Animals bred in captivity seem to prefer to mate with each other and spurn wild and free partner options, according to Discovery News.
If this is correct, it could lead to problems for threatened species when breeding attempts are made to increase population and foster genetic diversity, research suggests.
The study's findings were published on Nov. 19 in the Royal Society journal Biology Letters.
Confinement changes the mice and their behavior, according to the study that bred house mice for three generations in captivity. The mice were then released into "nine semi-natural outdoor circular enclosures," the study wrote.
After 20 weeks had passed, the mice were euthanized and the offspring was examined. "Only 17 percent of offspring were produced from mixed-source pairings," says Michael Magrath, study partner and senior scientist at Zoos Victoria.
Since millions of dollars a year are spent on breeding threatened species for reintroduction into the wild, this news could have some major implications for current conservation policies.
"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," Magrath said, according to Discovery News.
However, if you want captive animals to boost wild populations, there could be a problem. "They may pair with each other and this will reduce integration of their genetic material into the wild population," Magrath said, according to Discovery News.
And their off-spring would not get the street-smart genes needed for survival instincts.
Why are mice accustomed to captivity only picking like-raised mice? It may be due to smell. Animals prefer a community smell, and interred mice may smell alike because of diet and environment, the study suggests. Preferred location or activity at different times of the day may also contribute.
"At the end of the day, to recover species you really need to be addressing the key threats that they face in the wild, for example, habitat loss, disease and feral exotic predators like foxes and cats," Magrath said, according to Discovery News.
