Apomictic Reproduction in the Amazon Molly, Poecilia formosa, and Its Triploid Hybrids

Abstract

Poecilia formosa reproduces by gynogenesis, a mechanism that is sperm dependent. The obligatory dependence on sperm that is a hallmark of gynogenetic reproduction compels P. formosa to behave in nature as a sexual parasite on closely related, sympatric bisexual species. The continued propagation of heterozygous genomes by P. formosa and its related triploid unisexuals can stem only from ova with somatic ploidy levels produced in a manner that bypasses the first, reductional division of meiosis and is therefore functionally equivalent to apomixis. The fixed heterosis in such unisexual systems may function to replace the type of allelic variations that normally accompany sexual reproduction and thus may be of critical importance to the long term survival and evolutionary success of these all-female species