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

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • Amy E. Leedale
  • Michelle Simeoni
  • Stuart P. Sharp
  • Jonathan P Green
  • Jon Slate
  • Robert F Lachlan
  • Elva J. H. Robinson
  • Ben J. Hatchwell
<mark>Journal publication date</mark>7/07/2020
<mark>Journal</mark>Proceedings of the National Academy of Sciences of the United States of America
Issue number27
Number of pages7
Pages (from-to)15724-15730
Publication StatusPublished
Early online date22/06/20
<mark>Original language</mark>English


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 non-kin, 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 towards kin.