Male permissiveness in a unisexual–bisexual mating complex promotes maintenance of a vertebrate unisexual sperm-dependent species

Unisexual–bisexual mating complexes are found when an all female sperm-dependent (gynogenetic or hybridogenetic) species relies on heterospecific males for reproduction. Mistakes in species recognition or discrimination on the part of the males are fundamental for the persistence of unisexual–bisexual mating systems, but should be selected against because mating with heterospecific females does not lead to fitness benefits for the males. Here, we focused on the Poecilia latipinna–P. formosa–P. mexicana mating complex, where P. formosa is a gynogenetic species of hybrid origin and P. latipinna and P. mexicana are its parent species and sexual hosts (sperm donors). We examined male mating permissiveness (the propensity to express recognition errors) by presenting males of both sperm donor species with conspecific and heterospecific females in a no choice design. Whereas in prior studies males generally discriminated between heterospecific and conspecific females, we found no evidence for a greater conspecific recognition vs. recognition of P. formosa in males of either sperm donor species. This permissive behavior by males could be explained by the close relatedness between P. latipinna and P. mexicana to P. formosa.