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The iconic, prehistoric dire wolf, which prowled through Los Angeles and elsewhere in the Americas over 11 millennia ago, was a distinct species from the slightly smaller gray wolf, an international team of scientists reports today in the journal Nature.
The study, which puts to bed a mystery that biologists have pondered for more than 100 years, was led by researchers from UCLA, along with colleagues from Durham University in the U.K., Australia's Adelaide University and Germany's Ludwig Maximilian University.
"The terrifying dire wolf, a legendary symbol of Los Angeles and the La Brea Tar Pits, has earned its place among the many large, unique species that went extinct at the end of the Pleistocene epoch," said UCLA's Robert Wayne, a distinguished professor of ecology and evolutionary biology and the study's co-senior author. The Pleistocene, commonly called the Ice Age, ended roughly 11,700 years ago.
More than 4,000 dire wolves have been excavated from the La Brea Tar Pits, but scientists have known little about their evolution or the reasons for their ultimate disappearance. Gray wolves, also found in the fossil-rich pits, have survived until this day.
"Dire wolves have always been an iconic representation of the last ice age in the Americas, but what we know about their evolutionary history has been limited to what we can see from the size and shape of their bones," said co-lead author Angela Perri of Durham University.
Those bones are now revealing much more. Using cutting-edge molecular approaches to analyze five dire wolf genomes from fossil bones dating back 13,000 to 50,000 years ago, the researchers were able to reconstruct the evolutionary history of the long-extinct carnivore for the first time.
Significantly, they found no evidence for the flow of genes between dire wolves and either North American gray wolves or coyotes. The absence of any genetic transference indicates that dire wolves evolved in isolation from the Ice Age ancestors of these other species.
"We have found the dire wolf is not closely related to the gray wolf. Further, we've shown that the dire wolf never interbred with the gray wolf," said co-lead author Alice Mouton, who conducted the research as a UCLA postdoctoral scholar in ecology and evolutionary biology in Wayne's laboratory.
The ancestors of the gray wolf and the much smaller coyote evolved in Eurasia and are thought to have moved into North America less than 1.37 million years ago, relatively recently in evolutionary time. The dire wolf, on the other hand, based on its genetic difference from those species, is now believed to have originated in the Americas.
"When we first started this study, we thought that dire wolves were just beefed-up gray wolves, so we were surprised to learn how extremely genetically different they were, so much so that they likely could not have interbred," said the study's last author, Laurent Frantz, a professor at Ludwig Maximillian University and the U.K.'s Queen Mary University. "This must mean that dire wolves were isolated in North America for a very long time to become so genetically distinct."
"Dire wolves are sometimes portrayed as mythical creatures—giant wolves prowling bleak frozen landscapes—but reality turns out to be even more interesting," said Kieren Mitchell of Adelaide University, a co-lead author.
The dire wolf was a 'lone wolf' when it came to breeding
Interbreeding is quite common among wolf lineages when their geographical ranges overlap. Modern gray wolves and coyotes, for example, frequently interbreed in North America. Yet the researchers, using a data set that included a Pleistocene dire wolf, 22 modern North American gray wolves and coyotes, and three ancient dogs, found that the dire wolf hadn't interbred with any of the others—likely because it was genetically unable to reproduce with those species.
"Our finding of no evidence for gene flow between dire wolves and gray wolves or coyotes, despite the substantial range overlap during the Late Pleistocene, suggests that the common ancestor of gray wolves and coyotes probably evolved in geographical isolation from members of the dire wolf lineage," Wayne said. "This result is consistent with the hypothesis that dire wolves originated in the Americas."
Another hypothesis about the dire wolf—one untested in the current study—concerns its extinction. It is commonly thought that because of its body size—larger than gray wolves and coyotes—the dire wolf was more specialized for hunting large prey and was unable to survive the extinction of its regular food sources. A lack of interbreeding may have hastened its demise, suggested Mouton, now a postdoctoral researcher at Belgium's University of Liege.
"Perhaps the dire wolf's inability to interbreed did not provide necessary new traits that might have allowed them to survive," she said.
Uncovering the mystery of the dire wolf's DNA
While the dire wolves sequenced in this study possessed no ancestry from gray wolves, coyotes or their recent North American ancestors, a comparison of the DNA of dire wolves with that of gray wolves, coyotes and a wide variety of other wolf-like species revealed a common but distant evolutionary relationship.
"The ancestors of dire wolves likely diverged from those of gray wolves more than 5 million years ago—it was a great surprise to discover that this divergence occurred so early," Mouton said. "This finding highlights how special and unique the dire wolf was."
Based on their genomic analyses, the researchers also concluded that there are three primary lineages that descend from the shared ancestry: dire wolves, African jackals and a group comprising all other existing wolf-like species, including the gray wolf.
Gray wolves, which today live mostly in wilderness and remote regions of North America, are more closely related to African wild dogs and Ethiopian wolves than to dire wolves, Wayne noted.
The study is the first ever to report genome-wide data on dire wolves.
The genomic analyses—conducted in a joint effort at UCLA, Durham University, the University of Oxford, the University of Adelaide, Ludwig Maximilian University and Queen Mary University—focused on both the nuclear genome and the mitochondrial genome, which is abundant in ancient remains.
"The decreased cost of sequencing analyses, in addition to state-of-the-art molecular biology methods for highly degraded materials, allows us to recover DNA from fossils," Mouton said. "Ancient DNA genomic analyses represent an incredible tool to better understand the evolutionary history of ancient and extinct species."
https://phys.org/news/2021-01-dire-wolf-distinct-species-gray.html
More from 777 times
Honey bee health has been on the decline for two decades, with U.S. and Canadian beekeepers now losing about 25 to 40% of their colonies annually. And queen bees are failing faster than they have in the past in their ability to reproduce. The reason has been a mystery, but researchers at North Carolina State University and the University of British Columbia are finding answers.
Their latest research, published Jan. 8 in the journal Communications Biology, offers clues about what's behind queen bee failure, finding that when sperm viability is low, the expression of a protein known to act against pathogens such as bacteria and viruses is high.
David Tarpy, a University Faculty Scholar and professor in NC State's Department of Entomology and Plant Pathology, says the study has important implications for beekeepers and their customers, the farmers who rely on honey bees to pollinate their crops.
"Beekeepers have identified problem queens as a top management concern, but what's causing the problem is largely invisible. Queens go bad, and we don't know why," Tarpy said.
Alison McAfee, a postdoctoral scientist at NC State and UBC, was the study's lead author. She explained that to have a healthy hive, honey bees depend on a healthy queen, the only female bee in a colony that can reproduce.
The queen mates with many males, but only early in life, storing all the sperm that she'll use in her lifetime in her spermatheca, an abdominal organ that looks like a tiny pearl. When the sperm begin to die, the queen can't produce as many fertilized eggs. That causes the colony's population to decline.
"Queens have the potential to live for five years, but these days, half the time queens (in managed honey bee colonies) are replaced within their first six months because they are failing," McAfee said. "If a beekeeper is really lucky, a queen might live two years. Beekeepers need answers about why their queens are failing.
"The more we can find out about what is actually happening within these failed queens, the closer we can get to understanding why this queen failure is happening in the first place."
Scientists measured sperm viability with a technique called fluorescent staining. Green dots signify live sperm, while red ones are dead. This image is of mostly dead sperm from a failed queen. Credit: Alison McAfee.
In their research, McAfee, Tarpy and their colleagues found that queens that were failing reproductively had significantly fewer sperm than ones that were reproductively thriving. And a higher percentage of the sperm they did have were dead. The researchers also discovered that compared to reproductively healthy queen bees, the failed queens were more likely to have higher levels of two viruses—sacbrood virus and black queen cell virus.
"The high levels of these viruses and poor sperm viability made us interested in seeing if there was a trade-off happening in the honey bee queen," McAfee said. "There's a classical hypothesis in reproductive biology that you can't do everything well, so there's a trade-off between immunity and being able to reproduce. It's been found in quite a few other organisms, including insects, that there are such trade-offs."
To find out if the same would be true with the honeybee queen, the researchers used a tool known as a mass spectrometer to gain a better picture of what was going on in the spermatheca of the healthy and failed queens. They identified 2,000 different proteins and determined which ones were linked to sperm viability.
One of the most significant proteins linked to sperm viability, McAfee said, was lysozyme. Lysozyme is an enzyme that's part of animals' immune systems.
"The queens with the highest sperm viability had the lowest abundance of lysozyme, indicating that they weren't investing resources in this kind of immune response," McAfee added. "That supports this idea that there's a trade-off between the queens being able to fight off infections and being able to maintain their stored sperm."
Tarpy said that the research could begin allowing researchers to find the cause of queen failure and find molecular tools that could "help identify bad queens upstream in the process before beekeepers use them and before they realize they're bad."
Right now, the cause of queen failure isn't clear. "The underlying mechanisms could be disease. They could be pesticides. They could be improper nutrition," he said. "We don't know, so we are working our way backward to identify the causes."
Once the causes are clearly understood, Tarpy added, scientists can then work forward "to help beekeepers keep mortality levels down to sustainable levels and thus keep their colonies thriving."
https://phys.org/news/2021-01-secret-reproductive-honey-bees.html
123 views · Jan 13th
Researchers at the University of Maryland, Baltimore County (UMBC) have developed a technique to more quickly analyze extensive data from Arctic ice sheets in order to gain insight and useful knowledge on patterns and trends. Over the years, vast amounts of data have been collected about the Arctic and Antarctic ice. These data are essential for scientists and policymakers seeking to understand climate change and the current trend of melting. Masoud Yari, research assistant professor, and Maryam Rahnemoonfar, associate professor of information systems, have utilized new AI technology to develop a fully automatic technique to analyze ice data, published in the Journal of Glaciology. This is part of the National Science Foundation's ongoing BigData project.
For decades, researchers have kept close track of polar ice, snow, and soil measurements, but processing the large volume of available data has proven challenging. NASA's processes for collecting, tracking, and labeling polar data involve significant manual work, and changes detected in the data can take months or even years to see. Even Arctic data collected via remote sensing technologies require manual processing.
According to Rahnemoonfar, "Radar big data is very difficult to mine and understand just by using manual techniques." The AI techniques she and Yari are developing can be used to mine the data more quickly, to get useful information on trends related to the thickness of the ice sheets and the level of snow accumulation in a certain location.
The researchers developed an algorithm that learns how to identify objects and patterns within the Arctic and Antarctic data. An AI algorithm must be exposed to hundreds of thousands of examples in order to learn how to identify important elements and patterns. Rahnemoonfar and her team used existing incomplete and noisy labeled data from the Arctic to train the AI algorithm on how to categorize and understand new data.
The algorithm's training is not yet complete, as it will need to be scaled up over multiple sensors and locations to create a more accurate tool. However, it has already successfully begun to automate a process that was previously inefficient and labor-intensive.
The rapid expansion of using AI technology to understand ice and snow thickness in the Arctic will allow scientists and researchers to make faster and more accurate predictions to inform international dialogue about climate change. The rate at which Arctic ice is melting impacts sea level rise, and if scientists are better able to predict the severity of the melting, society can better mitigate the harm caused by sea level rise.
https://phys.org/news/2021-01-analysis-arctic-ice-ai.html
75 views · Jan 13th
Close to 5,700 lakes in the Northern Hemisphere may permanently lose ice cover this century, 179 of them in the next decade, at current greenhouse gas emissions, despite a possible polar vortex this year, researchers at York University have found.
Those lakes include large bays in some of the deepest of the Great Lakes, such as Lake Superior and Lake Michigan, which could permanently become ice free by 2055 if nothing is done to curb greenhouse gas emissions or by 2085 with moderate changes.
Many of these lakes that are predicted to stop freezing over are near large human populations and are an important source of drinking water. A loss of ice could affect the quantity and quality of the water.
"We need ice on lakes to curtail and minimize evaporation rates in the winter," says lead researcher Sapna Sharma, an associate professor in the Faculty of Science. "Without ice cover, evaporation rates would increase, and water levels could decline. We would lose freshwater, which we need for drinking and everyday activities. Ice cover is extremely important both ecologically and socio-economically."
The researchers, including Postdoctoral Fellows Kevin Blagrave and Alessandro Filazzola, looked at 51,000 lakes in the Northern Hemisphere to forecast whether those lakes would become ice-free using annual winter temperature projections from 2020 to 2098 with 12 climate change scenarios.
A northern lake, Credit: York University Postdoctoral Fellow Alessandro Filazzola
"With increased greenhouse gas emissions, we expect greater increases in winter air temperatures, which are expected to increase much more than summer temperatures in the Northern Hemisphere," says Filazzola. "It's this warming of a couple of degrees, as result of carbon emissions, that will cause the loss of lake ice into the future."
The most at-risk lakes are those in southern and coastal regions of the Northern Hemisphere, some of which are amongst the largest lakes in the world.
"It is quite dramatic for some of these lakes, that froze often, but within a few decades they stop freezing indefinitely," says Filazzola. "It's pretty shocking to imagine a lake that would normally freeze no longer doing so."
The researchers found that when the air temperature was above -0.9 C, most lakes no longer froze. For shallow lakes, the air temperature could be zero or a bit above. Larger and deeper lakes need colder temperatures to freeze—some as cold as -4.8 C—than shallow lakes.
A northern lake. Credit: York University Postdoctoral Fellow Alessandro Filazzola
"Ice cover is also important for maintaining the quality of our freshwater," says Sharma. "In years where there isn't ice cover or when the ice melts earlier, there have been observations that water temperatures are warmer in the summer, there are increased rates of primary production, plant growth, as well as an increased presence of algal blooms, some of which may be toxic."
To preserve lake ice cover, more aggressive measures to mitigate greenhouse gas emissions are needed now, says Sharma. "I was surprised at how quickly we may see this transition to permanent loss of ice cover in lakes that had previously frozen near consistently for centuries."
https://phys.org/news/2021-01-northern-lakes-ice-permanently-impacting.html
85 views · Jan 13th
More from 777 times
Honey bee health has been on the decline for two decades, with U.S. and Canadian beekeepers now losing about 25 to 40% of their colonies annually. And queen bees are failing faster than they have in the past in their ability to reproduce. The reason has been a mystery, but researchers at North Carolina State University and the University of British Columbia are finding answers.
Their latest research, published Jan. 8 in the journal Communications Biology, offers clues about what's behind queen bee failure, finding that when sperm viability is low, the expression of a protein known to act against pathogens such as bacteria and viruses is high.
David Tarpy, a University Faculty Scholar and professor in NC State's Department of Entomology and Plant Pathology, says the study has important implications for beekeepers and their customers, the farmers who rely on honey bees to pollinate their crops.
"Beekeepers have identified problem queens as a top management concern, but what's causing the problem is largely invisible. Queens go bad, and we don't know why," Tarpy said.
Alison McAfee, a postdoctoral scientist at NC State and UBC, was the study's lead author. She explained that to have a healthy hive, honey bees depend on a healthy queen, the only female bee in a colony that can reproduce.
The queen mates with many males, but only early in life, storing all the sperm that she'll use in her lifetime in her spermatheca, an abdominal organ that looks like a tiny pearl. When the sperm begin to die, the queen can't produce as many fertilized eggs. That causes the colony's population to decline.
"Queens have the potential to live for five years, but these days, half the time queens (in managed honey bee colonies) are replaced within their first six months because they are failing," McAfee said. "If a beekeeper is really lucky, a queen might live two years. Beekeepers need answers about why their queens are failing.
"The more we can find out about what is actually happening within these failed queens, the closer we can get to understanding why this queen failure is happening in the first place."
Scientists measured sperm viability with a technique called fluorescent staining. Green dots signify live sperm, while red ones are dead. This image is of mostly dead sperm from a failed queen. Credit: Alison McAfee.
In their research, McAfee, Tarpy and their colleagues found that queens that were failing reproductively had significantly fewer sperm than ones that were reproductively thriving. And a higher percentage of the sperm they did have were dead. The researchers also discovered that compared to reproductively healthy queen bees, the failed queens were more likely to have higher levels of two viruses—sacbrood virus and black queen cell virus.
"The high levels of these viruses and poor sperm viability made us interested in seeing if there was a trade-off happening in the honey bee queen," McAfee said. "There's a classical hypothesis in reproductive biology that you can't do everything well, so there's a trade-off between immunity and being able to reproduce. It's been found in quite a few other organisms, including insects, that there are such trade-offs."
To find out if the same would be true with the honeybee queen, the researchers used a tool known as a mass spectrometer to gain a better picture of what was going on in the spermatheca of the healthy and failed queens. They identified 2,000 different proteins and determined which ones were linked to sperm viability.
One of the most significant proteins linked to sperm viability, McAfee said, was lysozyme. Lysozyme is an enzyme that's part of animals' immune systems.
"The queens with the highest sperm viability had the lowest abundance of lysozyme, indicating that they weren't investing resources in this kind of immune response," McAfee added. "That supports this idea that there's a trade-off between the queens being able to fight off infections and being able to maintain their stored sperm."
Tarpy said that the research could begin allowing researchers to find the cause of queen failure and find molecular tools that could "help identify bad queens upstream in the process before beekeepers use them and before they realize they're bad."
Right now, the cause of queen failure isn't clear. "The underlying mechanisms could be disease. They could be pesticides. They could be improper nutrition," he said. "We don't know, so we are working our way backward to identify the causes."
Once the causes are clearly understood, Tarpy added, scientists can then work forward "to help beekeepers keep mortality levels down to sustainable levels and thus keep their colonies thriving."
https://phys.org/news/2021-01-secret-reproductive-honey-bees.html
123 views · Jan 13th
Researchers at the University of Maryland, Baltimore County (UMBC) have developed a technique to more quickly analyze extensive data from Arctic ice sheets in order to gain insight and useful knowledge on patterns and trends. Over the years, vast amounts of data have been collected about the Arctic and Antarctic ice. These data are essential for scientists and policymakers seeking to understand climate change and the current trend of melting. Masoud Yari, research assistant professor, and Maryam Rahnemoonfar, associate professor of information systems, have utilized new AI technology to develop a fully automatic technique to analyze ice data, published in the Journal of Glaciology. This is part of the National Science Foundation's ongoing BigData project.
For decades, researchers have kept close track of polar ice, snow, and soil measurements, but processing the large volume of available data has proven challenging. NASA's processes for collecting, tracking, and labeling polar data involve significant manual work, and changes detected in the data can take months or even years to see. Even Arctic data collected via remote sensing technologies require manual processing.
According to Rahnemoonfar, "Radar big data is very difficult to mine and understand just by using manual techniques." The AI techniques she and Yari are developing can be used to mine the data more quickly, to get useful information on trends related to the thickness of the ice sheets and the level of snow accumulation in a certain location.
The researchers developed an algorithm that learns how to identify objects and patterns within the Arctic and Antarctic data. An AI algorithm must be exposed to hundreds of thousands of examples in order to learn how to identify important elements and patterns. Rahnemoonfar and her team used existing incomplete and noisy labeled data from the Arctic to train the AI algorithm on how to categorize and understand new data.
The algorithm's training is not yet complete, as it will need to be scaled up over multiple sensors and locations to create a more accurate tool. However, it has already successfully begun to automate a process that was previously inefficient and labor-intensive.
The rapid expansion of using AI technology to understand ice and snow thickness in the Arctic will allow scientists and researchers to make faster and more accurate predictions to inform international dialogue about climate change. The rate at which Arctic ice is melting impacts sea level rise, and if scientists are better able to predict the severity of the melting, society can better mitigate the harm caused by sea level rise.
https://phys.org/news/2021-01-analysis-arctic-ice-ai.html
75 views · Jan 13th
Close to 5,700 lakes in the Northern Hemisphere may permanently lose ice cover this century, 179 of them in the next decade, at current greenhouse gas emissions, despite a possible polar vortex this year, researchers at York University have found.
Those lakes include large bays in some of the deepest of the Great Lakes, such as Lake Superior and Lake Michigan, which could permanently become ice free by 2055 if nothing is done to curb greenhouse gas emissions or by 2085 with moderate changes.
Many of these lakes that are predicted to stop freezing over are near large human populations and are an important source of drinking water. A loss of ice could affect the quantity and quality of the water.
"We need ice on lakes to curtail and minimize evaporation rates in the winter," says lead researcher Sapna Sharma, an associate professor in the Faculty of Science. "Without ice cover, evaporation rates would increase, and water levels could decline. We would lose freshwater, which we need for drinking and everyday activities. Ice cover is extremely important both ecologically and socio-economically."
The researchers, including Postdoctoral Fellows Kevin Blagrave and Alessandro Filazzola, looked at 51,000 lakes in the Northern Hemisphere to forecast whether those lakes would become ice-free using annual winter temperature projections from 2020 to 2098 with 12 climate change scenarios.
A northern lake, Credit: York University Postdoctoral Fellow Alessandro Filazzola
"With increased greenhouse gas emissions, we expect greater increases in winter air temperatures, which are expected to increase much more than summer temperatures in the Northern Hemisphere," says Filazzola. "It's this warming of a couple of degrees, as result of carbon emissions, that will cause the loss of lake ice into the future."
The most at-risk lakes are those in southern and coastal regions of the Northern Hemisphere, some of which are amongst the largest lakes in the world.
"It is quite dramatic for some of these lakes, that froze often, but within a few decades they stop freezing indefinitely," says Filazzola. "It's pretty shocking to imagine a lake that would normally freeze no longer doing so."
The researchers found that when the air temperature was above -0.9 C, most lakes no longer froze. For shallow lakes, the air temperature could be zero or a bit above. Larger and deeper lakes need colder temperatures to freeze—some as cold as -4.8 C—than shallow lakes.
A northern lake. Credit: York University Postdoctoral Fellow Alessandro Filazzola
"Ice cover is also important for maintaining the quality of our freshwater," says Sharma. "In years where there isn't ice cover or when the ice melts earlier, there have been observations that water temperatures are warmer in the summer, there are increased rates of primary production, plant growth, as well as an increased presence of algal blooms, some of which may be toxic."
To preserve lake ice cover, more aggressive measures to mitigate greenhouse gas emissions are needed now, says Sharma. "I was surprised at how quickly we may see this transition to permanent loss of ice cover in lakes that had previously frozen near consistently for centuries."
https://phys.org/news/2021-01-northern-lakes-ice-permanently-impacting.html
85 views · Jan 13th
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