Tasmanian devil pays for climate change

Climate change, not disease or hunting, could be the main cause of a decline in the numbers of Tasmanian devils, according to researchers in Australia.

The team from the University of Tasmania discovered that the devils' low genetic diversity and previous population declines were driven by climate change rather than hunting or a rampant facial tumor disease, as previously thought.

Their study, which examined the largest ever set of genetic data for Tasmanian devils, found that the marsupials have lived with low genetic diversity for thousands of years, having suffered two huge population declines that wiped out around 80 percent of animals in the past 50,000 years.

Those events coincided with two periods of arid climate patterns, 20,000 and 3,000 years ago, when the population of the devils' prey - mainly wallabies and small mammalswould have been adversely affected.

This led to inbreeding and low genetic diversity among the devils, making them unable to adapt rapidly.

"It seems like the devils have survived for thousands of years with low genetic diversity," said the study's lead author, Anna Bruniche-Olsen, from the University of Tasmania.

"Having a low genetic diversity for a species means that they are much more prone to disease, so if a disease impacts the population, because they are all genetically very similar, they are quite prone to being wiped out."

As a top predator, Tasmanian devils are reliant on the populations and survival of their prey.

A decline in the numbers of wallaby and small mammals due to more arid conditions would have had a dramatic effect on the devil population, the researchers said.

That, combined with a diminished ability to combat disease, has researchers concerned that global climate change will be the final nail in the coffin for the wild population.

"It seems like climate is the main driver," Bruniche-Olsen said.

"Given that all the climate predictions for the future point toward Australia having a more arid climate again, I think it has big implications for devils."

The devils, the world's largest carnivorous marsupials, are restricted to the small island of Tasmania, south of mainland Australia, despite being widespread on the continent up until a few thousand years ago.

(China Daily 11/06/2014 page11)