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From the same journal

Cost, risk and avoidance of inbreeding in a cooperatively breeding bird

Research output: Contribution to journalArticlepeer-review



Publication details

JournalProceedings of the National Academy of Sciences USA
DateAccepted/In press - 19 May 2020
DatePublished (current) - 22 Jun 2020
Issue number27
Number of pages7
Pages (from-to)15724-15730
Original languageEnglish


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.

Bibliographical note

© 2020, Published under the PNAS license. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

    Research areas

  • cooperation, mating, altruism, kin selection, breeding, communication, inbreeding, dispersal, birds

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