosynthesis and improve the heat response of the coral animal," Professor Madeleine van Oppen, of AIMS and the University of Melbourne, said"These exciting findings show that the microalgae and the coral are in direct communication with each other. "The next step is to further test the algal strains in adult colonies across a range of coral species."This breakthrough provides a promising and novel tool to increase the heat tolerance of corals and is a great win for Australian science," SynBio FSP Director Associate Professor Claudia Vickers said.This research was conducted by CSIRO in partnership with AIMS and the University of Melbourne. It was funded by CSIRO, Paul G. Allen Family Foundation (U.S.A.), AIMS and the University of Melbourne.
|
Extinction
| 2,020 |
May 8, 2020
|
https://www.sciencedaily.com/releases/2020/05/200508184559.htm
|
Seahorse and pipefish study opens window to marine genetic diversity
|
The direction of ocean currents can determine the direction of gene flow in rafting species, but this depends on species traits that allow for rafting propensity. This is according to a City College of New York study focusing on seahorse and pipefish species. And it could explain how high genetic diversity can contribute to extinction in small populations.
|
Published in the British-based journal It reveals that ocean circulation driving macro-algal rafting is believed to serve as an important mode of dispersal for many marine organisms. This leads to predictions on population-level genetic connectivity and the directionality of effective dispersal.The CCNY Division of Sciences researchers used genome-wide single nucleotide polymorphism data to investigate whether gene flow directionality in two seahorses ("We inferred demographic histories of these co-distributed syngnathid species, and coalescent model-based estimates indicate that gene flow directionality is in agreement with ocean circulation data that predicts eastward and northward macro-algal transport," said Hickerson. "However, the magnitude to which ocean currents influence this pattern appears strongly dependent on the species-specific traits related to rafting propensity and habitat preferences."The study, he said, highlights how the combination of population genomic inference together with ocean circulation data can help explain patterns of population structure and diversity in marine ecosystems.
|
Extinction
| 2,020 |
May 5, 2020
|
https://www.sciencedaily.com/releases/2020/05/200505121655.htm
|
Recent Australian wildfires made worse by logging
|
Logging of native forests increases the risk and severity of fire and likely had a profound effect on the recent, catastrophic Australian bushfires, according to new research.
|
In the wake of the country's worst forest fires in recorded history, University of Queensland researchers have been part of an international collaboration, investigating Australia's historical and contemporary land-use.UQ Professor and Wildlife Conservation Society Director James Watson said logging regimes have made many forests more fire prone for a host of reasons."Logging causes a rise in fuel loads, increases potential drying of wet forests and causes a decrease in forest height," Professor Watson said."It can leave up to 450 tonnes of combustible fuel per hectare close to the ground -- by any measure, that's an incredibly dangerous level of combustible material in seasonally dry landscapes."By allowing these practices to increase fire severity and flammability, we undermine the safety of some of our rural communities."It affects wildlife too by creating habitat loss, fragmentation and disturbance for many species, with major negative effects on forest wildlife."Lead author, Australian National University's Professor David Lindenmayer, said there are land management actions we can take to stop these fires from occurring in the future."The first is to prevent logging of moist forests, particularly those close to urban areas," Professor Lindenmayer said."We must also reduce forest fragmentation by proactively restoring some previously logged forests."In the event of wildfires, land managers must avoid practices such as 'salvage' logging -- or logging of burnt forests -- which severely reduces recovery of a forest."The Federal Government has launched a Royal Commission to find ways to improve Australia's preparedness, resilience, and response to natural disasters.Researcher Michelle Ward, from UQ's School of Earth and Environmental Sciences, said it was time for government to act."We urge policy makers to recognise and account for the critical values of intact, undisturbed native forests, not only for the protection of biodiversity, but for human safety," Ms Ward said."Let's act strongly and swiftly for the sake of our communities, the species they house, our climate and Australia's wild heritage."
|
Extinction
| 2,020 |
May 1, 2020
|
https://www.sciencedaily.com/releases/2020/05/200501120058.htm
|
Stopping deforestation: Lessons from Colombia
|
A study of deforestation in Colombia by researchers from The University of Queensland has revealed some valuable insights which could be used to help slow deforestation in areas around the globe.
|
PhD student Pablo Negret led an effort to compare the effectiveness of protected areas in Colombia with otherwise similar non-protected sites between 2000 and 2015."In Colombia, there has been constant deforestation within protected areas during this 15-year period," Mr Negret said."This is mainly due to a lack of capacity to control illegal exploitation of resources in these areas."However, there was around 40 per cent less deforestation in protected areas when compared to similar areas without protection," Mr Negret said.Despite poorer outcomes in some areas, it was clear to the researchers that most protected areas slowed deforestation."We also looked at regional differences and found that protected areas in the Pacific were less effective than elsewhere," Mr Negret said."The Pacific region of Colombia is extremely biodiverse and globally important with a high concentration of endemic species, so ensuring these protected areas work is especially important."The team used forest cover information collected from satellites, with data covering 17 variables associated with deforestation, to compare both protected and non-protected areas that had similar environmental and social characteristics.In total, the researchers analysed the effectiveness of 116 protected areas, which represent 9.8 per cent of the country's continental area.UQ's Professor Martine Maron said the study showed how understanding the effectiveness of protected areas could be extremely useful in informing national and global conservation decisions."Protected areas can be less effective -- either because they still experience deforestation or because they're placed in locations where no deforestation would have occurred even if they weren't protected," Professor Maron said."Evaluating the impact protected areas make to deforestation can help with determining whether to invest in improved management in existing protected areas or increase their coverage in strategic locations -- or both."We hope that these insights can be taken into account in Colombia and around the globe."A similar approach can help any country or region effectively assess the performance of their protected areas at preventing ecosystem loss."
|
Extinction
| 2,020 |
April 24, 2020
|
https://www.sciencedaily.com/releases/2020/04/200424081654.htm
|
Warming climate undoes decades of knowledge of marine protected areas
|
Climate change and warming seas are transforming tropical coral reefs and undoing decades of knowledge about how to protect these delicate and vital ecosystems.
|
Many of the world's coral reefs are seeing biodiversity plunge in the face of repeated coral bleaching events.Protected areas, called marine reserves, are an effective and long-established tool in the conservation toolbox. Marine reserves have been used for decades to enhance biodiversity and fish biomass by preventing damage and over-exploitation by fishing.However, a new study highlights that tropical coral reef marine reserves can offer little defence in the face of climate change impacts. And the changes that are being observed will force scientists, conservationists and reserve managers to rethink the role these protected areas can bring."Climate change is so fundamentally changing the structure and composition of coral reef ecosystems, that the way the ecosystem functions and responds to common management and conservation approaches needs to be carefully re-evaluated," explains Professor Nick Graham of Lancaster University and lead author of the study. "The rules we have come to rely on, no longer apply."Bleaching occurs when seas become too warm, causing corals to expel their colourful algae. This disrupts the ecosystem and reduces the availability of food and shelter for many fish species.Some coral reefs are able to recover over time, while others are transformed and become dominated by seaweed.The new study, published in the journal Professor Graham explains: "Our long-term records of Seychelles' coral reefs show that before the bleaching event marine reserves contained high coral cover, a very biodiverse range of fish, and high biomass of carnivorous and herbivorous fish."Following the bleaching event, the role of the marine reserves changed substantially. They no longer supported higher coral cover compared to adjacent fished areas, and their role in enhancing biodiversity decreased. Plant-loving fish, such as rabbitfish and parrotfish, dominated fish communities. This was the case for reefs where corals were recovering, as well as reefs transformed and dominated by seaweed."Reduced numbers of carnivorous predators, such as grouper and snapper species, show reserves are much less effective at protecting the tops of food webs in the years following bleaching events. These population drops are likely due to fewer fish for them to prey on after the loss of coral reef structures.Dr Shaun Wilson, of the Department of Biodiversity, Conservation and Attractions in Western Australia, a co-author on the study, said: "Despite these climate-driven transformations, marine protected areas still have a role to play in ocean conservation. It is encouraging that marine reserves continue to protect some species, especially when these species are critical for local fisheries."Gilberte Gendron of the Seychelles National Parks Authority, adds: "Although these reordered marine reserves are less biodiverse, they are still important to maintain. This is because, when compared to openly fished areas, they still protect higher levels of fish biomass of species that are important to our local fisheries. For example, the protected herbivorous fish can spill out into openly fished areas and help support adjacent fisheries."If the goal is to protect biodiversity then it may be better to target new marine reserves around those coral reefs where the rate of warming is slowest, or those where recovery from bleaching is more likely.While the scientists say marine reserves still have an important role to play in protecting fish biomass, they call in their paper for urgent reductions in global greenhouse gas emissions, as well as other pressures such as poor land practices that input nutrients and pollutants to coastal waters, to protect tropical coral reefs.
|
Extinction
| 2,020 |
April 23, 2020
|
https://www.sciencedaily.com/releases/2020/04/200423143102.htm
|
Iron deficiency in corals?
|
When iron is limited, the tiny algae that live within coral cells -- which can provide the majority of a coral's nutritional needs -- change how they take in other trace metals, which could have cascading effects on vital biological functions. A new study in the journal
|
"Iron deficiency is not just a problem for humans, but for other organisms as well," said Hannah Reich, a graduate student in biology at Penn State at the time of the research and author of the study. "Most organisms require a certain amount of iron and other trace metals to fulfill their basic physiological needs. Because warming ocean temperatures could alter iron availability, we wanted to know how microalgae in the family Symbiodiniaceae, which commonly live within coral cells, respond to limed amounts of iron to begin to understand how they might respond to a changing climate."These microalgae maintain a symbiotic relationship with corals, producing energy from photosynthesis and providing up to 90 percent of the coral's daily nutritional needs. The changing climate can affect both the coral and the microalgae, and corals under stress due to warming waters often expel their symbionts in a process known as bleaching.The researchers found that all five species of the microalgae they investigated grow poorly in cultures when iron was absent, and four of the species grew poorly when iron was present in very low concentrations. This is unsurprising, given the essential role of trace metals in basic physiologic functions like cellular respiration and photosynthesis. The researchers suggest that the fifth species may have less stringent iron requirements, which may help explain why it persists in some corals that are bleached or diseased.The researchers also found that, when iron was limited, the microalgae acquired other trace metals in different quantities, in a way that was unique to each species. For example, one species had much greater uptake of manganese, while another had greater copper uptake."We believe these differences reflect the broad physiologies and ecologies of the species we investigated," said Todd LaJeunesse, professor of biology at Penn State and an author of the paper. "We found that species with similar ecological niches -- either found in similar habitats or with shared ecological abilities -- had similar metal profiles. If the microalgae are using trace metals in different amounts or in different ways, limitation of iron could have cascading effects on vital functions, like photosynthesis and whether they are able to take in other nutrients for survival."Because changing temperature can affect iron availability, the researchers suggest that changing availability of iron due to warming waters could exacerbate the effects of thermal stress on corals. Next, the researchers plan to investigate how iron limitation and warm temperatures combine to impact the health of these microalgae."Our findings provide a foundation for understanding how iron availability affects cellular processes in Symbiodiniaceae and reveal that iron limitation, through its effects on the microalgae's growth and other trace metal usage, could exacerbate the effects of climate change on corals," said Reich.
|
Extinction
| 2,020 |
April 23, 2020
|
https://www.sciencedaily.com/releases/2020/04/200423143046.htm
|
Ocean biodiversity has not increased substantially for hundreds of millions of years, study finds
|
A new way of looking at marine evolution over the past 540 million years has shown that levels of biodiversity in our oceans have remained fairly constant, rather than increasing continuously over the last 200 million years, as scientists previously thought.
|
A team led by researchers from the School of Geography, Earth and Environmental Sciences at the University of Birmingham have used a big data approach to study this question, which has been disputed by palaeobiologists in recent years.Using fossil data collected over the past two centuries, and compiled by hundreds of researchers in the Paleobiology Database over the last 20 years, the team was able to show regional-scale patterns of diversity across geological time from the so-called Cambrian Explosion -- the point at which most major groups of animals started to appear in the fossil record -- to the present day. Their results are published today in Dr Roger Close, who led the research, explains: "Studies of marine animal diversity over the last five-hundred-odd million years have historically focussed on estimating how "global" diversity changed through time. The problem is that the fossil record is not really global, because both the amount and the parts of the world that are actually preserved in the fossil record changes so much through geological time. This means that so-called "global" diversity curves are misleading.""To get around this problem, we studied diversity at regional spatial scales. This meant that we could focus on places and times that are well-known in the fossil record. By comparing geographic regions that were similar in size, we could show how marine animal diversity varied across both time and space."Using these estimates for specific geographic regions, the team was also able to estimate the influence of other environmental factors, such as coral reef systems. At this more localised level, it's possible to see significant variations in diversity across the globe within time intervals, perhaps in response to environmental differences."We think of reefs today as being hotspots of diversity, responsible for housing a disproportionate amount of animal species," says Dr Close. "So in areas where there are a higher proportion of reefs, diversity will inevitably be higher.""Importantly, though we don't find any evidence that diversity increased in a continuous, sustained way through long intervals of geological time. This is a major departure from previous studies of "global" diversity. These studies concluded that marine animal biodiversity had increased steadily over the last 200 million years, culminating in modern levels that were greater than any point in Earth's history. In contrast, our work suggests that modern levels of biodiversity -- at least at the regional scales we studied -- are not exceptional."Interestingly, the researchers did observe one point in the fossil record where there was a step change in diversity. The team found this evidence at the end of the Cretaceous period, when the dinosaurs became extinct."Not long after this devastating mass extinction, we see a distinct shift towards greater regional diversity. This probably had something to do with ecological reorganisation after many species were wiped out. In particular, we see a rebound to much higher diversity among gastropods -- a huge group of invertebrates that we would recognise as snails and slugs. This suggests that such a widespread species loss cleared space for other groups to explode -- and gastropods were able to take advantage of this," says Dr Close."When you look at these individual animal groups, you can see fluctuations in diversity that are often substantial. But taken together, these patterns sum to one of constrained diversity. Some groups might benefit from the misfortune of others, but the overall levels of diversity that we see have remained fairly stable for hundreds of millions of years."This research was funded by the European Research Council via a Horizon 2020 grant, and was completed in collaboration with the University of Oxford and the University of California Santa Cruz.
|
Extinction
| 2,020 |
April 23, 2020
|
https://www.sciencedaily.com/releases/2020/04/200423130506.htm
|
How birds evolved big brains
|
An international team of evolutionary biologists and paleontologists have reconstructed the evolution of the avian brain using a massive dataset of brain volumes from dinosaurs, extinct birds like
|
The study, published online today in the journal "One of the big surprises was that selection for small body size turns out to be a major factor in the evolution of large-brained birds," says Dr. Daniel Ksepka, Curator of Science at the Bruce Museum and lead author of the study. "Many successful bird families evolved proportionally large brains by shrinking down to smaller body sizes while their brain sizes stayed close to those of their larger-bodied ancestors."In order to understand how bird brains changed, a team of 37 scientists used CT scan data to create endocasts (models of the brain based on the shape of the skull cavity) of hundreds of birds and dinosaurs, which they combined with a large existing database of brain measurements from modern birds. They then analyzed brain-body allometry: the way brain size scales with body size."There is no clear line between the brains of advanced dinosaurs and primitive birds," notes co-author Dr. Amy Balanoff of Johns Hopkins University. "Birds like emus and pigeons have the same brains sizes you would expect for a theropod dinosaur of the same body size, and in fact some species like moa have smaller-than-expected brains."The two groups of birds with truly exceptional brain sizes evolved relatively recently: parrots and corvids (crows, ravens, and kin). These birds show tremendous cognitive capacity, including the ability to use tools and language, and to remember human faces. The new study finds that parrots and crows exhibited very high rates of brain evolution that may have helped them achieve such high proportional brain sizes."Several groups of birds show above average rates of brain and body size evolution," remarks co-author Dr. N. Adam Smith of the Campbell Geology Museum at Clemson University. "But crows are really off the charts -- they outpaced all other birds. Our results suggest that calling someone 'bird-brained' is actually quite a compliment!""Crows are the hominins of the bird kingdom," says co-author Dr. Jeroen Smaers of Stony Brook University. "Like our own ancestors, they evolved proportionally massive brains by increasing both their body size and brain size at the same time, with the brain size increase happening even more rapidly."
|
Extinction
| 2,020 |
April 23, 2020
|
https://www.sciencedaily.com/releases/2020/04/200423130424.htm
|
Giant teenage shark from the dinosaur era
|
In 1996, palaeontologists found skeletal remains of a giant shark at the northern coast of Spain, near the city Santander. Here, the coast comprises meter high limestone walls that were deposited during the Cretaceous period, around 85 million years ago, when dinosaurs still roamed the world. Scientists from the University of Vienna examined this material now and were able to assign the remains to the extinct shark family, Ptychodontidae, a group that was very specious and successful in the Cretaceous but suddenly vanished mysteriously before the infamous end-Cretaceous extinction event.
|
Ptychodontid sharks are mainly known from their teeth, which are flattened and allowed them to crush hard-shelled prey, like bivalves or ammonites, similar to some of today's ray species. However, the find of Spain consists only of parts of the vertebral column and placoid scales (teeth-like scales), which are much rarer than teeth in the fossil record.In contrast to teeth, shark vertebrae bear important information about a species' life history, such as size, growth and age, which are saved as growth rings inside the vertebra, like in the stem of trees. Statistical methods and the comparison with extant species, allowed the scientists to decode these data and reconstruct the ecology of this enigmatic shark group."Based on the model, we calculated a size of 4-7m and an age of 30 years for the examined shark. Astonishing about this data is the fact that this shark was not yet mature when it died despite its rather old age." states Patrick L. Jambura, lead author of the study. Sharks follow an asymptotic growth curve, meaning that they grow constantly until maturation and after that, the growth curve flattens resulting from a reduced growth rate. "However, this shark doesn't show any signs of flattenings or inflections in the growth profile, meaning that it was not mature, a teenager if you want. This suggests that these sharks even grew much larger (and older)!"The study suggests that ptychodontid sharks grew very slow, matured very late, but also showed high longevity and reached enormous body sizes. "This might have been a main contributor to their success, but also, eventually, demise."Many living sharks, like the whale shark or the great white shark, show very similar life history traits, a combination of low recruitment and late maturation, which makes them vulnerable to anthropogenic threats, like overfishing and pollution."It might be the case that similar to today's sharks, ptychodontid sharks faced changes in their environment, to which they could not adapt quick enough and, ultimately, led to their demise before even dinosaurs went extinct. However, unlike in the Cretaceous period, it is up to us now, to prevent this from happening to modern sharks again and to save the last survivors of this ancient and charismatic group of fishes!"
|
Extinction
| 2,020 |
April 22, 2020
|
https://www.sciencedaily.com/releases/2020/04/200422214047.htm
|
Caribbean coral reef decline began in 1950s and 1960s from local human activities
|
Not long ago, the azure waters of the Caribbean contained healthy and pristine coral reef environments dominated by the reef-building corals that provide home to one-third of the biodiversity in the region.
|
But the Caribbean reefs of today pale in comparison to those that existed even just a generation ago. Since researchers began intensively studying these reefs in the 1970s, about one half of Caribbean corals have died. The iconic elkhorn and staghorn corals that once dominated Caribbean reefs have been hardest hit, with only 20% of their populations remaining today.Although researchers believe climate change, fishing and pollution are to blame, the lack of baseline data prior to the 1970s has made it hard to determine the precise reasons for these coral die offs. ASU researcher Katie Cramer wanted to document when corals first began dying to better understand the root causes of coral loss.Now, in a new paper in "I am interested in going back to the scene of the crime when humans first began to significantly impact coral reefs centuries ago, to understand when, why and how much reefs have been altered by humans," said Katie Cramer, an assistant research professor at the Julie Ann Wrigley Global Institute of Sustainability at Arizona State University and an Ocean Science Fellow at the Center for Oceans at Conservation International.The earlier, local roots of declines of elkhorn and staghorn corals in the 1950s and 1960s highlight the urgency of mitigating local human impacts on reefs to allow these corals to recover. "In an era where coral reefs are being hit with multiple human stressors at the same time, we need to resolve why and how much coral reefs have changed over human history to inform our responses to the current reef crisis.""Recent studies are showing that reefs are better able to cope with climate change impacts when they are not also stressed from overfishing and land-based runoff. So let's get a handle on these tractable problems now to give reefs a better chance of weathering the current climate crisis," said Cramer.
|
Extinction
| 2,020 |
April 22, 2020
|
https://www.sciencedaily.com/releases/2020/04/200422112258.htm
|
Online tool helps to protect tropical forests
|
A new tool maps the threats to the tropical dry forests in Peru and Ecuador. Bioscience engineers at KU Leuven combined data on possible threats to these forests -- including fires and overgrazing -- with data on the vulnerability of local tree species to these dangers, which the team estimated on the basis of species traits such as bark thickness and edibility of the leaves. The result is an online tool that local governments and NGOs can use to restore and conserve forests.
|
The tropical dry forests in Peru and Ecuador are under considerable strain due to fires, overgrazing, and overexploitation, among other things. And then there's climate change as well. In collaboration with the international research institution Bioversity International, researchers from the Division of Forest, Nature and Landscape at KU Leuven developed a model that advises local governments and NGOs on how to restore and conserve these forests.What makes the KU Leuven model unique is the combination of the threats that a forest is exposed to with the traits of local tree species. "Due to this combination of factors, our model provides an accurate representation of the resilience of a forest and its tree species," says doctoral student Tobias Fremout (KU Leuven), who is the lead author of this study. "A forest that mostly consists of trees with edible or 'palatable' leaves will be much more sensitive to overgrazing, for instance. Trees that are very useful for firewood, by contrast, are much more likely to suffer from overexploitation."The possible threats to a forest were divided into five categories: fire, habitat conversion, overexploitation, overgrazing, and climate change. These categories, in turn, were combined with several traits of tree species, including bark thickness, usability as firewood or timber, and growth rates.Tobias Fremout was able to map more than 40,000 kmIt was a very deliberate decision to make the tool available to local governments. "The online tool is freely accessible on the Internet. Local governments can consult it to check for each tree species where it is most at risk due to which specific threat," Tobias Fremout explains. This allows local governments to engage with the conservation and restoration of their forests in a very deliberate way. "The Peruvian authorities are aware of the enormous strain their forests are under, but their restoration efforts are sometimes still ill-considered. Via our tool, the authorities can see which species they should replant where, but especially also from which risks they should protect that specific area. After all, it's hardly useful to replant trees with edible leaves without also providing a fence to keep away cows and goats."Replanting often seems to be the most logical choice. Due to climate change, however, it may not always be the smartest option. "We have used five climate models to predict whether, in the future, the regions under consideration will still offer the right circumstances for the tree species that are currently found there. If certain species are likely to get difficulties in particular areas, it's a better idea to replant these species elsewhere or to store seeds in a seed bank," Tobias Fremout continues.As the model developed by Tobias Fremout and his colleagues uses existing data on threats to tree species and traits, the model can also be translated to tropical forests in regions such as Africa or Asia. "To map the risk of forest fires, for instance, we used NASA observations. This information is available for the entire world and can, therefore, also be used for Cameroon or Indonesia, for instance. The characteristics of African and Asian trees are known and can be used in our model."
|
Extinction
| 2,020 |
April 20, 2020
|
https://www.sciencedaily.com/releases/2020/04/200420084257.htm
|
Rising carbon dioxide levels will change marine habitats and fish communities
|
Rising carbon dioxide in the atmosphere and the consequent changes created through ocean acidification will cause severe ecosystem effects, impacting reef-forming habitats and the associated fish, according to new research.
|
Using submerged natural COWriting in In such conditions, species such as complex corals and canopy-forming macroalgae mostly disappeared. This shift from complex reefs to habitats dominated by opportunistic low-profile algae led to a 45% decrease of fish diversity, with a loss of coral-associated species and a rearrangement of feeding behaviour.Lead author Dr Carlo Cattano, from the University of Palermo, said: "Our findings show that the CO"Submerged volcanic degassing systems may provide realistic insights into future ocean conditions," added Dr Sylvain Agostini, from Shimoda Marine Research Center. "Studying organism and ecosystem responses off submerged COIn addition to the new findings, the study also reinforces previous research which has demonstrated the ecological effects of habitat changes due to ongoing ocean acidification.This has shown that decreased seawater pH may impair calcification and accelerate dissolution for many calcifying habitat-formers, while rising COAs a result, there will be losers and winners under increasingly acidified conditions, and fish species that rely on specific resources during their different life stages could disappear. This would lead to the composition of fish communities changing in the near future with potential severe consequences for marine ecosystem functioning and the goods and services they provide to humans.Jason Hall-Spencer, Professor of Marine Biology at the University of Plymouth, said: "Our work at underwater volcanic seeps shows that coastal fish are strongly affected by ocean acidification, with far fewer varieties of fish able to cope with the effects of carbon dioxide in the water. This underlines the importance of reducing greenhouse gas emissions to safeguard ocean resources for the future."
|
Extinction
| 2,020 |
April 20, 2020
|
https://www.sciencedaily.com/releases/2020/04/200420084251.htm
|
Rare South American ground beetles sport unusual, likely multi-purpose antennal cleaners
|
For 157 years, scientists have wished they could understand the evolutionary relationships of a curious South American ground beetle that was missing a distinctive feature of the huge family of ground beetles (Carabidae). Could it be that this rare species was indeed lacking a characteristic trait known in over 40,000 species worldwide and how could that be? Was that species assigned to the wrong family from the very beginning?
|
The species, No mention of the structure was made in the original description of the species, so, at one point, scientists even started to wonder whether the beetle they were looking at was in fact a carabid at all.Because the area where Fry's strange-combed beetle had been found was once Southern Atlantic Forest, but today is mostly sugar cane fields, cacao plantations, and cattle ranches, scientists have feared that additional specimens of strange-combed beetles might never be collected again and that the group was already extinct. Recently, however, a US team of entomologists have reported the discovery of a second specimen, one also representing a second species of strange-combed beetles new to science.Following a careful study of this second, poorly preserved specimen, collected in French Guiana in 2014, the team of Dr Terry Erwin (Smithsonian Institution), Dr David Kavanaugh () and Dr David Maddison (Oregon State University) described the species, Nototylus balli, or Ball's strange-combed beetle, in a paper that they published in the open-access scholarly journal Despite its poor, yet relatively better condition, the new specimen shows that probable antennal grooming organs are indeed present in strange-combed beetles. However, they looked nothing like those seen in other genera of ground beetles and they are located on a different part of the front legs. Rather than stout and barely movable, the setae (hair-like structures) in the grooming organs of strange-combed beetles are slender, flexible and very differently shaped, which led the researchers to suggest that the structure had a different role in strange-combed beetles.Judging from the shapes of the setae in the grooming organs, the scientists point out that they are best suited for painting or coating the antennae, rather than scraping or cleaning them. Their hypothesis is that these rare carabids use these grooming structures to cohabitate with ants or termites, where they use them to apply specific substances to their antennae, so that the host colony recognises them as a friendly species, a kind of behaviour already known in some beetles.However, the mystery around the strange-combed beetle remains, as the scientists found no evidence of special secretory structures in the specimen studied. It turns out that the only way to test their hypothesis, as well as to better understand the evolutionary relationships of these beetles with other carabids is finding and observing additional, preferably live, specimens in their natural habitat. Fortunately, this new discovery shows that the continued search for these beetles may yield good results because strange-combed beetles are not extinct.
|
Extinction
| 2,020 |
April 16, 2020
|
https://www.sciencedaily.com/releases/2020/04/200416151647.htm
|
Can coral reefs 'have it all'?
|
Though coral reefs are in sharp decline across the world, scientists say some reefs can still thrive with plentiful fish stocks, high fish biodiversity, and well-preserved ecosystem functions.
|
An international team, led by Professor Josh Cinner from the ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral CoE at JCU), assessed around 1,800 tropical reefs from 41 countries across the globe."Only five percent of the reefs were simultaneously able to meet the combined goals of providing enough fishing stocks, maintaining biodiversity and a working ecosystem," Prof Cinner said."These are like the Hollywood A-listers of coral reefs. They have it all, but they're also rare and live in exclusive areas -- remote locations with little human pressure. Our study shows how to help other coral reefs get on that A-list."The research team assessed if no-fishing marine reserves and other fisheries restrictions helped reefs to meet multiple goals. The study found that implementing such local efforts helped, "but only if the management efforts are in the right locations," Prof Cinner said."It's all about location, location, location," he said. "Marine reserves placed in areas with low human pressures had the best results for helping reefs get on the A-list.""We also had a B-list of reefs, which met all the goals, but to a lesser degree. Reserves in areas with intermediate human pressure made the biggest difference to getting reefs on our B-list. Quite simply, they occurred in less exclusive locations than our A-listers."However, marine reserves made little difference in areas where the environment was so severely degraded that only wider seascape conservation could help.Co-author Jessica Zamborain-Mason, a Coral CoE and JCU PhD candidate, says coral reefs worldwide are facing intense degradation due to numerous anthropogenic drivers, such as overfishing, pollution, and climate change."There is an increasing need to manage coral reefs to meet multiple goals simultaneously," she said."Our findings provide guidance on where to strategically place local management to achieve the greatest benefits."Co-author Professor Nick Graham from Lancaster University says the study uses data to show what works."Coral reef science and management is often focussed on meeting just a single goal," Prof Graham said."Managing for just one goal at a time is common, but what if you want it all? The multiple goals of biodiversity, fisheries and functioning ecosystems are often required at any given location, yet the science to understand when and how this can be achieved has been lacking.""We looked at the fish communities, not the coral communities, and these are affected by different drivers -- overfishing really drives the former and climate change the latter.""The study not only has important implications for the placement of new marine reserves, but is also relevant to future socioeconomic changes, such as how infrastructure development and population growth may impact the efficacy of reef conservation," Prof Cinner said."We show where managers will be able to maximise multiple goals, and likewise, where they will be wasting their time."The study concludes that, while international action on climate change is crucial for ensuring a future for coral-dominated reefs, effective management is also critical to sustaining reefs -- and the millions of people whose livelihoods depend on them.
|
Extinction
| 2,020 |
April 16, 2020
|
https://www.sciencedaily.com/releases/2020/04/200416072633.htm
|
Parasite carried by grey squirrels negatively impacts red squirrel behavior
|
Research published in the
|
An international team from universities in Italy and Belgium used a natural experiment of populations of native red squirrels (By comparing repeated measurements of red squirrel parasite infection and personality with those taken in sites where only the native species occurred, they demonstrated that infection by the alien parasite causes a significant reduction in red squirrels' activity and alters their relationship with native parasites.Red squirrels normally carry only one species of gastro-intestinal helminth (In their study, Dr. Francesca Santicchia and her co-authors found negative correlations between activity of red squirrels and infection with the alien parasite S. robustus in the sites invaded by grey squirrels. Activity was also negatively correlated with infection by its native helminth (Their findings, which show that parasite-mediated competition is energetically costly and can also alter the "normal" relationships between native host and native parasite, are published today in the "That our red squirrel is threatened with extinction due to the introduction of an 'alien' species, the North American grey squirrel, has become common knowledge," say Dr. Francesca Santicchia and Dr. Lucas Wauters of the Guido Tosi Research Group at the University of Insubria in Italy. "But that one of the mechanisms involved is the reduction of activity, a personality trait that tends to be related to foraging intensity or efficiency, caused by the spillover of a parasitic helminth from grey squirrels is a new finding.""This spillover is very similar to what occurs with the Squirrel Poxvirus in the UK and Ireland," add Dr. Claudia Romeo and Dr. Nicola Ferrari from the University of Milano, "although in this case of spillover of an endoparasite, the effect is much more subtle and does not lead directly to the death of the animal""For red squirrels, the 'natural' situation is being the only diurnal tree-dwelling mammal in our forests and woodlands," explain Dr. Lucas Wauters and Prof. Adriano Martinoli, also with the University of Insubria. "But when an alien species, such as the grey squirrel, colonizes these habitats, it acts as a true environmental stressor and carrier of potentially dangerous parasites."In this study, the researchers produced compelling evidence that indicate that spillover of the alien helminth to naive red squirrels causes not only a reduction in activity, a behaviour that requires high energy expenditure, but also alters the relationships between red squirrels and their native, common helminth, "This is a subtle form of parasite-mediated competition, which may exacerbate the effects of interspecific competition with grey squirrels for food, such as conifer seeds, hazelnuts, or chestnuts," underline Wauters and Romeo.In fact, reduced activity could result in lower food intake and together with chronically increased concentrations of glucocorticoids can produce a reduction in body growth or reproductive success, or even decrease survival, among the red squirrels that are forced to share their habitat with the invaders. The combination of these interacting ecological and physiological processes will lead to the extinction of the red squirrel population in few years' time.
|
Extinction
| 2,020 |
April 15, 2020
|
https://www.sciencedaily.com/releases/2020/04/200415133648.htm
|
Researchers challenge accuracy of methods that analyze trees of life
|
When species under a taxonomic umbrella have faced forks in the road, leading to extinction or adaptation, the path taken has been difficult to follow. In a newly published paper, two scientists argue that long-used approaches for reconstructing these paths are deeply flawed.
|
While paleontological evidence provides insights on how and why patterns of biodiversity have changed over geological time, fossil finds for many types of organisms are too scant to say anything, said University of Oregon biologist Stilianos Louca, lead author of a paper placed online April 15 ahead of print in the journal An alternative approach, he noted, relies on using identifiable changes in an organism's genetic makeup, but the signal in this type of data can be misleading."Our finding casts serious doubts over literally thousands of studies that use phylogenetic trees of extant data to reconstruct the diversification history of taxa, especially for those taxa where fossils are rare, or that found correlations between environmental factors such as changing global temperatures and species extinction rates," said Louca, who is a member of the UO's Institute of Ecology and Evolution.In their paper, Louca and Matthew W. Pennell, an evolutionary biologist at the University of British Columbia in Vancouver, also offer a way forward -- a mathematical model that introduces alternative variables to characterize long-term evolutionary scenarios that can be accurately identified from phylogenetic data."I have been working with these traditional types of models for a decade now," Pennell said. "I am one of the lead developers of a popular software package for estimating diversification rates from phylogenetic trees. And, as such, I thought I had a really good sense of how these models worked. I was wrong."In their paper, the researchers note that long-used methods extract information about evolution from still-living organisms, using variants of a mathematical birth-death process. These, however, cannot possibly extract information about both speciation and extinction rates, especially for a majority of taxa, such as bacteria, that have left no fossil record.The paleontological approach estimates the number of species that have appeared and disappeared in various intervals based on discovered fossils and their estimated minimum and maximum ages. In the phylogenetic approach, information is extracted from evolutionary relationships between existing species, using mostly genetic data, and structured in phylogenetic trees known as timetrees.This is often done by finding a speciation/extinction scenario that would have been the most likely to generate a given phylogenetic tree."While an impressive suite of computational methods has been developed over the past decades for extracting whatever information is left, until now we lacked a good understanding of exactly what information is left in these trees, and what information is forever lost," Louca said.Louca and Pennell's mathematically driven approach clarifies precisely what information can be extracted from extant timetrees under the generalized birth-death model. The researchers introduce new identifiable and easily interpretable variables that contain all available information about past diversification dynamics and how they can be estimated."We suggest that measuring and modeling these identifiable variables offers a more robust way to study historical diversification dynamics," they write in the paper. "Our findings also make clear that paleontological data will continue to be crucial for answering some macroevolutionary questions.""The future depends on synthesizing information from datasets of both molecules and fossils," Pennell said.The researchers emphasize that their results do not invalidate the theory of evolution itself, they just put constraints on what type of information can possibly be extracted from genetic data to reconstruct evolution's path.
|
Extinction
| 2,020 |
April 15, 2020
|
https://www.sciencedaily.com/releases/2020/04/200415133449.htm
|
Study unlocks the secret of corals' tolerance to climate change: Their diet
|
Researchers at School of Biological Sciences and Swire Institute of Marine Science, The University of Hong Kong have developed a new method for determining what corals eat, and demonstrated that reliance on certain nutritional sources underpins their bleaching susceptibility in warming oceans.
|
The research, published in the prestigious journal "We knew that polyp size is a factor that affects the surface area to volume ratio of a coral, a trait that other scientists have observed might be linked to delayed bleaching in the field. We decided to run a warming experiment with our Hong Kong corals to see if their diet accurately predicted how long they could withstand elevated temperatures without bleaching - and it did." explains Dr Conti-Jerpe.These results have implications for how coral reefs will change as climate change progresses. Corals dependent on photosynthesis bleach faster while predatory corals can withstand warming temperatures longer. "The results of our study help predict which coral species are more likely to survive as oceans warm. Unfortunately, what we found is that the most susceptible species are those that are commonly used in coral reef restoration efforts. To ensure the long-term success of reef rehabilitation, restoration initiatives should shift their focus to bleaching-resistant species." said Dr David Baker, Associate Professor of School of Biological Sciences and Swire Institute of Marine Science who supervised the study.While predatory nutrition can confer protection from bleaching, the scientists note that given sustained elevated temperatures, all the species in the study eventually bleached. "Capturing a lot of food doesn't save corals from bleaching," explains Dr Conti-Jerpe, "it just buys them a little more time - time that they desperately need." The findings of this study will help scientists, conservationists and policy makers anticipate which corals will disappear first and how this will change reef ecosystems overall, including the services they provide.Stable isotope data are an established tool for investigating diet - they are derived from measuring the different forms of common elements, such as carbon and nitrogen that have the same function biologically but differ ever so slightly in mass. For instance, nitrogen - an essential building block for DNA and protein - comes in a common 'light' isotope (14N) and a rare 'heavy' isotope (15N). When it comes to diet, animals accumulate 15N if they are sitting higher on the food chain - a carnivore will have more 15N than an herbivore. The corals in this study that had stable isotope values different from that of their algae had more 15N and thus must be more predatory.
|
Extinction
| 2,020 |
April 14, 2020
|
https://www.sciencedaily.com/releases/2020/04/200414125752.htm
|
Volcanic carbon dioxide emissions helped trigger Triassic climate change
|
A new study finds volcanic activity played a direct role in triggering extreme climate change at the end of the Triassic period 201 million year ago, wiping out almost half of all existing species. The amount of carbon dioxide released into the atmosphere from these volcanic eruptions is comparable to the amount of CO
|
The end-Triassic extinction has long been thought to have been caused by dramatic climate change and rising sea levels. While there was large-scale volcanic activity at the time, known as the Central Atlantic Magmatic Province eruptions, the role it played in directly contributing to the extinction event is debated. In a study for The researchers suggest that the end-Triassic environmental changes driven by volcanic carbon dioxide emissions may have been similar to those predicted for the near future. By analysing tiny gas exsolution bubbles preserved within the rocks, the team estimates that the amount of carbon emissions released in a single eruption -- comparable to 100,000 km3 of lava spewed over 500 years -- is likely equivalent to the total produced by all human activity during the 21st century, assuming a 2C rise in global temperature above pre-industrial levels."Although we cannot precisely determine the total amount of carbon dioxide released into the atmosphere when these volcanoes erupted, the correlation between this natural injection of carbon dioxide and the end-Triassic extinction should be a warning to us. Even a slight possibility that the carbon dioxide we are now putting into the atmosphere could cause a major extinction event is enough to make me worried," says professor of earth and planetary sciences Don Baker.
|
Extinction
| 2,020 |
April 1, 2020
|
https://www.sciencedaily.com/releases/2020/04/200401130842.htm
|
Fish have diverse, distinct gut microbiomes
|
The rich biodiversity of coral reefs even extends to microbial communities within fish, according to new research. The study in
|
"If you go snorkeling on a coral reef, you would never know about this incredible ecosystem feature because microbial communities are concealed to the naked eye," said Douglas Rasher, a senior research scientist at Bigelow Laboratory for Ocean Sciences and the senior author of the paper. "But the microbiome appears to be a defining feature of each herbivorous fish species, as unique as its size or feeding behavior."Rasher and collaborators from the Smithsonian Tropical Research Institute, the University of California Santa Barbara, and Florida International University documented the feeding behaviors of five common Caribbean fish species and found that they markedly differ in what they eat and where they feed on the reef. Using advanced genetic sequencing and computing techniques, the researchers identified the microbes collected from within each fish's gut -- and discovered that each herbivore species harbors a unique gut microbiome.The team found that some members of the gut microbiome probably live broadly throughout the ocean, while others appear to be resident microbes that may have symbiotic relationships with the fish. These "symbionts" need an animal host to live in -- and though some thrived in multiple fish species, the researchers found that they often were unique to just one."It's well known that each herbivorous fish species you see grazing on the reef eats different things and plays a unique role in the ecosystem," Rasher said. "However, differences between these fish species are equally striking when you look at their respective gut microbiomes, so it really makes you wonder how much symbiotic microbes influence the way that these fish feed."Grazing fish keep coral reefs free of harmful algae, and the scientists' previous research showed that a diverse portfolio of fish is needed to carry out this process. Though thousands of different microbes may thrive inside a fish's gut at once, the researchers found that only 59 total types of microbes dominated the guts of the five fish species they studied.Although the likely symbionts that the scientists discovered had never been identified before, genetic testing revealed that their closest known relatives are microbes living in the intestines of other reef fish. The team mapped the genetic relationships among these microbes, offering a new perspective on the relatedness of fish and their ecology around the globe."Our symbionts were remarkably similar to microbes found within the guts of related fishes in other, distant oceans," said Jarrod Scott, a postdoctoral researcher at the Smithsonian Tropical Research Institute and the lead author of the paper. "Such a finding indicates that herbivorous fishes that are separated by millions of years of evolution and thousands of kilometers nonetheless harbor similar microbes."Just like humans and other land animals, fish digest their food with help from microbes living in their guts, which help to capture energy and nutrients and even break down plant toxins. This study suggests that fish microbiomes may also be ecologically and evolutionarily important on a global scale.Scott, Rasher, and their collaborators hope to build upon their work by revealing the functions of symbionts in the gut, and how specific microbes aid their fish hosts. The other authors of this paper include Research Scientist Tom Adam and Professor Deron Burkepile from University of California Santa Barbara, and Affiliate Researcher Alain Duran from Florida International University."Our study is an exciting advance that sets the stage for future research in this area," Rasher said. "Treating microbiomes as a fundamental characteristic of fish can help us understand how the ocean functions and the hidden roles of microbes in nature."
|
Extinction
| 2,020 |
March 30, 2020
|
https://www.sciencedaily.com/releases/2020/03/200330181648.htm
|
Water pressure: Ancient aquatic crocs evolved, enlarged to avoid freezing
|
Taking the evolutionary plunge into water and abandoning land for good, as some crocodilian ancestors did nearly 200 million years ago, is often framed as choosing freedom: from gravity, from territorial boundaries, from dietary constraints.
|
Water might inflict more pressure in the pounds-per-square-inch sense, the thinking went, but it also probably relieved some -- especially the sort that kept crocs from going up a size or 10. If they wanted to enjoy the considerable spoils of considerable size, water seemed the easy way.A recent study from the University of Nebraska-Lincoln's Will Gearty, who compiled a database of 264 species stretching back to the Triassic Period, says that freedom was actually compulsion in disguise.After analyzing the database of crocodyliforms -- a lineage of crocodile-like species that share a common ancestor -- Gearty found that the average weights of aquatic crocodyliforms did easily surpass their semi-aquatic and landlocked counterparts, sometimes by a factor of 100.But the study suggests that this disparity represented a response to, not a release from, the pressures of natural selection. Rather than expanding the range of crocodyliform body sizes, as some longstanding theories would predict, taking to the water instead seemed to compress that range by raising the minimum size threshold needed to survive its depths. The maximum size of those aquatic species, by contrast, barely budged over time.And when Gearty derived a set of equations to estimate the largest feasible body sizes under aquatic, semi-aquatic and terrestrial conditions?"All three habitats had roughly the same upper limit (on size)," he said. "So even though it seems like you're released from this pressure, you're actually squeezed into an even smaller box than before."Two major factors -- lung capacity and body heat -- seem to have helped initiate the squeeze play. Prior research had proposed that aquatic crocodyliforms got big in part because they needed to dive deeply for food, including the choice prey that would sustain a larger size. Upon digging into the literature, though, Gearty learned that lung volume increases more or less in lockstep with body size."So you actually don't have much excess lung volume to spare," said Gearty, a postdoctoral researcher in biological sciences. "When you get bigger, (lung capacity) is just basically scaling up with your body size to accommodate that extra size. The amount of time you could stay underwater increases a little bit, but not that much."At larger sizes, the evolutionary tradeoff between the benefits of longer, deeper dives and the energy demands of finding more food probably also reached a stalemate, he said, that helped cement the aquatic ceiling on size.As for the higher floor? That's where the thermal conductivity of water cranked up the evolutionary heat, Gearty said. Unfortunately for the aquatic crocs, water steals heat far faster than air does. The issue was likely compounded by the fact that temperatures in the waters they occupied were lower than the air temperatures enjoyed by their land-dwelling counterparts.That would have left smaller aquatic crocodyliforms with only bad options: limit the duration and depth of their dives so that they could regularly return to the surface and warm themselves in the sun, or risk freezing to death during deeper hunts for food. Whether by starvation or hypothermia, either would eventually spell doom."The easiest way to counteract that is to get bigger," Gearty said.Getting bigger was especially appealing because the volume of body tissue, which generates heat, increases faster than the surface area of the skin that surrenders it. But the unforgiving consequences of heat loss still limited the pool of ancestors from which aquatic crocodyliforms could evolve."They actually needed to start at a larger size," Gearty said. "So it's not like a marine crocodile could have just evolved from anywhere. It had to be evolving from some non-marine crocodile that was already a little larger than normal."The fossil records of the crocodyliforms allowed Gearty and Jonathan Payne, his former doctoral adviser at Stanford University, to pinpoint the minimum weight threshold for aquatic survival: 10 kilograms, or about 22 pounds. And when they plotted the relationships of heat loss and lung capacity to body mass, they discovered that the two slopes crossed at almost exactly the same value: 10 kilograms."We were able to explain, with these physiological equations, exactly why there were no marine crocodiles below a certain size," Gearty said. "This indicates that these very fundamental physiological constraints and controls ... actually may be some of the strongest forces for pushing animals to different body sizes through time. Not whether there's an asteroid hitting the world, not whether you're being (hunted) by some other animal -- that just these physical and chemical properties of the world we live in are what drive this. And if you want to enter a new habitat, you need to conform to that new set of properties."The findings mostly reinforce a 2018 Gearty-led study that found similar trends among nearly 7,000 living and extinct mammal species. An elementary difference between mammals and reptiles, though, initially left the verdict in doubt."The whole (premise) of the marine mammal project was that these things are warm-blooded, and they have to keep their temperature up," Gearty said. "They have to really worry about this heat loss. So the idea was, 'Well, would the same constraint occur in cold-blooded organisms that are also living in the ocean?'"There have been a couple papers suggesting that some of these marine crocodiles may have been somewhat warm-blooded, and so they may have been able to kind of reheat their own bodies. But even if that's the case, they were still going to be losing heat like these marine mammals would. They were still constrained by these thermoregulatory controls."With the help of an undergraduate student at Stanford and funding from the National Science Foundation, Gearty spent most of the summer of 2017 tracking down the fossil records that informed the new study."But that was to find the stuff that's readily available online," he said. "Then you've got, you know, undocumented books that you need to find, and they have to get shipped from Europe or somewhere. So there were a lot of these one-offs. I was still measuring specimen photos and getting records up until I submitted the paper in the middle of last year."Gearty said he was mostly spared the time and expense of traveling to museums and physically measuring fossil dimensions, as some of his colleagues have in the name of their own research. But the haphazardness of some older classifications and documentation still had him following false leads and trying to make sense of the nonsensible."A lot of the crocodiles that people have described in papers have never actually been documented the way they're supposed to be," he said. "Someone might say, 'Here's the Nebraska crocodile.' It's just a colloquial name. And you'll be like, 'I guess I've got to go find the Nebraska crocodile.' You look this up, and you see that there's this crocodile from Nebraska, and this one, and this one. You don't know which one is the 'Nebraska crocodile.'"You need to follow this trail of breadcrumbs, sometimes, to find these papers that may or may not have ever been published on these crocodiles that may or may not have ever been found. Fortunately, I was able to get most of the specimens just from the literature. But it did take a lot of digging to find the last probably 10% of the crocodiles."Many of the terrestrial fossils, in particular, trace body shapes that barely resemble the low-slung profile of the modern crocodile."The example I like to give is: Imagine a greyhound, and then put a crocodile skull on it," Gearty said. "There were things like that running around on land probably 200 million years ago."Though their maximum size remained almost constant, marine species did evolve two to three times faster than the semi-aquatic and terrestrial groups, Gearty found. Along with increasing the size of smaller aquatic species, natural selection molded body forms to surmount the challenges presented by water. Scales, plates and other drag-increasing skin deposits disappeared. Heads and tails flattened. Snouts narrowed."All of these were probably more dolphin-like than modern crocodiles, with even longer, thinner tails," he said. "And some of them had very paddle-like feet, almost like flippers."Despite the fact that virtually all modern crocodile species are semi-aquatic, Gearty said those adaptations served the aquatic crocodyliforms well -- more than 100 million years before mammals ventured into the deep."No one has talked about it much, but really, these things were quite successful," he said. "And some of them weren't even fazed by some of the big, (cataclysmic) events. When the asteroid hit that killed all the dinosaurs, one of the marine groups just kind of kept going like nothing happened. A lot of the terrestrial species went extinct, but this group just kept ticking along for a long time."
|
Extinction
| 2,020 |
March 27, 2020
|
https://www.sciencedaily.com/releases/2020/03/200327161718.htm
|
In Earth's largest extinction, land animal die-offs began long before marine extinction
|
The mass extinction at the end of the Permian Period 252 million years ago -- one of the great turnovers of life on Earth -- appears to have played out differently and at different times on land and in the sea, according to newly redated fossils beds from South Africa and Australia.
|
New ages for fossilized vertebrates that lived just after the demise of the fauna that dominated the late Permian show that the ecosystem changes began hundreds of thousands of years earlier on land than in the sea, eventually resulting in the demise of up to 70% of terrestrial vertebrate species. The later marine extinction, in which nearly 95% of ocean species disappeared, may have occurred over the time span of tens of thousands of years.Though most scientists believe that a series of volcanic eruptions, occurring in large pulses over a period of a million years in what is now Siberia, were the primary cause of the end-Permian extinction, the lag between the land extinction in the Southern Hemisphere and the marine extinction in the Northern Hemisphere suggests different immediate causes."Most people thought that the terrestrial collapse started at the same time as the marine collapse, and that it happened at the same time in the Southern Hemisphere and in the Northern Hemisphere," said paleobotanist Cindy Looy, University of California, Berkeley, associate professor of integrative biology. "The fact that the big changes were not synchronous in the Northern and Southern hemispheres has a big effect on hypotheses for what caused the extinction. An extinction in the ocean does not, per se, have to have the same cause or mechanism as an extinction that happened on land."Members of Looy's lab have conducted experiments on living plants to determine whether a collapse of Earth's protective ozone layer may have irradiated and wiped out plant species. Other global changes -- a warming climate, a rise in carbon dioxide in the atmosphere and an increase in ocean acidification -- also occurred around the end of the Permian period and the beginning of the Triassic and likely contributed.On land, the end-Permian extinction of vertebrates is best documented in Gondwana, the southern half of the supercontinent known as Pangea that eventually separated into the continents we know today as Antarctica, Africa, South America and Australia. There, in the South African Karoo Basin, populations of large herbivores, or plant eaters, shifted from the Daptocephalus assemblage to the Lystrosaurus assemblage. These groups are now extinct.In the ocean, the extinction is best documented in the Northern Hemisphere, in particular by Chinese fossils. The end-Permian extinction is perhaps best associated with the demise of trilobites.To improve on previous dates for the land extinction, an international team of scientists, including Looy, conducted uranium-lead dating of zircon crystals in a well-preserved volcanic ash deposit from the Karoo Basin. Looy, who is also a curator of paleobotany at the campus's Museum of Paleontology and curator of gymnosperms at the University and Jepson Herbaria, confirmed that sediments from several meters above the dated layer were devoid of Glossopteris pollen, evidence that these seed ferns, which used to dominate late Permian Gondwanan floras, became extinct around that time.At 252.24 million years old, the zircons -- microscopic silicate crystals that form in rising magma inside volcanoes and are spewed into the atmosphere during eruptions -- are 300,000 years older than dates obtained for the confirmed Permian-Triassic (P-T) boundary in China. This means that the sediment layer assumed to contain the P-T boundary in South Africa was actually at least 300,000 years too old.Dates for an ash deposit in Australia, just above the layers that document the initial plant extinction, similarly came in almost 400,000 years older than thought. That work was published in January by Christopher Fielding and colleagues at the University of Nebraska in Lincoln."The Karoo Basin is the poster child for the end-Permian vertebrate turnover, but until recently, it was not well-dated," Looy said. "Our new zircon date shows that the base of the Lystrosaurus zone predates the marine extinction with several hundred thousand years, similar to the pattern in Australia. This means that both the floral and faunal turnover in Gondwana is out of sync with the Northern Hemisphere marine biotic crisis."For some years now, we have known that -- in contrast to the marine mass extinction -- the pulses of disturbance of life on land continued deep into the Triassic Period. But that the start of the terrestrial turnover happened so long before the marine extinction was a surprise."In their paper, Looy and an international team of colleagues concluded "that greater consideration should be given to a more gradual, complex, and nuanced transition of terrestrial ecosystems during the Changhsingian (the last part of the Permian) and, possibly, the early Triassic."Looy and colleagues published their findings March 19 in the open access journal
|
Extinction
| 2,020 |
March 25, 2020
|
https://www.sciencedaily.com/releases/2020/03/200325161118.htm
|
Renewable energy developments threaten biodiverse areas
|
More than 2000 renewable energy facilities are built in areas of environmental significance and threaten the natural habitats of plant and animal species across the globe.
|
A University of Queensland research team mapped the location of solar, wind and hydropower facilities in wilderness, protected areas and key biodiversity areas.UQ School of Earth and Environmental Sciences lead author Mr José Rehbein said he was alarmed by the findings."Aside from the more than 2200 renewable energy facilities already operating inside important biodiversity areas, another 900 are currently being built," Mr Rehbein said."Energy facilities and the infrastructure around them, such as roads and increased human activity, can be incredibly damaging to the natural environment."These developments are not compatible with biodiversity conservation efforts."The majority of renewable energy facilities in western Europe and developed nations are located in biodiverse areas.Mr Rehbein said there is still time for developers to reconsider facilities under construction in Asia and Africa.University of Amsterdam senior author Dr James Allan said effective conservation efforts and a rapid transition to renewable energy was essential to prevent species extinctions and avoid catastrophic climate change."The entire team agree that this work should not be interpreted as anti-renewables because renewable energy is crucial for reducing carbon emissions," Dr Allan said."The key is ensuring that renewable energy facilities are built in places where they do not damage biodiversity."Renewable energy developments must consider biodiversity as well as carbon, and avoid any negative impacts on biodiversity to be truly sustainable."The team urge governments, industry and development organisations to avoid expanding renewable energy facilities into conservation areas and plan for alternative locations.
|
Extinction
| 2,020 |
March 18, 2020
|
https://www.sciencedaily.com/releases/2020/03/200318143733.htm
|
Late cretaceous dinosaur-dominated ecosystem
|
A topic of considerable interest to paleontologists is how dinosaur-dominated ecosystems were structured, how dinosaurs and co-occurring animals were distributed across the landscape, how they interacted with one another, and how these systems compared to ecosystems today. In the Late Cretaceous (~100-66 million years ago), North America was bisected into western and eastern landmasses by a shallow inland sea. The western landmass (Laramidia) contained a relatively thin stretch of land running north-south, which was bordered by that inland sea to the east and the rising Rocky Mountains to the west. Along this ancient landscape of warm and wet coastal plains comes an extremely rich fossil record of dinosaurs and other extinct animals.
|
Yet, from this record, an unexpected pattern has been identified: Most individual basins preserve an abundant and diverse assemblage of dinosaur species, often with multiple groups of co-occurring large (moose- to elephant-sized) herbivorous species, yet few individual species occur across multiple putatively contemporaneous geological formations (despite them often being less than a few hundred kilometers apart). This is in fairly stark contrast to the pattern seen in modern terrestrial mammal communities, where large-bodied species often have very extensive, often continent-spanning ranges. It has therefore been suggested that dinosaurs (and specifically large herbivorous dinosaurs) were particularly sensitive to environmental differences over relatively small geographic distances (particularly with respect to distance from sea level), and may have even segregated their use of the landscape between more coastal and inland sub-habitats within their local ranges.In their new study published in One of the methods they're using to do that is stable isotope analysis. This process measures differences in the compositions of non-decaying (hence, "stable") isotopes of various common elements, as the degree of difference in these compositions in animal tissues and in the environment have known relationships to various factors such as diet, habitat use, water source, and temperature. So the team applied these methods to fossilized teeth and scales from a range of animals, including dinosaurs, crocodilians, mammals, bony fish, and rays, all preserved together from a relatively small region over a geologically short period of time in sites called vertebrate microfossil bonebeds.By analyzing the stable carbon and oxygen isotope compositions of these fossils they were able to reconstruct their isotopic distributions in this ecosystem -- a proxy for their diets and habitat use. They found evidence of expected predator-prey dietary relationships among the carnivorous and herbivorous dinosaurs and among aquatic reptiles like crocodilians and co-occurring fish species.Critically, says Cullen, "What we didn't see was evidence for large herbivorous dinosaurs segregating their habitats, as the hadrosaurs, ceratopsians, and ankylosaurs we sample all had strongly overlapping stable carbon and oxygen ranges. If some of those groups were making near-exclusive use of certain parts of the broader landscape, such as ceratopsians sticking to coastal environments and hadrosaurs sticking to more inland areas, then we should see them grouping distinctly from each other. Since we didn't see that, that suggests they weren't segregating their resource use in this manner. It's possible they were doing so in different ways though, such as by feeding height segregation, or shifting where in the landscape they go seasonally, and our ongoing research is investigating some of these possibilities."Another important part of their study was comparing the fossil results to an environmentally similar modern environment in order to examine how similar they are ecologically. For a modern comparison, they examined the animal communities of the Atchafalaya River Basin of Louisiana, the largest contiguous wetland area in the continental U.S. The landscape of this area is very similar to their Cretaceous system, as are many elements of the plant and animal communities (not including the non-avian dinosaurs, of course).From their comparisons, the team found that the Cretaceous system was similar to the Louisiana one in having a very large amount of resource interchange between the aquatic and terrestrial components of the ecosystem, suggesting that fairly diverse/mixed diets were common, and food being obtained from both terrestrial and aquatic sources was the norm. They also found that habitat use differences among the herbivorous mammals in the Louisiana system was more distinct than among those large herbivorous dinosaurs in the Cretaceous system, lending further evidence to their results about their lack of strict habitat use preferences.Lastly, the team used modified oxygen stable isotope temperature equations to estimate mean annual temperature ranges for both systems (with the Louisiana one being a test of the accuracy of the method, as they could compare their results to directly measured water and air temperatures). The team found that in their Late Cretaceous ecosystem in Alberta, mean annual temperature was about 16-20 degrees C, a bit cooler than modern day Louisiana, but much warmer than Alberta today, reflecting the hotter greenhouse climate that existed globally about 76 million years ago.Characterizing how these ecosystems were structured during this time, and how these systems changed across time and space, particularly with respect to how they responded to changes in environmental conditions, may be of great importance for understanding and predicting future ecosystem responses under global climate change. The team's research continues and should reveal much more about the food webs and ecology of the dinosaurs and other organisms that inhabited these ancient landscapes.
|
Extinction
| 2,020 |
March 18, 2020
|
https://www.sciencedaily.com/releases/2020/03/200318143729.htm
|
Reef manta rays in New Caledonia dive up to 672 meters deep at night
|
The first data collected on the diving behavior of reef manta rays in New Caledonia considerably extend the known depth range for this vulnerable species in decline, according to a study published March 18 in the open-access journal
|
Reef manta rays (Mobula alfredi) are declining worldwide, in large part due to fishing pressure. More detailed information on the distribution and habitat use of the reef mantas is necessary to inform conservation and fisheries management measures to ensure the long-term survival of the species, now listed as vulnerable on the International Union for Conservation of Nature Red List. Pop-up satellite archival tags (PSAT tags) are one of the most effective methods to investigate fine-scale movements and habitat use in manta rays, but until now, there have been no such studies conducted in New Caledonian waters. In the new study, Lassauce and colleagues report the results from nine PSAT tags deployed in New Caledonia, recording the world's deepest known dives for reef manta rays.All tagged individuals performed dives exceeding 300 m in depth, with a maximum depth of 672 m. Most of the deepest dives occurred during nighttime, possibly to access important food resources. The authors hypothesize that these results may indicate zooplankton abundance in the surface waters surrounding New Caledonian coral reefs is insufficient to sustain reef manta rays. According to the authors, many of the marine protected areas throughout the known range of reef manta rays are coastal and do not extend into deeper offshore waters. As deep-water fisheries increasingly exploit this zone, the study highlights the importance of incorporating offshore waters and deep-water foraging grounds in manta conservation initiatives.The authors add: Tagged Manta rays (Mobula alfredi) from the never-studied-before population of New Caledonia showed unprecedented deep dive behaviour. More frequent and deeper dives than ever recorded before, Manta rays of New Caledonia set a new depth range to 672 meters.
|
Extinction
| 2,020 |
March 18, 2020
|
https://www.sciencedaily.com/releases/2020/03/200318143724.htm
|
'Wonderchicken' fossil from the age of dinosaurs reveals origin of modern birds
|
The oldest fossil of a modern bird yet found, dating from the age of dinosaurs, has been identified by an international team of palaeontologists.
|
The spectacular fossil, affectionately nicknamed the 'Wonderchicken', includes a nearly complete skull, hidden inside nondescript pieces of rock, and dates from less than one million years before the asteroid impact which eliminated all large dinosaurs.Writing in the journal Detailed analysis of the skull shows that it combines many features common to modern chicken- and duck-like birds, suggesting that the 'Wonderchicken' is close to the last common ancestor of modern chickens and ducks. The fossil was found in a limestone quarry near the Belgian-Dutch border, making it the first modern bird from the age of dinosaurs found in the northern hemisphere.The fossil doesn't look like much on first glance, with only a few small leg bone fragments poking out from a piece of rock the size of a deck of cards. Even those small bones attracted the researchers' interest, since bird fossils from this point in Earth's history are so rare.Using high-resolution X-ray CT scans, the researchers peered through the rock to see what was lying beneath the surface. What they saw, just one millimetre beneath the rock, was the find of a lifetime: a nearly complete 66.7-million-year-old bird skull."The moment I first saw what was beneath the rock was the most exciting moment of my scientific career," said Dr Daniel Field from Cambridge's Department of Earth Sciences, who led the research. "This is one of the best-preserved fossil bird skulls of any age, from anywhere in the world. We almost had to pinch ourselves when we saw it, knowing that it was from such an important time in Earth's history."The ability to CT scan fossils, like we can at the Cambridge Biotomography Centre, has completely transformed how we study palaeontology in the 21st century.""Finding the skull blew my mind," said co-author Juan Benito, also from Cambridge, who was CT scanning the fossils with Field when the skull was discovered. "Without these cutting-edge scans, we never would have known that we were holding the oldest modern bird skull in the world."The skull, despite its age, is clearly recognisable as a modern bird. It combines many features common to the group that includes living chickens and ducks -- a group called Galloanserae. Field describes the skull as a kind of 'mash-up' of a chicken and a duck."The origins of living bird diversity are shrouded in mystery -- other than knowing that modern birds arose at some point towards the end of the age of dinosaurs, we have very little fossil evidence of them until after the asteroid hit," said co-author Albert Chen, a PhD student based at Cambridge. "This fossil provides our earliest direct glimpse of what modern birds were like during the initial stages of their evolutionary history."While the fossil is colloquially known as the Wonderchicken, the researchers have given it the slightly more elegant name of Asteriornis, in reference to Asteria, the Greek Titan goddess of falling stars."We thought it was an appropriate name for a creature that lived just before the end-Cretaceous asteroid impact," said co-author Dr Daniel Ksepka from the Bruce Museum in Greenwich, Connecticut. "In Greek mythology, Asteria transforms herself into a quail, and we believe Asteriornis was close to the common ancestor that today includes quails, as well as chickens and ducks."The fact that Asteriornis was found in Europe is another thing which makes it so extraordinary. "The late Cretaceous fossil record of birds from Europe is extremely sparse," said co-author Dr John Jagt from the Natuurhistorische Museum Maastricht in the Netherlands. "The discovery of Asteriornis provides some of the first evidence that Europe was a key area in the early evolutionary history of modern birds.""This fossil tells us that early on, at least some modern birds were fairly small-bodied, ground-dwelling birds that lived near the seashore," said Field. "Asteriornis now gives us a search image for future fossil discoveries -- hopefully it ushers in a new era of fossil finds that help clarify how, when and where modern birds first evolved."The announcement of the Wonderchicken find coincides with a new exhibit at Cambridge's Sedgwick Museum of Earth Sciences, where visitors can learn more about Asteriornis and see the fossil up close. "Dawn of the Wonderchicken" runs from 19 March to 15 June. Admission is free.Dr Daniel Field is funded by a UKRI Future Leaders Fellowship. He is a University Lecturer in the Department of Earth Sciences at the University of Cambridge, and a Fellow of Christ's College Cambridge.
|
Extinction
| 2,020 |
March 18, 2020
|
https://www.sciencedaily.com/releases/2020/03/200318143643.htm
|
Maggot analysis goes molecular for forensic cases
|
Maggots on a dead body or wound can help pinpoint when a person or animal died, or when maltreatment began in elder, child care or animal neglect cases. However, the current process for making this determination is time consuming and resource intensive. It also relies on species assessment by trained entomologists. Now, researchers report in ACS'
|
Pregnant blowflies, which can detect decomposing tissue from as far as 2 miles away, lay their eggs on remains within a few minutes or hours of death. After the eggs hatch, the emerging larvae -- known as maggots -- feed on the tissue. Forensic investigators collect the larvae, and entomologists determine their species and life stage, which can reveal when death occurred. However, this analysis can be difficult because a body might be infested with a mass of eggs and larvae from several species, all mixed together. In addition, the larvae from different species are hard to tell apart, so they are typically raised to adulthood when they can be more reliably identified. But that takes time and training that investigators might not have, and the larvae in the collected samples might not be alive at the time of examination. As a quicker and more objective alternative, researchers have tried DNA analysis to distinguish species, but genomes from many of these flies are unknown. So Rabi A. Musah and colleagues set out to develop a better method.Building on their previous work on single-species determinations, the researchers optimized their method for multispecies analyses. They used a method called direct analysis in real time-high resolution mass spectrometry to obtain molecular information about various combinations of maggot species. Then, they developed a new hierarchical conformal predictor and applied it to the data. With this method, for the first time, maggots from mixtures of up to six species could be distinguished.
|
Extinction
| 2,020 |
March 16, 2020
|
https://www.sciencedaily.com/releases/2020/03/200316145326.htm
|
Soft corals near Virgin Islands recover from hurricanes, but stony corals declining
|
Soft corals at three sites in the U.S. Virgin Islands were able to recover from the destructive effects of nearly back-to-back Category 5 storms in 2017, but the story of these apparently hardy communities of colorful marine life is part of a larger, rapidly shifting narrative surrounding the future of coral reefs, according to a new study led by a University at Buffalo marine ecologist.
|
The recently realized resilience of the soft corals is an important development toward our increasing understanding of these complex ecosystems, but the findings published in the journal "These soft corals are resilient," says Howard Lasker, a professor in the Department of Environment and Sustainability and the Department of Geology, and an expert on the ecology of coral reef organisms."But right now in the Caribbean we're seeing a drastic decline of stony corals, and the soft corals are not a simple replacement for what's being lost."Soft corals, also known as octocorals, are branching colonial organisms. The colonies with their impressionistic tree-like appearance sway in ocean currents like trees in a storm. The stony corals, which also form colonies, produce rigid skeletons and create the framework of coral reefs. The living animal sits atop the structure they create, slowly secreting calcium carbonate, essentially limestone, to build up the reef.These screen saver favorites are inspiring tourist destinations that on a more practical level play diverse ecological, economic and environmental roles, everything from protecting shorelines from erosion to providing habitats for a diverse populations of marine life.The soft corals are doing fine while the stony corals have declined as much as 40% in recent decades, according to Lasker, whose team examined three reefs on the south shore of St. John (part of the U.S. Virgin Islands) following Hurricanes Irma and Maria, storms that passed within two weeks of one another in September 2017. They compared data from the storm's aftermath with sampling that began in 2014 and continued in 2018."The octocoral communities we studied suffered dramatic declines with the passage of these hurricanes. In that sense, they weren't resistant to the effects of severe storms," says Lasker. "However they showed resilience -- the ability to recover."We found that many colonies were killed, but two years later it hadn't changed the nature of species distribution, and as importantly new colonies were developing making up for the losses" says Lasker.This pattern of loss and recovery was emblematic historically of stony corals as well, but that's no longer the case for the scleractinians, and Lasker says their soft coral counterparts while providing shelter for many reef animals will not build the hard physical structure of reefs."One of the big questions in marine ecology is what we should be doing," says Lasker. "Should we be trying to remediate the damage and attempt to prevent species loss by creating protected environments?"There is a range of opinions about taking the curator's approach to the reefs, but what certain is that these systems are already dramatically different from descriptions made during the 1950s. And those observations from the '50s stand in obvious contrast to what European explorers would have seen when they encountered the reefs centuries ago."Humans are responsible for the changes," says Lasker. "It's really pretty simple: land use, sediments, sewage, agricultural runoff, overfishing, and now climate change."As the stony corals wane the soft corals are replacing them, but the reason the stony corals aren't recovering comes back to us, according to Lasker."It's important to recognize that the resilience we're seeing in these communities may decline with the frequency and intensity of future storms," says Lasker. "This could be a temporary state."The real test will come when we examine these areas 10 years down the road."
|
Extinction
| 2,020 |
March 13, 2020
|
https://www.sciencedaily.com/releases/2020/03/200313180827.htm
|
Surprising research: Prehistoric hyenas and humans share migration patterns
|
Prehistoric humans left Africa for the first time about 2 million years ago. The research community has been aware of this for some time. Now, novel research reveals that hyenas apparently did the same thing.
|
'Our new study shows that prehistoric humans and hyenas left Africa at approximately the same time. And like humans, spotted hyenas have had extensive and complex migration between continents. We can observe repeated gene flow events between Africa and Eurasia', says Michael Westbury, corresponding author and postdoc at GLOBE Institute at the University of Copenhagen.The researchers collaborated with researchers at the University of Potsdam and sequenced complete genomes from both modern spotted hyenas in Africa and subfossils of the extinct cave hyena from Europe and Asia.The two kinds of hyena -- spotted and cave -- were previously believed to form a closely related evolutionary lineage. DNA analyses published 15 years ago showed that the two types of hyena were genetically intermingled. Today, however, thanks to technological advances, the researchers have been able to obtain a lot more genetic data and show that this genetic intermingling is limited. The new study thus reveals an ancient separation.'The results nicely illustrate the power of palaeogenome analyses. The relationship of spotted and cave hyenas could not be resolved using morphological or short mitochondrial DNA sequence data and was actually discussed quite controversially for decades', says Michael Hofreiter Professor at the University of Potsdam.While prehistoric hyenas show some similarities with humans in their trans-continental migration patterns, the researchers also found signs that modern humans of the species 'Historical population sizes of spotted hyenas seem to correlate negatively with that of humans after about 100,000 years ago, echoing similar results we found for herbivores', says Rasmus Heller, Assistant Professor at the Department of Biology at the University of Copenhagen.In addition, he explains that humans are believed to have played a role in the extinction of cave hyenas around the end of the last ice age.That means that coexistence between humans and hyenas -- like that between humans and other large mammals -- may have changed from being relatively benign to detrimental as humans became more advanced.The researchers argue that their study reveals new aspects of when and how animals moved across continents in prehistory."Our results conforms with the hypothesis that animal migration may have occurred in pulses during which several species migrated more or less at the same time, possibly as a response to climate change. More comparative work is needed to confirm this hypothesis," says postdoc Michael Westbury, postdoc at GLOBE Institute.
|
Extinction
| 2,020 |
March 9, 2020
|
https://www.sciencedaily.com/releases/2020/03/200309093021.htm
|
Why organisms shrink in a warming world
|
Everyone is talking about global warming. A team of palaeontologists at GeoZentrum Nordbayern at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) has recently investigated how prehistoric organisms reacted to climate change, basing their research on belemnites.
|
These shrunk significantly when the water temperature rose as a result of volcanic activity approximately 183 million years ago, during the period known as the Toarcian. The FAU research team published their results in the online publication 'Belemnites are particularly interesting, as they were very widespread for a long time and are closely related to the squid of today,' explains palaeontologist Dr. Patricia Rita. 'Their fossilised remains, for example the rostrum, can be used to make reliable observations.' Within the context of the DFG-funded research project 'Temperature-related stresses as a unifying principle in ancient extinctions,' the hypothesis was confirmed that climate has a significant influence on the morphology of adult aquatic organisms. The body size of dominant species fell by an average of up to 40 percent.The team of researchers believe that this Lilliput effect was a precursor to the later extinction of the animals. It is still unclear whether rises in temperature influenced the organisms' metabolism directly or indirectly, for example due to a shortage of food sources.
|
Extinction
| 2,020 |
March 3, 2020
|
https://www.sciencedaily.com/releases/2020/03/200303140236.htm
|
Coral reefs in Turks and Caicos Islands resist global bleaching event
|
A study that relied on citizen scientists to monitor the health of corals on Turks and Caicos Islands in the Caribbean from 2012 to 2018 found that 35 key coral species remained resilient during a 2014-17 global coral-bleaching event that harmed coral reefs around the world. Even corals that experienced bleaching quickly recovered, the researchers found. Some corals appeared healthier in 2017 than they were in 2014.
|
The researchers report their findings in the Springer Nature journal "Boulder-type corals on the Turks and Caicos Islands demonstrated no significant bleaching as a result of the peak thermal stress in late 2015," said Abby Knipp, who conducted the research while an undergraduate student at the University of Illinois at Urbana-Champaign. Knipp is the first author of a paper detailing the findings. "Plate-type corals did suffer bleaching, but they quickly rebounded. Their pigmentation levels were back to normal within months of the anomalously high thermal stress."Coral bleaching is a common response to extreme heat stress, and global coral-bleaching events are becoming more frequent as the oceans warm. The 2014-17 bleaching event occurred as record-breaking sea-surface temperatures pushed some corals past their physiological limits. Scientists call it "the most severe, widespread and longest-lasting" global coral-bleaching event on record.Pigmentation in corals comes from photosynthetic algae, on which the corals depend for nutrients, said U. of I. geology professor and study co-author J. Cory Pettijohn."The algae colonize the corals and feed on the byproducts of their metabolism," he said. "When sea-surface temperatures are too high, corals will expel the algae. Corals that experience prolonged bleaching usually die, leaving only a white calcium-carbonate skeleton behind."In Turks and Caicos Islands, pigmentation of the boulder corals was darker in 2017 than in 2014, suggesting these corals were even healthier after rebounding from the heat stress, Knipp said."We were surprised that apparent healing and darkening could happen so fast," she said.The scientists say more studies are needed to explain the unusual hardiness of the corals at Turks and Caicos Islands, but previous research offers clues to factors that promote coral health. For example, some algal types appear to confer added resilience to corals experiencing heat stress. Ocean salinity and acidity likely play a role. Turks and Caicos Islands tend to have lower water temperatures than other, more thermally stressed regions of the Caribbean. And the massive 2017 hurricanes Irma and Maria cooled surface waters and likely contributed to the corals' recovery, the researchers said.
|
Extinction
| 2,020 |
March 3, 2020
|
https://www.sciencedaily.com/releases/2020/03/200303140147.htm
|
Ancient Australian trees face uncertain future under climate change, study finds
|
Tasmania's ancient rainforest faces a grim future as a warming climate and the way people used the land have brought significant changes to the island state off mainland Australia's southeastern coast, according to a new Portland State University study.
|
The study holds lessons not only for Australia -- whose wildfires have been dominating headlines in recent months -- but for other areas of the world that are seeing drying conditions and increased risk of wildfires.Andrés Holz, the study's lead author and associate professor of geography at PSU's College of Liberal Arts and Sciences, studied the population decline of King Billy pine trees (The study found that increasingly frequent fires caused by regional dry and warming trends and increased ignitions -- by humans during the early arrival of Europeans to Tasmania and more recently due to increases in lightning -- are breaching fire refugia. Refugia are protected areas that don't burn or, if they do, are areas where trees survive most wildfires."The areas that have survived are in these very protected refugia," Holz said. "The refugia can be a bit of a buffer, but how long is that going to last? We might be witnesses of a whole lineage of a very ancient plant species that is going to go extinct."Holz said that the changes in how wildfires function, due to both management and climate change, are driving analogous ecosystem transformations not only in Australia, but also western North America and South America's Patagonia region.Untangling the complex relationships between landscape, fire disturbance, human fire usage, climate variability and anthropogenic climate change is key to understanding the rapid population declines of King Billy pines.The study found that the trees regenerated continuously before 1800AD under indigenous land management, but population declines followed European colonization as they cleared land for logging and mining. This coincided with a period of more fire-prone climate and weather conditions."Fires co-occur with dry, warm periods and those periods are more and more frequent now," Holz said, adding that the Billy King pines need wet and cool conditions to thrive. "We're moving away, climatically speaking, from the drivers that help the species."Holz and the research team also found few seedlings or saplings in the study area, meaning that recovery of the original forest is unlikely. Instead, the replacement forest has become a tall-shrubland ecosystem with lower species diversity that in turn are more flammable and recover more quickly following fire."The next time there are the same climate conditions and there's a spark, a lightning strike or an accidental fire, the plants themselves are now more dense in space and more flammable than before and have a higher change of burning again," Holz said. "It becomes a vicious cycle that is hard to break."The study said that as these critical climate-fire associations increase in strength, the survival of King Billy pines may require increasingly targeted fire management, including rapid attack of uncontrolled fires.
|
Extinction
| 2,020 |
March 3, 2020
|
https://www.sciencedaily.com/releases/2020/03/200303113250.htm
|
More than 60% of Myanmar's mangroves has been deforested in the last 20 years
|
Mangroves account for only 0.7 per cent of the Earth's tropical forest area, but they are among the world's most productive and important ecosystems. They provide a wealth of ecological and socio-economic benefits, such as serving as nursery habitat for fish species, offering protection against coastal surges associated with storms and tsunamis, and storing carbon.
|
While many countries have established legal protection for mangroves, their value for sustainable ecosystem services face strong competition from converting the land to other more lucrative uses, particularly for agriculture. In the past decade, studies have shown that mangrove deforestation rates are higher than the deforestation of inland terrestrial forests.New research from the National University of Singapore (NUS) provided additional support for this, with results showing that mangroves deforestation rates in Myanmar, an important country for mangrove extent and biodiversity, greatly exceed previous estimates.The research, led by Associate Professor Edward Webb and Mr Jose Don De Alban from the Department of Biological Sciences at the NUS Faculty of Science, was published online in the journal Using satellite images and multiple analytical tools, the NUS team was able to assess the extent of mangrove in 1996. The researchers then followed the fate of every 30-metre x 30-metre mangrove image pixel for 2007 and 2016.The team's estimates revealed that in 1996, Myanmar had substantially more mangroves than previously estimated. However, over the 20-year period, more than 60 per cent of all mangroves in Myanmar had been permanently or temporarily converted to other uses. These include the growing of rice, oil palm, and rubber, as well as for urbanisation."Although fish and prawn farms accounted for only a minor amount of mangrove conversion, this may change in the near future. These competing land cover types are commercially important, but incompatible with mangrove persistence," said Mr De Alban.With the loss of nearly two-thirds of its mangroves, there is a need for the Myanmar government to develop holistic strategies to conserve this important habitat. This is particularly important as Myanmar strives to become more integrated into the regional and global markets for agriculture and aquaculture products."The fate of mangroves in the country will be tied to the strength of policies and implementation of conservation measures. Through proper long-term planning, management and conservation, this resilient ecosystem can recover and be maintained for the future," shared Assoc Prof Webb.
|
Extinction
| 2,020 |
March 3, 2020
|
https://www.sciencedaily.com/releases/2020/03/200303113246.htm
|
Reef-building coral exhibiting 'disaster traits' akin to the last major extinction event
|
A study published Tuesday in
|
The research team -- which includes scientists from The Graduate Center, CUNY; Baruch College; Scripps Institution of Oceanography; University of Haifa; University of Leeds; and GEOMAR Helmholtz Centre for Ocean Research -- found that corals are currently exhibiting a suite of dynamic survival responses that correspond with their last major extinction 66 million years ago. These coral traits include increased prevalence of deep-water residing, cosmopolitan distributions, non-symbiotic relationship to algae, solitary or small colonies, and bleaching resistance.Scientists were able to trace these behaviors due to excellent fossil records that coral skeletons leave behind. This study compared those fossil records to the modern International Union for Conservation of Nature (IUCN) Red List data. The IUCN Red List of threatened species is world's most comprehensive information source on the global conservation status of animal, fungi, and plant species."It was incredibly spooky to witness how corals are now exhibiting the same traits as they did at the last major extinction event," said Professor David Gruber, a researcher and marine biologist with The Graduate Center, CUNY and Baruch College. "Corals seem to be preparing to jump across an extinction boundary, while we are putting our foot further on the pedal."The study highlights how primates do not possess survival characteristics or have a record of mass extinction survival as some corals do.The researchers examined 250 million years of fossil coral data from the IUCN Red List and then compared similarities in the corals' recorded survival behaviors between the Cretaceous-Tertiary (KT) extinction event 66 million years ago (when the dinosaurs disappeared) and the current extinction event. Using the data, they were able to infer relevant traits, including an 18% decrease in coloniality, an 18% decrease in photosymbiosis, and a 12% decrease in the occupation of shallow habitats. Scientists also noted an evolutionary selection toward slower-growing coral, which may increase their chances of survival."This study reminds us that corals are diverse and flexible organisms with a demonstrated success facing the most extreme environmental crisis in Earth's history: mass extinction," said the study's first author Gal Dishon, a marine biologist with the Scripps Institution of Oceanography at the University of California. "Nevertheless, based on the lessons we learned from fossil data, the surviving corals will not be those reef builders we know from hyper-diverse tropical coral reefs, but rather small, solitary, slow-growing, and deep-dwelling corals."The authors note that while slow recovery time (2-10 million years) of coral reefs following a mass extinction is distressing, they also call attention that primates (the order that also includes humans) are also increasingly becoming threatened with extinction."There is something very powerful about this message coming from the corals," said Gruber. "Corals are such a sensitive group of marine creatures, they are essentially the canary in the coal mine."
|
Extinction
| 2,020 |
February 27, 2020
|
https://www.sciencedaily.com/releases/2020/02/200227144315.htm
|
Environmental damage to coral reefs in South China Sea
|
New research reveals the unseen environmental damage being done to coral reefs in the hotly contested South China Sea, as China and other nations jostle for control of the disputed sea lanes.
|
Professor Eric Wolanski and Dr Severine Chokroun from James Cook University in Australia are physical oceanographers, researching the distribution, circulation, and physical properties of water.In a new scientific paper, they argue that the disputed Spratly Islands in the South China Sea are in even more serious trouble than first believed."The Spratlys are the sites of a military build-up and gross overfishing, mainly by China. Reefs and islands have been destroyed to construct military outposts to further territorial claims," said Professor Wolanski.He said it was already known that dredging to construct the new islands had damaged the environment and the region was massively overfished. There are typically 100-150 Chinese fishing boats working every reef that China controls, compared to between 0.1 and 0.5 fishing boats per reef in the Great Barrier Reef."We looked at the flows of fish and coral larvae from damaged reefs that produce, or used to produce, larvae and which reefs received them and are now deprived of them."The scientists determined the currents around the islands by using satellite data and then modelled the movement of larvae from and to every reef in the Spratly Islands archipelago."Reefs degraded or killed by island-building and overfishing produce less fish and coral larvae for those downstream. The levels vary, but in the most extreme case -- Namyit Island -- there are no more new coral and fish larvae getting through, due to all its sources of larvae being destroyed," said Professor Wolanski.He said China does not provide scientists with access to the reefs it occupies, neither does it provide data on the health of coral and fish populations at these reefs. But it now appears that the ecosystem of the whole Spratly Islands archipelago is at risk of collapse or severe degradation."We've pinpointed a priority list of reefs for vital conservation measures in the Spratly Islands archipelago. We recognise the political difficulties, but we have defined the problem and we have the solution based on the example of the developing collaboration between the Philippines and Vietnam that manages some reefs in the archipelago."We hope it's not just wishful thinking that action will follow," said Professor Wolanski.
|
Extinction
| 2,020 |
February 26, 2020
|
https://www.sciencedaily.com/releases/2020/02/200226095514.htm
|
Tropical nations worst hit by climate-related fish shifts
|
Policymakers will need to step up to the challenges caused by significant shifts in fish species distributions caused by climate change.
|
Tropical countries stand to lose the most fish species due to climate change, with few if any stocks replacing them, according to a study published in the journal As sea temperatures rise, fish species migrate towards cooler waters to maintain their preferred thermal environments.Jorge García Molinos of Hokkaido University and colleagues in Japan and the USA developed a computer model to project how the ranges of 779 commercial fish species will expand or contract under a moderate and more severe greenhouse gas emissions scenario between 2015 and 2100, compared to their 2012 distribution.The model showed that, under a moderate emissions scenario, tropical countries could lose 15% of their fish species by the year 2100. If a more high-end emissions scenario were to occur, they could lose more than 40% of their 2012 species.The model projects northwest African countries could lose the highest percentage of species; while Southeast Asia, the Caribbean, and Central America could experience steep species declines under the worst of the two climate scenarios.The scientists wondered if existing regional, multi-lateral or bilateral policies contain the necessary provisions to adequately manage climate-driven fish stock exits from each countries' jurisdictional waters (exclusive economic zones [EEZs]). They analyzed 127 publicly available international fisheries agreements. None contained language directly related to climate change, fish range shifts, or stock exits. Although some included mechanisms to manage short-term stock fluctuations, existing agreements also failed to contain long-term policies that prevent overfishing by nations losing fish stocks.García Molinos and his colleagues suggest fair multilateral negotiations may be necessary among countries benefiting from the shift in fish species and those losing from it. Tropical nations in particular should highlight compensation for fishery damage during these negotiations recurring to international frameworks such as the Warsaw International Mechanisms for Loss and Damage, which aims to address losses caused by climate change. This information should also be highlighted to other financial schemes, such as the Green Climate Fund, which have been set up to assist developing countries to adapt to and mitigate the effects of climate change."The exit of many fishery stocks from these climate-change vulnerable nations is inevitable, but carefully designed international cooperation together with the strictest enforcement of ambitious reductions of greenhouse gas emissions, especially by the highest-emitter countries, could significantly ease the impact on those nations," García Molinos concludes.
|
Extinction
| 2,020 |
February 25, 2020
|
https://www.sciencedaily.com/releases/2020/02/200225104954.htm
|
Mangrove forests provide cause for conservation optimism, for now
|
More than a decade ago, academics warned that mangrove forests were being lost faster than almost any other ecosystem, including coral reefs and tropical rainforests. But things are looking better.
|
An international team of 22 researchers from 24 institutes led by Associate Professor Daniel Friess and Dr Erik Yando of the Department of Geography at the National University of Singapore (NUS) have found that there is now cause for optimism, with the global loss rate of mangrove forests now less alarming than previously suggested.After studying various earlier presented works, the team found that globally, mangrove loss rates have reduced by almost an order of magnitude between the late 20th and early 21st century -- from what was previously estimated at one to three per cent per year, to about 0.3 to 0.6 per cent per year, thanks in large part to successful mangrove conservation efforts. This heightens conservation optimism amongst broader projections of environmental decline."The team deduced that the reduction in mangrove global loss rates has resulted from improved monitoring and data access, changing industrial practices, expanded management and protection, increased focus on rehabilitation, and stronger recognition of the ecosystem services provided by mangroves," explained Assoc Prof Friess.A commentary summarising the team's findings was published in the scientific journal Mangrove forests occur along the shorelines of more than 100 countries and are incredibly important as they provide a number of critical benefits to people, including protection from coastal erosion and storm as well as cyclone damage, natural filters for pollution and sediment, carbon sequestration which helps to mitigate climate change, and provide millions of people with products such as fuelwood, construction materials and fisheries resources, since mangroves act as nursing grounds for many coastal fishes."There is strong evidence that positive conservation change is occurring. Mangrove conservation has gained substantial momentum, with greater public and government awareness leading to investment and on-the-ground action. However, despite recent mangrove conservation successes, tempered optimism is necessary, as conservation gains are not evenly spread, nor guaranteed into the future," cautioned Assoc Prof Friess.The team gathered that mangroves continue to be threatened by aquaculture, agriculture and urban development across the world, particularly for new deforestation frontiers that are emerging throughout parts of Southeast Asia and West Africa. Southeast Asia is a traditional hot spot of mangrove deforestation as mangroves are cut down to make space for aquaculture ponds, cleared for rice paddy cultivation, and reclaimed for industrial and port development."Emerging deforestation frontiers need to be addressed early. Improved environmental governance and increased public intervention can help secure positive conservation outcomes in these locations. We need to take decisive steps to improve the success and scale of mangrove rehabilitation, and increase the resilience of mangroves to sea-level rise to maintain the current progress in mangrove conservation," commented Dr Candy Feller, Senior Scientist at the Smithsonian Environmental Research Center, who is one of the contributors to the study.The team also noted that while mangrove rehabilitation is lauded as a method to offset historical as well as ongoing losses and can yield long-term ecosystem service provision, successful rehabilitation is still a challenge to achieve at scale.Current mangrove rehabilitation projects around the world can fail because key ecological thresholds and rehabilitation best practices are ignored -- for instance, planting in low-intertidal locations that are not suitable for mangrove growth and using non-native species that can quickly become invasive, which gives rise to myriad ecological impacts on the intertidal zone.Another contributor, marine ecologist Professor Karen Diele of Edinburgh Napier University added, "The challenge of mangrove rehabilitation is to ensure that the best practices are executed correctly, including monitoring of rehabilitation projects, both in terms of flora and fauna, to learn from failure and successes. Work is required to overcome key socio-political hurdles. These include lack of training, unclear land tenure, and national governments or NGO targets that incentivise rehabilitation efforts in unsuitable coastal locations. These are not insurmountable challenges and can be addressed through engagement with policy makers and stakeholders.""Ensuring that mangrove conservation gains are not short-lived will require continued research, policy attention, and renewed efforts to improve the success of mangrove rehabilitation at a scale that will be ecologically impactful," said Dr Yando, Research Fellow at the NUS Department of Geography.Meanwhile, Assoc Prof Friess and his team will continue to monitor mangrove deforestation and conduct studies to assess the benefits and values of mangroves in Southeast Asia.
|
Extinction
| 2,020 |
February 20, 2020
|
https://www.sciencedaily.com/releases/2020/02/200220141724.htm
|
DNA from ancient packrat nests helps unpack Earth's past
|
New work shows how using next-generation DNA sequencing on ancient packrat middens -- nests made out of plant material, fragments of insects, bones, fecal matter, and urine -- could provide ecological snapshots of Earth's past. Published today in the journal
|
"Rodent middens are powerful tools in paleoecology," said Michael Tessler, a postdoctoral fellow at the American Museum of Natural History. "We wanted to see how we could take this invaluable resource and expand its use to give us a big-picture view of what life in the Americas was like 1,000, 10,000, or even 30,000 years ago, and measure how it has changed in the time since then."Packrats (Neotoma spp.) are long-tailed nocturnal rodents that create nests out of plant materials in dry caves and crevices. Their sticky, viscous urine helps the nests to bind together into a solid mass, capable of being preserved for tens of thousands of years -- some nests even date to beyond the last ice age. These plant-rich deposits -- called middens, which also can contain insects, bones, and other materials the packrats habitually collect -- are found in arid parts of North America. Because the foraging range of these small rodents is limited, the contents of packrat middens represent the local environment at the time the material was gathered, providing clues about past climates and environments. Since 1960, more than 2,000 ancient packrat middens from western North America have been analyzed for fossil contents and archived."Midden contents are so well preserved that fragments of ancient DNA can be extracted and analyzed across millennia," said Rob Harbert, an assistant professor at Stonehill College who conceived of this study when he was a postdoc at the Museum. "They have been used to identify an extinct ground sloth preserved in southern Argentina, tell us about the history of bighorn sheep in California, and provided evidence of papillomavirus infection in packrats over the last 27,000 years. Because of their dense distribution, fossil middens in the Americas offer the chance to genetically profile entire communities through time and space, but first, we need to improve the way we analyze data from these deposits -- the principal aim of this study."The researchers analyzed ancient DNA from 25 packrat midden samples between 300 and 48,000 years old from the North American Packrat Midden Collection at the University of Arizona's Tree Ring Laboratory. The samples come from two locations: City of Rocks National Reserve in south-central Idaho, and Guadalupe Canyon in Northern Baja California, Mexico. These two sites span the range of current climatic conditions across which North American packrat middens are preserved and have been studied.The researchers explored the use of two next-generation sequencing techniques to compare the DNA: amplicon, during which the same gene is sequenced from every sample, and shotgun, which randomly selects DNA fragments to sequence. They decided to focus on the shotgun technique for this study, finding that packrat middens up to 32,000 years old contain recoverable DNA that is consistent with fossils found in these deposits. As expected, a large portion of this DNA is bacterial, but between 20-40 percent is classified as belonging to eukaryotic organisms -- those whose cells have a nucleus -- including plants like grasses, pines, junipers, daisies, and roses, as well as a small number of vertebrates, including insects and fungi. Viruses were also present in small quantities.Although this study underscores the promise of deep DNA sequencing to illuminate previous ecosystems, a great deal of progress is required to make the work more accurate. Since shotgun sequences random fragments of DNA, it requires researchers to have a strong database they can use to match the sequences to an organism. If the data for that organism do not exist, scientists only get the closest match, or no match at all. Because of this, and DNA degradation, the researchers say that they were only able to definitively match the DNA fragments to the family level and were unable to match it to genus or species groupings."As the costs of DNA sequencing continue to decrease and computational power increases, the prospects for using this technique will greatly improve," Harbert said. "Further investigation into the taxonomic composition of middens could refine our understanding of the timeline of past climate change, species migration, and extinction, and this will better inform the study of the effects of current and future climate change."
|
Extinction
| 2,020 |
February 20, 2020
|
https://www.sciencedaily.com/releases/2020/02/200220130512.htm
|
How transient invaders can transform an ecosystem
|
When a plant or animal species is introduced to a new environment with few natural predators, it can spread uncontrollably, transforming the ecosystem and crowding out existing populations. One well-known example is the cane toad, which was introduced into Australia in 1935 and whose population is now well into the millions.
|
A related but less-understood scenario occurs when an invader arrives, transforms the ecosystem, and then dies out. MIT physicists have now shown how this kind of "transient invasion" can occur in bacterial populations, provoking a shift from one stable community state to another, while the invader itself disappears."These results highlight one possible way in which even if a species does not survive long term, it could nonetheless have long-term effects on the community," says Jeff Gore, an MIT associate professor of physics and the senior author of the study.The findings may also shed light on how transient invaders affect real-world ecosystems such as bacteria that alter the human gut microbiome before passing through the digestive tract, or reindeer whose grazing deforests an island so thoroughly that the population can no longer survive there.MIT postdoc Daniel Amor is the lead author of the paper, which appears today in The research team originally set out to explore factors that can drive ecosystems to switch between two stable states. Many ecosystems can exist in alternative stable states, but one may be more "desirable" than the other, such as a lake that can be healthy or eutrophic (excessively covered in algae). In one dramatic example, the Sahara region switched from a humid grassland to a desert about 5,000 years ago."The mechanisms that drive these transitions, and whether we can control them, are not very clear," Amor says.Gore's lab studies the principles that govern these kinds of complex ecological shifts by creating simplified versions that can be analyzed in a laboratory. In this case, the researchers studied populations of two bacterial species -- The researchers first allowed the bacterial populations to naturally reach a stable state in which one species dominated the overall community. Once the populations stabilized, the researchers introduced an invader and measured how it affected the previously stable populations.Of the six invader species that the researchers studied, three performed a takeover that shifted the overall population dynamics of the ecosystem, but then died out. This phenomenon occurred via changes in the acidity of the environment, the researchers found.In the original stable state, The researchers then explored whether this phenomenon could be seen in naturally occurring populations of bacteria. They took soil samples and grew the bacterial species they found, allowing these communities to reach a variety of alternative stable states in the new environment of the laboratory. After introducing the same invaders they used in the earlier experiments, they observed similar patterns of rapid growth and then disappearance of the invader, along with a shift in the composition of the original community."This suggests that it was not a rare effect that we only observe in hypothesis-guided experiments, but also in natural settings," Amor says.Stefano Allesina, a professor of ecology and evolution at the University of Chicago, described the experiments as "elegant and robust.""The work has clearly important implications for the manipulation of microbial communities. Being able to transition a microbial community from an unfavorable state to a favorable one is one of the most important challenges in the field, and the MIT team has shown how transient invaders may be the perfect 'light switch' -- they do their job and then disappear," says Allesina, who was not involved in the study.While it may seem counterintuitive that a species would create conditions that lead to its own demise, this may happen often in nature, the researchers say. In a paper published in 2018, Gore and two colleagues described several species of bacteria that essentially commit "ecological suicide" by growing so fast that the local environment becomes too polluted with acidic waste for them to survive.This occurs, in part, because genetic mutations that allow an individual to grow faster can spread rapidly through the population, even if it harms the environment."There are a lot of species that would modify the environment in such a way that it could lead to rapid population extinction," Gore says. "It could be the case that in some situations, the strategy of growing slowly and not polluting the environment may not be evolutionarily stable against a mutant that just takes advantage of the environment while it's good, growing quickly and leading to a lot of toxin production. The problem is that while it's rational in the short term for each individual to do that, it leads to a suboptimal outcome for the population."Gore says he hopes the findings will encourage scientists who study more complicated ecosystems, such as lakes or the human gut microbiome, to look for these types of transient invasions and their after-effects."The nature of these complex systems is that they can be a little bit overwhelming," he says. "You don't know what are the things you should even be looking for in the data or what kind of experiments you should be doing. Our hope is that some of our work can motivate other people to look for this sort of phenomenon in their systems."
|
Extinction
| 2,020 |
February 19, 2020
|
https://www.sciencedaily.com/releases/2020/02/200219152852.htm
|
New mathematical model reveals how major groups arise in evolution
|
Researchers at Uppsala University and the University of Leeds presents a new mathematical model of patterns of diversity in the fossil record, which offers a solution to Darwin's "abominable mystery" and strengthens our understanding of how modern groups originate. The research is published in the journal
|
The origins of many major groups of organisms in the fossil record seem to lie shrouded in obscurity. Indeed, one of the most famous examples, the flowering plants, was called "an abominable mystery" by Darwin. Many modern groups appear abruptly, and their predecessors -- if there are any -- tend to be few in number and vanish quickly from the fossil record shortly afterwards. Conversely, once groups are established, they tend to be dominant for long periods of time until interrupted by the so-called "mass extinctions" such as the one at the end of the Cretaceous period some 66 million years ago.Such patterns appear surprising, and often seem to be contradicted by the results from "molecular clocks" -- using calibrated rates of change of molecules found in living organisms to estimate when they started to diverge from each other. How can this conflict be resolved, and what can we learn from it?In a paper, Graham Budd, Uppsala University, and Richard Mann, University of Leeds, present a novel mathematical model for how the origin of modern groups based on a so-called "birth-death" process of speciation and extinction. Birth-death models show how random extinction and speciation events give rise to large-scale patterns of diversity through time. Budd and Mann show that the ancestral forms of modern groups are typically rather few in number, and once they give rise to the modern group, they can be expected to quickly go extinct. The modern group, conversely, tends to diversify very quickly and thus swamp out the ancestral forms. Thus, rather surprisingly, living organisms capture a great percentage of all the diversity there has ever been.The only exceptions to these patterns are caused by the "mass extinctions," of which there have been at least five throughout history, which can massively delay the origin of the modern group, and thus extend the longevity and the diversity of the ancestral forms, called "stem groups." A good example of this is the enormous diversity of the dinosaurs, which properly considered are stem-group birds. The meteorite impact at the end of the Cretaceous some 66 million years ago killed off nearly all of them, apart from a tiny group that survived and flourished to give rise to the more than 10 000 species of living birds.The new model explains many puzzling features about the fossil record and suggests that it often records a relatively accurate picture of the origin of major groups. This in turn suggests that increased scrutiny should be paid to molecular clock models when they significantly disagree with what the fossil record might be telling us.
|
Extinction
| 2,020 |
February 19, 2020
|
https://www.sciencedaily.com/releases/2020/02/200219152820.htm
|
Global relationships that determine bird diversity on islands uncovered
|
The study, a collection of molecular data from bird species found across 41 oceanic archipelagos, reveals how the area and isolation of islands are key to determining the diversity of species they contain.
|
It is known that biodiversity is unevenly distributed across the planet. But why do some islands such as the Galápagos and Hawaii harbour so many unique species of birds? In the 1960's, Robert MacArthur & Edward Wilson proposed what was to become a highly influential theory in biology: the Theory of Island Biogeography. This theory predicts the number of species expected on any given island as a function of the area (size) of the island and its isolation (distance) from the mainland.Remarkably, to date no study has shown on a global scale how island area and isolation determine the rates at which species colonise new islands, evolve new types or go extinct. These relationships have remained elusive for decades.However, in a new study published today in Dr Sonya Clegg, Associate Professor of Evolutionary Ecology at the Department of Zoology, says: 'This huge collaborative effort -- led by Dr Luis Valente of Museum für Naturkunde in Berlin -- has allowed us to create this remarkable global dataset of island birds worldwide. This data shows that indeed, colonisation decreases with isolation, and extinction decreases with area, confirming the key components of the Theory of Island Biogeography. Importantly we were able to extend the model framework to include speciation, showing that speciation increases with both area and isolation, and furthermore, describe the precise shape of these key global biodiversity relationships for birds.'A further fascinating result was the finding that the vast majority of island bird species represent unique evolutionary branches with no close relatives on the islands they inhabit.Dr Valente of Museum für Naturkunde in Berlin, says: 'Islands are frequently associated with spectacular radiations -- think of Darwin's finches of Galápagos, where a single coloniser went on to diversify into 15 different species -- but this is not the evolutionary scenario for most of the world's island bird diversity.'Dr Clegg says: 'It will be exciting to see how this major advance for testing island biology theory on a global scale can be applied to other taxa. How will the precise shape of relationships change when looking at ants, or mammals or reptiles? These types of comparisons will answer long-standing questions about biogeographical patterns, and no doubt stimulate new avenues for research.'
|
Extinction
| 2,020 |
February 18, 2020
|
https://www.sciencedaily.com/releases/2020/02/200218104708.htm
|
Enigmatic small primate finally caught on film in Taita, Kenya
|
Good news from the Kenyan Taita Hills: the Taita mountain dwarf galago still survives. This was confirmed by researchers working at the University of Helsinki Taita Research Station.
|
The tiny nocturnal prosimian, weighing only 100-180 grams, was first reported in 2002, but no sightings had been made since.The dwarf galagos in the Taita Hills live in relatively cool montane forests at the altitude of 1,400-1,950 metres. They -- as do all the dwarf galago species -- live in small family groups and communicate using several types of calls. Because all dwarf galago species look similar, they are most conveniently identified on the basis of their distinctive calls.Finding the small nocturnal animal is challenging, as the forest canopy is in places up to 50 metres high. The animals are spotted with a red light not visible to the animal itself."The tropical forest is magically beautiful at night, but one is lucky to catch even a glimpse of the tiny creatures," says University of Helsinki PhD student Hanna Rosti who has spent hours observing and recording the animals."Dwarf galagos make agile jumps from tree to tree and feed on moths, cicadas and other insects. I have seen them hunting above ground-dwelling safari ants, where they obviously take advantage of insects fleeing from the voracious ants."Unfortunately, the tiny mammal seems to be at the verge of extinction."The future of Taita mountain dwarf galagos and other endemic animal and plant species depends on the future of native montane forests of the Taita Hills. The conservation status of the forests must be strengthened and their area should be expanded by planting native trees in areas destroyed by cutting and fire. This will protect galago habitats and will ensure that the montane forests continue to provide many vital ecosystem services," says Professor Jouko Rikkinen from the University of Helsinki. He has been studying the biota of the Taita Hills since 2009.Many animals and plants of the local montane forests have evolved in isolation and the number of endemic species is remarkably high. The Taita Hills belong to the Eastern Arc Mountains, which represent a global biodiversity hotspot.The diversity of the Taita Hills will never stop surprising Professor Petri Pellikka, the director of the Taita Research Station. "The mountains represent a living laboratory, with great possibilities for ground-breaking research and fascinating new findings."
|
Extinction
| 2,020 |
February 13, 2020
|
https://www.sciencedaily.com/releases/2020/02/200213175917.htm
|
Caribbean sharks in need of large marine protected areas
|
Governments must provide larger spatial protections in the Greater Caribbean for threatened, highly migratory species such as sharks, is the call from a diverse group of marine scientists including Stony Brook University School of Marine and Atmospheric Sciences (SoMAS) PhD Candidate, Oliver Shipley, and led by the conservation NGO Beneath the Waves in a letter to published in
|
With up to one-third of all open ocean shark species threatened extinction due to overfishing, conservation strategies that protect areas where sharks spent significant portions of their time are becoming increasingly important. In light of recent calls to protect 30 percent of our oceans by 2030, large marine protected areas, which can stretch from 100,000 sq. km to over 300,000 sq. km, have emerged as a popular management tool for their potential to enhance ecological processes and promote sustainable fisheries. One of the greatest benefits of these large conservation zones is their potential to conserve sharks, which travel long distances and can connect multiple jurisdictions over short time periods.The letter in "Through conducting years of scientific research on sharks in the Caribbean, I have witnessed first-hand, the benefits that marine protected areas can have for shark populations," said Shipley, a close collaborator of Dr. Austin Gallagher, Chief Scientist at Beneath the Waves. "We hope that currently protected nations, such as The Bahamas, can carry the torch and provide a foundation on which to base broader policy. For this to be a success, we will need to continue to build strong relationships and further understand the needs of key stakeholder groups throughout the wider Caribbean. We are extremely confident that this is going to happen.""The diversity of countries sharing ocean space in the Greater Caribbean is remarkable, and we know that migratory shark species connect many of these countries along their migrations," said Gallagher. "Though there are many examples of establishing marine protected areas in the region, there are few that are big enough to encompass the space use of large sharks, such as tiger sharks which can move thousands of miles per year."Recent research suggests that sharks are surprisingly rare in many Caribbean nations, likely due to decades of unregulated overharvest. However, certain areas such as the Bahamas, which have banned longline fishing and protected sharks in recent decades, have benefitted from the significant socioeconomic inputs generated from live sharks in the diving industry, estimated to be over US $140 million per year.
|
Extinction
| 2,020 |
February 13, 2020
|
https://www.sciencedaily.com/releases/2020/02/200213135752.htm
|
Boom and bust for ancient sea dragons
|
Ichthyosaurs were fish-like reptiles that first appeared about 250 million years ago and quickly diversified into highly capable swimmers, filling a broad range of sizes and ecologies in the early Mesozoic oceans. However, this rapid pace didn't last long and an evolutionary bottleneck 200 million years ago, through which only one lineage of ichthyosaurs survived, led to much slower evolution in much of their long history.
|
Dr Ben Moon, who led the research, published in the journal "Because of this we expected to see a rapid evolution early after ichthyosaurs first appeared, but we were staggered by just how big this early burst was and how relatively short it was."There are over 100 known species of ichthyosaur from between 250-90 million years ago in the Mesozoic Era, when the infamous dinosaurs ruled the land and the seas were full of marine reptiles, the top predators that filled comparable roles to dolphins, orcas, and sharks in modern seas.The study used state-of-the-art computational methods and looked at two types of data, one covering skull size and the other including many features of ichthyosaurs' skeleton. All methods show an 'early burst' of evolution in ichthyosaurs, with high rates and rapid variation soon after the appearance of the group, that quickly diminishes later on.Co-author Dr Tom Stubbs said: "Ichthyosaurs really dominated early in the Triassic (252-201 million years ago), rapidly evolving in an ocean with few predators soon after the largest known mass extinction in Earth's history. However, the seas quickly became more crowded and competitive, and ichthyosaurs lost their top position in the Jurassic (201-145 million years ago) to other marine reptiles like plesiosaurs and pliosaurs."It may well have been the ichthyosaurs' decreasing evolutionary rates which made them less able to adapt quickly, and therefore less diverse and competitive, allowing other marine reptiles to take over as the top predators."Despite slower evolution and going through a bottleneck at the end of the Triassic period, ichthyosaurs remained a common group but had less variation between them. These are perhaps best known ichthyosaurs, found in several UK locations, including Lyme Regis in Dorset, and first collected by Mary and Joseph Anning.Dr Ben Moon added: "Even though ichthyosaurs were evolving more slowly in their last 100 million years, they are still known from many species, but with less variety between them."It's possible that we might find more ichthyosaurs out there that buck this trend, but it seems that this lack of variety was eventually the cause of their extinction when global conditions became less favourable around 90 million years ago. Ichthyosaurs were simply unable to adapt."
|
Extinction
| 2,020 |
February 12, 2020
|
https://www.sciencedaily.com/releases/2020/02/200212150200.htm
|
Extinct giant turtle had horned shell of up to three meters
|
The tropical region of South America is one of the world's hot spots when it comes to animal diversity. The region's extinct fauna is unique, as documented by fossils of giant rodents and crocodylians -including crocodiles, alligators, caimans and gavials -- that inhabited what is today a desert area in Venezuela. Five to ten million years ago, this was a humid swampy region teeming with life. One of its inhabitants was
|
Researchers of the University of Zurich (UZH) and fellow researchers from Colombia, Venezuela, and Brazil have now reported exceptional specimens of the extinct turtle recently found in new locations across Venezuela and Colombia. "The carapace of some Stupendemys individuals reached almost three meters, making it one of the largest, if not the largest turtle that ever existed," says Marcelo Sánchez, director of the Paleontological Institute and Museum of UZH and head of the study. The turtle had an estimated body mass of 1,145 kg -- almost one hundred times that of its closest living relative, the big-headed Amazon river turtle.In some individuals, the complete carapace showed a peculiar and unexpected feature: horns. "The two shell types indicate that two sexes of Stupendemys existed -- males with horned shells, and females with hornless shells," concludes Sánchez. According to the paleobiologist, this is the first time that sexual dimorphism in the form of horned shells has been reported for any of the side-necked turtles, one of the two major groups of turtles world-wide.Despite its tremendous size, the turtle had natural enemies. In many areas, the occurrence of Stupendemys coincides with Purussaurus, the largest caimans. This was most likely a predator of the giant turtle, given not only its size and dietary preferences, but also as inferred by bite marks and punctured bones in fossil carapaces of Stupendemys.Since the scientists also discovered jaws and other skeleton parts of Stupendemys, they were able to thoroughly revise the evolutionary relationships of this species within the turtle tree of life. "Based on studies of the turtle anatomy, we now know that some living turtles from the Amazon region are the closest living relatives," says Sánchez. Furthermore, the new discoveries and the investigation of existing fossils from Brazil, Colombia and Venezuela indicate a much wider geographic distribution of Stupendemys than previously assumed. The animal lived across the whole of the northern part of South America.
|
Extinction
| 2,020 |
February 11, 2020
|
https://www.sciencedaily.com/releases/2020/02/200211104913.htm
|
How some butterflies developed the ability to change their eyespot size
|
New insight on how a butterfly species developed the ability to adjust its wing eyespot size in response to temperature has been published today in
|
The study reveals that the African satyrid butterfly Many butterflies in the nymphalidae family have circular eyespot patterns on their wings that are typically used to deflect attacks from predators. However, in certain seasons, such as the dry season in Africa, the butterflies' best survival strategy is to avoid drawing attention to themselves, and they will shrink the size of their eyespots to make them look like a dead leaf.How butterflies accomplish this feat has only been studied in one species of African satyrid, "For our study, we investigated how this hormone-mediated system came to regulate the size of eyespots by examining the process in several other species of butterflies with and without eyespots," explains lead author Shivam Bhardwaj, who conducted this work as part of his doctoral research in the Department of Biological Sciences at the National University of Singapore (NUS), and who is now a postdoctoral fellow at Mississippi State University. "We wanted to find out which other species change their eyespot size in response to temperature and whether they achieve this through the same mechanism as To do this, Bhardwaj and his team reared 13 different species of satyrid at two different temperatures. They found that all species had lower levels of the 20E hormone in response to low temperatures, but most of them were unable to change the size of their eyespots accordingly. This included species that are known to have different eyespot sizes during wet and dry seasons. "We also saw that a small group of species expressed the hormone receptor in their eyespot centres just like The team then manipulated the 20E hormone in four of the 13 species, and found that Further studies are now needed to understand the different environmental cues that other butterflies use to alter the size of their eyespots during dry and wet seasons."For now, our work uncovers a complex, gradual adaptation to seasonal environments in
|
Extinction
| 2,020 |
February 11, 2020
|
https://www.sciencedaily.com/releases/2020/02/200211092335.htm
|
New method to allow corals to rapidly respond to climate change
|
For the first time, a team of marine biology and environmental genomics researchers at NYU Abu Dhabi (NYUAD) and KAUST (King Abdullah University of Science and Technology) have demonstrated that epigenetic modifications in reef-building corals can be transmitted from parents to their offspring. This discovery, reported in a new study in the journal
|
Climate change is causing significant declines in coral reefs worldwide. The long generation times of corals has inspired fears that corals may not be able to genetically adapt in time to overcome the rapid pace of climate change. However, in the study "Intergenerational epigenetic inheritance in reef-building corals," the NYU Abu Dhabi team led by NYUAD Assistant Professor of Biology Youssef Idaghdour; NYUAD Associate Professor of Biology John Burt; former NYUAD postdoctoral associate Emily Howells and colleagues from King Abdullah University of Science and Technology found that a species of stony coral Epigenetics allows the modification of the "context" of the genome without altering the actual genetic code. Instead, it alters how it is used -- such as when, and to what degree, a gene will be turned on or off.The researchers collected colony fragments from the stony coral from two different ocean environments (Abu Dhabi and Fujairah) and sampled adults, sperm, and larvae from reciprocal crosses. Epigenetic profiles of corals were determined by whole genome sequencing. They identified a strong environmental signature in the epigenome of the coral, as well as the epigenetic factors strongly associated with the extreme hot and saline environment and highlighted their potential effect on coral fitness."What we are finding is a surprising amount of potential for both male and female corals to transmit their epigenome to their offspring," said Idaghdour. "This research shows the capacity of coral parents to positively impact the resilience of their offspring in environments that are changing too quickly. Our learnings in this exciting field hold great potential for the preservation of these unique ecosystems for future generations.""Climate change represents the most pressing threat to coral reefs globally, with most research estimating widespread loss of corals within the next century. Given the long generation times of corals, it has commonly been accepted that the rapid rate of climate change is outpacing the capacity for corals to genetically adapt to cope with increasing temperatures," said Burt. "This study demonstrates that epigenetic changes that enhance thermal tolerance can be passed to offspring, dramatically enhancing corals' capacity to rapidly respond to environmental change."
|
Extinction
| 2,020 |
February 10, 2020
|
https://www.sciencedaily.com/releases/2020/02/200210133210.htm
|
Global warming and extinction risk
|
Rapid climate change is putting increasing pressure on marine organisms. Warming, acidification and oxygen deprivation of seawater are already causing massive changes in marine ecosystems and are likely to lead to massive species extinction by the end of the century. So which groups of animals are particularly at risk? To assess this, biology and paleontology go different ways. Biologists extrapolate from experimental studies and especially predict a gloomy future for those species that are particularly sensitive to warming or oxygen deprivation in the laboratory. Paleontologists, on the other hand, interpolate from fossil data which groups of animals were particularly badly affected in earlier, "natural" warming phases. They argue that these groups should continue to be more sensitive in the future.
|
The study, published in In view of the gigantic differences in the space-time scales considered, the results agree surprisingly well. Bony fish stand out as particularly sensitive in both approaches, while snails and oysters are less threatened. The study thus lays an important basis for future collaboration. Using fossil data, biologists can make more precise predictions of the fate of species for which there are no experimental studies. Meanwhile, paleontologists can use modern experiments to assess the most relevant factors in species extinction. For example, experiments show that the combination of heating and oxygen deprivation is particularly lethal.The study is a result of the research group TERSANE, which is based at the FAU (FOR 2332). In this interdisciplinary project, eight working groups are investigating the conditions under which natural greenhouse gas emissions can reach catastrophic proportions and how they are related to biodiversity crises.
|
Extinction
| 2,020 |
February 10, 2020
|
https://www.sciencedaily.com/releases/2020/02/200210091157.htm
|
'Rule breaking' plants may be climate change survivors
|
Plants that break some of the 'rules' of ecology by adapting in unconventional ways may have a higher chance of surviving climate change, according to researchers from the University of Queensland and Trinity College Dublin.
|
Dr Annabel Smith, from UQ's School of Agriculture and Food Sciences, and Professor Yvonne Buckley, from UQ's School of Biological Sciences and Trinity College Dublin Ireland, studied the humble plantain ("The plantain, a small plant native to Europe, has spread wildly across the globe -- we needed to know why it's been so incredibly successful, even in hot, dry climates," Dr Smith said.The global team of 48 ecologists set up 53 monitoring sites in 21 countries, tagged thousands of individual plants, tracked plant deaths and new seedlings, counted flowers and seeds and looked at DNA to see how many individual plants have historically been introduced outside Europe.What they discovered went against existing tenets of ecological science."We were a bit shocked to find that some of the 'rules of ecology' simply didn't apply to this species," Dr Smith said."Ecologists use different theories to understand how nature works -- developed and tested over decades with field research -- these are the so-called 'rules'."One of these theories describes how genetic diversity or variation in genes embedded in DNA are produced by changes in population size."Small populations tend to have little genetic diversity, while large populations with many offspring, such as those with lots of seeds, have more genetic diversity."Genetic diversity sounds boring, but actually it's the raw material on which evolution acts; more genetic diversity means plants are better able to adapt to environmental changes, like climate change."We discovered that, in their native range, the environment determined their levels of genetic diversity."But, in new environments, these rule breakers were adapting better than most other plants."The team found the plantain's success was due to multiple introductions around the world.Professor Buckley, who coordinates the global project from Trinity College Dublin Ireland, said the DNA analysis revealed that ongoing introductions into Australia, NZ, North America, Japan and South Africa quickly prompted genetic diversity,It gave these 'expats' a higher capacity for adaptation," Professor Buckley said."In Europe plantains played by the rules, but by breaking it outside of Europe, it didn't matter what kind of environment they were living in, the plantains almost always had high genetic diversity and high adaptability."Dr Smith said the finding was fascinating and critical, for two crucial reasons."It's important we now know that multiple introductions will mix genetic stock and make invasive plants more successful quite quickly -- an important finding given invasive species cause extinction and cost governments billions of dollars," she said."And secondly, research on invasive plants gives us clues about how our native plants might adapt to climate change.
|
Extinction
| 2,020 |
February 10, 2020
|
https://www.sciencedaily.com/releases/2020/02/200210074243.htm
|
El Niño contributes to insect collapse in the Amazon
|
Hotter and drier El Niño events are having an alarming effect on biodiversity in the Amazon Rainforest and further add to a disturbing global insect collapse, scientists show.
|
A new study focusing on the humble, but ecologically key, dung beetle has revealed for the first time that intense droughts and wildfires during the last El Niño climate phenomenon, combined with human disturbance, led to beetle numbers falling by more than half -- with effects lasting for at least two years.Although the El Niño of 2015-16 captured less attention than the deforestation fires of 2019, it delivered a very significant drought and, in combination with human activities such as agriculture and deforestation, contributed to mega wildfires that burned more than 3 million hectares of Amazon forests, including a million hectares in just one region.The effects of droughts and wildfires on Amazonia's trees have been studied for decades, but researchers were less clear about the impacts on fauna and the role they have in ecosystem functioning.Dung beetles are key for spreading nutrients and seeds, and they are important indicator insects used to gauge the overall health of an ecosystem.An international team of scientists from the UK, Brazil and New Zealand counted more than 14,000 dung beetles from 98 species across 30 forest plots in the Brazilian state of Pará, within the Amazon, through several surveys conducted between 2010 and 2017. They also monitored how much dung was removed and how many seeds were dispersed by dung beetles.The researchers counted around 8,000 beetles across the plots in 2010. However, in 2016, following the El Niño, numbers had plummeted to around 3,700 and in 2017 they found just 2,600 beetles.Human disturbance, through activities such as deforestation and predatory logging, significantly increases the flammability of the forests -- as forest fires do not occur naturally in the Amazon.All surveyed forests saw beetle numbers fall, though the results also show that forests that burned had fewer beetles than those areas that had just experienced drought."Our investigation provides important insights into how human activities and climate extremes can act together and affect tropical forest biodiversity and ecosystem functioning," said lead researcher Dr Filipe França from the Lancaster Environment Centre at Lancaster University and associate researcher at Embrapa Amazônia Oriental in Brazil.He also said that "The loss of these hardworking beetles could indicate a wider problem that many mammals living in the forest may have also succumbed to the drought and fires. Dung beetles depend on mammal's poo for nesting and feeding, therefore declining in beetles are likely associated with the loss of mammals due to that El Niño drought and fires."Previous research has shown that mammal presence has a large influence on dung beetles.The loss of beetles may indicate other animals were lost, but also raises concerns that forest regeneration will be negatively affected after extreme drought and fire events."We found far fewer dung beetles after the El Niño event, and those that survived were struggling to do their work of spreading nutrients and seeds in forests already impacted either by drought alone or in areas that also experienced fires," explained Professor Rodrigo Fadini from the Federal University of Western Pará in Brazil.Taken together, the research findings suggest that human activities can interact with climate extremes in different ways and that, combined or not, these disturbances can threat the delicate balance of tropical forest fauna, including insects, and their key contribution to ecosystem processes.Professor Jos Barlow from the Federal University of Lavras in Brazil and Lancaster University, said: "Tropical forests around the globe are increasingly threatened by anthropogenic climate change, local human disturbances and more frequent and severe weather extremes. We need actions to mitigate the ongoing climate and biodiversity crisis if we want to keep the forest biodiversity and its contribution to people for future generations."
|
Extinction
| 2,020 |
February 6, 2020
|
https://www.sciencedaily.com/releases/2020/02/200206184326.htm
|
East African fish in need of recovery
|
A study of East African coral reefs has uncovered an unfolding calamity for the region: plummeting fish populations due to overfishing, which in turn could produce widespread food insecurity.
|
In a newly published paper in the journal The remedy, says the sole author of the study, is to recognize the need to rebuild fish stocks to ensure they are providing the maximum possible catch for the developing countries of Kenya, Tanzania, and Mozambique. The African continent has among the highest human population growth rates and associated food security issues."Whereas fish stocks within marine parks and areas in distant or turbulent locations were found to be at healthy levels, coastal areas open to fishing were another story," said McClanahan. "We have found that fish catches have been declining in Africa in recent years by a million tons a year, and this study shows that much of this decline in East Africa is due to declining fish stocks."Based on a sample of 239 sites -- data gathered over several years -- the study and previous estimates show that 70 percent of the reefs have fish stocks below the levels that will produce the maximum fisheries yields. The few areas above this level were in marine parks, rural areas, and remote or dangerous seas.The study further shows that low stocks not only affects food production but also the diversity of fish and reef ecology. Numbers of fish species decline rapidly when stocks decline below sustainable levels. This loss of species will have consequences for the long-term recovery and the potential to produce food.In light of the central finding that fish stocks in East Africa are severely depleted to unsustainable levels, the study suggests that rebuilding fish biomass is the key management action needed for long-term sustainability of the fisheries. Stricter fisheries management and enforcement alongside expanding spatially diverse fishing restrictions are essential to rebuilding stocks, maintaining species diversity, recovering fisheries and ensuring longterm ecosystem services for the East African coast.The study follows on recent fisheries research that reveals that, where fisheries science is active and evaluating reefs, stocks are rebuilding. The fisheries division of the FAO in Rome recently evaluated their needs in the coming decades and concluded that knowing the stock levels of countries without good fisheries science is undermining efforts to achieve global fisheries sustainability.
|
Extinction
| 2,020 |
February 4, 2020
|
https://www.sciencedaily.com/releases/2020/02/200204163654.htm
|
Microbes linked to cancer in threatened California foxes
|
Can staph microbes lead to cancer?
|
Microbes are known to affect digestion, mood and overall health, and now Princeton researchers have shown that a shift in the microbiome is linked to cancer -- at least in a threatened subspecies of foxes found only on one island off the California coast.Their research suggests a several-step process: First, the cat-sized Santa Catalina foxes become infested with ear mites, which change the foxes' microbiome and allow a staph infection to take hold. As Staphylococcus pseudintermedius runs rampant, the antibiotic-resistant infection leads to chronic inflammation of the foxes' ears. In that environment of inflamed tissue, tumors can flourish. The researchers detailed their findings in the journal "We were really excited to find such clear results," said Alexandra DeCandia, the first author on the paper and a graduate student in the lab of Bridgett vonHoldt, an associate professor of ecology and evolutionary biology at Princeton University. "Everything we found -- reduced species diversity, shifts in community composition, overabundance of potentially pathogenic species -- fit within our expectations."The project started during conservation efforts on Santa Catalina Island, when researchers noticed that roughly half of the adult foxes had tumors growing in their ears. That's one of the highest tumor rates ever observed in wildlife, prompting immediate follow-up study.Early work demonstrated a link between ear mite infection and tumor growth. Most researchers theorized that ear mites led to chronic inflammation, ultimately sparking the growth of tumors. DeCandia and vonHoldt's team wanted to know whether the microbiome also played a role in this system.That focus on diversity within the microbiome makes their work "an excellent example of where the field is going to move in the future," said George Amato, the director of conservation genomics at the American Museum of Natural History, who was not involved in this research. "We've only recently learned how important the microbiome is to an individual's health -- whether it's an animal or a human," he said. "Previously, scientists only examined part of the picture. They certainly weren't looking at microbiomes -- they didn't even have tools to do it. ... By examining that, we've come to understand that a lack of diversity in that microbial community, combined with the genetics of the foxes, best helps us understand not only the threat of this particular disease but other diseases as well. This really is a new paradigm for understanding threats to endangered species."The threatened Santa Catalina foxes are one of six subspecies of Channel Island foxes (Urocyon littoralis) that live on six of the eight Channel Islands off the coast of southern California. Several of the subspecies, including those on Santa Catalina (U. littoralis catalinae), have made impressive rebounds from the brink of extinction -- with the result that they are all incredibly similar genetically, nearly clones of each other.The foxes' almost total lack of genetic diversity makes them fascinating research subjects, said DeCandia."We typically view genetic diversity as a good and necessary thing," she said. "It keeps organisms healthy -- think of the negative health effects associated with inbreeding -- and helps populations survive unexpected changes to their environment. But despite having almost no genetic variation, these foxes exhibit very few signs of poor health or inbreeding depression. That leads us to wonder whether other forms of diversity -- such as their resident organisms -- become important players in health and immunity. That's why we focused our study on the microbiome and disease in these foxes."The link between microbes and cancers was an unexpected find, DeCandia said. "When we first set out to do this study, we simply wanted to characterize the microbiome across a few different body sites in the foxes. Just as 19th-century naturalists would charge into a new habitat and catalogue species, we originally intended to catalogue microbes. However, after looking at ear canals more closely, we found there was a lot of variation associated with mite infection status. We then pivoted the paper to focus almost entirely on ear canal microbes associated with mite infection!"With their collaborators from the Catalina Island Conservancy, they swabbed dozens of foxes to collect microbes, then extracted DNA to determine which microbes were present in all of their samples -- and in what relative abundances."Since microbes exist within a community, relative proportion matters," DeCandia said.They found that mite-infected ear canals had significantly different microbial communities than uninfected ears. Overall species richness was lower, and relative abundance was skewed toward one bacterial species: S. pseudintermedius, which is common on canids (including dogs) and can become an opportunistic pathogen when communities are disrupted -- such as by an infestation of mites.The staph microbe then forms antibiotic-resistant biofilms that are "incredibly difficult" for the immune system to eradicate, said DeCandia. As a result, this strain of staph is linked to chronic inflammation in many species.The researchers are still trying to clarify the cause and effect relationships -- for example, whether the mites bring in the staph microbes or they were present but latent until the mites caused enough structural damage to allow the staph to have a population boom -- but the string of correlations is clear: mite infection is linked to a proliferation of S. pseudintermedius, which is linked to the chronic inflammation associated with tumorigenesis.One major outstanding question is why, of the six Channel Island fox subspecies, only three have mites and only one -- the Catalina Island foxes -- show significant tumor growth.The new study reinforces previous research in which members of vonHoldt's lab, including Kennedy Leverett of the Class of 2020, studied changes in the skin microbiome associated with sarcoptic mange, which is caused by a different species of mite. They looked at coyotes, red foxes and gray foxes and found remarkably consistent signatures of microbial disruption that almost exactly matched the island fox study: Infected individuals had reduced microbiome diversity and higher abundance of S. pseudintermedius."Considered together, these two studies suggest that this microbial species is an important player in canid microbiomes and may function in a number of diseases," DeCandia said.
|
Extinction
| 2,020 |
February 4, 2020
|
https://www.sciencedaily.com/releases/2020/02/200204125715.htm
|
Size matters! What drives zoo attendance and how does footfall impact conservation?
|
Scientists from Trinity College Dublin, Species360 and NUI Galway have quantified what drives attendance to zoos by assessing how variations in animal collections affect footfall. Crucially, they link their findings to the contributions made to conservation efforts in situ (in the wild), and find that zoos are making significant, positive impacts on our attempts to conserve biodiversity as our planet enters its sixth mass extinction.
|
Among the headline findings are that zoos with lots of animals, lots of different species (particularly mammals), and with large animals such as elephants, tigers and pandas attract higher numbers of visitors. It is difficult for zoos to fulfil all of these requirements simultaneously however as large animals take up a lot of space and resources meaning relatively few can be accommodated.The research found that instead of a "one size fits all" approach to a zoo collection there are several different strategies that can be used to encourage attendance, including the inclusion of unusual animals. Ultimately higher numbers of visitors led to zoos contributing more conservation activity in the wild.This research used a global data-set for 458 zoos in 58 countries, including species holdings data from the Zoological Information Management System (ZIMS) managed by Species360. More than 1,200 wildlife institutions curate and share animal data as members of Species360, contributing real-time demographic, medical, genetic, and population insights for more than 22,000 species and 10,000,000 individual animals, both living and historic.The research has been published today [Tuesday 4th February 2020] in the journal, Andrew Mooney, PhD Candidate in Trinity's School of Natural Sciences, is first author on the paper. He said:"Zoos and aquariums not only breed and maintain populations of thousands of wildlife species but they also act as centres for public education, wildlife rehabilitation, scientific research and public entertainment. Zoos and aquariums attract more than 700 million people annually around the world and thus they provide an unparalleled audience for conservation education.""Housing large, charismatic animals in zoos and aquariums is being questioned more and more from an ethical perspective, but our research concludes that these animals do not solely play an entertainment role but also serve a broader conservation purpose by indirectly increasing in situ project investment."Yvonne Buckley, Professor of Zoology at Trinity College Dublin, added:"Conserving species in the wild remains the gold standard and with multiple habitats and species coming under ever-more serious threats from a variety of angles, there is an increasing relevance and importance to the role played by the thousands of zoos and aquariums across the globe in supporting conservation in the wild.""Our study provides global evidence to suggest that zoos don't need to compromise their economic viability and entertainment value in order to have a significant value to conservation."
|
Extinction
| 2,020 |
February 4, 2020
|
https://www.sciencedaily.com/releases/2020/02/200204094728.htm
|
New thalattosaur species discovered in Southeast Alaska
|
Scientists at the University of Alaska Fairbanks have identified a new species of thalattosaur, a marine reptile that lived more than 200 million years ago.
|
The new species, Gunakadeit joseeae, is the most complete thalattosaur ever found in North America and has given paleontologists new insights about the thalattosaurs' family tree, according to a paper published today in the journal Thalattosaurs were marine reptiles that lived more than 200 million years ago, during the mid to late Triassic Period, when their distant relatives -- dinosaurs -- were first emerging. They grew to lengths of up to 3-4 meters and lived in equatorial oceans worldwide until they died out near the end of the Triassic."When you find a new species, one of the things you want to do is tell people where you think it fits in the family tree," said Patrick Druckenmiller, the paper's lead author and director and earth sciences curator at the University of Alaska Museum of the North. "We decided to start from scratch on the family tree."Prior to the discovery of Gunakadeit joseeae, it had been two decades since scientists had thoroughly updated thalattosaur interrelationships, Druckenmiller said. The process of re-examining a prehistoric animal's family tree involves analyzing dozens and dozens of detailed anatomical features from fossil specimens worldwide, then using computers to analyze the information to see how the different species could be related.Druckenmiller said he and collaborator Neil Kelley from Vanderbilt University were surprised when they identified where Gunakadeit joseeae landed."It was so specialized and weird, we thought it might be out at the furthest branches of the tree," he said. Instead it's a relatively primitive type of thalattosaur that survived late into the existence of the group."Thalattosaurs were among the first groups of land-dwelling reptiles to readapt to life in the ocean," Kelley said. "They thrived for tens of millions of years, but their fossils are relatively rare so this new specimen helps fill an important gap in the story of their evolution and eventual extinction."That the fossil was found at all is a remarkable. It was located in rocks in the intertidal zone. The site is normally underwater all but a few days a year. In Southeast Alaska, when extreme low tides hit, people head to the beaches to explore. That's exactly what Jim Baichtal, a geologist with the U.S. Forest Service's Tongass National Forest, was doing on May 18, 2011, when low tides of -3.7 feet were predicted.He and a few colleagues, including Gene Primaky, the office's information technology professional, headed out to the Keku Islands near the village of Kake to look for fossils. Primaky saw something odd on a rocky outcrop and called over Baichtal, "Hey Jim! What is this?" Baichtal immediately recognized it as a fossilized intact skeleton. He snapped a photo with his phone and sent it to Druckenmiller.A month later, the tides were forecasted to be almost that low, -3.1 feet, for two days. It was the last chance they would have to remove the fossil during daylight hours for nearly a year, so they had to move fast. The team had just four hours each day to work before the tide came in and submerged the fossil."We rock-sawed like crazy and managed to pull it out, but just barely," Druckenmiller said. "The water was lapping at the edge of the site."Once the sample was back at the UA Museum of the North, a fossil preparation specialist worked in two-week stints over the course of several years to get the fossil cleaned up and ready for study.When they saw the fossil's skull, they could tell right away that it was something new because of its extremely pointed snout, which was likely an adaptation for the shallow marine environment where it lived."It was probably poking its pointy schnoz into cracks and crevices in coral reefs and feeding on soft-bodied critters," Druckenmiller said. Its specialization may have been what ultimately led to its extinction. "We think these animals were highly specialized to feed in the shallow water environments, but when the sea levels dropped and food sources changed, they had nowhere to go."Once the fossil was identified as a new species, it needed a name. To honor the local culture and history, elders in Kake and representatives of Sealaska Corp. agreed the Tlingit name "Gunakadeit" would be appropriate. Gunakadeit is a sea monster of Tlingit legend that brings good fortune to those who see it. The second part of the new animal's name, joseeae, recognizes Primaky's mother, Joseé Michelle DeWaelheyns.
|
Extinction
| 2,020 |
January 29, 2020
|
https://www.sciencedaily.com/releases/2020/01/200129143358.htm
|
The health of foundation species promotes the stability of the ecosystems that depend on them
|
Anyone who's read "The Lorax" will recognize that certain species serve as the foundation of their ecosystems. When the truffula trees disappear, so to do the swomee-swans and bar-ba-loots. However, the same is not necessarily true the other way around.
|
Scientists have taken a growing interest in ecological stability -- the factors that make an ecosystem robust against pressures and perturbations -- especially in light of human impacts like climate change and pollution. Though many presume that the stability of an ecosystem's foundation species will promote stability overall, few have quantified this effect as of yet.Researchers at UC Santa Barbara's Marine Science Institute (MSI) have leveraged long-term ecological data to probe this question in Southern California's kelp forests. They found a correlation between the stability of giant kelp and the stability in understory seaweed and seafloor invertebrates, such as sponges, as well as higher biodiversity over all. Their results appear in the journal A foundation species shapes its entire environment and defines an ecosystem. "The ecosystem in which they live is often named after them, like oyster beds, coral reefs, or redwood forests," said Robert Miller, a research biologist at MSI and one of the paper's coauthors. They generally provide the ecosystem's physical structure or main source of food, and as such, have a strong effect on the species that live there."The fact that a foundation species, such as giant kelp, could promote the stability of the species for which it provides food and habitat might seem trivial," said lead author Thomas Lamy, a postdoctoral researcher at MSI. "This was part of the original definition of a foundation species -- which dates back to around 1972 -- but had never been tested before."The researchers pored over 18 years of ecological data from nine shallow reefs in the Santa Barbara Channel. The information included species size and abundance, biodiversity, and biomass, among many other useful data. Statistics and mathematical modeling enabled the scientists to uncover trends and patterns in the data.The team considered different groups of organisms separately to better understand the ecosystem's dynamics. "It's hard to compare the diversity of, for example, bacteria with the diversity of whales," Miller remarked. For this study, that meant looking at understory algae and invertebrates separately, which revealed nuances that were hidden when the groups were lumped together."We found a positive link between the stability of the giant kelp and the stability of understory macroalgae and seafloor invertebrates," said Lamy.So, giant kelp has a giant effect on the kelp forest. "It can sound rather intuitive," he acknowledged, "but sometimes these are the most difficult ideas to test. As pointed out before, this requires a lot of ecological data."Fortunately, the researchers had the benefit of nearly two decades of data and observations courtesy of the Santa Barbara Coastal Long-Term Ecological Research Project (SBC LTER). The Marine Science Institute manages the SBC LTER, which is part of a network of sites run by the National Science Foundation."That's the advantage of the LTER program: It enables us to look at long-term questions that are critical to ecology," Miller said.The group found that most of giant kelp's influence on the forest's stability came indirectly. Robust kelp increased species diversity and this in turn increased the ecosystem's stability. In a previous study, the group found that biodiversity alone can bolter stability. If the abundance of different species fluctuates out of sync with each other, their variability tends to even out as a whole, leading to a more stable ecosystem overall. And greater biodiversity means more species contribute to this effect."This is what we would expect if giant kelp truly is a foundation species that the whole ecosystem is depending on," Miller said.Stable kelp forests may harbor more species by promoting steady recruitment, balancing the availability of limiting resources, or providing refuge from different stresses, Lamy suggested. The team plans to investigate these mechanisms in future work.The relationship between kelp and kelp forests is of particular interest and concern to scientists, who think that the stability of kelp is likely to change in the future. Climate change promises to bring more warming events, larger waves, and stronger storms, all conditions that place pressure on giant kelp. Understanding the relationship between foundation species' stability and ecosystem stability will help us anticipate how the ecosystem will react and then respond accordingly.
|
Extinction
| 2,020 |
January 29, 2020
|
https://www.sciencedaily.com/releases/2020/01/200129143341.htm
|
The 'firewalkers' of Karoo: Dinosaurs and other animals left tracks in a 'land of fire'
|
In southern Africa, dinosaurs and synapsids, a group of animals that includes mammals and their closest fossil relatives, survived in a "land of fire" at the start of an Early Jurassic mass extinction, according to a study published January 29, 2020 in the open-access journal
|
The Karoo Basin of southern Africa is well-known for its massive deposits of igneous rocks left behind by extensive basaltic lava flows during the Early Jurassic. At this time, intense volcanic activity is thought to have had dramatic impacts on the local environment and global atmosphere, coincident with a worldwide mass extinction recorded in the fossil record. The fossils of the Karoo Basin thus have a lot to tell about how ecosystems responded to these environmental stresses.In this study, Bordy and colleagues describe and identify footprints preserved in a sandstone layer deposited between lava flows, dated to 183 million years ago. In total, they report five trackways containing a total of 25 footprints, representing three types of animals: 1) potentially small synapsids, a group of animals that includes mammals and their forerunners; 2) large, bipedal, likely carnivorous dinosaurs; and 3) small, quadrupedal, likely herbivorous dinosaurs represented by a new ichnospecies (trace fossils like footprints receive their own taxonomic designations, known as ichnospecies).These fossils represent some of the very last animals known to have inhabited the main Karoo Basin before it was overwhelmed by lava. Since the sandstone preserving these footprints was deposited between lava flows, this indicates that a variety of animals survived in the area even after volcanic activity had begun and the region was transformed into a "land of fire." The authors suggest that further research to uncover more fossils and refine the dating of local rock layers has the potential to provide invaluable data on how local ecosystems responded to intense environmental stress at the onset of a global mass extinction.Bordy adds: "The fossil footprints were discovered within a thick pile of ancient basaltic lava flows that are ~183 million years old. The fossil tracks tell a story from our deep past on how continental ecosystems could co-exist with truly giant volcanic events that can only be studied from the geological record, because they do not have modern equivalents, although they can occur in the future of the Earth."
|
Extinction
| 2,020 |
January 23, 2020
|
https://www.sciencedaily.com/releases/2020/01/200123152509.htm
|
Large marine parks can save sharks from overfishing threat
|
'No-take' marine reserves -- where fishing is banned -- can reverse the decline in the world's coral reef shark populations caused by overfishing, according to an Australian study.
|
But University of Queensland, James Cook University (JCU) and University of Tasmania researchers found that existing marine reserves need to be much larger to be effective against overfishing.UQ's Dr Ross Dwyer said the study estimated that no-take reserves that extend between 10 and 50 kilometres along coral reefs can achieve significant improvements in shark populations."Existing protected areas on coral reefs would need to be enforced as strict no-take reserves and be up to five times larger to effectively conserve reef sharks," Dr Dwyer said."Those in the Atlantic where reef sharks are generally less abundant would need to be on average 2.6 times larger than those in the Indian and Pacific Oceans."Species such as grey reef sharks have experienced severe population declines across parts of their distribution, largely due to their low fecundity, late age at sexual maturity, and high susceptibility to fishing pressure.They are listed as Near Threatened in the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species.The researchers combined large volumes of tracking data on five species of sharks found on coral reefs in the Indian, Pacific and Atlantic oceans, with video survey data from 36 countries."This allowed us to predict the conservation benefits no-take reserves of different sizes could generate," Dr Dwyer said.JCU Professor Colin Simpfendorfer from James Cook University said shark populations were in trouble in most parts of the world."Finding ways to rebuild their populations is critical to ensuring our oceans remain healthy," Professor Simpfendorfer said."This project is providing options for managers of coral reefs to address declines in shark populations which scientists know have occurred in many areas."Dr Nils Krueck from the University of Tasmania said researchers now have the ability to estimate conservation and fishery impacts of marine reserves much more precisely."Our results show that marine parks for reef sharks need to be large. But if reserves extend along 15 kilometres of coral reef, then fishing mortality can be reduced by fifty per cent," Dr Krueck said.The study, funded by the Shark Conservation Fund, is published in the journal
|
Extinction
| 2,020 |
January 23, 2020
|
https://www.sciencedaily.com/releases/2020/01/200123095848.htm
|
Bending with the wind, coral spawning linked to ocean environment
|
During the early summer, corals simultaneously release tiny balls composed of sperms and eggs, known as bundles, that float to the ocean surface. Here the bundles open, allowing the sperm to fertilize the eggs where they eventually settle on the seafloor and become new coral on the reef.
|
This spectacular annual event is known as "mass-spawning," and usually occurs at night. Although the occurrence of mass-spawning happens around the time of a full moon, it is difficult to predict precisely when. Now, a research team from Tohoku University, Ochanomizu University, and the National Institute for Basic Biology have utilized modeling analysis to indicate that environmental factors act as a determinant in the timing of mass spawning."Coral spawning is a complex phenomenon," says Shinchiro Maruyama, an assistant professor at Tohoku University. "It is too complicated to model all the factors involved in a spawning event, so we decided to focus on which day they spawn. Although we know that they spawn a few hours after the dusk, the days can differ according to regions, and even within the same reef."Maruyama and his team utilized a multidisciplinary approach to address the role of environmental factors, such as temperature; wind speed; and sunlight, to determine the night of spawning, teaming up with specialists in ecology, statistics, physiology, developmental biology, and evolutionary biology. Drawing upon field research, satellite data and literature reviews, they discovered that corals changed the nights of spawning according to the environmental conditions for a period of time before 'the big night.'Maruyama adds that, "Such fine-tuning for the night of spawning might be advantageous for corals to maximize their chances or meeting future partners in the vast expanses of the ocean."Coral reefs are a natural treasure of biodiversity in the ocean and understanding mass-spawning gives us further insight into their behavior. Identifying that environmental changes play a role in the mass-spawning timing provides a building block for scientists to address corals behavior going forward.
|
Extinction
| 2,020 |
January 22, 2020
|
https://www.sciencedaily.com/releases/2020/01/200122080504.htm
|
Biologists recommend urgent action to protect California spotted owls
|
In the Pacific Northwest, the range expansion of Barred Owls has contributed to a conservation crisis for Northern Spotted Owls, which are being displaced from their old-growth forest habitat. How will this interaction between species play out in the Sierra Nevada, where Barred Owls are just starting to move into the range of the California Spotted Owl? New research published in
|
The University of Wisconsin's Connor Wood and his colleagues used passive acoustic monitoring to survey Barred Owl populations over two years, deploying audio recorders over an area spanning more than 6,000 square kilometers across two national forests in northern California. Locating owl calls in the audio data allowed them to determine which sites were and were not occupied by owls. They found a 2.6-fold increase in the amount of territory occupied by Barred Owls between 2017 and 2018, and the old forest habitat preferred by Spotted Owls was the most likely to be colonized.Populations of invasive species typically remain at low densities for several generations before growing rapidly. Because intervening to control a potentially damaging invasive species requires many resources, land managers often wait for strong evidence that a species will pose a threat before taking action. But, by the time the "growth phase" has started, it's often too late. Wood and his colleagues believe their results show that the growth phase of the Barred Owl population in the region is just beginning, meaning wildlife managers still have time to act. Only a narrow band of fairly unsuitable habitat connects the existing Pacific Northwest population of Barred Owls to the Sierra Nevada stronghold of California Spotted Owls, and the researchers recommend experimentally removing Barred Owls from the Sierra Nevada side of this pinch point to see if this can prevent them from becoming established further south."We suggested that managers act according to the Precautionary Principle: when there is a serious threat to human health or the environment, proactive responses are justified even if there is some uncertainty," says Wood. "We feel that experimental Barred Owl removals in the Sierra Nevada are an important step in determining the best long-term management strategy. This is not something that anyone takes lightly, but we feel that it is warranted because of the very real possibility that continued Barred Owl population growth could seriously endanger the California Spotted Owl. By catching this invasion in the early stages, we have a unique but potentially fleeting opportunity to inform policies that could prevent the California Spotted Owl from being driven extinct in the core of its range."
|
Extinction
| 2,020 |
January 22, 2020
|
https://www.sciencedaily.com/releases/2020/01/200122080530.htm
|
Caterpillar loss in tropical forest linked to extreme rain, temperature events
|
Using a 22-year dataset of plant-caterpillar-parasitoid interactions collected within a patch of protected Costa Rican lowland Caribbean forest, scientists report declines in caterpillar and parasitoid diversity and density that are paralleled by losses in an important ecosystem service: biocontrol of herbivores by parasitoids.
|
The study by University of Nevada, Reno researchers, published in "Declines in herbivore and enemy diversity, as well as parasitism frequency, are partly explained by changes in climate, including increases in extreme precipitation events and increases in mean temperatures," lead author of the study Danielle Salcido said.In 2017, the observation by Professor Lee Dyer, of the University's College of Science, that La Selva Biological Research Station, Costa Rica experienced more frequent flooding events, became the catalyst for a study led by graduate student Salcido to examine patterns in extreme precipitation events and their potential ecological impact for plant-caterpillar-parasitoid interactions in this lowland tropical forest."La Selva is an isolated patch of forest surrounded by agriculture that is responsible for global exports of banana, pineapple and palm," Salcido said. "Habitat patches like La Selva are source populations of parasitoids that control pest populations in surrounding agriculture plantations. Reductions in parasitism by specialized parasitoids threaten this service and ultimately ecosystem health within the forest."Along with the help of coauthor and University of Nevada, Reno professor, biologist and butterfly expert Matthew Forister, these researchers found staggering declines in caterpillar and parasitoid diversity and density across the 22 years of the study. More than 40% of the 64 common caterpillar genera collected declined in frequency- a result that suggested the loss of entire groups of caterpillar.Researchers also found an ecological cost associated with the observed losses. Tandem with declines in diversity, was the reduction in parasitism across years- a natural form of biocontrol and important ecosystem service. Observed declines represented a 30% reduction in parasitism over the next 100-years.Increased precipitation variability and shifts in mean maximum and minimum temperatures were the most important climate variables associated with declines in diversity."We show climate change partially explains the observed declines," Salcido said. "The variable with largest effect in all models was the effect of time, and indicates the role of unmeasured variables such as surrounding land-use change and pesticide use."In the decades prior to the study, much of the forest surrounding La Selva was deforested for pasture which was converted to high-yield, high input plantation farming such that pesticide use increased substantially during the years of the study.Time-lag effects of extreme climate events were a notable contributor to the reduction in parasitism."We found floods in a given year affected parasitism in the subsequent year," she said. "Caterpillar-parasitoid interactions are intimately linked and depend on narrow windows for synchronous development. Subtle shifts in host and parasitoid population cycles due to variable lag effects can have major consequences for these highly-specialized and synched interactions."Declines in insect biodiversity reported in this study come as little surprise amidst a recognized global biodiversity crisis. This study maintains a level of urgency to the matter of insect declines and more importantly, has revealed the vulnerability of the most speciose regions and taxa even within protected habitats, and the role of extreme climate events on ecosystem function."This dataset represents one of few of its kind and is notable for the contribution by Earthwatch community scientists," Salcido said. "Ideally results like ours provide an impetus for policy change that promotes research, conservation and management. In the least, we hope it motivates continued research related to the ecological effects of global change drivers in the tropics."The data used for this study is primarily collected by continuous teams of community scientists the scientists bring to the site each year, which highlights the importance of harnessing public participation for the success and longevity of long-term and continuous tropical collection and monitoring.The Paper in the Nature research journal Forister and Dyer recently coauthored, with 70 other scientists from around the world, a second paper in the Nature publication Nature Ecology and Evolution titled "International scientists formulate a roadmap for insect conservation and recovery" that is testament to the call-to-action prompted from increased public awareness on insect declines. Their road map to insect conservation and recovery was published this week.
|
Extinction
| 2,020 |
January 21, 2020
|
https://www.sciencedaily.com/releases/2020/01/200121124024.htm
|
The little auks that lived in the Pacific
|
Findings from a 700,000-year-old fossil bone indicate that a close relative of the most abundant seabird species in the North Atlantic, the modern dovekie, or 'little auk', used to thrive in the Pacific Ocean and Japan.
|
Seabirds are top predators in the marine ecosystem, and their distributions are shaped by numerous environmental factors in the ocean. As such, extensive scientific inquiries have been conducted on how seabirds respond to fluctuating oceanic environments in the ecologic and geologic timescales."The North Pacific has been one of the most intently investigated regions, but the fossil record of seabirds in the Pleistocene Epoch, about 2.6 to 0.01 million years ago, has been scarce," explains first author Junya Watanabe of Kyoto University's School of Science. "This has led to a frustrating lack of information in this critical time period concerning the origin of modern seabird communities."In recent years, Watanabe and his team had been investigating seabird fossils from several locations in Chiba and Tokyo prefectures, gaining new insight on the Pleistocene seabird community in the region.The group had been successful in identifying 17 fossils representing at least 9 species of birds: three species of ducks, a loon, an albatross, a shearwater, a cormorant, an extinct penguin-like seabird called mancalline auk, and a dovekie. Most of these species can be found in the region today; however, the presence of a dovekie was completely unexpected.Watanabe explains his findings published in "At first it confused us that the fossil didn't match any of the Pacific auks, but once we compared it with Atlantic ones, the similarity with the modern dovekie was apparent. It is not clear whether the present fossil is from the same species or a very close cousin, but we are positive it at least comes from the same lineage."The dovekies we know today are mostly restricted to the North Atlantic and Arctic oceans, with their rare sightings in Japan considered accidental visits. Given the unlikeliness of such accidental visitors to be preserved as fossils, the new findings suggest that dovekies were once fairly common in Japan and the Pacific.He continues, "Now the question is Interestingly, local decline and extinction events in the past are common in many seabird groups. Deciphering possible causes of such events requires integration of knowledge from various disciplines, including paleontology, paleoclimatology, oceanography and seabird ecology. Watanabe and his team see this as a challenging but rewarding endeavor.
|
Extinction
| 2,020 |
January 21, 2020
|
https://www.sciencedaily.com/releases/2020/01/200121112939.htm
|
Corals' partnership with microalgae helps in stressful times but there's a trade-off
|
In the warmer and brighter shallow waters of Kāne'ohe Bay, O'ahu, the Hawaiian rice coral (Montipora capitata) hosts more heat-tolerant symbiotic microalgae in their tissues compared to corals in deeper waters. This pattern was demonstrated in a recent study by scientists at the University of Hawai'i (UH) at Manoa School of Ocean and Earth Science and Technology (SOEST), and they suggest that while this can help corals weather a heat wave, it may have a price -- lower nutrition when the heat wave has passed and seawater temperatures cool down.
|
Kāne'ohe Bay has experienced significant human impacts over the last century related to dredging, sewage pollution, and urbanization, in addition to regional bleaching events due to climate change. Despite this unique and troubled history, corals thrive in Kāne'ohe Bay. In some corals, this enhanced ability to tolerate environmental stress can in part be attributed to the species of microalgae corals harbor within their tissues.Research over the last two decades has shown that coral's symbiotic algae are quite distinct, each group having different abilities and capacities to tolerate stress, like elevated seawater temperatures that cause coral bleaching."We wanted to know more about how these symbionts affected corals and whether trade offs existed for corals harboring different symbiont species," said Chris Wall, lead author of the study and postdoctoral researcher at SOEST's Pacific Biosciences Research Center.Rice corals form partnerships with two distinct communities of symbiotic microalgae. Using genetic sequencing, the research team found that light availability is shaping the distribution of these symbiont communities in corals sampled from Kāne'ohe Bay, with the heat-tolerant symbionts being more common in shallow depths. Interestingly, although the heat-tolerant microalgae were present in much greater abundance inside the coral's tissues relative to other symbiont species, they were providing less energy to their shallow coral hosts.Reef corals rely on two sources of energy: from their symbiotic microalgae that live harmoniously within the coral, and food in the surrounding water, such as microscopic shrimp-like animals."What was surprising was that corals did not compensate for less food from their symbionts by eating more food in the water column," said Wall. "This was a very cool finding, because we confirmed for the first time that the symbiont species living in corals were affecting nutrition in the field."Together, the dark water and greater frequency of disturbances may have allowed stress-tolerant coral symbionts, thought to be more opportunistic and 'selfish', to proliferate within the local coral population. This study shows that while stress tolerance may be favorable during challenging periods, these symbionts provide less food to their corals, which may not be as beneficial to the corals in the long term."Climate change and ocean warming are changing the costs and benefits of these interactions between corals and their symbiont algae," said Wall. "As we consider techniques for assisting corals in their ability to tolerate environmental stress, our work highlights the need to consider how symbiont communities influence corals beyond stress tolerance. Our findings are also important for people in Kāne'ohe Bay, considering the corals with these stress-tolerant algae are found at higher abundance in the shallows. Any damage from anchors and boat-strikes could seriously harm these coral populations."
|
Extinction
| 2,020 |
January 21, 2020
|
https://www.sciencedaily.com/releases/2020/01/200121112910.htm
|
Zero-deforestation pledges to protect wildlife in oil palm
|
New research has found that environmental efforts aimed at eliminating deforestation from oil palm production have the potential to benefit vulnerable tropical mammals.
|
These findings, published by In a promising development, the Roundtable on Sustainable Palm Oil (RSPO) has recently committed to zero-deforestation on plantations certified as sustainable, as a way to prohibit forest clearance during the development of new agricultural areas. This is achieved using the High Carbon Stock (HCS) Approach, a land-use planning tool that aims to protect patches of well-connected, high quality forest.In their study of forest patches in Borneo Dr Deere and his colleagues found that those forests greater than 100 hectares, and afforded the highest conservation priority by High Carbon Stock protocols, supported larger populations of threatened species particularly sensitive to deforestation, such as sun bears and orangutans.Using camera-trap information, the size of the mammal population was greatest in larger and more connected forest patches. However, hunting and forest quality compromised the suitability of the patch for many species, indicating the importance of accounting for the impacts of human activities on wildlife in agricultural areas.While the study highlights the potential for zero-deforestation approaches to contribute to wildlife conservation, the feasibility of protecting patches large enough to sustain sufficient numbers of species was called into question.The study found that in the 100 hectares patches (the minimum criterion for high priority conservation status in HCS), only 35% of mammal species that would otherwise be present in continuous forest would be protected. In fact, patches would need to be 30 times larger to support the mammal community, and even larger if the effects of hunting were considered. Preserving forest patches of this size is simply unrealistic in most plantations.Dr Deere said: 'The HCS protocols seem to work well in prioritising patches of wildlife-friendly forest within oil palm plantations, but it's not enough for many of the species we studied. A switch in emphasis towards joining up forest patches and managing them together across farmland landscapes would really help wildlife conservation in the long term.'
|
Extinction
| 2,020 |
January 17, 2020
|
https://www.sciencedaily.com/releases/2020/01/200117122119.htm
|
Transformational innovation needed to reach global forest restoration goals
|
The U.N. and other international organizations agree that forest restoration is a critical part of the collective global effort to combat climate change, reduce extinctions, and improve the lives of people in rural communities. Dozens of nations have pledged to restore 230 million hectares of forest so far as part of projects such as the Bonn Challenge and REDD+. The Bonn Challenge goal is to restore 350 million hectares by 2030.
|
The leaders behind this work agree that ambitious goals are important if humanity is going to avoid the worst effects of climate change. However, a new paper in The authors found that most of the gap between goals and reality exists in the global South, a group of nations generally south of the equator previously referred to as developing countries. These are also the countries that pledged to restore the greatest amounts of land, the paper reports. For example, Rwanda pledged to restore 81 percent of its total land area, and Burundi pledged 79 percent. One-third of the countries pledged greater than 10 percent of their total area, which would require significant shifts in land use and food production.The authors hypothesize multiple reasons for the large pledges from global South countries. "It could be that global South countries are more aware of the risks they face from climate change, and are therefore more interested in doing something about it," says Matthew Fagan, assistant professor of geography and environmental systems at UMBC and lead author on the paper. "They also generally have lower labor and land costs, making it easier for them to do restoration." On the other hand, they could be trying to access more dollars from international donor organizations to reach these aspirational goals, or could have underestimated the challenges of restoration at that scale.The paper also attempted to predict which countries would have the greatest difficulty meeting their goals based on a dozen factors the team analyzed, such as population growth, government corruption, and previous deforestation rates.Justin Drew '20, computer science, and a co-author on the paper, compiled the data for all 12 factors by writing computer code to pull quantitative information from public international databases. He also scoured the internet for information on individual countries' progress. Drew collected reliable information on the 12 factors for all 62 countries making restoration commitments, and progress information for 12 of them. "When we asked how they did based on these twelve factors, we found they did about as well as we expected," says Fagan. Countries with the lowest combined score considering all the implementation factors tended to be farther from meeting their goals.But all is not lost. "We've identified countries that need help" to achieve their ambitious environmental goals, says Fagan. "It's clear that there's a whole set of countries that are facing headwinds, and if we expect them to be able to accomplish their goals, then the international community needs to support them."Increased financial aid is important, but so are other means of support. That might mean providing technical tools and training to help governments and local communities make informed decisions about restoration efforts. Above all, it means listening to local communities' needs and working in collaboration to create solutions."Restoration efforts have a better chance of achieving sustained improvement when local communities have a voice early in the process, feel empowered to participate actively throughout, and can experience direct and long-term benefits from these efforts," says Maggie Holland. She is an associate professor of geography and environmental systems at UMBC and a co-author on the paper.In one location, the best solution might be planting trees on agricultural land, such as shade-grown coffee. Other places, it might be tree plantations, reclaiming agricultural land for forest, or thinning existing forests to prevent fires."Different efforts will yield different benefits for mitigating climate change, for helping people, for restoring ecosystem health and conserving biodiversity," Holland says. She suggests that more social science research on the results of different strategies is needed to deploy them most effectively.There are other, less direct, efforts that can also have a huge effect on forests. "Even if countries haven't necessarily made big strides in restoration, in some cases they're making big policy changes that will hopefully result in restoration in the longer term," Fagan says. For example, bringing electricity to more rural communities reduces the need for fuel wood and charcoal. That reduces forest loss while also improving human health by removing smoke from homes.Ultimately, the researchers argue that while it may sound good to pledge huge areas of land, that might not be the best strategy to reach the goals of combating climate change, improving people's lives, and protecting species from extinction. If countries feel pressured to meet their ambitious goals, they might employ the easiest restoration strategies, such as thinning forest. The U.S., for example, has already met its goal of 15 million hectares, and the vast majority of it was through this method. That may have some beneficial effects, like decreasing the chance of forest fires, but it's not the same as planting trees on agricultural land or shifting land use patterns.In addition to supporting countries in need, "I think the wealthier countries need to get on this bandwagon and do more themselves as well," Fagan says. Ambitious, but realistic, and locally appropriate goals are the best way to succeed, Fagan and Holland agree.Overall, Fagan is "guardedly optimistic." "There's a lot of potential and a lot of interesting policy work going on. I believe, though, that there's a time to build your castles in the air, and now it's time to put foundations under them. We're underinvesting in the foundations, and we need to spend more international aid money on helping countries figure out how to meet these commitments," he says."I'd like to hope that this article helps generate more support for that kind of work," Fagan shares, "because I think it is possible to make this kind of change."
|
Extinction
| 2,020 |
January 16, 2020
|
https://www.sciencedaily.com/releases/2020/01/200116141708.htm
|
In death of dinosaurs, it was all about the asteroid -- not volcanoes
|
Volcanic activity did not play a direct role in the mass extinction event that killed the dinosaurs, according to an international, Yale-led team of researchers. It was all about the asteroid.
|
In a break from a number of other recent studies, Yale assistant professor of geology & geophysics Pincelli Hull and her colleagues argue in a new research paper in Most scientists acknowledge that the mass extinction event, also known as K-Pg, occurred after an asteroid slammed into Earth. Some researchers also have focused on the role of volcanoes in K-Pg due to indications that volcanic activity happened around the same time."Volcanoes can drive mass extinctions because they release lots of gases, like SOTo pinpoint the timing of volcanic gas emission, Hull and her colleagues compared global temperature change and the carbon isotopes (an isotope is an atom with a higher or lower number of neutrons than normal) from marine fossils with models of the climatic effect of CO"Volcanic activity in the late Cretaceous caused a gradual global warming event of about two degrees, but not mass extinction," said former Yale researcher Michael Henehan, who compiled the temperature records for the study. "A number of species moved toward the North and South poles but moved back well before the asteroid impact."Added Hull, "A lot of people have speculated that volcanoes mattered to K-Pg, and we're saying, 'No, they didn't.'"Recent work on the Deccan Traps, in India, has also pointed to massive eruptions in the immediate aftermath of the K-Pg mass extinction. These results have puzzled scientists because there is no warming event to match. The new study suggests an answer to this puzzle, as well."The K-Pg extinction was a mass extinction and this profoundly altered the global carbon cycle," said Yale postdoctoral associate Donald Penman, the study's modeler. "Our results show that these changes would allow the ocean to absorb an enormous amount of COThe International Ocean Discovery Program, the National Science Foundation, and Yale University helped fund the research.
|
Extinction
| 2,020 |
January 15, 2020
|
https://www.sciencedaily.com/releases/2020/01/200115093439.htm
|
Analyzing DNA in soil could be an effective way of tracking animals
|
It's hard to protect something you can't find. A new Stanford study reveals sampling soil for animals' left-behind DNA can provide valuable information for conservation efforts -- with significantly less cost and time -- than currently used methods, such as camera traps.
|
The process, outlined Jan. 14 in "We need a quantum leap in the way we identify and track animals," said study lead author Kevin Leempoel, a postdoctoral research fellow in biology at Stanford. "This may be it."The specter of extinction hangs over more than a quarter of all animal species, according to the best estimate of the International Union for Conservation of Nature, which maintains a list of threatened and extinct species. Conservationists have documented extreme declines in animal populations in every region of Earth.One of the most promising tools for monitoring biodiversity -- key to large-scale conservation efforts -- is the study of environmental DNA, or eDNA, in discarded animal materials, such as hair, feces, skin and saliva. After extracting DNA, scientists sequence and compare it to online DNA sequence databases to identify the species. It's a relatively fast, low-maintenance process compared to traditional approaches, such as live-trapping, animal tracking and camera trapping, for studying species diversity, distribution and abundance. The researchers spent about $4,500 for all the study's supplies, other than lab equipment. A similar study with camera traps could cost more than twice as much.Despite the obvious advantages, questions about the efficacy of eDNA analyses have remained. That's in part because most research so far has been done only in ocean and freshwater environments. Among the few studies done on land, most have been in enclosed areas, such as zoos, or limited to a small number of species.Working at Stanford's 1,193-acre Jasper Ridge Biological Preserve, Leempoel and his colleagues studied eDNA in soil. Not only did they identify almost every animal that nearby camera traps had spotted in the previous four years, they also found genetic evidence of a number of small mammals, including bats and voles, rarely if ever seen by the cameras. These creatures had likely escaped the cameras' gaze because they are too small to trigger them. Overall, there was an 80 percent chance of finding an animal's eDNA in an area within 30 days of the animal's presence there.Another advantage of eDNA is the possibility of distinguishing species that look similar. For example, the researchers found the DNA of the Norway rat in soil samples, confirming the presence of this species in the area for the first time. Previous camera surveys could not tell the difference between Norway and black rats.Compared with camera records and other observations, eDNA identifications appeared to be closely correlated with how frequently and recently animals had been in the area. The analysis turned up no hint of badgers -- unrecorded on cameras for the previous four years -- domestic cats or weasels -- caught on camera only a few times in the previous two years."By corroborating photographs of animals with their genetic remains in the environment, this study reveals both hidden biodiversity in a terrestrial ecosystem and how well these eDNA techniques will work in other places," said study senior author Elizabeth Hadly, the Paul S. and Billie Achilles Professor in Environmental Biology in Stanford's School of Humanities and Sciences.Despite these positive results, questions remain about the potential of eDNA analysis. Scientists do not know how frequently an animal must pass by a given area to be detectable in an eDNA sample, or how recent that passage must be. If an animal's size affects the amount of DNA it leaves behind, as the researchers speculate, some animals would only rarely be sampled while others would be overrepresented. No one knows the precise volume and number of samples that should be collected for maximum accuracy, which environmental source -- soil or something else -- is the most versatile, or whether all species are even detectable via eDNA analysis.The study results appeared to overrepresent some species, such as mountain lions and bobcats, possibly due to the felines' habit of frequently marking their territory with urine and feces, and because they frequently use trails such as those where the researchers took soil samples. In general, it's impossible to know whether pieces of skin, fur or dried scat were transported by wind or by other species that had consumed the animal as prey.Perhaps most importantly, incomplete DNA databases and limitations of the study's design made it difficult to detect all species present in the area, and caused at least two inconsistent results among the genetic sequencing approaches the researchers used. Analyzing eDNA remains relatively time-consuming because proven protocols have yet to be established. Still, the researchers are optimistic about the approach's promise."Its overall accuracy, combined with decreasing costs of genetic sequencing and new portable sequencers, makes eDNA a likely candidate to become the standard for biodiversity surveys in the next decade," Leempoel said.
|
Extinction
| 2,020 |
January 14, 2020
|
https://www.sciencedaily.com/releases/2020/01/200114104031.htm
|
New parasitoid wasp species discovered in the Amazon -- can manipulate host's behavior
|
A research group from the Biodiversity Unit of the University of Turku studies the diversity of parasitoid insects around the world. Parasitoid wasps (Hymenoptera) are one of the most species rich animal taxa on Earth, but their tropical diversity is still poorly known. In the latest study, the group discovered 15 new, sizeable species that parasitise spiders in the lowland rainforests of the Amazon and the cloud forests of the Andes.
|
The researchers from the Biodiversity Unit of the University of Turku have studied the diversity of tropical parasitoid insects for almost 20 years already. During their research, they have discovered large numbers of new species from different parts of the world. In the newest study, the research group sampled parasitoid wasps of the genus - The parasitoid - The The University of Turku and INPA continue to study the diversity of the parasitoid wasps in collaboration in the west Amazon area and in the Andes. On each research trip, the researchers discover many new species with unknown habits.
|
Extinction
| 2,020 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.