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Stabilizing sexual selection for female ornaments in a dance fly
J Wheeler1, D T Gwynne, L F Bussière
1Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada. jill.wheeler@utoronto.ca
Journal of Evolutionary Biology
|May 4, 2012
Summary
Female dance flies show stabilizing selection on ornaments, suggesting intermediate ornamentation is favored. This challenges the idea that ornaments always face directional selection for mating success.
Area of Science:
- Evolutionary Biology
- Behavioral Ecology
- Sexual Selection
Background:
- Ornamental traits typically evolve via directional sexual selection for increased mating success.
- Female ornaments can signal fecundity but may incur costs, potentially leading to stabilizing selection.
Purpose of the Study:
- To investigate the form of sexual selection acting on female-specific ornaments in the dance fly Rhamphomyia longicauda.
- To test theoretical predictions of stabilizing selection on female ornaments due to fecundity costs.
Main Methods:
- Analysis of sexual selection on female ornaments (abdominal sacs, tibial scales) in Rhamphomyia longicauda.
- Statistical methods including canonical analysis and Mitchell-Olds and Shaw tests to detect selection gradients.
Main Results:
- No evidence for directional sexual selection on female ornaments was found.
- Marginally nonsignificant quadratic selection was detected for ornament expression, suggesting stabilizing selection.
- Nonlinear selection vectors were strongest for ornamental traits, particularly pinnate leg scales.
Conclusions:
- Provides tentative, first evidence for stabilizing selection on female-specific ornaments.
- Suggests that female ornaments may be constrained by fecundity costs, leading to selection for intermediate expression.
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