title: Additive genetic variance in polyandry enables its evolution, but polyandry is unlikely to evolve through sexy or good sperm processes.
abstract: Polyandry is widespread despite its costs. The sexually selected sperm hypotheses ('sexy' and 'good' sperm) posit that sperm competition plays a role in the evolution of polyandry. Two poorly studied assumptions of these hypotheses are the presence of additive genetic variance in polyandry and sperm competitiveness. Using a quantitative genetic breeding design in a natural population of Drosophila melanogaster, we first established the potential for polyandry to respond to selection. We then investigated whether polyandry can evolve through sexually selected sperm processes. We measured lifetime polyandry and offensive sperm competitiveness (P2 ) while controlling for sampling variance due to male × male × female interactions. We also measured additive genetic variance in egg-to-adult viability and controlled for its effect on P2 estimates. Female lifetime polyandry showed significant and substantial additive genetic variance and evolvability. In contrast, we found little genetic variance or evolvability in P2 or egg-to-adult viability. Additive genetic variance in polyandry highlights its potential to respond to selection. However, the low levels of genetic variance in sperm competitiveness suggest that the evolution of polyandry may not be driven by sexy sperm or good sperm processes.
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia.
authors.forename: L M
authors.initials: LM
authors.lastname: Travers
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia.
authors.forename: L W
authors.initials: LW
authors.lastname: Simmons
authors.affiliation: Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia.|Doñana Biological Station, Spanish Research Council CSIC, Sevilla, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Garcia-Gonzalez
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004331:Drosophila melanogaster / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D008297:Male; D012726:Sexual Behavior, Animal; D013094:Spermatozoa / Q000502:physiology*
keywords: female multiple mating; fisherian runaway selection; indirect benefits; post-copulatory female choice; sexual selection; sperm competition