Wednesday, April 01, 2020

American robins now migrate 12 days earlier than in 1994

Every spring, American robins migrate north from all over the U.S. and Mexico, flying up to 250 miles a day to reach their breeding grounds in Canada and Alaska. There, they spend the short summer in a mad rush to find a mate, build a nest, raise a family, and fatten up before the long haul back south.

Now climate change is making seasonal rhythms less predictable, and springtime is arriving earlier in many parts of the Arctic. Are robins changing the timing of their migration to keep pace, and if so, how do they know when to migrate? Although many animals are adjusting the timing of their migration, the factors driving these changes in migratory behavior have remained poorly understood.

A new study, published in Environmental Research Letters, concludes that robin migration is kicking off earlier by about five days each decade. The study is also the first to reveal the environmental conditions along the migration route that help the birds keep up with the changing seasons. Lead author Ruth Oliver completed the work while earning her doctorate at Columbia University's Lamont-Doherty Earth Observatory.

At Canada's Slave Lake, a pit stop for migrating birds, researchers have been recording spring migration timing for a quarter century. Their visual surveys and netting censuses revealed that robins have been migrating about five days earlier per decade since 1994.

In order to understand what factors are driving the earlier migration, Oliver and Lamont associate research professor Natalie Boelman, a coauthor on the paper, knew they needed to take a look at the flight paths of individual robins.

Their solution was to attach tiny GPS "backpacks" to the birds, after netting them at Slave Lake in mid-migration. "We made these little harnesses out of nylon string," Oliver explained. "It basically goes around their neck, down their chest and through their legs, then back around to the backpack." The unit weighs less than a nickel—light enough for the robins to fly unhindered. The researchers expect that the thin nylon string eventually degrades, allowing the backpacks to fall off.

The researchers slipped these backpacks onto a total of 55 robins, tracking their movements for the months of April through June. With the precise location from the GPS, the team was able to link the birds' movements with weather data on air temperature, snow depth, wind speed, precipitation, and other conditions that might help or hinder migration.

The results showed that the robins start heading north earlier when winters are warm and dry, and suggest that local environmental conditions along the way help to fine-tune their flight schedules.

"The one factor that seemed the most consistent was snow conditions and when things melt. That's very new," said Oliver. "We've generally felt like birds must be responding to when food is available—when snow melts and there are insects to get at—but we've never had data like this before."

Boelman added that "with this sort of quantitative understanding of what matters to the birds as they are migrating, we can develop predictive models" that forecast the birds' responses as the climate continues to warm. "Because the timing of migration can indirectly influence the reproductive success of an individual, understanding controls over the timing of migratory events is important."

For now, it seems as though the environmental cues are helping the robins to keep pace with the shifting seasons. "The missing piece is, to what extent are they already pushing their behavioral flexibility, or how much more do they have to go?" said Oliver.

Because the study caught the birds in mid-migration, the tracking data doesn't reflect the birds' full migration path. To overcome this limitation, the researchers plan to analyze tissue from the robins' feathers and claws, which they collected while attaching the GPS harnesses, to estimate where each bird spent the previous winter and summer.

Over the long term, Oliver says, she hopes to use the GPS trackers to sort out other mysteries as well, such as how much of the change in migration timing is due to the behavioral responses found in the study versus natural selection to changing environments, or other factors.

"This type of work will be really cool once we can track individuals throughout the course of their life, and that's on the near-term horizon, in terms of technological capabilities," she said. "I think that will really help us unpack some of the intricacies of these questions."Fifty years of data show new changes in bird migration

More information: Ruth Y Oliver et al, Behavioral responses to spring snow conditions contribute to long-term shift in migration phenology in American robins, Environmental Research Letters (2020). DOI: 10.1088/1748-9326/ab71a0

Journal information: Environmental Research Letters

Provided by Columbia University

Modern humans, Neanderthals share a tangled genetic history, study affirms

by Charlotte Hsu, University at Buffalo

In recent years, scientists have uncovered evidence that modern humans and Neanderthals share a tangled past. In the course of human history, these two species of hominins interbred not just once, but at multiple times, the thinking goes.

A new study supports this notion, finding that people in Eurasia today have genetic material linked to Neanderthals from the Altai mountains in modern-day Siberia. This is noteworthy because past research has shown that Neanderthals connected to a different, distant location—the Vindija Cave in modern-day Croatia—have also contributed DNA to modern-day Eurasian populations.

The results reinforce the concept that Neanderthal DNA has been woven into the modern human genome on multiple occasions as our ancestors met Neanderthals time and again in different parts of the world.

The study was published on March 31 in the journal Genetics.

"It's not a single introgression of genetic material from Neanderthals," says lead researcher Omer Gokcumen, a University at Buffalo biologist. "It's just this spider web of interactions that happen over and over again, where different ancient hominins are interacting with each other, and our paper is adding to this picture. This project will now add to an emerging chorus — we've been looking into this phenomenon for a couple of years, and there are a couple of papers that came out recently that deal with similar concepts."

"The picture in my mind now is we have all these archaic hominin populations in Europe, in Asia, in Siberia, in Africa. For one reason or another, the ancestors of modern humans in Africa start expanding in population, and as they expand their range, they meet with these other hominins and absorb their DNA, if you will," Gokcumen says. "We probably met different Neanderthal populations at different times in our expansion into other parts of the globe."

Gokcumen, associate professor of biological sciences in the UB College of Arts and Sciences, led the study with first author Recep Ozgur Taskent, a recent UB Ph.D. graduate in the department. Co-authors include UB Ph.D. graduate Yen Lung Lin, now a postdoctoral scholar at the University of Chicago; and Ioannis Patramanis and Pavlos Pavlidis, Ph.D., of the Foundation for Research and Technology in Greece.

The research was funded by the U.S. National Science Foundation.

To complete the project, scientists analyzed the DNA of hundreds of people of Eurasian ancestry. The goal was to hunt for fragments of genetic material that may have been inherited from Neanderthals.

This research found that the Eurasian populations studied could trace some genetic material back to two different Neanderthal lineages: one represented by a Neanderthal whose remains were discovered in the Vindija cave in Croatia, and another represented by a Neanderthal whose remains were discovered in the Altai mountains in Russia.

Scientists also discovered that the modern-day populations they studied also share genetic deletions — areas of DNA that are missing — with both the Vindija and Altai Neanderthal lineages.

The DNA of the Vindija and Altai Neanderthals, along with the modern human populations studied, were previously sequenced by different research teams.

"It seems like the story of human evolution is not so much like at tree with branches that just grow in different directions. It turns out that the branches have all these connections between them," Gokcumen says. "We are figuring out these connections, which is really exciting. The story is not as neat as it was before. Every single ancient genome that is sequenced seems to create a completely new perspective in our understanding of human evolution, and every new genome that's sequenced in the future may completely change the story again."

Earliest interbreeding event between ancient human populations discovered

More information: Ozgur Taskent et al, Analysis of Haplotypic Variation and Deletion Polymorphisms Point to Multiple Archaic Introgression Events, Including from Altai Neanderthal Lineage, Genetics (2020). DOI: 10.1534/genetics.120.303167

Evolutionary adaptation helped cave bears hibernate, but may have caused extinction

by Ellen Goldbaum-Kolin, University at Buffalo

A study published in Science Advances on April 1 reveals a new hypothesis that may explain why European cave bears went extinct during past climate change periods. The research was motivated by controversy in the scientific literature as to what the animal (Ursus spelaeus) ate and how that affected their demise.

The new hypothesis emerged, in part, from computational analysis and computer biting simulations conducted in the laboratory of Jack Tseng, Ph.D., assistant professor of pathology and anatomical sciences in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo.

Tseng is a co-author on the paper with corresponding authors Borja Figueirido, Ph.D., and Alejandro Pérez-Ramos, Ph.D., his doctoral student and first author, both of the Departamento de Ecologia y Geologia of the Universidad de Malaga, Spain.

Dietary dilemma

Cave bears were a species of bear (Ursus spelaeus) that lived in Europe and Asia that went extinct about 24,000 years ago. According to Figueirido, researchers have proposed different diets for cave bears, ranging from pure herbivory to carnivory or even scavenging.

"Knowing the feeding behaviour of the cave bear is not a trivial aspect," he said. "Feeding behaviour is intimately related to its decline and extinction."

He noted that two main hypotheses, not necessarily exclusive, have been proposed to explain cave bear extinction: a human-driven decline, either by competition for resources or by direct hunting; or a substantial demise in population sizes as a result of the climatic cooling that occurred during the late Pleistocene which caused vegetation to wane.

Previous research shows that cave bears were primarily herbivorous at least from 100,000 to 20,000 years ago. But even during the cooling periods, when vegetation productivity waned, these bears didn't change their diets. The researchers propose that this dietary inflexibility, combined with competition for cave shelters by humans, is what led to their extinction.

To find out if there were biomechanical explanations behind their inflexible diets, meaning that the bears weren't physically capable of adjusting their diets effectively during times of limited vegetation resources, the researchers analyzed three-dimensional computer simulations of different feeding scenarios.

Critical sinuses

They were especially interested in the sinuses of the bears because large paranasal sinuses allow for greater metabolic control, critical to survival during hibernation.

"Our study proposes that climate cooling probably forced the selection of highly developed sinuses," which in turn led to the appearance of the characteristic domed skull of the cave bear lineage," said Alejandro Pérez-Ramos.

Tseng explained that when the sinus system expands, the act of chewing may cause more or less strain on the skull. In both humans and bears, the sinus system lightens the weight of the face, reducing the amount of bone tissue needed to grow the skull.

"Mechanically speaking, being 'thickheaded' may not be a bad thing because more bone means more structural strength," he said. "However, our findings support the interpretation that requirements for sinus system function in cave bears necessitated a trade-off between sinus development and skull strength."

Tseng and Pérez-Ramos, who spent three months at UB to learn the procedure, used a biomechanical simulation methodology to estimate the biting stresses and strains in different bear species and different models of them. The bear skull specimens used were from several European institutions, where CT scans had been done on them, as well as the scientific CT repository, also known as the digital morphology library, at the University of Texas at Austin.

They found that the development of paranasal sinuses in cave bears caused the cranial dome to expand upward and backward from the forehead, changing the geometry of the bear's skull.

"This geometrical change generated a mechanically suboptimal cranial shape, with a very low efficiency to dissipate the stress along the skull, particularly when biting with the canines or carnassials, the teeth most often used by predatory mammals," said Pérez-Ramos.

When the sinus system expands, Tseng explained, it results in bone reduction relative to the size of the skull and therefore less structural support to resist the physical forces that chewing generates. Although other mammals with expanded sinuses, such as hyenas, appear to have evolutionarily modified their skull shape to effectively deal with decreased structural support, cave bear skulls showed compromised biomechanical capability compared to living bear species.

"Through the use of new techniques and virtual methods, such as biomechanical simulations across each tooth and the comparative internal anatomical study of the paranasal sinuses, we propose that large sinuses were probably selected in cave bears in order to be able to hibernate for longer periods with very low metabolic costs," said Pérez-Ramos.

Ultimately, though, that trade-off may have resulted in the extinction of the species, a finding that also has relevance to humans, Tseng said.

"Being able to stay alive during the coldest periods would have been equally important to human and bear alike," he said. "The success or demise of prehistoric megafauna, such as cave bears, provide crucial clues as to how humans may have out-competed and out-survived other large mammals during a critical time for the evolution of our own species.

Ancient extinct cave bear DNA found in modern bears

More information: A. Pérez-Ramos el al., "Biomechanical simulations reveal a trade-off between adaptation to glacial climate and dietary niche versatility in European cave bears," Science Advances (2020). advances.sciencemag.org/content/6/14/eaay9462

Skull scans reveal evolutionary secrets of fossil brains

by William Kimbel, Arizona State University

Brain imprints in fossil skulls of the species Australopithecus afarensis (famous for "Lucy" and the "Dikika child" from Ethiopia pictured here) shed new light on the evolution of brain growth and organization. The exceptionally preserved endocranial imprint of the Dikika child reveals an ape-like brain organization, and no features derived towards humans. Credit: Philipp Gunz, MPI EVA Leipzig.

Scientists have long been able to measure and analyze the fossil skulls of our ancient ancestors to estimate brain volume and growth. The question of how these ancient brains compare to modern human brains and the brains of our closest primate cousin, the chimpanzee, continues to be a major target of investigation.

A new study published in Science Advances used CT-scanning technology to view three-million-year old brain imprints inside fossil skulls of the species Australopithecus afarensis (famous for "Lucy" and "Selam" from Ethiopia's Afar region) to shed new light on the evolution of brain organization and growth. The research reveals that while Lucy's species had an ape-like brain structure, the brain took longer to reach adult size, suggesting that infants may have had a longer dependence on caregivers, a human-like trait.

The CT-scanning enabled the researchers to get at two long-standing questions that could not be answered by visual observation and measurement alone: Is there evidence for human-like brain reorganization in Australopithecus afarensis, and was the pattern of brain growth in this species more similar to that of chimpanzees or that of humans?

To study brain growth and organization in A. afarensis, the researchers, including ASU paleoanthropologist William Kimbel, scanned eight fossil crania from the Ethiopian sites of Dikika and Hadar using high-resolution conventional and synchrotron-computed tomography. Kimbel, leader of the field work at Hadar, is director of the Institute of Human Origins and Virginia M. Ullman Professor of Natural History and the Environment in the School of Human Evolution and Social Change.

VIDEO 3-million-year old brain imprints in fossil skulls of the species Australopithecus afarensis (famous for “Lucy” and the “Dikika child” from Ethiopia shown here) shed new light on the evolution of brain growth and organization. Credit: Paul Tafforeau, ESRF Grenoble

Lucy's species inhabited eastern Africa more than three million years ago—"Lucy" herself is estimated to be 3.2 million years old—and occupies a key position in the hominin family tree, as it is widely accepted to be ancestral to all later hominins, including the lineage leading to modern humans.

"Lucy and her kin provide important evidence about early hominin behavior—they walked upright, had brains that were around 20 percent larger than those of chimpanzees, and may have used sharp stone tools," explains coauthor Zeresenay Alemseged (University of Chicago), who directs the Dikika field project in Ethiopia and is an International Research Affiliate with the Institute of Human Origins.

Brains do not fossilize, but as the brain grows and expands before and after birth, the tissues surrounding its outer layer leave an imprint on the inside of the bony braincase. The brains of modern humans are not only much larger than those of our closest living ape relatives but are also organized differently and take longer to grow and mature. Compared with chimpanzees, modern human infants learn longer and are entirely dependent on parental care for longer periods of time. Together, these characteristics are important for human cognition and social behavior, but their evolutionary origins remain unclear.

Brains do not fossilize, but as the brain grows, the tissues surrounding its outer layer leave an imprint in the bony braincase. The Dikika child's endocranial imprint reveals an ape-like brain organization, and no features derived towards humans. Credit: Philipp Gunz, CC BY-NC-ND 4.0

The CT scans resulted in high-resolution digital "endocasts" of the interior of the skulls, where the anatomical structure of the brains could be visualized and analyzed. Based on these endocasts, the researchers could measure brain volume and infer key aspects of cerebral organization from impressions of the brain's structure.

A key difference between apes and humans involves the organization of the brain's parietal lobe—important in the integration and processing of sensory information—and occipital lobe in the visual center at the rear of the brain. The exceptionally preserved endocast of "Selam," a skull and associated skeleton of an Australopithecus afarensis infant found at Dikika in 2000, has an unambiguous impression of the lunate sulcus—a fissure in the occipital lobe marking the boundary of the visual area that is more prominent and located more forward in apes than in humans—in an ape-like position. The scan of the endocranial imprint of an adult A. afarensis fossil from Hadar (A.L. 162-28) reveals a previously undetected impression of the lunate sulcus, which is also in an ape-like position.

Some scientists had conjectured that human-like brain reorganization in australopiths was linked to behaviors that were more complex than those of their great ape relatives (e.g., stone-tool manufacture, mentalizing, and vocal communication). Unfortunately, the lunate sulcus typically does not reproduce well on endocasts, so there was unresolved controversy about its position in Australopithecus.

Brain imprints (shown in white) in fossil skulls of the species Australopithecus afarensis shed new light on the evolution of brain growth and organization. Several years of painstaking fossil reconstruction, and counting of dental growth lines, yielded an exceptionally preserved brain imprint of the Dikika child, and a precise age at death. Credit: Philipp Gunz, CC BY-NC-ND 4.0

"A highlight of our work is how cutting-edge technology can clear up long-standing debates about these three million-year-old fossils," notes coauthor Kimbel. "Our ability to 'peer' into the hidden details of bone and tooth structure with CT scans has truly revolutionized the science of our origins."

A comparison of infant and adult endocranial volumes also indicates more human-like protracted brain growth in Australopithecus afarensis, likely critical for the evolution of a long period of childhood learning in hominins.

In infants, CT scans of the dentition make it possible to determine an individual's age at death by counting dental growth lines. Similar to the growth rings of a tree, virtual sections of a tooth reveal incremental growth lines reflecting the body's internal rhythm. Studying the fossilized teeth of the Dikika infant, the team's dental experts calculated an age at death of 2.4 years.

VIDEO Brain imprints in fossil skulls of the species Australopithecus afarensis (famous for “Lucy”, and the “Dikika child” from Ethiopia shown here) shed new light on the evolution of brain growth and organization. Several years of painstaking fossil reconstruction, and counting of dental growth lines, yielded an exceptionally preserved brain imprint of the Dikika child, and a precise age at death. These data suggest that Australopithecus afarensis had an ape-like brain and prolonged brain growth. Credit: Philipp Gunz, MPI EVA Leipzig

The pace of dental development of the Dikika infant was broadly comparable to that of chimpanzees and therefore faster than in modern humans. But given that the brains of Australopithecus afarensis adults were roughly 20 percent larger than those of chimpanzees, the Dikika child's small endocranial volume suggests a prolonged period of brain development relative to chimpanzees.

"The combination of apelike brain structure and humanlike protracted brain growth in Lucy's species was unexpected," says Kimbel. "That finding supports the idea that human brain evolution was very much a piecemeal affair, with extended brain growth appearing before the origin of our own genus, Homo."

VIDEO Brain imprints in fossil skulls of the species Australopithecus afarensis (famous for “Lucy”, and the “Dikika child” from Ethiopia pictured here) shed new light on the evolution of brain growth and organization. Several years of painstaking fossil reconstruction, and counting of dental growth lines, yielded an exceptionally preserved brain imprint of the Dikika child, and a precise age at death. These data suggest that Australopithecus afarensis had an ape-like brain and prolonged brain growth. Credit: Philipp Gunz, MPI EVA Leipzig

Among primates, different rates of growth and maturation are associated with different infant-care strategies, suggesting that the extended period of brain growth in Australopithecus afarensis may have been linked to a long dependence on caregivers. Alternatively, slow brain growth could also primarily represent a way to spread the energetic requirements of dependent offspring over many years in environments where food is not always abundant. In either case, protracted brain growth in Australopithecus afarensis provided the basis for subsequent evolution of the brain and social behavior in hominins and was likely critical for the evolution of a long period of childhood learning.

Peering into Little Foot's 3.67 million-year-old brain
More information: "Australopithecus afarensis endocasts suggest ape-like brain organization and prolonged brain growth," Science Advances (2020). DOI: 10.1126/sciadv.aaz4729 , https://advances.sciencemag.org/content/6/14/eaaz4729

Journal information: Science Advances

Ocean data portal maps show significant shifts by mid-Atlantic fish species

by Karl Vilacoba, Urban Coast Institute

A series of interactive maps published on the Mid-Atlantic Ocean Data Portal illustrates the shifts that have taken place over the last five decades by several commercially and recreationally important fish species living along the East Coast.

Users of the free and publicly accessible portal can automatically animate or toggle through hundreds of maps representing fish distributions during the spring or fall seasons in the 1970s, 1980s, 1990s, 2000s or 2010s. These maps can be activated in combination with any of the portal's 5,000 map layers showing data for commercial fishing hot spots, marine life habitats, zones being examined for offshore wind development and much more.

The Fish Species Through Time map collection was made possible by a grant from the Virginia Coastal Zone Management Program (CZM) to The Nature Conservancy. It was created based on an analysis of federal Northeast Fisheries Science Center (NEFSC) bottom trawl survey data collected between 1972 and 2017.

Many of the maps show a trend in fish moving to waters further north and further offshore from the 1970s to the present day. Some fish species that showed little presence off the New England coast decades earlier have since migrated past Cape Cod and established themselves in the Gulf of Maine.

"Our analysis and the maps make no assumptions as to the factors causing these shifts," said Chris Bruce, GIS manager at The Nature Conservancy in Virginia and a member of the portal's technical team. "However, there is no shortage of scientific research to refer to on how factors like climate change and increasing water temperatures are impacting marine habitats."

The fish species analyzed were alewife, American shad, Atlantic mackerel, black sea bass, blueback herring, bluefish, butterfish, longfin squid, monkfish, northern shortfin squid, red hake, sand lance, scup, spiny dogfish, spot, summer flounder, winter flounder and yellowtail. In addition to individual species, a pair of summary maps was created to illustrate shifts by demersal fish and forage fish. Overlap area maps were also created for each species showing the places where fish were consistently present each decade.

The portal also added a collection of maps projecting future shifts by the fish species through the year 2100. Users can animate these maps, which are based on data previously released by OceanAdapt (https://oceanadapt.rutgers.edu/), a collaboration between the Pinsky Lab of Rutgers University, NMFS, and Fisheries and Oceans Canada.

Users can access these maps in the portal's Marine Planner application by clicking on the Marine Life theme and then clicking on the dropdowns for Fish Species Through Time (for the data showing the 1970s-present) or Fish Species Future Projections.

"These maps tell an important story about the challenges our region's economies and communities face due to the rapid changes taking place in our ocean," said Laura McKay, program manager with Virginia CZM and the chair of MARCO's mapping and data team that manages the portal. "We hope that they help the region's ocean stakeholders and decision-makers understand the trends so they can plan and adapt accordingly."

The portal is an online toolkit and resource center that consolidates available data and enables state, federal and local users to visualize and analyze ocean resources and human use information such as fishing grounds, recreational areas, shipping lanes, habitat areas, and energy sites, among others.

"Regional coordination on ocean use planning is essential to ensure the long-term health of our invaluable ocean resources, and an important piece of this coordination is data accessibility," said Kisha Santiago-Martinez, chair of MARCO and deputy secretary of state at New York's Department of State. "Information on the portal is available to anyone who wishes to view data for any reason, such as ocean planning, education, or decision-making."Climate change threatens commercial fishers from Maine to North Carolina

Police officers' views before and after Ferguson counter accuracy of 'Ferguson Effect'

by Crime and Justice Research Alliance

The Ferguson Effect is the idea that increased public criticism and distrust of police following the 2014 shooting of Michael Brown in Ferguson, Missouri, lowered police morale, which caused officers to withdraw from proactive policing and boosted the crime rate in major U.S. cities. A new longitudinal study examined whether this effect was real. The study, of law enforcement officers before and after Ferguson, found little support for the concept, though it did identify a reduction in officers' job satisfaction and an increase in their cynicism.

The study, by researchers at the University of South Florida, appears in Criminology & Public Policy, a publication of the American Society of Criminology.

"Post-Ferguson protests in 2014 did not appreciably worsen police morale, nor did they lead to substantial withdrawal from most police work," notes Chris Marier, a Ph.D. student at the University of South Florida, who led the study. "This suggests that the institution of policing is resilient to external shocks and that criticism of police is not detrimental to policing or public safety."

To examine the veracity of the Ferguson Effect, researchers examined whether widespread criticism of and protests against police following the police-related deaths of Brown and other Black men in late 2014 and early 2015 reduced police morale and led to de-policing (a slowdown of or withdrawal from proactive work, in which police perform their duties but reduce their productivity and efficiency). The researchers also examined whether low morale among police officers was associated with de-policing.

The study examined 18,413 surveys of law enforcement officers in 87 police departments across the United States before and after Brown was shot in Ferguson, a nationally representative sample. Morale was measured by survey items reflecting job satisfaction, burnout, and cynicism. De-policing was measured as a reduction in foot patrols, attendance at community meetings, and the number of citations issued.

The researchers found that after Ferguson, officers were significantly less satisfied with their jobs and more burned out than they were before Ferguson, but the before and after differences were negligible in size. The study also found statistically significant differences between officers' responses before and after Ferguson on several measures of cynicism, but two of the five measures showed improved rather than worsened attitudes, and the magnitude of change was insubstantial.

In addition, while officers surveyed after Ferguson issued fewer citations and conducted fewer foot patrols, the changes were very small in magnitude, suggesting that commitment to proactive community policing remained largely unchanged.

The authors suggest that because low job satisfaction was associated with fewer citations, and cynicism was associated negatively with both the number of citations issued and the rate of attendance at community meetings, police departments need to address officers' attitudes in order to promote proactive policing and community engagement. In fact, they suggest that officers' cynicism, which was high before and after Ferguson, may be an enduring cultural element that merits further attention at any time of stress.

"Although we didn't find strong evidence of de-policing following Ferguson, our results indicate that low morale is associated with reduced police activity by officers," says Lorie Fridell, a professor of criminology at the University of South Florida, who coauthored the study. "Police administrators must address officers' cynicism and distrust regardless of current public sentiment. The implications of our findings extend beyond the Ferguson Effect to a more general understanding of police culture."

The study's authors note a few limitations: First, officers who were most affected by post-Ferguson protests may have been those least likely to respond to the survey, which may mean that the study's results underestimate changes in morale and police activity over time. But officers who felt most aggrieved may have been more likely to respond, which may overestimate changes. And some officers may have provided responses they thought were socially desirable, avoiding responses that appeared unprofessional or unappealing.Despite general support for police use of body-worn cameras, impacts may be overestimated

More information: Marier, Christopher J. and Lorie A. Fridell. Demonstrations, Demoralization, and Depolicing. Criminology and Public Policy. (2020)

Provided by Crime and Justice Research Allia

Bison in northern Yellowstone proving to be too much of a good thing

by Oregon State University

Increasing numbers of bison in Yellowstone National Park in recent years have become a barrier to ecosystem recovery in the iconic Lamar Valley in the northern part of the park, according to a study by Oregon State University scientists.

In the valley, foraging by bison exerts 10 times the environmental pressure of elk, historically the area's dominant herbivore—that's a problem because bison are powerful "ecosystem engineers."

Large numbers of bison disrupt species distribution across shrub steppe and grasslands. They do so via what they eat, trample and rub their horns and bodies on—i.e., tree bark. Thus, bison have tremendous capacity to limit the structure and composition of woody plant communities.

That in turn affects the character of riparian plant communities, as well as stream and river channels, altering habitats and food webs for terrestrial and aquatic wildlife species alike.

The findings were recently published in the journal Food Webs.

In the United States, the range of the bison originally ran from east of the Appalachians to west of the Rocky Mountains, with most of them living on their evolutionary home base, the Great Plains.

Their numbers once totaled an estimated 30 million, perhaps more, said OSU College of Forestry researcher Bob Beschta, corresponding author of the Lamar Valley ecosystem study.

"The bison population sharply decreased in the 1800s and their distribution became more constricted as European-Americans extended their influences westward across the country," Beschta said.

By the 1830s, there were no bison east of the Mississippi River or on the Snake River Plains. Fifty years later, the Plains bison were close to extinction.

"Several small herds were reported near Yellowstone National Park just before the park's establishment in 1872, perhaps driven there by hunting pressure on the Great Plains," said study co-author Bill Ripple, also of the OSU College of Forestry. "Poaching of bison occurred after park establishment, until 1901, at which time only 22 bison were present in the park."

In 1907, more than 60 bison from a growing herd in the Mammoth Hot Springs area of Yellowstone were transferred to the Lamar Valley. By 1925 the Lamar Valley bison herd had grown to more than 750, necessitating population reduction measures. Culling of the Lamar herd continued for more than four decades.

Meanwhile, National Park Service managers became increasingly concerned about the environmental effects of Rocky Mountain elk in the park's northern range, which includes the Lamar Valley, and began to cull them as well. In the early 1900s both gray wolves and cougars, predators that influenced elk behavior and density, had been extirpated.

In the absence of these predators, combined with hunting prohibitions inside the park, wintering elk populations began to heavily browse young woody plants in the northern range, which led to a decrease in "recruitment"—the growth of seedlings and sprouts into tall saplings and trees—of quaking aspen, cottonwood, willow, thinleaf alder and berry-producing shrubs.

Culling of both elk and bison stopped amid public and congressional concerns in 1968, at which time there were about 4,000 elk and 100 bison in the northern range. Within two decades, those numbers had increased to 20,000 and 1,000.

Cougars returned to the northern range in the 1980s, followed by wolf reintroduction a decade later, thus restoring the park's guild of large predators.

"Changes in elk behavior were observed shortly after the return of wolves" Beschta said. "And, with predation pressure from wolves, cougars and grizzly bears, a degraded winter range, and human hunting of elk that wintered outside the park, annual counts of the northern range elk herd began to decrease from their historical highs in the 1990s."

In the years since wolf reintroduction, the northern range's elk population has declined to about 5,000, with most them wintering outside the park. Bison numbers inside the park, on the other hand, have increased to a historical high of about 4,000.

Deciduous woody plant species in many areas of the northern range started to increase in establishment, young plant height, diameter growth, recruitment, canopy cover and berry production—all associated with reduced browsing pressure from elk.

"But in portions of the northern range, like the Lamar Valley where bison are common, woody vegetation has continued to decline," Ripple said. "We hypothesized that was because of the bison. We also hypothesized that bison, via the suppression of riparian vegetation and trampling of streambanks, may be increasingly influencing the channel of the Lamar River and tributary streams that cross the valley floor."

Photo analysis indicated a near complete loss of willow-dominated riparian communities for at least some parts of the Lamar River and the West Fork of Rose Creek.

"And the roughly 7.5 hectares of aspen stands that were present on the valley floor in 1954 had diminished to one-tenth of a hectare by 2015, representing a 99% loss in the cover of overstory aspen trees," Ripple said. "The rapid increase in bison numbers in recent years suggests the park's large carnivore guild may be incapable of controlling bison populations. And prey switching by wolves—from elk to bison—looks unlikely to provide a stabilizing effect on bison populations."

The researchers stress that the long-term recovery of the Yellowstone bison herd has been a major conservation success story and, as one of the few remaining herds that has not hybridized with cattle, Yellowstone bison "are an invaluable conservation resource."

"However, increased bison numbers over the last two decades appear to have come at a major ecological cost to the biological diversity and functioning of the riparian ecosystems in the Lamar Valley," Beschta said. "Even to a casual observer there are clear indicators of highly altered ecological conditions across the Lamar Valley, including a high density of bison trails, wallows and scat. High bison numbers have been an effective agent for accelerating the biological and physical modification of the valley's seeps, wetlands, floodplains, riparian areas and channels, trends that had begun decades earlier by elk."

Ecosystem simplification—a loss of biodiversity, landscape complexity and ecological integrity—is well underway, much like as is associated with high levels of domestic livestock use in areas of the mountain west, Beschta added.

"The ongoing environmental effects of bison would have to be significantly reduced in order to restore biologically diverse communities dominated by willows, cottonwoods and aspen," Beschta said. "As park administrators make management decisions that affect ungulate densities and distributions in Yellowstone, as well as those in other parks and reserves with high ungulate densities, our findings indicate a need to take into account the often wide range of ecological effects that abundant large herbivores can have on terrestrial and aquatic ecosystems."

Letting nature take its course: Wolves in Yellowstone National Park

More information: Robert L. Beschta et al, Bison limit ecosystem recovery in northern Yellowstone, Food Webs (2020). DOI: 10.1016/j.fooweb.2020.e00142

Preservation of testicular cells to save endangered feline species

by Forschungsverbund Berlin e.V. (FVB)

A research team at the German Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) developed a method to isolate and cryopreserve testicular cells. This will allow the safekeeping and biobanking of gametes and other cells of the male reproductive tract of threatened or endangered feline species. The findings have been published in the scientific journal Cryobiology.

Cryopreservation in liquid nitrogen at -196°C is a common procedure to store germ cells (sperm and eggs) and embryos but can be damaging to cells. Initially, the team tested two different "freezing speeds," as the extent of freezing damage strongly depends on the speed of temperature reduction during the freezing process. To ensure that germ cells and embryos are functional again after thawing, cryoprotectants are usually applied before freezing. These must penetrate the cells before the temperature is lowered in order to prevent or weaken the formation of ice crystals inside the cells and thus prevent damage. Since the most commonly used cryoprotectants are cytotoxic at higher concentrations, the scientists tested two different concentrations for freezing.

Whereas usually a cryoprotectant penetrates individual cells relatively quickly, cells inside the tissue of an organ are difficult to reach by the cryoprotectant. In this study, the testicular tissue was therefore not preserved in small pieces but—after dissolution of the tissue complex—as a cell suspension so that the cryoprotectant could penetrate individual cells faster. This method has already been successfully used in some mammalian species and was adapted by scientists at the Leibniz-IZW for the conservation of feline testicular cells. To dissolve the tissue complex as gently as possible, the Leibniz-IZW researchers combined the mechanical preparation steps with the interruption of cell to cell contacts using a cocktail of enzymes.

"A particular problem in cryopreserving tissue or cell suspensions is the assessment of cell recovery after thawing. Ultimately, cell functionality can only be achieved in long-term cell culture experiments. However, in order to optimise the freezing process in the short term, we used two methods to assess the viability of the cells," explains Mohammad Bashawat, scientist at the Leibniz-IZW. Using fluorescent reporter molecules, the lower concentration of cryoprotectant combined with a slow freezing speed was clearly the most beneficial method. About 45 % of cryopreserved testicular cells of castrated domestic cats were vital again after thawing. Comparably good results were obtained in two pilot studies with testicular cells of an Asian golden cat and a cheetah. The Leibniz-IZW research team sees this as an important step towards preserving the germ lines of valuable animals for future applications in the context of species conservation and the maintenance of diversity in their genomes.

Of the 39 cat species that are currently extant, 25 are on the "Red List" of the International Union for the Conservation of Nature (IUCN) with a status varying from "vulnerable" to "critically endangered." Measures to enhance reproduction are becoming increasingly important for the conservation of genetic diversity in these species. These measures include cryopreservation of germ cells and artificial insemination. The testes of males which died or had to be euthanised contain stem cells and numerous immature precursors of male germ cells. In future, these could hopefully be matured into spermatozoa during spermatogenesis in the "test tube," as has previously been shown by research groups working with mice and humans. In order to have testicular cells of feline species available for such future projects, their cryopreservation is the method of choice, as this allows an almost unlimited storage of this valuable gene reserve ("cryobanking"). This is especially true for individuals which cannot supply functionally "mature" sperm because of their age or state of health.

A new way to 'freeze' cells promises to transform the common cell-freezing practice

More information: M. Bashawat et al, Cell survival after cryopreservation of dissociated testicular cells from feline species, Cryobiology (2020). DOI: 10.1016/j.cryobiol.2020.03.001

New study explores fiscal issues related to NYC teachers retirement system

by New York University

new york city — Credit: CC0 Public Domain

The volatility of the financial markets amid the COVID-19 pandemic has significant implications for taxpayer-supported pension systems nationally.

The Marron Institute of Urban Management at New York University today issued a new report looking at fiscal issues and risks related to the New York City Teachers' Retirement System (TRS), the second-largest of New York City's five major retirement systems as measured by assets.

With city contributions totaling $37 billion in 2018, or 6 percent of tax revenue, TRS has two important characteristics that distinguish it from most other public pension plans in the nation, the report's authors—Marron Institute collaborators Don Boyd, Gang Chen and Yimeng Yin of The State and Local Government Finance Project, Center for Policy Research, Rockefeller College of the University at Albany.

First, like other New York City pension plans, its contribution policy is more conservative than the typical public plan in the sense that city contributions rise relatively rapidly in response to investment shortfalls. This protects the solvency of the pension plan. The trade-off is greater risk to the city budget of sharp contribution increases in short time periods, relative to other commonly used contribution policies.

Second, in addition to their regular retirement benefit, TRS members may contribute to a Tax-Deferred Annuity (TDA) program that offers guaranteed fixed returns backed by the defined benefit pension fund and thus by city taxpayers. The guaranteed rate for most members is 7 percent, set by the state legislature. It is well above guaranteed fixed returns that may be purchased in the private market, which are currently 2 to 2.5 percent or less. TDA assets are invested by TRS along with regular defined benefit pension assets. The guarantee provides valuable benefits to plan members but creates special risks to the city. It does not have the constitutional protection that the regular retirement benefit has and therefore is more directly under the control of state and city policymakers.

If TDA assets earn more than the guarantee, the additional earnings accrue to the TRS pension fund, keeping city contributions funded by taxpayers lower than they otherwise might be. If TDA assets earn less than the guarantee, the pension fund must make up the difference, increasing costs to the city and its taxpayers, according to the report, titled "The New York City Teachers' Retirement System: Fiscal Issues and Risks."

Stock market declines of recent weeks illustrate the potential risk to city taxpayers. If TDA assets fall short of the guarantee by 10 percent—for example, if TRS were to lose approximately 3 percent in 2020—then TRS will have to make up the difference. TDA had approximately $25 billion of assets at the end of 2019, so this would mean a guarantee payment of approximately $2.5 billion, ultimately funded by city taxpayers.

City policymakers need to understand the risks that City pension funds create, and make informed decisions about those risks, the report's authors urged, noting the report provides valuable information designed to help them to understand those risks better.Compulsory super contributions: There's no 'one-size-fits-all' percentage

Whales are dying, but numbers are unknown. Coronavirus has stalled scientific field work

by Susanne Rust and Rosanna Xia

As gray whales began their northern migration along the Pacific Coast earlier this month—after a year of unusually heavy die-offs—scientists were poised to watch, ready to collect information that could help them learn what was killing them.

The coronavirus outbreak, however, has largely upended that field work—and that of incalculable other ecological studies nationwide.

A large network of marine biologists and volunteers in California normally spend this time of year keeping an eye on gray whales, documenting their numbers and counting strandings as the leviathans swim from Mexico to the Arctic.

Scott Mercer, who started Point Arena's Mendonoma Whale and Seal Study seven years ago, said the watch was called off last week, as he and his wife were told by a local sheriff to disperse and go home.

"I guess two people are now considered a public gathering," he said, with a wry chuckle.

In Los Angeles, Alisa Schulman-Janiger said she had to shut her survey down March 20, meaning this will be the first time in 37 years that data on the northern migration will not be complete.

"We had to," said Schulman-Janiger, director of the Los Angeles chapter of the American Cetacean Society. "We couldn't hazard anybody's health."

Up and down the West Coast and beyond, field research on a variety of endangered, threatened and migrating species has ground to a halt. Plovers? Abalone? They are on their own now, as scientists are forced to stay at home.

Schulman-Janiger said that before her work was called off, she had noticed an unusually early migration, with several skinny whales.

Even more alarming, she said, were observations of moms with very small calves—baby whales that, to her eye, looked too small to be making a 5,000-mile trip north.

"They looked like newborns," she said. "Like what you'd typically see in December or January. Not calves who'd just spent months nursing in the lagoons, getting stronger and bigger."

Last year, 215 gray whales were stranded on North America's Pacific Coast as they migrated north, sparking a federal investigation into this unusual die-off event.

This year, 49 have been stranded, so far, in Mexico.

As local authorities close a growing number of parks and beaches, notifications and alerts about whale strandings and sightings will become increasingly erratic, she said, making it harder for researchers to know what is happening.

"Field teams may or may not respond to strandings and entanglements depending on the location and personnel availability," said Michael Milstein, spokesman for the National Oceanic and Atmospheric Administration, adding that the agency is advising its partners "to follow the guidance provided by local, state, and federal authorities."

It's not just whales.

Hundreds of environmental and ecological monitoring projects are now on pause, creating marked data holes in several long-term analyses. And in some cases, there's been a halt in the protection and vigilance of some endangered species, including the snowy plover.

The timing couldn't be worse.

"It's springtime," said Andrea Jones, Director of Bird Conservation for Audubon California, noting this is when many birds nest and migrate. Research teams are stuck indoors, as are thousands of volunteers who take part in Audubon Society bird counts, vital for judging the health of annual bird migrations.

Elsewhere, in research labs and aquariums across California, scientists are scrambling to adjust their projects and conservation efforts—many of which are time sensitive to the seasons.

Plans to cull an ambitious number of purple sea urchins—aggressive creatures that have devoured the kelp forests in Northern California and crowded out most all other life on the seafloor—for instance, is in limbo pending stay-at-home restrictions.

Every University of California campus has closed its labs, and California's coast and ocean research efforts have largely been suspended. Coastal officials have also lost critical assistance from numerous universities and colleges in monitoring the state's fisheries and marine protected areas.

"The lack of data impacts everything from fisheries management to assessing the effectiveness of our marine protected area network," said Mark Gold, executive director of the state's Ocean Protection Council.

"The biggest challenge we're facing is the planning for the unknown. So many 'what ifs' need to be considered," Heather Burdick, director of marine operations at the Bay Foundation, said last week.

The Bay Foundation, a research nonprofit, is usually out on the water several times weekly to restore kelp and feed the endangered species that scientists have been trying to reintroduce into the ocean. "Our team ... call today was focused on contingency plans for contingency plans," she said.

Gray whales starving to death in the Pacific, and scientists want to know why

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