Abstract
Sexual selection has been proposed to increase genetic variation for condition-dependent ornaments. The condition capture model predicts the genetic variance for a sexually selected trait from the genetic variance in condition and the slope of the relationship between the ornament and condition. Assuming that body size reflects condition we assess the efficacy of this model using six species of stalk-eyed flies (Diopsidae). Prior evidence indicates that male eye span exhibits strong condition dependence and is under sexual selection in sexually dimorphic but not monomorphic species. In contrast, thorax width is weakly related to condition and probably under stabilizing selection. We estimated additive genetic variances for eye span, body length and thorax width from half-sib breeding studies and found that the condition capture model explained 97% of the variation in eye span genetic variance but only 7% of thorax width genetic variance. Comparison of phylogenetically independent contrasts revealed that evolutionary change in male eye span genetic variance is due to evolutionary change in the allometric relationship between eye span and condition: not to evolutionary change in genetic variance for condition. These results suggest that sexual selection can accelerate evolutionary change in condition-dependent male ornaments by increasing the genetic variation available for selection.
Full Text
The Full Text of this article is available as a PDF (181.9 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Houle D. How should we explain variation in the genetic variance of traits? Genetica. 1998;102-103(1-6):241–253. [PubMed] [Google Scholar]
- Kirkpatrick M., Barton N. H. The strength of indirect selection on female mating preferences. Proc Natl Acad Sci U S A. 1997 Feb 18;94(4):1282–1286. doi: 10.1073/pnas.94.4.1282. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lande R. Models of speciation by sexual selection on polygenic traits. Proc Natl Acad Sci U S A. 1981 Jun;78(6):3721–3725. doi: 10.1073/pnas.78.6.3721. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nijhout H. F., Emlen D. J. Competition among body parts in the development and evolution of insect morphology. Proc Natl Acad Sci U S A. 1998 Mar 31;95(7):3685–3689. doi: 10.1073/pnas.95.7.3685. [DOI] [PMC free article] [PubMed] [Google Scholar]
- doi: 10.1098/rspb.1998.0561. [DOI] [PMC free article] [Google Scholar]