Friday, September 23, 2022

Study findings suggest association between exposure to air pollution -- particularly in the first 5 years of life -- and alterations in brain structure

Experts have assessed, for the first time, children’s exposure to air pollution from conception to 8.5 years of age on a monthly basis

Peer-Reviewed Publication

BARCELONA INSTITUTE FOR GLOBAL HEALTH (ISGLOBAL)

A study published in the journal Environmental Pollution has found an association, in children aged 9‑12, between exposure to air pollutants in the womb and during the first 8.5 years of life and alterations in white matter structural connectivity in the brain. The greater the child’s exposure before age 5, the greater the brain structure alteration observed in preadolescence.The study was led by the Barcelona Institute for Global Health (ISGlobal), a research centre supported by the ”la Caixa” Foundation.

Tracts or bundles of cerebral white matter ensure structural connectivity by interconnecting the different areas of the brain. Connectivity can be measured by studying the microstructure of this white matter, a marker of typical brain development. Abnormal white matter microstructure has been associated with psychiatric disorders (e.g., depressive symptoms, anxiety and autism spectrum disorders).

In addition to the association between air pollution and white matter microstructure, the study also found a link between specific exposure to fine particulate matter (PM2.5) and the volume of the putamen, a brain structure involved in motor function, learning processes and many other functions. As the putamen is a subcortical structure, it has broader and less specialised functions than cortical structures. The study found that the greater the exposure to PM2.5, especially during the first 2 years of life, the greater the volume of the putamen in preadolescence.

“A larger putamen has been associated with certain psychiatric disorders (schizophrenia, autism spectrum disorders, and obsessive-compulsive spectrum disorders),” says Anne-Claire Binter, ISGlobal researcher and first author of the study.

“The novel aspect of the present study is that it identified periods of susceptibility to air pollution” Binter goes on to explain. "We measured exposure using a finer time scale by analysing the data on a month-by-month basis, unlike previous studies in which data was analysed for trimesters of pregnancy or childhood years. In this study, we analysed the children’s exposure to air pollution from conception to 8.5 years of age on a monthly basis.

Effects Observed Even at Pollution Levels Complying With European Union Standards

Another strong point of this study is that the data analysed came from a large cohort of 3,515 children enrolled in the Generation R Study in Rotterdam (Netherlands).

To determine each participant’s exposure to air pollution during the study period, the researchers estimated the daily levels of nitrogen dioxide (NO2) and particulate matter (PM2.5 and PM2.5 absorbance) at their homes during the mother’s pregnancy and until they reached 8.5 years of age. When participants were between 9 and 12 years analysed of age they underwent brain magnetic resonance imaging to examine the structural connectivity and the volumes of various brain structures at that time.

The levels of NO2 and PM2.5 recorded in the present study exceeded the annual thresholds limits specified in the current World Health Organization guidelines (10 µg/m3 and 5 µg/m3, respectively) but met European Union (EU) standards, an indication that brain development can be affected by exposure to air pollution at levels lower than the current EU air quality limit values.

“One of the important conclusions of this study” explains Binter “is that the infant’s brain is particularly susceptible to the effects of air pollution not only during pregnancy, as has been shown in earlier studies, but also during childhood.”

"We should follow up and continue to measure the same parameters in this cohort to investigate the possible long-term effects on the brain of exposure to air pollution” concludes Mònica Guxens, ISGlobal researcher and last author of the study.

JOURNAL

Environmental Pollution

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Air pollution, white matter microstructure, and brain volumes: periods of susceptibility from pregnancy to preadolescence

ARTICLE PUBLICATION DATE

23-Sep-2022

New study shows higher death toll among Puerto Ricans following Hurricane Maria than reported following 2017 disaster

Findings suggest undercounting of official Hurricane Maria death toll due to those displaced from Puerto Rico by the storm

Peer-Reviewed Publication

UNIVERSITY OF TORONTO

FOR IMMEDIATE RELEASE from the UNIVERSITY OF TORONTO

TORONTO, ON – As the Caribbean island of Puerto Rico begins recovery from destruction brought by Hurricane Fiona this past weekend, a new study led by researchers at the University of Toronto (U of T) finds an irregular increase in deaths of Puerto Ricans in the United States in the six-month period after the devastating Hurricane Maria cyclone passed over the island five years ago this week.

With implications for future natural disaster response and reporting, the researchers say the findings suggest an additional 514 deaths should be added to the official estimate of 2,975 deaths caused by Hurricane Maria, due to the displacement of thousands of Puerto Ricans to the U.S. mainland in the aftermath of the disaster.

“Overlooking deaths among displaced hurricane survivors provides an incomplete understanding of the magnitude of the health consequences of natural disasters like Hurricane Maria,” said Gustavo Bobonis, a professor in the Department of Economics in the Faculty of Arts & Science at U of T and a co-author of a study published in the BMJ Open. “Doing so affects society’s ability to remediate and proactively craft a readiness plan for the next disaster, which, unfortunately, is precisely what Puerto Rico is facing again.”

Bobonis, along with recent U of T PhD graduate Boriana Miloucheva and Mario Marazzi, former executive director of the Puerto Rico Institute of Statistics, examined death register data from the National Vital Statistics System maintained by the National Center for Health Statistics at the Centers for Disease Control and Prevention, together with population estimates from the U.S. Census Bureau. They found that between October 2017 and March 2018, the mortality rate of people of Puerto Rican origin in the U. S. was 3.7% higher than in preceding years.

“In absolute terms, this amounts to 514 additional deaths over that six-month period,” said Miloucheva, who is currently a postdoctoral research associate at the Centre for Health and Wellbeing at Princeton University and an incoming faculty member at the Institute of Health Policy, Management and Evaluation in the Dalla Lana School of Public Health at U of T. “The monthly pattern suggests this effect began just after Hurricane Maria struck Puerto Rico, gradually increased through the end of 2017, and then fluctuated in a downward trajectory in the beginning of 2018.”

The researchers were prompted by the knowledge that many survivors of the hurricane were displaced to the United States, with some dying while there. As a result, their death certificates were registered in demographic registers on the U.S. mainland and not in Puerto Rico, which has come to be seen as a limitation of the assessment done by researchers at George Washington University that placed the official estimate at 2,975 deaths upon its release in August 2018.

“The excess deaths were concentrated among both men and women aged 65 years and older, many of whom left Puerto Rico due to fears of being unable to obtain adequate health care,” said Marazzi. “Among this age group, the excess deaths were concentrated among people suffering from heart diseases, cancer and diabetes, who ultimately may not have received the care required after arriving in the United States.”

The researchers say that although there were excess deaths in all educational groups, they were more evident among the most vulnerable populations with relatively lower levels of education.

“This is consistent with previous studies – including the official George Washington University study sponsored by the Puerto Rican government – and supports the hypothesis that many of these additional deaths came from people exposed and displaced by Hurricane Maria” said Miloucheva.

The study, which was cited on Twitter by the chief data scientist at the U.S. White House in the wake of Hurricane Fiona as an example of the value of equitable data in fully understanding disaster impacts, is the first to take into account deaths of Puerto Ricans outside of Puerto Rico in the months following Hurricane Maria. The researchers emphasize the importance of being comprehensive when establishing death tolls following such events and cite the inclusion of out of state death certificates in calculating the cost in human lives after Hurricane Katrina made landfall in New Orleans in 2005.

The researchers say the analysis suggests the need for not only equitable disaster preparedness but also the importance of cross-jurisdiction data sharing.

“These already vulnerable populations may face additional hurdles on relocation, such as healthcare disruptions and psychological stressors, which may exacerbate health impacts of the disaster,” said Bobonis. “Receiving jurisdictions would, thus, benefit from an improved understanding of the dynamics of post-disaster displacement and would make possible a timelier surveillance of the mortality consequences of natural disasters in the future.”

– 30

JOURNAL

BMJ Open

DOI

10.1136/bmjopen-2021-058315

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Mortality of Puerto Ricans in the USA post Hurricane Maria: an interrupted time series analysis

A sarbecovirus found in Russian bats is capable of using human ACE2 to enter cells, and is resistant to the antibodies of people vaccinated against SARS-CoV-2

Peer-Reviewed Publication

PLOS

A sarbecovirus found in Russian bats is capable of using human ACE2 to enter cells, and is resistant to the antibodies of people vaccinated against SARS-CoV-2

Article URL: http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1010828

Article Title: An ACE2-dependent Sarbecovirus in Russian bats is resistant to SARS-CoV-2 vaccines

Author Countries: United States

Funding: This work was supported by WSU and the Paul G. Allen School for Global Health (ML BG, SNS, SF, SB). Funding for the clinical study specimens was provided under NIH Project U54CA260581-01 (JR, KZ, EN) The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

JOURNAL

PLoS Pathogens

DOI

10.1371/journal.ppat.1010828

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Cells

Newly discovered COVID-like virus could infect humans, resist vaccines

Peer-Reviewed Publication
WASHINGTON STATE UNIVERSITY
A recently discovered virus in a Russian bat that is similar to SARS-CoV-2, the virus behind COVID-19, is likely capable of infecting humans and, if it were to spillover, is resistant to current vaccines.
A team lead by researchers in Washington State University’s Paul G. Allen School for Global Health found spike proteins from the bat virus, named Khosta-2, can infect human cells and is resistant to both the monoclonal antibodies and serum from individuals vaccinated for SARS-CoV-2. Both Khosta-2 and SARS- CoV-2 belong to the same sub-category of coronaviruses known as sarbecoviruses.
“Our research further demonstrates that sarbecoviruses circulating in wildlife outside of Asia – even in places like western Russia where the Khosta-2 virus was found – also pose a threat to global health and ongoing vaccine campaigns against SARS-CoV-2,” said Michael Letko, WSU virologist and corresponding author of the study published in the journal PLoS Pathogens.
Letko said the discovery of Khosta-2 highlights the need to develop universal vaccines to protect against sarbecoviruses in general, rather than just against known variants of SARS-CoV-2.
“Right now, there are groups trying to come up with a vaccine that doesn't just protect against the next variant of SARS-2 but actually protects us against the sarbecoviruses in general,” Letko said. “Unfortunately, many of our current vaccines are designed to specific viruses we know infect human cells or those that seem to pose the biggest risk to infect us. But that is a list that's everchanging. We need to broaden the design of these vaccines to protect against all sarbecoviruses.”
While hundreds of sarbecoviruses have been discovered in recent years, predominantly in bats in Asia, the majority are not capable of infecting human cells. The Khosta-1 and Khosta-2 viruses were discovered in Russian bats in late 2020, and it initially appeared they were not a threat to humans.
“Genetically, these weird Russian viruses looked like some of the others that had been discovered elsewhere around the world, but because they did not look like SARS-CoV-2, no one thought they were really anything to get too excited about,” Letko said. “But when we looked at them more, we were really surprised to find they could infect human cells. That changes a little bit of our understanding of these viruses, where they come from and what regions are concerning.”
Letko teamed with a pair of WSU faculty members, first author viral ecologist Stephanie Seifert and viral immunologist Bonnie Gunn, to study the two newly discovered viruses. They determined Khosta-1 posed low risk to humans, but Khosta-2 demonstrated some troubling traits.
The team found that like SARS-CoV-2, Khosta-2 can use its spike protein to infect cells by attaching to a receptor protein, called angiotensin converting enzyme 2 (ACE2), found throughout human cells. They next set out to determine if current vaccines protect against the new virus.
Using serum derived from human populations vaccinated for COVID-19, the team saw that Khosta-2 was not neutralized by current vaccines. They also tested serum from people who were infected with the omicron variant, but the antibodies, too, were ineffective.
Fortunately, Letko said the new virus is lacking some of the genes believed to be involved in pathogenesis in humans. There is a risk, however, of Khosta-2 recombining with a second virus like SARS-CoV-2.
“When you see SARS-2 has this ability to spill back from humans and into wildlife, and then there are other viruses like Khosta-2 waiting in those animals with these properties we really don't want them to have, it sets up this scenario where you keep rolling the dice until they combine to make a potentially riskier virus,” Letko said.
In addition to Letko, Seifert and Gunn, co-authors on this study include Shuangyi Bai and Stephen Fawcett of WSU as well as Elizabeth Norton, Kevin Zwezdaryk and James Robinson of Tulane University.

JOURNAL

PLoS Pathogens

DOI

10.1371/journal.ppat.1010828

ARTICLE TITLE

An ACE2-dependent Sarbecovirus in Russian bats is resistant to SARS-CoV-2 vaccines

ARTICLE PUBLICATION DATE

22-Sep-2022

Hunga Tonga-Hunga Ha’apai Eruption blasted vast quantities of water vapor into the stratosphere

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

The explosive eruption of the underwater volcano Hunga Tonga-Hunga Ha’apai in January 2022 injected at least 50 million metric tons of water vapor directly into the stratosphere, potentially increasing the amount of global stratospheric water vapor by more than 5%, according to a new study. The findings suggest that this event has likely initiated an atmospheric response different from that of previous well-studied large volcanic eruptions. Although rare, large volcanic eruptions can eject large amounts of gasses, ash and other particulates high into the atmosphere, where they can influence stratospheric chemistry and dynamics for several years following eruption. In addition to ash, sulfur-containing gasses are often considered the most important gases injected into the stratosphere and can result in a decrease in global climate temperature and accelerated ozone destruction. While it is thought that direct injection of water vapor could help moderate the climate impacts of volcanic aerosols, volcanic eruptions are generally not considered to be a major source for stratospheric water vapor. Even the largest eruptions over the past century have only resulted in minor water vapor injections. According to Holger Vömel and colleagues, however, the hydromagmatic eruption of Hunga Tonga-Hunga Ha’apai was quite different. Using in situ measurements from radiosondes carried aloft by high-altitude weather balloons, Vömel et al. show that this event injected a massive amount – at least 50 teragrams – of water vapor directly into the stratosphere, potentially increasing stratospheric water vapor by at least 5% on a global average. While the atmospheric impacts of this observationally unprecedented event remain uncertain, the authors suggest that the increased amounts of stratospheric water vapor could contribute to stratospheric cooling and surface warming over the months to come, and that these effects could persist longer than those caused by injected aerosols, which tend to drop out of the stratosphere through gravitational settling.

JOURNAL

Science

DOI

10.1126/science.abq2299

ARTICLE TITLE

Water vapor injection into the stratosphere by Hunga Tonga-Hunga Ha’apai

ARTICLE PUBLICATION DATE

23-Sep-2022

*Free* Dryland forestation lends limited climate change mitigation potential

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

Despite being a promising and widely considered approach, a new study finds that forestation of Earth’s vast drylands would do little to slow climate change, researchers report. The findings show that although smart dryland forestation can be an important tool in some respects, its limited short-term climate benefits argue that it cannot be a substitute for rapidly reducing emissions. Growing forests sequester carbon. Leveraging this ability through forestation, which includes both afforestation to create new forests where there was no previous tree cover and reforestation to restore depleted forests, has been widely proposed as a promising approach to counteract increasing carbon emissions to mitigate ongoing global climate change. However, the actual climatic benefits of forestation are uncertain because increased tree coverage reduces the landscape’s albedo or its ability to reflect solar energy, which, depending on the scale, could result in local or global warming effects. This is particularly true for the dryland regions covering nearly 40% of the global land area where the albedo warming effect of afforestation could strongly outweigh any cooling effect from carbon sequestration as reflective desert land is converted to darker energy absorbing forest cover. To better understand the possible climatic benefits for dryland forestation, Shani Rohatyn and colleagues performed a high-resolution spatial analysis of global drylands and simulated the climatic effects of afforestion in these regions. Through their investigation, Rohatyn et al. identified 448 million hectares suitable for forestation and sequestration potential of more than 32 billion tons of carbon over the next 80 years. However, the authors found that this would do little to slow our warming climate. Accounting for the significantly decreased albedo in these regions, the authors show that the cooling effect of forestation of this vast area would only amount to that of a decrease of about 1% of projected greenhouse gas emissions under medium-emissions and business-as-usual climate scenarios. Despite this, Rohatyn et al. note that carefully planned and implemented dryland afforestation could provide other, more local benefits and potentially longer-term climate mitigation beyond their 80-year evaluation period.

JOURNAL

Science

DOI

10.1126/science.abm9684

ARTICLE TITLE

Limited climate-change mitigation potential through forestation of the vast dryland regions

ARTICLE PUBLICATION DATE

23-Sep-2022

It may already be too late to meet UN genetic diversity target, but new findings could guide conservation efforts

More than one-tenth of the world’s terrestrial genetic diversity may already be lost

Peer-Reviewed Publication

CARNEGIE INSTITUTION FOR SCIENCE

Rhino at risk — IMAGE: ARTIST’S CONCEPT ILLUSTRATING THE RHINO'S DECREASING GEOGRAPHICAL RANGE AND LOSS OF GENETIC VARIABILITY. view more
CREDIT: ARTWORK IS COURTESY OF MARK BELAN | ARTSCISTUDIOS.COM.

Palo Alto, CA—Climate change and habitat destruction may have already caused the loss of more than one-tenth of the world’s terrestrial genetic diversity, according to new research led by Carnegie’s Moises Exposito-Alonso and published in Science. This means that it may already be too late to meet the United Nations’ proposed target, announced last year, of protecting 90 percent of genetic diversity for every species by 2030, and that we have to act fast to prevent further losses.

Several hundred species of animals and plants have gone extinct in the industrialized age and human activity has impacted or shrunk half of Earth’s ecosystems, affecting millions of species. The partial loss of geographic range diminishes population size and can geographically prevent populations of the same species from interacting with each other. This has serious implications for an animal or plant’s genetic richness and their ability to meet the coming challenges of climate change.

“When you take away or fundamentally alter swaths of a species’ habitat, you restrict the genetic richness available to help those plants and animals adapt to shifting conditions,” explained Exposito-Alonso, who holds one of Carnegie’s prestigious Staff Associate positions—which recognizes early career excellence—and is also an Assistant Professor, by courtesy, at Stanford University.

Until recently, this important component has been overlooked when setting goals for preserving biodiversity, but without a diverse pool of natural genetic mutations on which to draw, species will be limited in their ability to survive alterations to their geographic range.

In popular culture, mutations convey super powers that defy the laws of physics. But in reality, mutations represent small, random natural variations in the genetic code that could positively or negatively affect an individual organism’s ability to survive and reproduce, passing down the positive traits down to future generations.

CAPTION

Infographic illustrating how loss of habitat is tied to loss of genetic diversity and extinction risk.

CREDIT

Illustration is courtesy of Mark Belan | artscistudios.com.

“As a result, the greater the pool of mutations upon which a species is able to draw, the greater the chances of stumbling upon that lucky blend that will help a species thrive despite the pressures created by habitat loss, as well as shifting temperature and precipitation patterns,” Exposito-Alonso added.

He and his collaborators set out to develop a population genetics-based framework for evaluating the richness of mutations available to a species within a given area.

They analyzed genomic data for more than 10,000 individual organisms across 20 different species to demonstrate that Earth’s terrestrial plant and animal life could already be at much greater risk from genetic diversity loss than previously thought. Because the rate at which genetic diversity is recovered is much slower than that at which it is lost, the researchers consider it effectively irreversible.

“The mathematical tool that we tested in 20 species could be expanded to make approximate conservation genetics projections for additional species, even if we don’t know their genomes,” Exposito-Alonso concluded. “I think our findings could be used to evaluate and track the new global sustainability targets, but there is still much uncertainty. We need to do a better job in monitoring populations of species and developing more genetic tools.”

“Moi took a bold, creative approach to probing a scientific question that’s crucial for policymakers and conservationists to understand if they want to implement strategies that will meet the coming challenges our world faces,” said Margaret McFall-Ngai, Director of Carnegie’s newly launched Divison of Biosphere Sciences & Engineering. “This kind of intellectual courage is illustrative of the Carnegie model of doing oustside-of-the-box science and the kind of work that is a hallmark of our prestigious Staff Associate program.”

The research team included members of Exposito-Alonso’s lab—Lucas Czech, Lauren Gillespie, Shannon Hateley, Laura Leventhal, Megan Ruffley, Sebastian Toro Arana, and Erin Zeiss—as well as collaborators Tom Booker of the University of British Columbia; Christopher Kyriazis of UCLA; Patricia Lang, Veronica Pagowski, Jeffrey Spence, and Clemens Weiß of Stanford University; and David Nogues-Bravo of the University of Copenhagen.

CAPTION
Infographic illustrating that genetic biodiversity loss already outpaces U.N. conservation targets.
CREDIT
Illustration is courtesy of Mark Belan | artscistudios.co

__________________

This work was supported by a U.S. National Institutes of Health Early Investigator Award, the U.S. Department of Energy Office of Biological and Environmental Research, the Carnegie Institution for Science, Stanford’s Center for Computational Evolutionary and Human Genomics, a Human Frontier Science Program Long-Term Fellowship, and the U.S. National Science Foundation’s Plant Genome Postdoctoral Research Fellowship in Biology.

The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with three research divisions on both coasts. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in the life and environmental sciences, Earth and planetary science, and astronomy and astrophysics.

JOURNAL

Science

DOI

10.1126/science.abn5642

METHOD OF RESEARCH

Computational simulation/modeling

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Genetic diversity loss in the Anthropocene

ARTICLE PUBLICATION DATE

23-Sep-2022

Disclaimer: A

Toward a European carbon footprint rule for batteries

Focus on upstream production, not downstream use

Reports and Proceedings

ETH ZURICH

Top energy, tech, and climate researchers at ETH Zurich engaged in an informed debate over the European regulation that sets an upper carbon footprint limit for European markets. The limits, to be established this year, come into force in 2027 and will apply to electric vehicle batteries and stationary batteries with more than 2 kilowatt-hours (kWh) of storage capacity. Researchers anticipate that any throughput-based design option for quantifying the Carbon Footprints of batteries may fall short of its expectations and do more harm than good.

The regulation could play a pioneering role in climate change policy. Experience with it may also prove invaluable for non-European regulators and for the regulatory design of products that share characteristics with batteries. The European take on addressing the Carbon Footprint of complex, multipurpose technologies will, therefore, be closely observed internationally.

JOURNAL

Science

DOI

10.1126/science.abp9505

METHOD OF RESEARCH

News article

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Toward a European carbon footprint rule for batteries

ARTICLE PUBLICATION DATE

22-Sep-2022

Villaseñor co-authors PNAS paper on extinction of megafauna

A study coauthored by Amelia Villaseñor shows that a megafaunal extinction in North America more than 10,000 years ago resulted in a reorganized, vulnerable ecosystem

Peer-Reviewed Publication

UNIVERSITY OF ARKANSAS

Amelia Villasenor.jpg — IMAGE: AMELIA VILLASENOR, UNIVERSITY OF ARKANSAS view more
CREDIT: RUSSELL COTHREN, UNIVERSITY OF ARKANSAS

Anthropologist Amelia Villaseñor coauthored a paper describing the ecological effects of an extinction event that occurred more than 10,000 years ago in North America, one that had major consequences for the surviving mammal species.

The paper, titled "Late Pleistocene megafauna extinction leads to missing pieces of ecological space in a North American mammal community,” was published in Proceedings of the National Academy of Sciences, or PNAS, a journal of the National Academy of Sciences.

“Our findings show that the extinction of large-bodied animals, like mammoths, substantially changed how the remaining mammal communities were organized,” Villaseñor said. “The findings also suggest that human impacts have likely played a major role in large-scale degradation of North American ecosystems for thousands of years.”

Villaseñor’s research uses the remains of fossil mammals to understand how humans and other animals interacted with each other over the last 3.5 million years, as well as the ecological impacts of extinction.

For this study, to gain a better understanding of modern biodiversity loss, she and colleagues relied on the fossil record of mammals from the Texas Memorial Museum that span roughly 50,000 years ago to recent times. These collections include extinct megafauna from Texas. Megafauna are large-bodied mammals such as mammoths and sabertooth cats.

The researchers characterized the roles of extinct and surviving mammals using stable isotopes and body size. Stable isotopes are present in all parts of an animal’s body, and certain kinds of isotopes can stay preserved for millions of years. They provided Villaseñor and her team with a record of animal diets and how those diets changed through time.

The researchers also estimated the body size of animals, which gave them another piece of information about how animals interacted with their environment and each other. Together, this information describes the job an animal has in its community or its “niche.”

The team found that after the extinction, the surviving animal community was reorganized in what they ate and where they fell in the food chain, particularly among carnivores. Jaguars moved into a specialized dietary niche previously occupied by extinct cats like the sabertooth and the American lion. Puma, which were previously rare in the community, became common.

Biodiversity loss also led to “vacant niches,” or missing pieces, within the community, meaning that the roles of species such as mammoths, mastodons, and sabertooth cats were never again filled by the native mammal community. This biodiversity and ecological loss led to an overall reduction in ecosystem resilience that will affect the ability of native North American mammal communities to respond to future environmental changes.

The study’s lead author was Felisa Smith, biology professor at the University of New Mexico. In addition to Villaseñor, co-authors were Seth Newsome at the University of New Mexico, Emma Elliot Smith at the Smithsonian Institution and Kate Lyons and Catalina Tomé at the University of Nebraska-Lincoln.

Findings from this study support those of previous work published by Villaseñor this year in Nature Communications. The earlier study showed that mammal communities of North America have been homogenizing, or becoming more similar to one another, at faster rates over the last 10,000 years.

The earlier study also suggested lasting impacts from the megafaunal extinction on remaining mammal communities. Both studies showed that human impacts have likely played a major role in the reorganization and loss of resiliency of North American ecosystems for thousands of years.

The studies also have implications for the future.

“Our research of ancient mammals highlights what might happen if Earth’s remaining large-bodied mammals go extinct — animals such as elephants, rhinos, zebra, and lions — and it demonstrates how insights from the past can really inform modern conservation efforts,” said Smith.

JOURNAL

Proceedings of the National Academy of Sciences

METHOD OF RESEARCH

Observational study

ARTICLE TITLE

Late Pleistocene megafauna extinction leads to missing pieces of ecological space in a North American mammal community

ARTICLE PUBLICATION DATE

19-Sep-2022