Cancer won't drive Tassie Devils extinct
As Australia makes leaps towards defeating coronavirus on our shores, one of the nation's endangered icons looks to be overcoming its own epidemic.
At the height of the unusual, transmissible cancer decimating Tasmanian Devil populations, they were expected to become extinct.
Although 80 per cent of the wild population has been wiped out, researchers have found the rate at which the disease is spreading has drastically reduced, bringing them back from the edge of extinction.
That indicates the devils are genetically evolving to safeguard against it, University of Tasmania Professor Menna Jones says.
"In the early years of the epidemic we were very concerned for the future of the devil. However in the last few years our research has hinted that the devil is evolving resistance to the disease," she said.
"We now have strong evidence that the epidemic phase is coming to an end and DFTD (Tasmanian devil facial tumour disease) is becoming an endemic disease. That means the devil will live with it as part of its normal life without this disease spelling the end."
TDFD is spread when the devils fight and bite each other on the face and is still largely fatal.
However the researchers found its spread is slowing to the point each infected devil is infecting only one additional animal or less, down from 3.5 at the peak of the epidemic.
"It is cautiously optimistic good news," Washington State University biologist Professor Andrew Storfer, who led the study, said.
"I think we're going to see continued survival of devils, initially at lower numbers and densities than original population sizes but extinction seems really unlikely even though it was predicted a decade ago."
However the new evidence suggests a key current conservation method, the practice of releasing captive-bred devils into the wild, could do more harm than good.
"It looks like the devil populations are naturally evolving to tolerate and possibly even resist the cancer," Prof Storfer.
"When devils that have never been exposed to the disease interbreed with wild animals in diseased populations, the evolution we have seen in wild populations is likely to slow down or even reverse, endangering those populations."
Releasing captive-bred devils also increases the potential number of animals exposed exponentially, the researchers say.
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