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The Little-known Downsides to Captive Breeding Programs

A recent study looks at the drawbacks of captive breeding programs.

Downsides to Captive BreedingA recent study published from researchers at the University of Melbourne and Zoos Victoriain looked at the potential negative impacts associated with captive breeding programs.  Their results were reported in the journal Biology Letters. To learn more, check out The Little-known Downsides to Captive Breeding Programs by Jason G. Goldman, in Conservation This Week from Conservation Magazine. Below are a few quotes from the article:

"Breeding over multiple generations in captive settings will inevitably lead to small biological changes between the captive and wild lineages, and those tweaks can become magnified over time. But what happens when those changes in phenotype – that is, the way genes are expressed – impact reproduction-related behaviors?"

"If reintroduced animals are more likely to mate with other reintroduced animals and their descendants – even after being returned to the wild – then the captive bred animals aren’t actually supporting the wild population. In effect, there would simply be two relatively independent populations of similar-looking animals, and given enough time, they could diverge into two separate species."

"How much of this concern is conjecture and how much of it reflects a real possibility? That’s what University of Melbourne zoologist Brendan Slade wanted to know. So and his colleagues from the University of Melbourne and Zoos Victoria put together an experiment to find out."

"By the end of the twentieth week of their reintroduction, there were a total of 59 litters of 189 baby mice, from 40 pairings. A staggering 83 percent of these litters resulted from same-source pairings, meaning both parents were either captive-bred or wild. Put another way, fewer than one out of five litters was the result of a mixed marriage between captive-bred and wild mice. This phenomenon is called 'assortative mating,' and it means that there were strong preferences among the mice to mate with their own kind."

"It’s a worrying trend because if these findings apply more broadly than just mice, it could impact the long-term success of captive breeding programs. Just because reintroductions are successful doesn’t mean that the genes of reintroduced individuals mix in to the wider population of at-risk animals. And that’s a problem, according to Slade, when 'there is an urgent need to improve fitness of wild individuals by the integration of new genes to bolster genetic diversity.'”

The full article can be found at


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