The male hybrid Mountain Pygmy-possum bred through relocation by a team of Australian researchers.
Credit: DSE/Tim Arch
The mouse-sized Mountain Pygmy-possum weighs no more than 45 grams.
Credit: DSE/Tim Arch
SYDNEY: Two genetically distinct Mountain Pygmy-possums have been bred for the first time by Australian scientists, who hope this success will play a major role in protecting the critically endangered species from extinction.
Mountain Pygmy-possums (Burramys parvus) are Australia's sole hibernating marsupial, found only in harsh, alpine environments. The remaining populations in the Victorian Alpine region had declined in numbers so dramatically that they had lost all genetic diversity, which meant certain extinction for the species.
Late last year, a research team took six wild males from Mount Hotham and released them into the territory of females at Mount Buller. The relocation resulted in the first wild-born male Pygmy-possum carrying genetic features from both populations.
"The smaller populations meant the species was open to inbreeding which would affect their ability to survive and adapt to change and the hybrid offspring would reinvigorate the species, so this in an excellent outcome," said Andrew Weeks of the Department of Genetics and Bio21 Institute at the University of Melbourne.
Heading for inevitable extinction
While being the largest of the Pygmy-possum species, the mouse-sized Mountain Pygmy-possum weighs no more than 45 grams and its prehensile tail makes up 14 cm of its total 25 cm length.
It has one breeding season per year and can have up to four young at one time. In the wild during winter they hibernate at two degrees Celsius for up to six months under the snow.
The species was assumed to be extinct until 1966, when a living specimen was identified in a ski-hut on Mount Hotham. Since then there have been extensive searches for populations in the wild and it's now believed that there are only about 1,500 to 2000 individuals left on the planet. The current estimate of the Mount Buller population size is just 20-30 animals.
According to researchers, the genetic diversity of the population was being sustained by just three individuals, which meant they were heading for inevitable extinction. "Unfortunately the Mountain Pygmy-possum on Mount Buller has gone through a dramatic and drastic decline in both numbers and genetic diversity," said Weeks.
Forcing their hands
Captive breeding commenced in 2006 at Healesville Sanctuary, a zoo specialising in native Australian animals in rural Victoria. This year has been the sanctuary's most successful in captive breeding so far, with the birth of 38 young, bringing their total to 82 Mountain Pygmy-possums, including 45 males and 37 females.
"The decision to move an endangered species in the wild is never an easy one but the isolation of the population on Mount Buller, combined with a drastic decline in the numbers and the resulting in-breeding amongst the remaining population, forced our hands," said Department of Sustainability and Environment (DSE) scientist Ian Mansergh, who was involved in the project.
"We knew through the Healesville captive breeding program that the two genetically distinct Mount Hotham and Mount Buller populations could breed and it would strengthen the genetics of the Mount Buller population."
Improving genetic diversity
According to Mansergh, the young Hotham/Buller male hybrid (nicknamed 'Lil' Lou') has created new opportunities to save the wild population from extinction. The research team will return to the Mount Buller breeding habitat in November 2011 to see whether Lil' Lou' has hibernated successfully and produced young of his own.
"We're hoping to improve genetic diversity on Mount Buller so that it can sustain itself until the captive breeding program can re-introduce more animals," said Rupert Baker, a senior veterinarian at Healesville Sanctuary.
"The breeding program has been highly successful, however it was not planned to produce enough young to allow for any to be re-introduced to the wild until between 2013 and 2017, prompting the translocation project in 2010," he said.
"With fewer than 30 Mountain Pygmy-possums left on Mount Buller, the bumper breeding year at Healesville and the birth of the first wild-born hybrid are all the more significant and exciting."
