The last known Tasmanian tiger, or thylacine, died in 1936 on the island for which it was named. But, by then, the animal had been extinct on the Australian mainland for more than 3,000 years.

Jeremy Austin and his colleagues at the University of Adelaide in Australia collected samples from thylacine (Thylacinus cynocephalus) museum specimens. They sequenced DNA contained in cell structures called mitochondria for 51 animals, including 15 from mainland Australia. Mapping of the relationships between animals suggests that there were two separate mainland populations — a larger, more genetically diverse population in the west and a smaller, less-diverse population in the east and Tasmania — that diverged about 30,000 years ago.

When Europeans settled on Tasmania in the 1800s, the thylacine population seems to have been expanding after long being kept small and genetically similar by centuries-long drought. This severe dry spell could have contributed to the species’ extinction on the mainland, where it was more severe.