Preferential Mating versus Mimicry: Disruptive Selection and Sex-limited Dimorphism in Papilio glaucus

Spermatophore counts in wild females of Papilio glaucus show that the monomorphic nonmimetic male mates less frequently with the mimetic female morph than with the nonmimetic female morph. Female dimorphism in this species cannot be maintained by heterozygous advantage. Mating preference for the nonmimetic female may sufficiently counteract avian predation pressure favoring the mimetic female to account for the maintenance of the nonmimetic morph in the population in those areas in which the model is abundant and to account for the reduction in frequency or elimination of the mimetic morph in those areas in which the model is less numerous or absent.