Paternity analysis reveals opposing selection pressures on crown coloration in the blue tit (Parus caeruleus)

Kaspar Delhey, Arild Johnsen, Anne Peters, Staffan Andersson, Bart Kempenaers

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104 Citations (Scopus)

Abstract

In socially monogamous species, extra-pair paternity can increase the variance in reproductive success and thereby the potential for sexual selection on male ornaments. We studied whether male secondary sexual ornaments are selected through within- and/or extra-pair reproductive success in the blue tit (Parus caeruleus). Male blue tits display a bright blue crown plumage, which reflects substantially in the ultraviolet (UV) and previously has been indicated to be an important sexual signal. We show that males with a more UV-shifted crown hue were less cuckolded, which probably resulted from female preference for more ornamented mates. By contrast, however, older males and males with a less UV-shifted hue sired more extra-pair young. This probably did not reflect direct female preference, since cuckolders were not less UV-ornamented than the males they cuckolded. Alternatively, a trade-off between UV ornamentation and other traits that enhance extra-pair success could explain this pattern. Our results might reflect two alternative male mating tactics, where more UV-ornamented males maximize within-pair success and less UV-ornamented males maximize extra-pair success. Since crown colour was selected in opposite directions by within-pair and extra-pair paternity, directional selection through extra-pair matings seemed weak, at least in this population and breeding season. Reduced intensity of sexual selection due to alternative mating tactics constitutes a potential mechanism maintaining additive genetic variance of male ornaments.

Original languageEnglish
Pages (from-to)2057-2063
Number of pages7
JournalProceedings of the Royal Society B: Biological Sciences
Volume270
Issue number1528
DOIs
Publication statusPublished - 7 Oct 2003
Externally publishedYes

Keywords

  • Extra-pair paternity
  • Parus caeruleus
  • Sexual selection
  • Structural plumage coloration

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