Male mate preferences in a gynogenetic species complex of Amazon mollies

Female Amazon mollies, Poecilia formosa, are gynogenetic and mate with males of a sexual species, P. latipinna or P. mexicana, for successful reproduction. It was found that both species of males are able to distinguish between conspecific females and Amazon mollies, and preferentially mate with the former. Male mate preference per se is not an evolved response to avoid mating with Amazon mollies; male P. latipinna that are from populations currently allopatric with Amazon mollies also prefer conspecifics. The strength of this preference, however, is stronger in P. latipinna from populations sympatric with Amazon mollies than in P. latipinna from populations that are allopatric with the gynogen, suggesting that reproductive character displacement in mating preferences has occurred. Male size did not influence mating decisions; thus, the hypothesis was rejected that the gynogens are usually mated by smaller, younger males, which have yet to learn to discriminate between females. Unlike some previous studies, it was shown that P. mexicana can discriminate between conspecific females and Amazon mollies, although the strength of preference might be weaker in P. mexicana than in P. latipinna. Male P. latipinna and P. mexicana differed in their choices between females of the two heterospecific species in the complex. Male P. latipinna were reluctant to mate at all when given a choice between the two heterospecific females, P. mexicana and P. formosa. Poecilia mexicana males, alternatively, showed high mate attraction to P. formosa when these females were paired with P. latipinna females. This result is intriguing, given that it is thought that female P. mexicana and male P. latipinna were involved in the original hybridization event that gave rise to P. formosa. Therefore, the strong attractiveness of P. formosa to P. mexicana may be related to a maternally derived genetic component. (C) 1996 The Association for the Study of Animal Behaviour