Four thousand years ago, the last woolly mammoth on an island near modern-day Siberia met its end. The isolation of these mammoths on the island may have caused significant inbreeding and drastic population declines, contributing to their extinction.
However, recent research has shown that although the woolly mammoth population on Wrangel Island was inbred, it wasn’t necessarily destined for extinction. Instead, these mammoths gradually shed harmful genetic mutations, which suggests that a random event like disease or environmental change ultimately led to their demise.
A study published on June 27 in Cell explores this in detail, highlighting that the final woolly mammoth population managed to adapt by losing detrimental genetic traits. This finding provides new insights into how the last mammoths on Wrangel Island lived and what might have caused their extinction.
Paleontologist Joshua Miller from the University of Cincinnati, although not part of the study, praised the research for its thoroughness. He noted that it sheds light on the end of the Wrangel Island mammoths and offers important lessons for monitoring genetics in today’s endangered species conservation.
Approximately 10,000 years ago, woolly mammoths roamed mainland Siberia. However, rising sea levels stranded these populations on separate islands, which likely limited their genetic diversity and contributed to their eventual extinction.
Genetic variation is crucial for animals to adapt to environmental changes, as explained by Love Dalén, an evolutionary geneticist at the Centre for Palaeogenetics in Stockholm. Previous theories about woolly mammoth extinction suggested that isolated populations suffered from increased inbreeding, reduced genetic diversity, and greater susceptibility to harmful mutations, diseases, and death.
However, Dalén and his team have challenged this idea for over a decade. They have gathered woolly mammoth bone fragments, tusks, and teeth from Siberia to extract mammoth genomes. In their latest study, they analyzed 21 genomes, including eight previously published ones, covering the last 50,000 years of the woolly mammoth’s existence, especially their isolation on Wrangel Island.
The researchers used computer modeling to compare the genomes of woolly mammoths with those of elephants, their closest living relatives, and humans. This comparison aimed to determine how harmful genetic mutations impacted the mammoths and whether these mutations were eliminated over time.
The analysis revealed that although Wrangel Island’s woolly mammoth population initially had as few as eight individuals, it grew to about 200 to 300 and remained stable until their extinction.
Over time, the most harmful genetic mutations became less frequent, likely because individuals with these mutations were less likely to reproduce.
The researchers concluded that minor genetic mutations alone were unlikely to have caused the extinction of the Wrangel Island woolly mammoths.
Vincent Lynch, an evolutionary biologist at the University at Buffalo in New York, acknowledged that the evidence strongly challenges the meltdown model, though it doesn’t entirely rule it out. While island isolation and reduced genetic variation might not have been the decisive factors in the woolly mammoth’s extinction, even minor genetic mutations could have made these mammoths more susceptible to other environmental changes such as disease, climate shifts, and human arrival.
Marianne Dehasque from the Centre for Palaeogenetics pointed out that due to difficulties in obtaining high-quality DNA, the researchers couldn’t analyze the genetic condition of the Wrangel Island woolly mammoth population during their final 300 years, which is about five generations. However, with advancements in sequencing technologies, the team hopes to complete their analysis of the Wrangel Island mammoths’ genetic history in the future.
Despite ongoing studies, the exact circumstances of the woolly mammoth’s final moments remain unclear. Dalén suggested that perhaps an unexpected disaster struck Wrangel Island, implying that without such an event, woolly mammoths might still be roaming today.
- ONLINE NEWS Yuan, C. (2024, June 27). The last woolly mammoths offer new clues to why the species went extinct. Science News. [Science News]
- JOURNAL Dehasque, M., Morales, H. E., Díez-Del-Molino, D., Pečnerová, P., Chacón-Duque, J. C., Kanellidou, F., Muller, H., Plotnikov, V., Protopopov, A., Tikhonov, A., Nikolskiy, P., Danilov, G. K., Giannì, M., Van Der Sluis, L., Higham, T., Heintzman, P. D., Oskolkov, N., Gilbert, M. T. P., Götherström, A., . . . Dalén, L. (2024). Temporal dynamics of woolly mammoth genome erosion prior to extinction. Cell. [Cell]
- JOURNAL Nyström, V., Humphrey, J., Skoglund, P., McKEOWN, N. J., Vartanyan, S., Shaw, P. W., Lidén, K., Jakobsson, M., Barnes, I., Angerbjörn, A., Lister, A., & Dalén, L. (2012). Microsatellite genotyping reveals end‐Pleistocene decline in mammoth autosomal genetic variation. Molecular Ecology, 21(14), 3391–3402. [Molecular Ecology]
APA 7: TWs Editor. (2024, June 28). Woolly Mammoth: Genetic Insights into Their Extinction. PerEXP Teamworks. [Online News Link]
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