About 10,000 years ago, a small population of mammoths was isolated on Wrangel Island off the Siberian coast. This isolation was a result of rising sea levels, a phenomenon that is all too familiar today.
In just two generations, the mammoth population on Wrangel Island grew from just eight individuals to 300 members.
Conflicting assumptions about woolly mammoths
In a fascinating study, genomic analysis was performed on these mammoths, disproving the long-held notion that inbreeding and low genetic diversity were responsible for their eventual demise.
Love Dalén, an evolutionary geneticist at the Center for Paleogenetics, a joint initiative of the Swedish Museum of Natural History and Stockholm University, sheds light on this topic.
“We can now confidently reject the idea that the population was simply too small and that it was doomed to extinction for genetic reasons,” Dalén said. “That means it was probably just some random event that killed them, and if that random event hadn’t happened, then we’d still have mammoths today.”
Mammoth waves and modern protection
The research doesn’t just provide insights into the extinction of woolly mammoths. It also contains valuable lessons for modern conservation strategies and combating the ongoing biodiversity crisis.
“Mammoths are an excellent system for understanding the ongoing biodiversity crisis and what happens genetically when a species passes through a population bottleneck, as they mirror the fate of many contemporary populations,” said study lead author Marianne Dehasque. , also a researcher at the Center for Paleogenetics.
Dehasque and her team performed extensive genomic analyzes of 21 woolly mammoths, including 14 from Wrangel Island and 7 from the mainland, that lived before the population bottleneck. Their analysis spanned roughly 50,000 years of mammoth history and tracked genetic diversity over time.
Tracing the genetic pathway
The results of the analyzes were interesting. Mammoths from Wrangel Island showed signs of inbreeding and reduced genetic diversity.
However, this decline in diversity was a slow process, visible during the 6,000 years they inhabited the island. This suggests that the population remained stable until their sudden disappearance.
“If an individual has an extremely deleterious mutation, it’s basically not viable, so those mutations gradually disappeared from the population over time, but on the other hand, we see that mammoths accumulated mildly deleterious mutations almost to the point of extinction,” he added. Dehasque explained.
“It is important for current conservation programs to remember that it is not enough to get the population back to a decent size; you also have to monitor it actively and genetically because these genomic effects can last over 6,000 years.
This provides an important lesson for current conservation efforts, suggesting that it is not just about increasing population size, but also actively monitoring genomic health.
The mystery of the mammoths
The team did not include genomes from the last 300 years of mammoth existence in their study. However, they plan to sequence fossils from this period to understand the extinction event even better.
“What happened at the end is still a bit of a mystery – we don’t know why they went extinct after being more or less fine for 6,000 years, but we think it was something sudden,” Dalén said. “I’d say there’s still hope to find out why they went extinct, but no promises.
The study is published in the journal Cell.
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