Incorporating mate choice into conservation breeding programs to prevent evolution of tameness

Conservation breeding programs face a dual challenge of maintaining genetically diverse populations while minimizing unintentional adaptation to captivity. These two problems may be linked if genetically valuable lineages are rare because they retain traits, such as fear of humans, that prevent them from successfully breeding. Recent studies suggest that allowing mate choice can improve reproductive success in captive populations, raising the possibility that it could also offset the fitness costs of fearfulness toward humans. In this study, we combined pedigree-based pairing protocols and a mate choice experiment to test whether mate choice and fear of humans interact to influence breeding success in zebra finches. When females were allowed to choose their mate, pairs had higher reproductive success, irrespective of their fearfulness. Yet, when females were assigned a mate, only relatively tame pairs performed well, suggesting that forced pairings may accelerate adaptation to captivity. Females offered a choice of mates preferred males that matched their own tameness which led to assortative mating. However, greater behavioral similarity did not explain the reproductive advantage of mate choice; instead, our results suggest that allowing mate choice may improve coordination between partners during offspring rearing, leading to higher fledging success. Overall, we provide evidence that incorporating mate choice into captive breeding protocols may simultaneously limit inadvertent adaptation to captivity and promote genetic diversity in ex situ populations. Thus, conservation breeding programs should consider integrating mate choice into pedigree-based pairing frameworks, particularly in biparental species where reproductive success depends on coordination between partners.