September 03, 2016

Tasmanian Devils Build Resistance To Devil Facial Tumour Disease


Tasmanian devils — already known for their feistiness and bone-crunching ferocity — may enter the natural history books for pulling off one of the animal kingdom’s great escapes.
More than 80 per cent of the devils have been wiped out by a rare communicable cancer and there have been projections they would rapidly follow their fabled relative, the thylacine, into extinction.

However, research published today suggests that the species is rapidly evolving in response to the devil facial tumour disease, with survivors showing genes resistant to the disease absent in pre-disease populations.

“Our study suggests hope for the survival of the Tasmanian devil in the face of this devastating disease,” said study co-author Andrew Storfer of Washington State University.
The disease, one of only two communicable cancers known in the wild, has decimated populations as it sweeps across Tasmania. It is spread when the devils bite each other during mating and fighting, killing 95 per cent in affected areas.

This scale of devastation has led to predictions of doom for the world-famous devil, but the study suggests it has also imposed rapid natural selection, leading to the evolution of genetic resistance; Charles Darwin’s theory in fast forward.

“Our results reflect a rapid evolutionary response to this strong selection imposed by DFTD, and such a response to a highly lethal, novel pathogen has rarely, if ever, been documented in wild populations,” the research concludes.

Even the irrepressible rabbit took many more generations to evolve resistance to myxomatosis, placing the devil among the planet’s great escape artists; if, as leading scientists now believe, it can defeat DFTD.

The research, led by scientists at universities including Washington State, Idaho, Tasmania, Griffith and Cambridge, could be invaluable in guiding captive breeding programs of disease-resistant devils.

“Disease-free individuals with the selectively favoured genotypes … can be bred to enhance the genetic diversity of the off-island captive assurance population, in case devil reintroductions are needed in the future,” the study, published today in Nature Communications, concludes.

It also increases pressure on the Tasmanian government to do more to protect those precious few devils which survive DFTD, as well as captive-bred devils released into the wild, by reducing other major threats, particularly road kill.

Scientific opinion that the devil would not go extinct was first revealed by The Australian on May 11.

By Matthew Denholm

With many thanks to The Australian

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