Geographical variation in reproductive character displacement in mate choice by male sailfin mollies

Female Amazon mollies, Poecilia formosa, are a unisexual species that repro duce by gynogenesis. They must coexist and mate with males of other species (usually the mollies Poecilia latipinna or Poecilia mexicana) to induce em bryogenesis, but inheritance is strictly maternal. We examined the mating p reference of the male sailfin molly, P. latipinna, for female sailfin molli es versus Amazon mollies, P. formosa. We compared the mating preferences of sympatric and allopatric populations collected throughout the Gulf Coast o f North America. Male P. latipinna from six populations sympatric with Amaz on mollies showed a significantly greater strength of preference for conspe cific sailfin females than males from five populations that were allopatric with Amazon mollies. These results provide strong evidence for reproductiv e character displacement of male mate choice in sympatry. Furthermore, the large geographical range of populations that we tested revealed variation a mong populations within sympatry and allopatry, indicating that it is impor tant to evaluate a large number of populations when examining reproductive character displacement.