If the findings in house mice translate to threatened species, it means captive-bred animals may not be as effective at increasing the genetic diversity of wild populations as originally expected, the researchers say.
Their findings are published today in the Royal Society journal Biology Letters.
Millions of dollars are spent each year on breeding threatened species in captivity for release into the wild, says team member Dr Michael Magrath, a senior scientist at Zoos Victoria.
In some cases, he says, the aim is to increase the genetic diversity of existing populations, but the success of such programs is variable.
The strategy relies on captive-bred animals interbreeding with wild animals but there is much evidence that captivity affects the behaviour of animals.
Magrath and colleagues wondered whether periods of captivity could affect an animal's preference for a mate.
The researchers kept house mice in captivity for three generations before releasing them into a larger "semi-naturalistic" enclosure with mice freshly caught from the wild.
After 20 weeks they took genetic samples of the offspring that resulted to find out which mice had mated together.
They discovered the vast majority of mice mated with their own kind.
"Only 17 per cent of offspring were produced from mixed-source pairings," says Magrath.
Magrath says the mate preferences found in the study could have implications for the success of captive breeding programs.
"If you are starting a new population and there is no existing wild population then it is not an issue because the animals you are introducing are all from captivity," he says.
But, says Magrath, if the aim is to introduce captive animals to increase genetic diversity of an existing wild population there may be a problem -- at least in the short term.
"They may pair with each other and this will reduce integration of their genetic material into the wild population," he says.
Magrath says if a batch of introduced captive-bred males failed to mate with wild females conservation programs could fail.
Alternatively, a batch of introduced males and females may breed with each other and form a sub-population.
But this sub-population may be at a disadvantage because failing to mix with the wild animals means they may not inherit or learn crucial 'streetwise' behaviours like predator awareness.
Magrath, who is involved in captive breeding programs for the eastern barred bandicoot, Leadbeater's possom and Tasmanian devil, among others, says the next step is to monitor programs to see if mate choice is affecting their success.
If it is, he says, then it would be good to find out what causes this behaviour.
One explanation is that animals may stick to breeding with their own kind because other animals have a different smell due to the diet and environment they had when they were reared, says Magrath.
Read more at Discovery News
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