In unisexual-bisexual species complexes individuals must discriminate between potential mates of their own species (conspecifics) and individuals of closely related species (heterospecifics). Mating individuals can further benefit from recognizing high quality conspecifics. When heterospecifics resemble high quality conspecific mates there can be an antagonistic relationship between the two processes. One unisexual, all female, species is the clonal Amazon molly (Poecilia formosa), who sexually parasitizes male sailfin mollies (P. latipinna). Amazon mollies rely on sperm from these males to initiate egg development. However, the male's sperm does not contribute genes to the females' offspring. Where the two species overlap, male sailfin mollies may forgo using traits such as large body size as mate-quality cues, to avoid heterospecific matings, while males from populations where they do not co-occur may retain preferences for larger body size. This would suggest that there is a conflict between mate-quality and species recognition. The research described in this proposal will provide information on the process by which individuals recognize their own species and either avoid compromises between mate-quality and species recognition or sacrifice mate-quality at the expense of mating with a heterospecific. To examine differences in male discrimination ability between populations, we will examine: (1) male mating preferences, (2) differential sperm production, and (3) differential sperm allocation between conspecific and heterospecific females. These results will ultimately provide information on the process of speciation.
