Humans didn’t cause devil disease, study finds

By AAP with AG staff 6 December 2012
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Genes are to blame for the disease that has wiped out much of the Tasmanian devil population, researchers say.

HUMANS ARE UNLIKELY TO have caused the deadly Tasmanian devil facial tumour disease (DFTD), a new study has found.

Researchers at the University of Sydney have found the low immune gene diversity that enables the spread of the disease in Tasmanian devils, also existed in this species thousands of years ago.

Fossils reveal devil development through history

The team examined DNA from four different periods, as far back as 10,000 years ago when devils also ran around on the Australian mainland.

“We found that the immune gene diversity was actually low in Tasmania even before European arrival and also that mainland devils had low immune gene diversity,” lead author Katrina Morris says. “So this wasn’t caused by European settlers, it’s a much longer historical trend in devils.”

Devil fossils have been found in every Australian state and it is thought they became extinct on the mainland around 3000 years ago. However, it is unlikely that an earlier outbreak of the facial tumour, which has wiped out more than 80 per cent of the Tasmanian population in recent years, was to blame.

“It’s possible that it has occurred previously but it wouldn’t really leave evidence so we can’t really be sure,” Katrina says. “Nothing like DFTD has occurred in the last 200 years.”

Katrina says diseases brought with the introduction of dingoes would have had a significant impact.

Dogs to blame for earlier population crashes

While devil populations in Tasmania have crashed several times over the past 200 years, DFTD did not first appear until 1996. Dogs, this time brought by Europeans, are again thought to be the culprits.

“Since devils had this lack of immune gene diversity they were very susceptible to disease epidemics,” says Katrina.

“If the dogs brought anything like distemper with them they might have got into the devil population and then had quite a devastating impact.”

The new study reinforces the importance of captive breeding programs for Tasmanian devils, which promote genetic diversity. “They have such a lack of immune gene diversity,” Katrina says.

“They still do have some, though, so we need to maintain what they have left so that we don’t make the problem any worse.”