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Divorce is linked with extra-pair paternity in a monogamous passerine
  • Jamie Dunning,
  • Terry Burke,
  • Julia Schroeder
Jamie Dunning
Imperial College London

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Terry Burke
The University of Sheffield
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Julia Schroeder
Imperial College London
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The question of why socially monogamous females engage in extra-pair behaviour is long-standing in evolutionary biology. Recent theoretical work has moved away from the indirect-benefits hypothesis to explain female extra-pair behaviours, instead favouring suggestions that they are the result of pleiotropic effects. That is, a trait under strong positive selection in either or both sexes are genetically linked to another, often unrelated, trait. For example, where genes beneficial to female fecundity (contributing to within-pair solicitation of her social partner) are linked with extra-pair behaviour (soliciting copulations from extra-pair males). Here, we test two predictions from this hypothesis: We test the prediction that female divorce, measured from the number of social mates within a given year, is linked with (1) the number of extra-pair males and (2) the proportion of her offspring that are extra-pair. Our results suggest that females who frequently divorce social partners are more likely to produce extra-pair offspring than those who maintain social monogamy. However, by contrast, those females do not also have a higher proportion of extra-pair offspring. The number of broods initiated was also positively correlated with extra-pair males, probably through increased opportunity for extra-pair males to sire offspring over a longer breeding season. Our results provide an empirical example of a behavioural trait, beneficial to female fecundity, that is linked with extra-pair behaviour. These empirical results support the intrasexual pleiotropy hypothesis as a driver of female extra-pair behaviour.
24 May 2023Submitted to Journal of Avian Biology
24 May 2023Submission Checks Completed
24 May 2023Assigned to Editor
24 May 2023Review(s) Completed, Editorial Evaluation Pending
30 May 2023Reviewer(s) Assigned
16 Jul 2023Editorial Decision: Revise Major
04 Aug 20231st Revision Received
07 Aug 2023Submission Checks Completed
07 Aug 2023Assigned to Editor
07 Aug 2023Review(s) Completed, Editorial Evaluation Pending
15 Aug 2023Reviewer(s) Assigned
21 Sep 2023Editorial Decision: Accept