Female choice in Drosophila: evidence from Hawaii and implications for evolutionary biology.

Details of female choice of mate in Drosophila silvestris of Hawaii strikingly parallels epigamic behavioral systems in many other animals and may be common in other species of Drosophilidae. Females respond selectively to male circling, wing displays, songs and tactile stimulation with foreleg cilia, a quantitative character that is highly variable in some populations. I hypothesize that the female can exert choice based on these cues from individual males that differ genetically by quantitative trait loci. Laboratory tests show that one third of courting males are repeatedly rejected in favor of a minority of 'alpha' males. This result imposes non-random mating at the local population level. Past multiple-choice lab tests, widely used to measure 'isolation' between pairs of populations or species of Drosophila may be flawed, since random mating has been assumed in the interpretation of results. Pre-mating sexual selection is clearly a powerful intrapopulation force in population biology. This view creates difficulties for discerning any proposed simultaneous interpopulation selective events in the presence of strong female choice. The long-held theory assuming that there is significant selection for pre-mating isolation between groups is questionable.