Rebekah Rogers, now a faculty member in the Bioinformatics and Genomics Department, is garnering media attention for research on woolly mammoths that she conducted while a professor at the University of California, Berkeley, with colleague Montgomery Slatkin.
The two researchers reported in a study published in PLOS Genetics that dwindling populations created a “mutational meltdown” in the genomes of the last woolly mammoths, which had survived on an isolated island until a few thousand years ago.
“When I first started this project, I was excited to be working with the new woolly mammoth sequences, published by Love Dalen’s lab,” said Rogers in a release from PLOS. “It was even more exciting when we found an excess of what looked like bad mutations in the mammoth from Wrangel Island. There is a long history of theoretical work about how genomes might change in small populations. Here we got a rare chance to look at snapshots of genomes ‘before’ and ‘after’ a population decline in a single species. The results we found were consistent with this theory that had been discussed for decades.”
Woolly mammoths were one of the most common large herbivores in North America, Siberia and Beringia until a warming climate and human hunters led to their extinction on the mainland about 10,000 years ago. Small island populations persisted until about 3,700 years ago before the species finally disappeared. Researchers compared existing genomes from a mainland mammoth that dates back to 45,000 years ago, when the animal was plentiful, to one that lived about 4,300 years ago. The recent genome came from a mammoth that had lived in a group of about 300 animals on Wrangel Island in the Arctic Ocean. The analysis showed that the island mammoth had accumulated multiple harmful mutations in its genome, which interfered with gene functions. The animals had lost many olfactory receptors, which detect odors, as well as urinary proteins, which can impact social status and mate choice. The genome also revealed that the island mammoth had specific mutations that likely created an unusual translucent satin coat.
Coverage of this research is in Scientific American and The New York Times.