Quolls get genetic passport to survival
Genetics is being enlisted to test the success of rescue programs for quolls, carnivorous marsupials that live in the native forests of Australia and New Guinea.
Biologist Dr Karen Firestone of Sydney's University of New South Wales and team have just received A$870,000 (US$620,000) from government conservation agencies and the Australian Research Council to study the threatened species.
"These are top level marsupial predators and play a very important role in ecology," said Firestone, also the conservation biologist at Sydney's Taronga Zoo, which helped fund the project. "They've also got attitude. They're very charismatic."
There are four quoll species in Australia: the spotted tailed quoll (also known as the tiger quoll), the northern quoll, the western quoll and the eastern quoll.
Each is threatened by factors such as habitat loss, predators such as foxes and cats, disease and the spread of the toxic cane toad. So, researchers have set up rescue programs, including breeding the marsupials in captivity before releasing them back into the wild.
But scientists are not sure how well these programs have been working.
The role of genetic diversity
The most established rescue program, which began in the 1990s, involved breeding the western quoll in captivity and moving it to six sites, mainly in the jarrah forests of south-west Western Australia.
"They seem to be doing OK but we're going to be looking at them genetically," Firestone told ABC Science Online.
"The higher the genetic diversity, the better the survival of the species, the more evolutionary potential."
Firestone has more than 300 DNA samples from western quolls that were the founders of the captive breeding program and those that were first reintroduced into the wild.
She will also take samples from today's quoll communities and compare these with the two earlier groups to assess the change in genetic diversity over time.
This will tell her how well the translocation program has worked from the point of view of genetic diversity.
If all animals are healthy and breeding then genetic diversity should be more or less constant. But if only a few animals are breeding genetic diversity will be lost.
"This would raise warning bells for the manager," she said. "They may need to import new animals or alter their management strategies in another way such as putting in corridors between the different populations.
"We might need to make recommendations that they need to add new blood," she said.
A more recent translocation program has involved the northern quoll, which once occupied the northern third of Australia from Western Australia to Queensland. But it is now limited to six major hotspots and is under threat in Kakadu National Park due to the advance of the introduced cane toad.
In recent years around 60 to 70 individuals were translocated to a couple of Northern Territory islands, populations that Firestone's team will also assess for genetic diversity.
Such techniques could also be useful for conserving eastern quolls. These used to live on mainland Australia but are now restricted to the island state of Tasmania where they could be affected by a facial tumour killing the related Tasmanian devil.
"In the future we may need to bring them [the quolls] onto the mainland," said Firestone, who said her team could help work out which populations would be a good source population for the translocation.