Mammoths suffered a genetic meltdown near their extinction, a new study by scientists at University of California claims thereby lending credibility to the existing theories of genome deterioration stemming from small population sizes.
Researchers at the university compared genomes from a mainland mammoth that dates back to 45,000 years ago – a time when scientists believe that woolly mammoths were found commonly in North America, Siberia, and Beringia – with the genome of one that lived about 4,300 years ago – a mammoth that is believed to have lived in a group of around 300 animals on Wrangel Island in the Arctic Ocean.
On comparison scientists found that the mammoth on the Wrangel Island had multiple harmful mutations in its genome and these mutations could have interfered with the gene functions. According to the team, the animal would have lost many olfactory receptors, which detect odors, as well as urinary proteins, which can impact social status and mate choice. Scientists also found genetic mutations that could have created an unusual translucent satin coat on the animal.
The findings are startling and give us a rough look at how dwindling populations of any species could pick up pace near extinction with even genetic factors playing a major role alongside other environmental factors such as habitat loss, climate change, warming, or ocean acidification. The comparison gives researchers the rare opportunity to see what happens to the genome as a population declines, and supports existing theories of genome deterioration stemming from small population sizes.
Authors of the study urge conservationists to give attention as preservation steps alone might not be the optimal method as preserving a small group of isolated animals is not sufficient to stop negative effects of inbreeding and genomic meltdown. For those interested in wooly mammoth “de-extinction,” the study demonstrates that some mammoth genomes carry an overabundance of negative mutations.
The mammoth genome analysis was also a great project to do with Monty Slatkin. He has spent his career developing mathematical models of how genomes will look different when population conditions change. With only two specimens to look at, these mathematical models were important to show that the differences between the two mammoths are too extreme to be explained by other factors.”