Mammoth (Mammutus primigenius) is isolated Wrangel Island Mammoths were discovered off the coast of Siberia approximately 10,000 years ago and survived for over 200 generations before going extinct approximately 4,000 years ago. To study the evolutionary events leading up to their extinction, scientists analyzed the genomes of 21 Siberian mammoths and found that mammoth populations recovered quickly from a severe bottleneck and remained demographically stable for the next 6,000 years.
Three mammoths (Mammutus primigenius) walks up a snow-covered hill with snow-capped mountains rising behind him above a dense green forest of fir trees. Image by Daniel Eskridge.
“We can confidently reject the idea that the population was so small that it was destined to go extinct for genetic reasons,” said Dr Love Dalen, an evolutionary geneticist at the National Academy of Sciences of Canada. Center for PaleogeneticsIt is a joint collaboration between the Swedish Museum of Natural History and Stockholm University.
“This means that it was probably just a chance event that caused the mammoths to go extinct, and if that chance event hadn't occurred, mammoths would still be around today.”
“In addition to shedding light on the population dynamics of woolly mammoths, analysis of the Wrangel Island mammoths could inform conservation strategies for this currently endangered animal.”
“The mammoth is an excellent system for understanding the ongoing biodiversity crisis and what happens from a genetic perspective when a species experiences a population bottleneck, because it reflects the fate of many modern populations,” said Dr Marianne DeHask, also from the Centre for Palaeogenetics.
To understand the genomic impact of the Wrangel Island bottleneck on mammoth populations, the researchers analyzed the genomes of 21 woolly mammoths, 14 from Wrangel Island and seven from the mainland population that existed before the bottleneck.
Overall, the samples span the woolly mammoth's existence over the past 50,000 years and provide insight into how the animal's genetic diversity has changed over time.
Compared to their mainland ancestors, the genomes of the Wrangel Island mammoths showed signs of inbreeding and low genetic diversity.
In addition to the overall low genetic diversity, Major histocompatibility complexA group of genes known to play important roles in the immune response of vertebrates.
The scientists showed that the genetic diversity of the population continued to decline, albeit at a very gradual rate, throughout the 6,000 years that the mammoths lived on Wrangel Island, suggesting that the population size remained stable until the end.
They also showed that the island's mammoth population gradually accumulated moderately deleterious mutations over its 6,000-year existence, but that the most deleterious mutations were slowly eliminated.
“If an individual had a highly deleterious mutation, they would basically not be able to survive, so over time those mutations would slowly disappear from the population. But we know that mammoths accumulated mildly deleterious mutations almost all the way up until their extinction,” Dr DeHask said.
“It's important to remember that current conservation programs will not be enough to simply re-establish populations to a reasonable size. They also need to be actively and genetically monitored, as these genomic effects could last for more than 6,000 years.”
The mammoth genomes analyzed in this study span a long period of time, but do not include the last 300 years of the species' existence.
However, the authors plan to excavate fossils from the final stages of the mammoth and analyze its genome sequence in the future.
“What happened to them at the end is still a mystery. We don't know why they went extinct after surviving fairly well for 6,000 years, but we think it was probably a sudden event,” Dr Dallen said.
“I think there's still hope we can figure out why they went extinct, but I can't make any promises.”
of Investigation result Published in the online journal this week cell.
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Marianne DeHask othersTemporal dynamics of genomic erosion in pre-extinction mammoths. cellPublished online June 27, 2024, doi: 10.1016/j.cell.2024.05.033
Source: www.sci.news
