COVID-19 in Africa is severely underestimated, finds Zambia study by Boston University

A new study concluding out of Lusaka, Zambia last summer has found that as many as 19% (almost 1 in 5) of recently-deceased people tested positive for COVID-19

BOSTON UNIVERSITY SCHOOL OF MEDICINE

Research News

 

A new study concluding out of Lusaka, Zambia last summer has found that as many as 19% (almost 1 in 5) of recently-deceased people tested positive for COVID-19. A new Boston University School of Public Health (BUSPH) study in Lusaka, Zambia's capital, challenges the common belief that Africa somehow "dodged" the COVID-19 pandemic.

The findings indicate that low numbers of reported infections and deaths across Africa may simply be from lack of testing, with the coronavirus taking a terrible but invisible toll on the continent.

Published in The BMJ, the study found that at least 15% and as many as 19% of recently-deceased people arriving at Lusaka's main morgue over the summer had the coronavirus, peaking at 31% in July. Despite most having had COVID symptoms, few were tested before death.

"Our findings cast doubt on the assumption that COVID-19 somehow skipped Africa or has not impacted the continent as heavily," says study co-author Dr. Lawrence Mwananyanda, a BUSPH adjunct research assistant professor of global health based in Lusaka. "This study shows that with proper diagnostics and testing, we can begin to identify the scale of COVID-19 in African countries such as Zambia. I hope this study will encourage African governments to look closer at the rollout of COVID-19 testing, as well as empower Africans to take proactive steps--such as wearing masks, physically distancing, and skipping handshakes--to protect themselves from COVID-19."

The findings also have important implications for global health decision makers, says study corresponding author Dr. Christopher Gill, associate professor of global health at BUSPH. "We will only end the COVID-19 pandemic if we ensure equitable access to a vaccine. Without the full data picture of the spread of COVID-19 in Africa, it will be impossible to ensure COVID-19 vaccines can get to the people and places that need it most," he says.

An estimated 80% of people who die in Lusaka pass through the University Teaching Hospital morgue. From June to September, polymerase chain reaction tests on 364 recently-deceased people found the coronavirus in 70 of them. While the majority of COVID-19 deaths in the United States and Europe have been in older adults, most of the deceased people who tested positive in this study were under 60 years old, including seven children. The researchers say that such a high proportion of pediatric deaths was particularly surprising given how rare COVID-19 deaths in children have been reported elsewhere.

Of the 70 people who tested positive, the researchers sought information about the symptoms they had been experiencing leading up to their fatal illness. "In nearly all cases where we had those data, we found typical symptoms for COVID-19, yet only 6 had been tested before death," Gill says. And among the 75% of deaths that occurred outside of the hospital, none had been tested before they died.

However, detecting the coronavirus in any country is no easy feat, much less in countries with limited resources. The researchers say Zambia's Ministry of Health has been very proactive and supportive of this and other COVID studies. "They're really grateful that we can provide them this data, and they can make informed decisions moving forward with this epidemic," Mwananyanda says.

The researchers were well-positioned to track COVID in Zambia. With funding from the Bill & Melinda Gates Foundation, they have been conducting the Zambia Pertussis/RSV Infant Mortality Estimation Study (ZPRIME) at the University Teaching Hospital morgue in Lusaka since 2017. In that ongoing study, nurses and physicians' assistants approach families who have lost a child between the ages of four days and six months for consent to conduct a nasal swab of the infant, and to offer grief counseling.

"Building studies such as this from scratch can take time and resources that can be difficult in the time needed to tackle the COVID-19 pandemic. We invested a lot of time and money and human resources to building infrastructure that allowed for that extensive surveillance," says study co-author Rachel Pieciak a research fellow at BUSPH. "So, what we've done was repurpose ZPRIME study capacity to focus on enrolling all deaths across all ages and testing for COVID-19."

Other research teams in similar situations might also be able to pivot in this way, Pieciak says. While many governments don't have the resources to effectively track COVID rates, "there's a lot of research money in places where we're not seeing really great COVID data," she says. "I would encourage other groups like us to think creatively about the resources that they have available, and to contribute to this effort."

For their part, the research team's findings will help inform COVID-19 efforts not just in Zambia, but many other countries. "What this study tells us is that when we looked for COVID-19 in Zambia, we found it--and there are a whole lot of other countries where there's similar lack of testing," says study co-author Dr. William MacLeod, research associate professor of global health at BUSPH.

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About the Boston University School of Public Health

Founded in 1976, the Boston University School of Public Health is one of the top five ranked private schools of public health in the world. It offers master's- and doctoral-level education in public health. The faculty in six departments conduct policy-changing public health research around the world, with the mission of improving the health of populations--especially the disadvantaged, underserved, and vulnerable--locally and globally.

Contact: Michelle Samuels, msamu@bu.edu

Pandemic got you down? A little nature could help

UNIVERSITY OF CONNECTICUT

Research News

 

IMAGE: A JAPANESE WORD MEANING 'FOREST-BATHING' SUGGESTS TIME IN NATURE CAN REDUCE STRESS; RESEARCHERS SAY THERE'S A LOT TO THAT. view more 

CREDIT: PETER MORENUS/UCONN PHOTO

Having trouble coping with COVID?

Go take a hike. Literally.

Researchers have long been aware of the positive impact of a connection with nature on psychological health and, according to a new study published in the journal Personality and Individual Differences, the pandemic hasn't decreased the power of nature to improve mental well-being.

"Thinking about the natural world in an interconnected and harmonious way corresponds to improved psychological health, no matter where you are," says Brian W. Haas, the lead author of the new study and an associate professor in the Behavioral and Brain Sciences Program at the University of Georgia.

Haas and his collaborators - Fumiko Hoeft, a professor of psychological sciences at UConn and director of UConn's Brain Imaging Research Center; and Kazufumi Omura, faculty of Education, Art and Science at Yamagata University in Japan - used a survey in America and Japan to measure worldviews on nature as well as how much the pandemic impacted people's lives, and their current psychological health.

The survey sought to gauge whether the participants had a worldview in harmony with nature - being in tune or connected with the natural world, or a worldview of mastery over nature - the belief that people have the ability to control the natural world. They also reported on their stress levels and were asked if the COVID-19 pandemic has affected them personally or impacted their employment or finances.

The researchers found that, while participants in general report greater stress levels during the pandemic, individuals with a harmony-with-nature worldview were coping better regardless of whether they lived in Japan or in the United States.

"Clearly there's great need for study as relates to the pandemic, not just now during COVID, but also of previous pandemics and for possible future pandemics," says Hoeft. "I feel like this is a really great lesson, and a moment for us to really appreciate that things like our relationship with nature do matter and make an impact on more tangible things, like our mental health, which we often forget."

The researchers found that the difference between the two cultures, however, became apparent when looking at individuals with a mastery-over-nature worldview.

"We found that the Americans who believed that humans are, and should be, the masters of the natural world did not tend to cope well during the pandemic," Haas says. "While this was not the case in Japan."

Rather, in Japan, having a mastery-over-nature worldview was not correlated with poor coping. The researchers suggest the difference might be rooted in the concept of naïve dialecticism - the acceptance or tolerance of contradiction.

"In other cultures outside of the United States, people tend to be more comfortable with contradiction; in other cultures, it is generally more accepted to possess conflicting ideas within your mind at the same time," Haas says. "But in the United States, it's not. We can apply this concept to nature and the current global pandemic. For instance, if I hold a view that I am the master of the natural world, and then a global pandemic happens, this is a clear natural disaster. If I believe that I am the master of the natural world, then surely I would never allow a natural disaster to happen. These concepts are inconsistent with one another, and a consequence of inconsistency is often negative mood."

While the study offers only a snapshot view of just two cultures, Haas believes other cultures would likely demonstrate a similar positive association with a harmony-with-nature worldviews, predicting that "it's likely a universal phenomenon."

Both Haas and Hoeft say that, in an increasingly virtual and technology driven world, taking a moment to appreciate nature has clear benefits regardless of where you live.

"In Japanese, there's this word called 'forest-bathing,'" Hoeft says. "It's basically when you go out into nature, and enjoy being surrounded by trees. It's usually for forests, but you go walking and it's supposed to refresh you. People often talk about how they went out 'forest bathing.' I love thinking about these kinds of old phrases - do they have some real impact or real scientific background in the end? And I think this is one of them where this really does have a connection. There is some scientific truth behind this."

"Think about taking a step away from Zoom for a moment and taking a walk and listening to the birds chirp," Haas says. "I mean, just the benefit of that, and understanding that we have a role in this natural world, and we're part of it. I think that's really intuitive and it's obvious, but I think it's also really, really important. We're showing very convincingly with empirical data that, during a very difficult time like we are in now, that it's important to do these things to maintain your psychological health."

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This study was supported with funding from a Global Research Collaboration Grant from the University of Georgia and a National Science Foundation grant, NSF #202937.

Wolves prefer to feed on the wild side

Research team studies feeding behavior of wild predators in Mongolia

UNIVERSITY OF GÖTTINGEN

Research News

 

IMAGE: TRACKS OF BEAR AND WOLF view more 

CREDIT: NINA TIRALLA

When there is a choice, wolves in Mongolia prefer to feed on wild animals rather than grazing livestock. This is the discovery by a research team from the University of Göttingen and the Senckenberg Museum Görlitz. Previous studies had shown that the diet of wolves in inland Central Asia consists mainly of grazing livestock, which could lead to increasing conflict between nomadic livestock herders and wild predatory animals like wolves. The study has been published in the journal Mammalian Biology.

Around three million people live in Mongolia, making it the most sparsely populated country in the world. In addition, there are more than 40 million grazing animals. These animals are not just a source of food but also the only source of income for more than half of the population. Livestock cultivation is leading to a massive change in Mongolia's landscape: areas close to nature are increasingly being converted into pastureland: in fact, one third of the country is now used for this purpose. This inevitably leads to conflict with the indigenous wild animals, especially large predators such as the wolf.

CAPTION

The Chentii Mountains in the north of Mongolia.

CREDIT

Nina Tiralla, University of Göttingen

Biologist and forest scientist Nina Tiralla from the University of Göttingen studied the feeding behaviour of wolves for her Master's thesis. Together with colleagues from the Senckenberg Museum, she analysed 137 wolf droppings collected during fieldwork in Mongolia between 2008 and 2012. "We were able to show that 89 percent of the wolves' diet consisted of wild ungulates, predominantly Siberian roe deer," says Tiralla. "The remaining 11 per cent consisted of small mammals such as hares or mice." Even remnants of insects and berries could be detected in the faeces - but there was no trace of farmed animals. "This was surprising for us because previous studies had shown grazing animals to be the main food source for wolves," says Tiralla.

The key difference could lie in the situation of the animals: unlike the earlier studies on Mongolian wolves, the samples examined in this study come from near-natural regions with high species diversity. "Although there is also a supply of grazing animals here, the wolves seem to prefer wild animals such as the Siberian roe deer as prey, possibly because they are easier and less dangerous to hunt," the authors explain. They conclude that if wolves live in a near-natural and species-rich landscape with sufficient prey, they pose only a very low threat to grazing livestock. This could apply not only in Mongolia, but in principle also to other countries.

CAPTION

Nina Tiralla from the University of Göttingen follows a wolf trail in Mongolia.

CREDIT

Nina Tiralla, University of Göttingen

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Original publication: Nina Tiralla, Maika Holzapfel, Hermann Ansorge (2021). Feeding ecology of the wolf (Canis lupus) in a near-natural ecosystem in Mongolia. Mammalian Biology 101: 83-89. https://doi.org/10.1007/s42991-020-00093-z

Contact: Nina Tiralla
University of Göttingen
Faculty of Forest Sciences and Forest Ecology
Bioclimatology Group
Büsgenweg 2, 37077 Göttingen, Germany
Email: ntirall1@gwdg.de
http://www.uni-goettingen.de/en/197704.html

Spotted lanternfly: Research accelerates in effort to contain invasive pest

New collection showcases growing body of knowledge on spotted lanternfly biology and management

ENTOMOLOGICAL SOCIETY OF AMERICA

Research News

 

IMAGE: THE SPOTTED LANTERNFLY (LYCORMA DELICATULA) IS A TREEHOPPER NATIVE TO ASIA BUT WAS DISCOVERED IN PENNSYLVANIA IN 2014, AND IT HAS SINCE SPREAD TO FIVE OTHER NORTHEASTERN STATES. ITS PRIMARY... view more 

CREDIT: STEPHEN AUSMUS, U.S. DEPARTMENT OF AGRICULTURE-AGRICULTURAL RESEARCH SERVICE, PUBLIC DOMAIN

Annapolis, MD; February 17, 2021--When the invasive spotted lanternfly arrived in the United States in 2014, it was immediately recognized for the threat it posed to native plants and crops. A community of researchers and experts in science, agriculture, and government sprang into action to respond, improving our chances for containing the pest and curbing its potential for damage.

While the effort continues, a new collection curated by the Entomological Society of America's family of journals showcases the growing body of research that is helping us understand the spotted lanternfly's biology and how to contain it. The collection features 25 articles published in ESA journals since 2015, with 16 of them new additions since June 2020.

The spotted lanternfly (Lycorma delicatula) is a treehopper native to Asia but was discovered in Pennsylvania in 2014, and it has since spread to five other northeastern states. Its primary host is tree of heaven (Ailanthus altissima), but it is known to feed on more than 100 types of plants--mostly trees, shrubs, and stout vines. Valuable crops the spotted lanternfly can damage include grapes, apples, and peaches, as well as hardwood trees. One study of the lanternfly's potential range in the U.S., based on environmental and climatic conditions, suggests most of New England and the mid-Atlantic states as well as parts of the central U.S. and Pacific Northwest are vulnerable to establishment of the spotted lanternfly if it finds its way there.

Melody Keena, Ph.D., research entomologist at the U.S. Forest Service, is co-editor-in-chief of the ESA journal Environmental Entomology and compiled the collection on spotted lanternfly. Like many, Keena was struck by the insect's potential when she first learned about it. "I was surprised because it is so much bigger than the treehoppers that are native. I was also surprised by the large numbers congregating on single trees," she says.

Early on, the U.S. Department of Agriculture's Animal Plant Health Inspection Service and the state of Pennsylvania led the charge, says Keena, while more states and groups have joined in as the spotted lanternfly has spread.

"Both federal and university groups--with Pennsylvania State University taking the early lead--have developed a lot of knowledge and tools rapidly for dealing with this pest, as this collection demonstrates," Keena says.

Engaging the public has been critical as well.

"The public has taken an interest in it because of the major nuisance the adults are in the fall, with all the honey dew the lanternflies produce and black sooty mold that grows on it," Keena says. "They are willing to help in any way they can, like removing its egg masses or smashing adults they find or allowing researchers to use their property."

The research collection showcases progress made so far, as continued awareness and research will be necessary to slow the spotted lanternfly's spread.

"Multiple tools for trapping and killing spotted lanternfly have been developed but still need improvement, especially for adults. Biological control organisms have been found and are being evaluated. Prospects for managing it are good," says Keena. "We don't yet know how far it will successfully be able to spread, but there are indications that it may have some climatic limitations. Current work to understand how humans are aiding its spread, and how to cut off those avenues, is underway."

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The ESA spotted lanternfly collection is available at http://www.academic.oup.com/ee/pages/research-on-spotted-lanternfly, featuring 25 articles published across the ESA family of journals. Several articles in the collection have also been featured in accompanying posts at the Entomology Today blog, available at http://www.entomologytoday.org/tag/slf-collection.

CONTACT: Joe Rominiecki, jrominiecki@entsoc.org, 301-731-4535 x3009

ABOUT: ESA is the largest organization in the world serving the professional and scientific needs of entomologists and people in related disciplines. Founded in 1889, ESA today has more than 7,000 members affiliated with educational institutions, health agencies, private industry, and government. Headquartered in Annapolis, Maryland, the Society stands ready as a non-partisan scientific and educational resource for all insect-related topics. ESA publishes eight internationally acclaimed journals that provide unsurpassed coverage of the broad science of entomology, as well as the quarterly magazine American Entomologist. For more information, visit http://www.entsoc.org and http://www.insectscience.org.

A study with 1,600 dogs: More than 20 gene loci associated with canine hip dysplasia

UNIVERSITY OF HELSINKI

Research News

 

Hip dysplasia is a developmental disorder common in most dog breeds, and its onset is affected by both hereditary and environmental factors.

Prior studies have identified dozens of genetic loci associated with hip dysplasia in various breeds. The relevance of the loci to disease susceptibility remains an open question. The previously identified loci were reinvestigated at the University of Helsinki, Finland, using a large independent cohort of 1,600 dogs representing ten breeds.

The individual genetic variants at the target loci were determined from blood samples. The standardized radiographic hip phenotypes as assessed by expert veterinarians were obtained from the Finnish Kennel Club.

"Key to the study was the opportunity to utilize the world's largest canine DNA bank maintained by Professor Hannes Lohi's research group. We validated the disease association of 21 loci from 14 chromosomes," says Professor Antti Iivanainen from Faculty of Veterinary Medicine, University of Helsinki, and continues: "Genes related to a protein modification process known as neddylation were overrepresented among the genes residing in the validated loci. This was an interesting new find."

Lea Mikkola, PhD, who wrote her doctoral thesis on the topic at the University of Helsinki, emphasizes that, genetically, hip dysplasia is a highly complex disease.

"A multitude of genes affect the development of the disease. There are marked differences in the genetic background of the disease between breeds, even if certain gene loci associated with it are the same."

In the future, the researchers want to pay closer attention to the loci now identified as relevant to uncover the actual genes underlying hip dysplasia and their variants.

"The findings do not boost disease diagnostics or dog breeding as such, but they can likely be used as part of broader risk profiles in the future. The identified loci also contain new candidate genes associated with hereditary hip dysplasia in humans, which may eventually improve humans' care. More hip dysplasia studies should be conducted, through increased international collaboration, with different dog breeds," notes Professor Hannes Lohi from the Faculty of Veterinary Medicine and the Faculty of Medicine.

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 New piece of the puzzle increases understanding of speciation

UNIVERSITY OF GOTHENBURG

Research News

 

IMAGE: SNAILS: MATING INTERTIDAL MARINE SNAILS. PHOTOGRAPHER: PATRIK LARSSON. view more 

CREDIT: PATRIK LARSSON

Speciation is important because it increases biodiversity. A thesis from the University of Gothenburg examines the speciation process in multiple marine species where different populations of the same species might evolve into two completely new species.

When two populations of a species become isolated, their genes no longer intermix and over time, the two populations become increasingly different from each other. What is known as a reproduction barrier has then been formed because the two different populations no longer mate with each other even if they would meet again.

For a long time, researchers proposed that new species could be formed only if two populations were separated by a physical barrier over a very long period of time, for hundreds of thousands of generations or more.

New species can form without physical isolation

Today, there are many examples of species being formed without isolation, such as during ongoing genetic exchange. This exchange should prevent two populations to become different and so, understanding how reproductive barriers can still develop is an intriguing question for speciation researchers.

Samuel Perini, researcher at the Department of Marine Sciences and author of the new thesis, has studied what happens in species with populations that are genetically different and meet at a contact zone, a boundary area between the two populations.

"I have investigated reproductive barriers that exist between two different forms of Littorina saxatilis, an intertidal marine snail, and I have analyzed data on reproductive barriers found in several marine species around the mouth of the Baltic Sea," says Perini.

Surrounding marine environment plays a role

In a review of reproductive barriers in 23 different species, including cod, herring and plaice, Samuel Perini found large genetic differences between the Baltic Sea populations and the North Sea populations.

"These differences are maintained partly because the populations survive differently in different salinities and partly because their reproduction is separated in time or space, or both."

For the Littorina saxatilis snail, which is common in the Atlantic along the coasts of both Europe and North America, two different populations or ecotypes have formed under ongoing genetic exchange, according to previous research. One population is known as the "Crab" ecotype and the other population is known as the "Wave" ecotype.

Crab snails live in and are adapted to portions of the rocky shore with large stones and crabs, while Wave snails live on portions of the rocky shore with rock slabs exposed to waves. Crab snails and Wave snails meet at the boundary of these two habitats but genetic and phenotypic differences are still maintained between the two populations. Adaptations to the Crab and Wave habitat is strongly driven by natural selection and survival in the non-native environment is low. Hence, natural selection reduces genetic exchange between Crab and Wave snail populations because it decreases the opportunity for a Crab snail to survive and reproduce in the Wave habitat with a Wave snail of the opposite sex (and vice versa).

Size matters

The size of the intertidal marine snail is important for adaptation to the different environments. Large snails are selected for in environments where there are crabs, and small snails are favoured in environments exposed to waves.

"My studies show that the size of intertidal marine snails is important not only for survival but also for mating. I show in my thesis that mating is more common between snails of similar sizes and that small males have more matings. Both of these factors help to counteract gene exchange between the large Crab snails and the smaller Wave snails when they meet both inside and outside the contact zones."

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Contact:

Samuel Perini, Department of Marine Sciences, University of Gothenburg
+46 (0)31-786 20 47, +46 (0)766-18 20 47, samuel.perini@gu.se

The dissertation's title: Reproductive isolation at contact zones

Link to the thesis: http://hdl.handle.net/207

MONDO KUKRI

Unique feeding behavior of Asian kukri snakes gutting frogs and toads

PENSOFT PUBLISHERS

Research News

 

After describing a unique behaviour in the Small-banded Kukri Snake (Oligodon fasciolatus) last September, two new studies, also led by Henrik Bringsøe, are now reporting the same gruesome feeding strategy in another two species: the Taiwanese Kukri Snake (Oligodon formosanus) and the Ocellated Kukri Snake (Oligodon ocellatus). In their research across Asia, the scientists also observed and contemplated other rare behaviours in kukri snakes.

CAPTION

An Ocellated Kukri Snake (Vietnam) first pierced this poisonous Asian common toad and buried its head deeply into the abdomen of the amphibian, as it was probably eating the organs. However, as seen in the photo, the kukri snake proceeded to swallow the toad whole.

CREDIT

James Holden

The closely related three species of snakes within the genus Oligodon have evolved an unusual behaviour where they pierce the abdomens of the amphibians, tear off their organs and swallow them one by one, keeping the prey alive for up to a few hours. Given that these species have also been recorded to feed in a more typical way: by swallowing their prey whole, the scientists find it likely that the alternative strategy has evolved specifically in their species group, in order to be able to eat larger animals. The latest findings are also published in the peer-reviewed, open-access scholarly journal Herpetozoa.

One of the new studies reports about two instances from Hong Kong, where Taiwanese Kukri Snakes were observed to disembowel Painted Burrowing Frogs (Kaloula pulchra). In one of the cases, the snake had cut open the belly of the frog and inserted its head into the frog's abdomen. Further, the reptile was seen to repeatedly rotate its body longitudinally in a "performance" also known as "death rolls". In the other case, reported in the study, the organs of the frog had been forced out of its abdomen. The researchers also provide video recordings of these unique behaviours.

"We believe that the purpose of these death rolls was to tear out organs to be subsequently swallowed," comments Bringsøe.

Meanwhile, the study mentions a new observation of one of the studied snake species (the Small-banded Kukri Snake, Oligodon fasciolatus), however preferring to swallow its Painted Burrowing Frog whole, after doing the same "death rolls", which led the scientists to think that it is the size of the prey that determines how exactly the snake would go about its dinner. The researchers also add that in both cases, the snake would eventually swallow its prey's remains.

The second newly published research paper studies a third species: the Ocellated Kukri Snake, which was observed to eat the toxic Asian Black-spotted Toad (Duttaphrynus melanostictus) in Vietnam. Initially, the snake was seen to have buried its large head eyes-deep into the amphibian's abdomen. Eventually, though, the snake swallowed the toad whole despite its toxicity, providing further evidence that kukri snakes are in fact resistant to the cardiac glycoside toxins of the toads.

"We hope that future observations may uncover additional aspects of the fascinating feeding habits of kukri snakes though we may indeed call them gruesome!" says Bringsøe.

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Research papers:

Bringsøe H, Suthanthangjai M, Suthanthangjai W, Lodder J, Komanasin N (2021) Gruesome twosome kukri rippers: Oligodon formosanus (Günther, 1872) and O. fasciolatus (Günther, 1864) eat Kaloula pulchra Gray, 1831 either by eviscerating or swallowing whole. Herpetozoa 34: 49-55. https://doi.org/10.3897/herpetozoa.34.e62688

Bringsøe H, Holden J (2021) Yet another kukri snake piercing an anuran abdomen: Oligodon ocellatus (Morice, 1875) eats Duttaphrynus melanostictus (Schneider, 1799) in Vietnam. Herpetozoa 34: 57-59. https://doi.org/10.3897/herpetozoa.34.e62689

VIDEO

CAPTION

A Taiwanese Kukri Snake with its head buried deep into the abdomen of a Painted Burrowing Frog. During the initial immobility of both individuals, the frog moves its long fourth toe of the left hind foot up and down 21 times. During the subsequent active struggle, the snake makes three rotations ("death rolls"), first two counterclockwise, then one clockwise.

CREDIT

Jonathan Rotbart

CAPTION

A Taiwanese Kukri Snake has cut open the abdomen of a Painted Burrowing Frog and has extracted several organs which it is biting and chewing. The video shows the snake in the process of swallowing. The observation took place in Hong Kong.

CREDIT

Vince Natteri

New revelations of tiger genomes

Tiger genomes reveal signatures of population bottlenecks, recent divergence between subspecies, local adaptation, and ongoing impacts of fragmentation

NATIONAL CENTRE FOR BIOLOGICAL SCIENCES

Research News

 

IMAGE: RANTHAMBORE TIGER view more 

CREDIT: RANTHAMBORE TIGER TEAM, NCBS

Genetic variation is like money in the bank: the more you have, the better your chances of survival in the future. Population bottlenecks decrease genetic variation, especially in endangered species. An individual's genome comprises the events that have impacted genetic variation over time, and relatively recent sequencing technologies allow us to read and interpret genetic variation across the genome. Although tigers have received significant conservation attention, little is known about their evolutionary history and genomic variation. This is especially true for Indian tigers, and with 70% of the world's tigers living in India, such understanding is critical to tiger conservation.

A team of researchers from the National Centre for Biological Sciences (NCBS), Stanford University, and zoological parks and NGOs across the world recently completed a three-year project to gain insights into genomic variation in tigers and the processes that have sculpted it. The work, just published in Molecular Biology and Evolution, reiterates that tiger subspecies are genetically distinct and reveals that although Indian tigers have the highest total genetic variation, some individuals are inbred. Simulations based on the genomic data suggest relatively recent divergences between subspecies, and intense population bottlenecks. Analyses also indicate adaptation to cold environments in Russian far east tigers, and potential selection on body size in Sumatran tigers.

The team sequenced whole genomes from 65 individual tigers from four subspecies, with a specific aim to enhance genomes from wild tigers in different habitats in India. They used these data to conduct a variety of population genomic analyses that quantify genetic variability, and investigate the partitioning of genetic variation, possible impacts of inbreeding and founder events, demographic history (including population divergence) and possible signatures of local adaptation.

They found that total genomic variation in Indian tigers was higher than in other subspecies. However, several individual tigers in India had low variation, suggesting possible inbreeding and founding bottlenecks. Tigers from northeast India were the most divergent/different from other populations in India. "Given our results, it is important to understand why some Bengal tigers appear inbred and what the consequences of this are," says Anubhab Khan, co-first author, NCBS.

The history of tiger populations from across their current range shows recent divergences between tiger subspecies, within the last 20,000 years, which is concordant with a transition from glacial to interglacial climate change and increasing human impacts across Asia. These findings are in sharp contrast to an earlier study by ShuJin Luo and others in 2018 that suggested much older divergence times. The recent divergence between populations will need to be investigated further with expanded datasets and analyses of more tiger genomes.

The data and analyses also suggest strong bottlenecks in all tiger populations, highlighting the importance of population size decline on the erosion of genetic variation. "Most studies focusing on species of conservation concern use limited numbers of specimens to try to gain understanding into how genomic variation is partitioned. It is clear from our work here, and a growing number of other studies, that it is crucial to increase our sampling efforts and use caution when interpreting results from limited sample sizes," comments Ellie Armstrong, co-first and co-corresponding author, Stanford University.

Genomes of tigers in the Russian far east suggest adaptation to the cold, while those of Sumatran tigers suggest selection based on body size. Co-senior author Elizabeth Hadly of Stanford University says, "The tiger is an excellent example of the myriad historic events that sculpt species' genomic diversity and points to the importance of understanding this diversity as we attempt to stave off extinction of our most precious species on Earth. While some populations demonstrate the importance of adaptation to local conditions, other evidence suggests that particular populations may suffer the effects of climatic change in the Anthropocene." Such information will be critical to the success of genetic rescue efforts, which should take local adaptation into consideration.

'I have worked on Indian tiger genetic variation for over a decade and always wondered how they compared to other wild tigers. Our study reveals that while the total variation in Indian tiger genomes is high, they have also been dramatically shaped by population bottlenecks. The genomic variation of Indian tigers continues to be shaped by the ongoing loss of connectivity. Population management and conservation action must incorporate information on genetic variation. I hope doing so will help India maintain the gains in tiger conservation achieved so far,' says Uma Ramakrishnan, co-senior and co-corresponding author, NCBS.

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https://academic.oup.com/mbe/advance-article/doi/10.1093/molbev/msab032/6133235?searchresult=1

Increasingly fragmented tiger populations may require 'genetic rescue'

STANFORD UNIVERSITY

Research News

 

Despite being one of the world's most charismatic species, tigers face uncertain futures primarily due to habitat fragmentation, human-wildlife conflict and poaching. As global tiger populations decline, so does their genetic diversity. But until now it's been unclear how the animals' dwindling numbers are affecting them at the genetic level.

To find out, researchers at Stanford University, the National Centre for Biological Sciences, India, and various zoological parks and NGOs sequenced 65 genomes from four of the surviving tiger subspecies. Their findings confirmed that strong genetic differences exist between different tiger subspecies but showed, surprisingly, that these differences emerged relatively recently, as Earth underwent a major climatic shift and our own species grew increasingly dominant.

The research, detailed in a new paper published this week in the journal Molecular Biology and Evolution, shows how genomics can help guide conservation efforts toward wild tigers and other species, said study co-leader Elizabeth Hadly, the Paul S. and Billie Achilles Professor in Environmental Biology in the School of Humanities and Sciences.

"The increasing dominance of humans across the world means that our understanding of which attributes of species and populations are best suited to the Anthropocene becomes ever more important," said Hadly, referring to the proposed geological epoch marked by significant human impact on the environment.

"Some populations are well adapted to a future dominated by humans and our new climates and others are not, so any type of management of species should be informed by what we can glean from their genomes," added Hadly, who is also a senior fellow at the Stanford Woods Institute for the Environment. "Conservation genomics is far from a perfect science, but this tiger study hints at the power of adequate sampling across both the species range and its genome."

The study reveals that the world's existing tiger subspecies began exhibiting signs of dramatic and recent contractions starting only around 20,000 years ago - a period that coincided with both the global transition out of the Pleistocene Ice Age and the rise of human dominance in Asia. Each subspecies of tiger the team studied showed unique genomic signatures as a consequence of their increasing isolation from one another.

For example, local environmental genomic adaptation to cold temperatures was found in the Siberian (or Amur) tigers, the northernmost tigers found in the Russian Far East. These adaptations were absent in the other tiger subpopulations studied. Tigers from Sumatra, meanwhile, showed evidence of adaptations for body size regulation, which could help explain their overall smaller size. Despite these adaptations, tigers from these populations have low genetic diversity, suggesting that if populations continue to decline, genetic rescue may need to be considered.

One form that rescue might take is through the mating of different tiger subspecies together as a way of increasing their genetic diversity and protecting against the ill effects of inbreeding. Inbreeding occurs when populations are so small and isolated from other populations that related individuals breed with each other. Over time, this leads to lower genomic diversity and to the emergence of recessive diseases, physical deformities and fertility problems that often result in behavioral, health and population declines. Although increasing genetic diversity is one goal, another might be to select for inherited traits that confer higher survival in a changing world.

Even Bengal tigers from India, which comprise about 70 percent of the world's wild tigers and exhibit relatively high genomic diversity compared to other subspecies, showed signs of inbreeding in some populations, the study concluded.

"Some Bengal tiger populations are essentially small islands surrounded by an inhospitable sea of humanity. These tigers cannot disperse and so have only their close relatives to choose as mates," Hadly said.

While many studies investigating endangered species using genomics sequences from a single or just a few individuals, this work reiterates that individuals are not likely to be representative of a population or species status. Further work investigating the consequences of potential inbreeding and diversity declines across the subspecies are needed.

"As genomics has become available to conservation, it is apparent that collaborative studies to investigate the diversity within species are critical," said study first author Ellie Armstrong, a Stanford PhD student in Hadly's lab. "Inferences made from single genomes, while excellent additions to our knowledge of diversity in general, cannot be extrapolated to entire species, especially when using captive animals to infer adaptation to complex habitat change."

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Other Stanford co-authors on the study, titled "Recent Evolutionary History of Tigers Highlights Contrasting Roles of Genetic Drift and Selection," include former postdoctoral scholars Ryan Taylor and Stefan Prost; PhD students Jonathan Kang and Sergio Redondo; Gregory Barsh, professor of genetics and pediatrics, emeritus; Dmitri Petrov, professor of biology; and Christopher Kaelin, staff geneticist.