Scientists long have been curious about the genetic factors that influence species survival, extinction, and evolution.
Now, a team of researchers from the Centre for Palaeogenetics, in collaboration with the Swedish Museum of Natural History and Stockholm University, studied the genomic factors of the woolly mammoths’ last surviving population on Wrangel Island.
The woolly mammoth is a type of large, extinct elephant that lived during the Ice Age. It is known for its long, curved tusks and thick, shaggy fur, which helped it survive in cold, harsh environments.
Woolly mammoth extinct despite stable population
Researchers aimed to ascertain whether the Wrangel Island (located off the coast of Siberia) mammoths went extinct due to genetic reasons or another cause.
Additionally, the experts sought to reject the hypothesis that a small population size and low genetic diversity led to their extinction.
This led them to discover that the extinction of the woolly mammoths on Wrangel Island was likely due to a sudden random event rather than genetic factors, as their population remained stable despite low genetic diversity and inbreeding.
Marianne Dehasque from the Centre for Palaeogenetics, also the first author of the study told Interesting Engineering that mammoths survived for such a long time on Wrangel Island.
“This is because it was one of the last places with the right kind of vegetation for mammoths to survive –– the steppe tundra typically associated with the last Ice Age.”
The study aspired to shed light on the looming concern of species going extinct or becoming endangered, with the hope of conserving them by maintaining and monitoring genetic diversity in small populations.
Despite signs of stable population size and efforts to purge harmful mutations, the woolly mammoths went extinct. In fact they remained isolated on the island roughly 10,000 years ago and seemed to remain there for another 6,000 years before going extinct.
‘Short or catastrophic event caused the population’s demise’
The genomic analysis covers samples from the last 50,000 years of the woolly mammoth’s existence, though it does not include the final 300 years of the species’ life on the island.
Dehasque told IE that the final 300 years could give us a better understanding of what happened right before mammoths went extinct.
“In mammoth generations, 300 years is a very short time. That is also why we think a short or catastrophic event caused the population’s demise,” she added.
“But if there was a sudden population collapse due to genetic defects, or if a disease outbreak caused the population’s extinction, we would need data from those last 300 years to see that. Alternatively, no change supports the hypothesis of an external environmental event.”
The author explained to IE that while the mammoths faced certain challenges such as reduced genetic diversity and an increase in inbreeding, the extinct animal survived despite them.
The population increased rapidly after the initial bottleneck and remained stable. One hypothesis is that the mammoths may have altered their behavior to avoid inbreeding with close relatives, Dehasque says.
The team analyzed the genomes of 21 woolly mammoths, including 14 from Wrangel Island and seven from the mainland according to a statement by the scientists. The analysis looked for signs of inbreeding, genetic diversity, and the accumulation of harmful mutations over time.
“What happened at the end is a bit of a mystery still—we don’t know why they went extinct after having been more or less fine for 6,000 years, but we think it was something sudden,” stated senior author Love Dalén, an evolutionary geneticist at the Centre for Palaeogenetics.
“I would say there is still hope to figure out why they went extinct, but no promises.”
The study was published earlier today [June 26, 2024] in the journal – Cell.
