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Sexual selection resulting from extrapair paternity in collared flycatchers
Animal Behaviour
|May 18, 1999
Summary
Extrapair paternity in collared flycatchers drives sexual selection on male traits, with sperm competition being a major factor. This selection, though present, is relatively weak compared to other natural population studies.
Area of Science:
- Evolutionary Biology
- Behavioral Ecology
- Ornithology
Background:
- Extrapair paternity is a proposed driver of sexual selection on male secondary sexual characters, especially in socially monogamous species.
- Few studies quantify extrapair paternity's role in sexual selection or compare it to other selection mechanisms.
Purpose of the Study:
- Estimate sexual selection gradients on male plumage in collared flycatchers due to extrapair paternity.
- Compare the importance of extrapair paternity-driven sexual selection with selection from mate fecundity.
Main Methods:
- Microsatellite genotyping to identify extrapair offspring.
- Multivariate selection analyses using fledgling number and recruitment as fitness measures.
- Path analysis to partition selection pathways (mate fecundity vs. sperm competition).
Main Results:
- 15% of nestlings resulted from extrapair paternity across 33% of broods.
- Significant positive directional selection on forehead and wing patch size (using fledgling number).
- Sperm competition accounted for 64-90% of total sexual selection via analyzed pathways.
Conclusions:
- Extrapair paternity exerts sexual selection on collared flycatcher plumage traits.
- Sperm competition is a more significant pathway than mate fecundity for this selection.
- Detected sexual selection is relatively weak compared to other natural populations.
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