Cost, risk, and avoidance of inbreeding in a cooperatively breeding bird.
Inbreeding is often avoided in natural populations by passive processes such as sex-biased dispersal. But, in many social animals, opposite-sexed adult relatives are spatially clustered, generating a risk of incest and hence selection for active inbreeding avoidance. Here we show that, in long-tailed tits (Aegithalos caudatus), a cooperative breeder that risks inbreeding by living alongside opposite-sex relatives, inbreeding carries fitness costs and is avoided by active kin discrimination during mate choice. First, we identified a positive association between heterozygosity and fitness, indicating that inbreeding is costly. We then compared relatedness within breeding pairs to that expected under multiple mate-choice models, finding that pair relatedness is consistent with avoidance of first-order kin as partners. Finally, we show that the similarity of vocal cues offers a plausible mechanism for discrimination against first-order kin during mate choice. Long-tailed tits are known to discriminate between the calls of close kin and nonkin, and they favor first-order kin in cooperative contexts, so we conclude that long-tailed tits use the same kin discrimination rule to avoid inbreeding as they do to direct help toward kin.
['Leedale|Amy E|AE|0000-0001-6017-8247', 'Simeoni|Michelle|M|0000-0001-9396-2353', 'Sharp|Stuart P|SP|', 'Green|Jonathan P|JP|0000-0001-8728-2810', 'Slate|Jon|J|0000-0003-3356-5123', 'Lachlan|Robert F|RF|', 'Robinson|Elva J H|EJH|', 'Hatchwell|Ben J|BJ|']
D000818:Animals D001947:Breeding D005260:Female D006579:Heterozygote D007178:Inbreeding D008297:Male D046109:Passeriformes D012098:Reproduction D012726:Sexual Behavior, Animal D020308:Songbirds
inbreeding cooperative breeder kin discrimination mate choice