Love Dalen, a geneticist at Stockholm University, has studied Wooly Mammoths for two decades. He and his team have successfully mapped the genome of an iconic species of the Pleistocene. Through their efforts, it has been determined the last small herd of mammoths perished 4,000 years ago on Wangle Island, an arctic land mass the size of Delaware, 80 miles north of Siberia. They suffered from a host of genetic abnormalities due to inbreeding, which may have contributed to their demise. Opinions differ on this point. Dr. Dalen compared the genomes of 14 mammoths that lived on Wrangle to seven genomes of mammoths that lived on the mainland. Mammoths began disappearing from their range about 15,000 years ago. Climate change and human predation are thought to have caused their extinction.
The genetic record indicates that the herd began with fewer than ten individuals. How they got to Wrangle from mainland Asia is open to debate, but they probably were isolated on what became an island when sea levels rose from melting glaciers. It was a fortuitous event for the stranded since the climate on Wrangle was favorable and allowed edible plants to flourish. There were no competing herbivores present, and the island was free of humans and other predators. Wrangle Island's isolated colony managed to survive for 6,000 years. The population grew from around ten to 300, the maximum allowed by the island's plant resources. The early inbreeding eventually took its toll on the population. The earliest signs of human habitation occur 400 years after the disappearance of the mammoths. It's possible that they died in a volcanic eruption, tundra fire, or even from a pathogen like bird influenza that migrated to the island. Dr, Dalen has not been able to return to Siberia to study possible causes due to the war in Ukraine.
[graphic credit: B. Zaiken]The research on Wrangle Island mammoths is a cautionary tale for scientists seeking to resurrect extinct species like the thylacine. A late survivor from which DNA is extracted may be burdened with accumulated defects caused by inbreeding. Recovering populations of endangered animals need to have their genetic diversity boosted by re-location of individuals or even cloning. Researchers successfully cloned a black-footed ferret in 2021 from a population that became extinct in the 1980s.
