Not all is rosy for the pink pigeon, study finds

Hexbyte Glen Cove

Pink pigeon of Mauritius. Credit: Mauritian Wildlife Foundation

The authors of a major study on the once critically endangered pink pigeon say boosting the species’ numbers is not enough to save it from extinction in the future.

Despite the , the team’s analysis shows the pink pigeon has a high genetic load of bad mutations, which puts it at considerable risk of extinction in the wild within 100 years without continued actions.

An led by scientists from the University of East Anglia (UEA), Durrell Institute of Conservation and Ecology (DICE) at the University of Kent and the Earlham Institute in the UK, working with organizations on the ground in Mauritius, investigated the genetic impacts of a population “bottleneck”—a rapid collapse in numbers that affected the pink pigeon from Mauritius in the late 1980s, with only 12 birds surviving in the wild.

The team analyzed the DNA of 175 birds sampled over nearly 20 years as subsequent conservation efforts took place.

With the help of biologists from the Mauritian Wildlife Foundation and the Durrell Wildlife Conservation Trust, and in partnership with the Government of Mauritius’ National Parks and Conservation Service, the free-living population of the has increased to around 500 birds.

Consequently, the pink pigeon has been down-listed twice on the International Union for Conservation of Nature Red List from critically endangered to vulnerable.

However, to keep these populations viable, the researchers warn that “genetic rescue” is needed to recover lost caused by inbreeding and to reduce the effects of the harmful mutations. This can be achieved by releasing captive-bred birds from UK and EU zoos.

Pink pigeon of Mauritius. Credit: Mauritian Wildlife Foundation

The study, published in Conservation Biology, used conservation genetic work at DICE, cutting-edge genomic techniques developed at UEA and the Earlham Institute, and computer modeling to closely examine the species’ DNA and assess the risk of future extinction, as well as forecasting what needs to be done to secure the pink pigeon’s viability. The authors say their findings could help other threatened species.

“By studying the genome of a recovered species that was once critically endangered, we can learn how to help other species to bounce back from a population collapse,” said UEA’s Prof Cock van Oosterhout, one of the lead authors.

“During the pigeon’s population bottleneck, the gene pool lost a lot of variation, and many bad mutations increased in frequency. This genetic load still poses a severe threat, even though the population has recovered in numbers.”

Prof van Oosterhout, of the School of Environmental Sciences at UEA, added: “The problem is that all individuals are somehow related to each other. They are the descendants of the few ancestors that managed to survive the bottleneck. Hence, it becomes virtually impossible to stop inbreeding, and this exposes these bad mutations. In turn, this can increase the mortality rate, and it could cause the population to collapse again.”

Prof Jim Groombridge, from the University of Kent, explained how the initial recovery of the pink pigeon population was achieved: “A captive population of pink pigeons in the Gerald Durrell Endemic Wildlife Sanctuary in Mauritius, jointly managed by the Mauritian Wildlife Foundation and the National Parks and Conservation Service, was established in the 1970s.

“This was used to breed birds for release into the wild, which boosted population numbers. The team also restored habitat by controlling introduced species and provided supplementary food as part of a field program of intensive conservation management, which further increased the free-living population.”

The study used sophisticated software called SLiM that can model an entire bird chromosome, including all its bad mutations. The researchers simulated the bottleneck and population recovery, and then they compared the predicted outcomes of different reintroduction programs. The study was therefore able to predict the viability of the population in the future under different conservation management scenarios.

Pink pigeon of Mauritius. Credit: Mauritian Wildlife Foundation

“We didn’t know how many bad mutations the population carried initially, before the bottleneck,” said Dr. Hernan Morales from University of Copenhagen, in Denmark, who performed the SLiM modeling. “We first had to simulate the ancestral population to find out how many bad mutations could have evolved. We then checked this data with data on inbreeding depression data from zoo populations of the pink pigeon.”

Using pedigree and fitness data held at Jersey Zoo for over 1,000 birds, the team estimated the genetic load, which showed that the pink pigeon carried a high genetic load of 15 lethal equivalents. This was then used to calibrate the computer models.

“The computer simulations clearly show that just boosting numbers isn’t enough,” added Dr. Morales. “The population also needs ‘genetic rescue’ from more genetically diverse birds bred in European zoos. These birds are not as closely related, and they can help to reduce the level of inbreeding. However, there is a risk that we could introduce other bad mutations from the zoo population into the wild.”

Dr. Camilla Ryan, who worked on the project at the Earlham Institute and UEA, said: “Our bioinformatics analysis indicated the importance of genetic diversity and the unique genetic rescue model to help other species from the brink of extinction. This research highlights the value of collaborations between NGOs, institutes and universities which draw together a range of expertise. This ensures that a holistic approach is taken to a species conservation which includes an understanding of its genetic health.”

Sam Speak, a Ph.D. student at UEA and co-author of the paper, added: “We are now analyzing the genome of the pink pigeon from zoo populations here in the UK, trying to locate these bad mutations. We can do this now using bioinformatics tools developed for studying human genetics and the genomes of other model bird species such as the chicken.

“By using conservation genomics, future reintroduction programs can avoid releasing individuals with high genetic load. This would help reduce inbreeding and improve the long-term recovery of such as the pink pigeon.”

“Genomic erosion in a demographically recovered bird species during conservation rescue” is published in Conservation Biology on May 13.

More information:
Genomic erosion in a demographically recovered bird species during conservation rescue, Conservation Biology (2022). DOI: 10.1111/cobi.13918

Not all is rosy for the pink pigeon, study finds (2022, May 12)
retrieved 13 May 2022

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A gene in tuberculosis bacteria is found essential for siderophore secretion and virulence

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Fish and humans: A new approach to Bloom syndrome research

Fluorescent microscopy images of healthy (left) and Bloom mutant (right) testes. Cell nuclei are shown in blue, a key protein of division in reproductive cells (Sycp3) is shown in yellow. In healthy testes the protein localizes to the nuclei, where it can fulfil its role, whereas in mutants it accumulates around the nucleus. The latter phenomenon was previously linked to cell death in rats. Credit: Credit: Tamas Annus / Eötvös Loránd University

Researchers at Eötvös Loránd University (ELTE) have created a new disease model that has contributed to a better understanding of Bloom syndrome and the sex determination processes of zebrafish. The study, linking two seemingly unrelated topics, was carried out by the research teams of Mihály Kovács (Department of Biochemistry) and Máté Varga (Department of Genetics) and published in the scientific journal Cell Death and Disease. In addition to providing important information on the cellular effects of Bloom syndrome, the new model could contribute to the development of compounds capable of mitigating symptoms and thus improve the quality of life of people living with the disease.

Bloom syndrome is a rare hereditary genetic disease characterized by , reduced fertility, reddish lesions on the skin upon being exposed to sun and increased risk of cancer development leading to premature death.

The cause of the symptoms is the malfunction of a single gene which was also named Bloom, as was the protein which it encodes.

Bloom and the four other members in its are involved in a multitude of cellular processes responsible for DNA integrity maintenance, moreover their roles often overlap, making the task of studying the syndrome equally considerably challenging and necessary. The importance of uncovering the functional roles of Bloom is further compounded by the fact that via its inhibition the survival and growth of certain cancerous cells might be hindered.

Owing to their complexity, it is beneficial to examine diseases such as Bloom syndrome not just using and computer models, but also by involving whole organisms. There are various vertebrate (African clawed frog, house mouse, brown rat, domestic rabbit) and invertebrate (roundworm, fruit fly) animals used in “in vivo” studies worldwide. In the past decades, zebrafish have also become a prime member of this group.

Zebrafish as a disease model

Zebrafish are easy to keep, relatively small and produce many rapidly growing offspring that develop outside of the bodies of the parents. Although at first glance they differ vastly from humans, their genetic material is remarkably similar as is shown by the fact that 82% of the genes associated with human diseases have zebrafish counterparts. Bloom is one such gene, thus allowing researchers to create mutants in order to study the symptoms of the mutation.

“The disease model established by our researchers showed marked similarities to human Bloom syndrome, however a number of species-specific novelties were also uncovered. The first such result is that early development of zebrafish was not hampered by the absence of the Bloom protein, moreover there were no observable differences between Blm-deficient and healthy fish even after they were subjected to DNA damaging treatments. It is likely that this was due to the absence of Bloom being compensated for by other proteins of Bloom’s family in ,” says Tamás Annus, the first author of the publication, Ph.D. student at the research group DanioLab at the Department of Genetics at Eötvös Loránd University.

However, this compensatory effect is not complete as, according to a years-long lifespan analysis and much like Bloom syndrome afflicted humans, zebrafish also live shorter lives. Upon analysis of fertilization success, it was also discovered that like humans, mutant zebrafish exhibit reduced fertility compared to their healthy fellows. This effect however could only be studied in male fish, as an additional curiosity of the mutant population was that it was entirely comprised of males. Total sex bias in zebrafish mutants is not a , but to understand it we need to know more about the determination of the sexes in this species of fish.

New model animal could contribute to the development of compounds capable of mitigating symptoms

Unlike zebrafish living in the wild, domesticated laboratory zebrafish strains do not have sex chromosomes: In their absence development of the sexes is regulated by the combined effects of a multitude of genes scattered across the genome as well as environmental factors. These processes converge in the regulation of the number of the reproductive stem cells that have not yet been committed to developing into eggs or sperm cells. If the number of these cells reaches a critical threshold during a certain phase of development, the individual will develop as female; otherwise, the develop as male.

In the absence of proteins responsible for DNA integrity maintenance, these cells cannot multiply to the quantity required for female development even if it was possible according to the above-mentioned factors, resulting in all Bloom mutants becoming males. As an additional consequence of the mutation, the production of sperm cells is also impaired, leading to drastically reduced fertilization success compared to healthy fish.

“In the future this model may provide additional valuable information about the regulation of the processes necessary for sex determination and the cellular effects of Bloom syndrome which in time might even contribute to improving the quality of life of the people living with this disorder via development of compounds capable of mitigating symptoms,” says András.

More information:
Tamás Annus et al, Bloom syndrome helicase contributes to germ line development and longevity in zebrafish, Cell Death & Disease (2022). DOI: 10.1038/s41419-022-04815-8

Fish and humans: A new approach to Bloom syndrome research (2022, May 12)
retrieved 13 May 2022

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NASA’s ECOSTRESS detects ‘heat islands’ in extreme Indian heat wave

NASA’s ECOSTRESS instrument made this image of ground temperatures near Delhi (lower right), around midnight on May 5. The urban “heat islands” of Delhi and smaller villages peaked at 102 degrees Fahrenheit (39 degrees Celsius) while nearby fields were about 40 degrees Fahrenheit cooler. Credit: NASA/JPL-Caltech

A relentless heat wave has blanketed India and Pakistan since mid-March, causing dozens of deaths, fires, increased air pollution, and reduced crop yields. Weather forecasts show no prospect of relief any time soon. NASA’s Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station instrument (ECOSTRESS) has been measuring these temperatures from space, at the highest spatial resolution of any satellite instrument.

This image, taken shortly before local midnight on May 5, shows and northwest of Delhi (the large red area in the lower right) that are home to about 28 million people. The image covers about 4,800 square miles (12,350 square kilometers).

Cities are usually markedly warmer than the surrounding countryside due to human activities and the materials used in the built environment. The image clearly delineates these urban “heat islands.” Nighttime temperatures in Delhi and several smaller villages were above 95 degrees Fahrenheit (35 degrees Celsius), peaking at about 102 degrees F (39 degrees C), while the rural fields nearby had cooled to around 60 degrees F (15 degrees C). This data suggests that are experiencing considerably higher temperatures than the average temperatures reported for their regions.

ECOSTRESS measures the temperature of the ground itself, which is very similar to air temperature at night (though the ground may be warmer than the air in daylight hours). The instrument launched to the in 2018. Its primary mission is to identify plants’ thresholds for water use and water stress, giving insight into their ability to adapt to a warming climate. However, ECOSTRESS also records other heat-related phenomena, like this heat wave. With a pixel size of about 225 feet (70 meters) by 125 feet (38 meters), its high-resolution images serve as a powerful tool for understanding aspects of the weather event that might be overlooked by traditional observation networks.

More information:

NASA’s ECOSTRESS detects ‘heat islands’ in extreme Indian heat wave (2022, May 12)
retrieved 13 May 2022

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More gender segregation in jobs means more harassment, lower pay

Hexbyte Glen Cove

Credit: CC0 Public Domain

A new paper in The Quarterly Journal of Economics, published by Oxford University Press, indicates that people who are the gender minority in their workplace are more likely to experience sexual harassment. This harassment discourages people from taking jobs in workplaces where they would be a gender minority. It also leads current minorities to leave their jobs for new ones with lower pay.

Women and men are segregated across workplaces, and previous research indicates that such segregation may explain 15 to 20% of the . Researchers here studied how gender discrimination in work conditions contributes to such inequality. Using information from the bi-annual Swedish Work Environment Survey, the study shows that women’s and men’s risks grow with the share of opposite-sex people in their workplace. Women are about three times as likely as men to experience sexual harassment, but in the most male-dominated workplaces, they are nearly six times more likely than men to do so. Meanwhile, men’s risk is almost twice as high as women’s in the most female-dominated workplaces.

The research used a survey experiment to measure workers’ aversion to taking jobs in workplaces where a sexual harassment incident had occurred. Both women and men had a high aversion to jobs in such workplaces, but their aversion was three times larger if the harassment victim had the same sex as themselves. These findings imply that harassment deters women from taking jobs in male-dominated workplaces, where women are the main harassment victims, and vice versa for men.

Workplaces with a larger share of men pay more. A workplace with more than 80% men offers a 9% higher wage for the same work as a workplace with 80% female employees.

The researchers here find that harassment produces through job changes among harassment victims. Investigators found that women who report sexual harassment are 25 percent more likely to have left for a new job in the three years after the harassment. Men who report sexual harassment are 15 percent more likely to have left for a new job. The study indicates women who experience sexual harassment are more likely to leave for a job at a company with a lower share of men and a lower wage premium.

“By deterring women from taking jobs in male-dominated workplaces, harassment also keeps women away from the highest-paying employers in the labor market, and men from the lowest-paying ones,” said Johanna Rickne, one of the paper’s authors. “In this way, sexual harassment contributes to the wage gap.”

More information:
Sexual harassment and gender inequality in the labor market, The Quarterly Journal of Economics (2022). DOI: 10.1093/qje/qjac018

More gender segregation in jobs means more harassment, lower pay (2022, May 12)
retrieved 12 May 2022

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Museum discovers 150-year-old platypus and echidna specimens that proved some mammals lay eggs

A preserved echidna from the newly discovered collection by William Caldwell. Credit: Jacqueline Garget

Jars of tiny platypus and echidna specimens, collected in the late 1800s by the scientist William Caldwell, have been discovered in the stores of Cambridge’s University Museum of Zoology.

At the time of their collection, these were key to proving that some lay —a fact that changed the course of scientific thinking and supported the theory of evolution.

This unique collection had not been catalogued by the museum, so until recently staff had been unaware of its existence. The exciting find was made when Jack Ashby, Assistant Director at the museum, was doing research for a new book on Australian mammals.

“It’s one thing to read the 19th-century announcements that platypuses and echidnas actually lay eggs. But to have the physical specimens here, tying us back to that discovery almost 150 years ago, is pretty amazing,” said Ashby.

He added, “I knew from experience that there isn’t a natural history collection on Earth that actually has a comprehensive catalog of everything in it, and I suspected that Caldwell’s specimens really ought to be here.” He was right: Three months after Ashby asked Collections Manager Mathew Lowe to keep an eye out, a small box of specimens was found in the museum with a note suggesting they were Caldwell’s. Ashby’s investigations confirmed this was indeed the case.

Until Europeans first encountered platypuses and echidnas in the 1790s, it had been assumed that all mammals give birth to live young. The question of whether some mammals lay eggs then became one of the biggest questions of 19th-century zoology, and hotly debated in scientific circles. The newly discovered collection of little jars represents the huge scientific endeavor that went into solving this mystery.

“In the nineteenth century, many conservative scientists didn’t want to believe that an egg-laying mammal could exist, because this would support the theory of evolution—the idea that one animal group was capable of changing into another,” said Ashby.

He added, “Lizards and frogs lay eggs, so the idea of a mammal laying eggs was dismissed by many people—I think they felt it was degrading to be related to animals that they considered ‘lower life forms.'”

Platypus specimen in the Cambridge University Museum of Zoology. Credit: University of Cambridge

The newly discovered collection includes echidnas, platypuses and marsupials at varying life stages from fertilized egg to adolescence. Caldwell was the first to make complete collections of every life stage of these species—although not all of the specimens have been found in the museum.

For 85 years, European naturalists had been attempting to find proof that platypuses and echidnas lay eggs—including by asking Aboriginal Australians—but any results they sent home were ignored or dismissed.

William Caldwell was sent to Australia in 1883—with substantial financial backing from the University of Cambridge, the Royal Society and the British Government—to resolve the long-standing mystery.

In an extensive search, Caldwell collected around 1,400 specimens with the help of a large group of Aboriginal Australians. In 1884 the team eventually found an with an egg in her pouch, and a with one egg in her nest and another just about to be laid.

This was the definitive proof Caldwell had been looking for, and the news was sent around the world. The colonial scientific establishment was apparently only willing to accept this result now that it had been confirmed by “one of their own.”

Ashby says that over the last two centuries, scientists have consistently belittled Australian mammals by describing them as strange and inferior. He believes that this language continues to affect how we describe them today, and undermines efforts to conserve them.

“Platypuses and echidnas are not weird, primitive animals—as many historic accounts depict them—they are as evolved as anything else. It’s just that they’ve never stopped laying eggs,” he said, adding, “I think they’re absolutely amazing and definitely worth valuing.”

The quill-covered echidnas are the most widespread mammal in Australia. They cover the whole continent and have adapted to live in all climates—from snow-covered mountains through to the driest deserts.

Platypuses are one of the only mammals that can detect electricity, and one of the only mammals to produce venom. With a tail like a beaver, a flat bill, and webbed feet like a duck, when the first specimens were brought to Europe people thought they were fakes that had been sewn together.

Both platypuses and echidnas have a unique combination of that 19th-century scientists thought should only exist individually in either mammals, reptiles or birds. This made them central to debates around evolution.

Ashby’s new book, “Platypus Matters: The Extraordinary Story of Australian Mammals,” is published in the UK on 12 May, 2022 by HarperCollins.

Museum discovers 150-year-old platypus and echidna specimens that proved some mammals lay eggs (2022, May 11)
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