Researchers say facial tumour disease unlikely to wipe devils out

Previous fears of extinction for our iconic devils could soon be put to bed, new research has revealed.

Professor Rodrigo Hamede

THE transmission of a deadly facial tumour disease which decimated the State’s Tasmanian devil population is slowing and unlikely to wipe out the species as first feared, researchers have revealed.

Researchers from the University of Tasmania’s School of Natural Sciences say it is now time to rethink releasing captive-bred devils into the wild.

A study, published in the journal science, indicated that the devils’ pandemic is shifting from an emerging disease to an endemic one. That means the disease spread is slowing to the point that each infected devil is infecting only one additional animal or fewer.

“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,” Professor Menna Jones said.

University of Tasmania disease ecologist Professor Menna Jones (Photo credit: University of Tasmania)

“We now have strong evidence that the epidemic phase is coming to an end, and that DFTD 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.”

For the first time, a research team led by Washington State University biologist Professor Andrew Storfer employed genomic tools of phylodynamics, typically used to track viruses, such as influenza and SARS-CoV-2, to trace DFTD.

The approach opened the door for application to other genetically complex pathogens.

“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,” Professor Storfer said.

Devil populations have fallen by 80 per cent since DFTD was first identified in 1996.

The study – A transmissible cancer shifts from emergence to endemism in Tasmanian devils -was authored by Austin H. Patton, Matthew Lawrance, Mark J. Margres, Christopher P. Kozakiewicz, Rodrigo Hamede, Manuel Ruiz-Aravena, David G. Hamilton, Sebastien Comte, Lauren Ricci, Robyn Taylor, Tanja Stadler, Adam Leaché, Hamish McCallum, Menna Jones, Paul A. Hohenlohe and Andrew Storfer.

University of Tasmania disease ecologist Dr Rodrigo Hamede prepares to release a devil into bushland in North-West Tasmania (Photo credit: Eddie Safarik)

It found that the R number (the number of secondary cases per primary case) has reduced from about 3.5 at the peak of the epidemic to around one.

The authors say it is now time for managers to reconsider the practice of releasing captive-bred devils into the wild.

“It looks like the devil populations are naturally evolving to tolerate and possibly even resist the cancer. 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,” Professor Storfer said.

University of Tasmania disease ecologist Dr Rodrigo Hamede said reintroductions should only be undertaken once scientific evidence demonstrates that the benefits of doing so are greater than allowing wild devil populations to recover through natural selection.”