DNA in rodent droppings reveals 700,000-year-old Beringian ecosystem

DNA preserved in frozen faeces from Arctic ground squirrel burrows has revealed details of an ecosystem that existed in Beringia between 700,000 and 30,000 years ago. The burrows, located in central Yukon, Canada, contained 1-to-2-centimetre faecal pellets. Researchers extracted genetic material from 13 of these pellets.

Genetic findings The DNA belonged to microbes, more than 200 plant groups, insects, rodents, woolly mammoths, horses, grey wolves, steppe bison, and a large cat that was either an American cheetah or a cougar. Mitochondrial genomes were reconstructed for 12 ground squirrels, three horses, two bison, and one hare. Six woolly mammoth genomes were also assembled.

Research context Arctic ground squirrels remain active for four months each year and store food and waste in their burrows. The animals are omnivorous and have been observed scavenging large carcasses. A researcher at the Hakai Institute noted that the presence of large-animal DNA in the pellets is consistent with known feeding behaviour.

A palaeogeneticist at Clemson University said the samples demonstrate ecological diversity through time but cautioned that some DNA may have entered the pellets through environmental leaching rather than direct consumption.