07.12.2017

Sexual Conflict and Sexually Antagonistic Genes

Contrary to theoretical predictions of sexual selection that genes conferring a male reproductive advantage should be driven to fixation (thus depleting their additive genetic variation), a considerable additive genetic variance for sexually selected male traits has been found. However, the mechanisms that maintain this variance are poorly understood since empirical evidence is lacking. It has been proposed that evolutionary conflict at the intra-specific level, including sexually antagonistic genes and sexual conflict, is one potential mechanism that maintains additive genetic variation.

Sexually antagonistic alleles are those that benefit one sex but are maladaptive for the other. The expression of these genes can have differential effects on males and females relating to fitness and/or survival. The discovery of antagonistic genes for reproductive success has affected long-held views on the good genes theory of sexual selection. Sexually antagonistic genes may be gender specific, thus the female may need to choose different sires to optimise the fitness of her sons and daughters. As a result, pre-mating directional selection on male traits can be offset by non-directional, post-mating cryptic female choice. In this way, genetic variation for sexually selected traits can be maintained. So far, taxon-wide empirical evidence for this mechanism is lacking.

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Relevant publications:

  • Mills S.C., Koskela E., & Mappes T. (2012) Intralocus sexual conflict for fitness: sexually antagonistic alleles for testosterone.Proceedings of Royal Society, Biological Sciences (in press).
  • Mokkonen M., Koskela E., Mappes T. & Mills S.C. (2012) Sexual antagonism for testosterone maintains multiple mating behaviour. Journal of Animal Ecology 81:277-283. article
  • Mokkonen M., Kokko H., Koskela E., Lehtonen J., Mappes T., Martiskainen H. & Mills S.C. (2011) Negative frequency dependent selection of sexually antagonistic alleles in Myodes glareolusScience 334: 972-974