Polygyny and extra-pair paternity enhance the opportunity for sexual selection in blue tits

Oscar Vedder*, Jan Komdeur, Marco van der Velde, Elske Schut, Michael J. L. Magrath

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Polygyny and extra-pair paternity are generally thought to enhance sexual selection. However, the extent to which these phenomena increase variance in male reproductive success will depend on the covariance between success at these two strategies. We analysed these patterns over four breeding seasons in facultatively polygynous blue tits Cyanistes caeruleus. We found that both polygyny and extra-pair paternity increased variance in male reproductive success and that standardised variance in annual number of genetic fledglings was 2.6 times higher than standardised variance in apparent success when assuming strict monogamy. Nevertheless, male success at securing within-pair paternity was unrelated to success at gaining extra-pair paternity and, when considering the positive effect of age on extra-pair success and attracting a second female, polygynous males were no more likely to sire extra-pair fledglings. Overall, polygynous males fledged more genetic offspring than monogamous males, but first-year polygynous males lost a greater share of within-pair paternity. A literature review suggests that this adverse effect of polygyny on within-pair paternity is frequent among birds, inconsistent with the prediction that females engage in extra-pair copulation with successful males to obtain good genes. Furthermore, a male's share of paternity was repeatable between years, and among females of polygynous males within years, such that a compatibility function of extra-pair copulations was likewise unsupported. Instead, we suggest that the observed patterns are most consistent with a fertility insurance role for extra-pair copulations, which does not exclude the greater opportunity for sexual selection through differential ability of males to gain paternity.

Original languageEnglish
Pages (from-to)741-752
Number of pages12
JournalBehavioral Ecology and Sociobiology
Volume65
Issue number4
DOIs
Publication statusPublished - Apr-2011

Keywords

  • Compatible genes
  • Extra-pair fertilisations
  • Female choice
  • Male-male competition
  • Mating system
  • Sperm competition
  • RED-WINGED BLACKBIRDS
  • SEXY SON HYPOTHESIS
  • INTRASPECIFIC BROOD PARASITISM
  • SPARROW PASSER-DOMESTICUS
  • IN-HOUSE WRENS
  • REPRODUCTIVE SUCCESS
  • CYANISTES-CAERULEUS
  • PARUS-CAERULEUS
  • FERTILIZATION SUCCESS
  • PIED FLYCATCHERS

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