Seasonal plasticity in male mating preferences in sailfin mollies

Although male choosiness may be influenced by predation risk, variation in mate availability, and fecundity that may vary spatially and over time, there is little evidence for variation in male mate choice preferences. In mixed populations of bisexual sailfin mollies (Poecilia latipinna) and unisexual Amazon mollies (Poecilia formosa), males encounter 2 types of potential mates: conspecific sexual sailfin and asexual Amazon mollies. The latter is gynogenetic, thus an all-female species that produces clonal offspring but requires sperm from sexual host males to trigger embryogenesis. Sailfin males do not benefit directly from mating with Amazon mollies, which raises the question why males mate with Amazons at all. Mate choice might be crucial in this context. So far, the possibility that male choice might vary during the mating season remained unexplored. We tested for frequency-dependent or seasonally influenced behavioral plasticity in mating preferences of males originating from natural mixed populations that may contribute to the maintenance of coexistence in this asexual--sexual mating complex. In simultaneous choice tests, we studied male association preferences in P. latipinna originating from populations in South and Central Texas, USA. There was high seasonal variation in male association patterns: males spent less time with asexual females at times that may potentially coincide with reproductive peaks in this species complex, for example, during spring. Male body size and local current relative proportion of Amazon mollies in the populations did not influence male preferences. We discuss potential causes for the variation of a sexual preference for conspecific females and how nondiscriminating male mating behavior can be adaptive in this complex. Copyright 2008, Oxford University Press.