Male killing can select for male mate choice: a novel solution to the paradox of the lek

In lekking species, intense directional selection is applied to aspects of the male genotype by female choice. Under conventional quantitative genetic s theory, the expectation is that this will lead to a rapid loss in additiv e genetic variance for the trait in question. However, despite female choic e, male variation is maintained and hence it pays females to continue choos ing. This has been termed the 'paradox of the lek: Here we present a theore tical analysis of a putative sex-role-reversed lek in the butterfly Acraea encedon. Sex-role reversal appears to have come about because of infection with a male-killing Wolbachia. The bacterium is highly prevalent in some po pulations, such that there is a dearth of males. Receptive females form den se aggregations, and it has been suggested that males preferentially select females uninfected with the bacterium. As with more conventional systems, this presents a theoretical problem exactly analogous to the lek paradox, n amely, what maintains female variation and hence why do males continue to c hoose? We model the evolution of a male choice gene that allows discriminat ion between infected and uninfected females, and show that the stable maint enance of both female variation and male choice is likely, so long as males make mistakes when discriminating between females. Furthermore, our model allows the maintenance, in a panmictic population, of a male killer that is perfectly transmitted. This is the first model to allow this result, and m ay explain the long-term persistence of a male killer in Hypolimnas bolina.