A major DNA analysis is reshaping what scientists thought they knew about koala evolution. According to ScienceDaily, researchers found evidence that koalas went through a severe population decline about 100,000 years ago, well before humans arrived in Australia.
The study was led by researchers from the University of Sydney and Texas A&M University and was published in Molecular Biology and Evolution. Lead researcher Toby Kovacs said the work “rewrites the timeline” of the koala’s genetic history.
To build that timeline, the team measured the koala mutation rate by sequencing genomes from four parent-offspring trios. They then applied that rate to 457 koala genomes, which helped them trace how the species expanded, contracted and split over thousands of years.
According to the study, koala numbers dropped sharply during a period of major environmental disruption in the late Pleistocene. The researchers say the decline began around 100,000 years ago and reached a genetic bottleneck nearly 60,000 years ago, with the western population eventually disappearing and the eastern population surviving.
The findings also have conservation value today. ScienceDaily reports that koala populations in Queensland and New South Wales continue to decline, while those in Victoria appear to be recovering, and the species is listed as endangered in Queensland, New South Wales and the Australian Capital Territory.
