Tasmanian Devil joeys
A Tasmanian devil joey's first vet check. Photo: Joe Armao
TASMANIAN devils suffered from low genetic diversity long before European settlement, according to research which sheds light on the animal's battle with the deadly facial tumour disease.
Low genetic diversity has been linked to the spread of devil facial tumour disease but it has never been clear when devils, which once roamed the mainland, lost their immune diversity.
Since European settlement in Tasmania, there have been several population crashes, although the cause has been a mystery.
However, findings by scientists from Adelaide and Sydney universities show mainland and Tasmanian devils had shallow gene pools long before the facial tumour disease arrived. This low diversity aided the spread of the disease.
''When a population has low immune gene diversity it means that if one individual is susceptible to a disease then generally the entire population is susceptible,'' the University of Sydney's Katrina Morris said.
As part of the faculty of veterinary science, Ms Morris is a member of a research team that, for the first time, took a genetic approach to the problem.
Using ancient DNA from Tasmanian devil specimens collected over the past 200 years, scientists established that low genetic diversity in Tasmanian devils dates back thousands of years.
The research included testing the oldest marsupial genes ever to have had their genetic code sequenced, using samples taken from mainland devil specimens at least 3000 years old.
Tasmanian devils disappeared from the mainland about 3000 years ago, possibly because of competition from dingoes.
The aggressive facial tumour disease was first described in 1996. Spread by devils biting each other's heads when fighting over food, it has caused a collapse in the population from about 130,000 to 150,000 in the mid-1990s to fewer than 24,000 mature individuals now.
In 2009, it was listed nationally as endangered. Unless spread of the disease is stopped, extinction in the wild is likely within 35 years.