Gynogenesis
Gynogenesis, a form of parthenogenesis, is a system of asexual reproduction that requires the presence of sperm without the actual contribution of its DNA for completion. The paternal DNA dissolves or is destroyed before it can fuse with the egg. The egg cell of the organism is able to develop, unfertilized, into an adult using only maternal genetic material. Gynogenesis is often termed "sperm parasitism" in reference to the somewhat pointless role of male gametes. Gynogenetic species, "gynogens" for short, are unisexual, meaning they must mate with males from a closely related bisexual species that normally reproduces sexually.
Gynogenesis is a disadvantageous mating system for males, as they are unable to pass on their DNA. The question as to why this reproductive mode exists, given that it appears to combine the disadvantages of both asexual and sexual reproduction, remains unsolved in the field of evolutionary biology. The male equivalent to this process is androgenesis where the father is the sole contributor of DNA.
Taxonomic range
Most gynogenetic species are fishes or amphibians. Among the fishes, Amazon mollies require the sperm of closely related male Poecilia latipinna to engage in gynogenesis. P. latipinna males prefer to mate with females of their own species. This presents a problem for P. formosa, as they must compete for males who do not favour them. However, those P. formosa successful in finding a mate make up the deficit by producing twice as many female offspring as their competitors.Among salamanders, the Ambystoma platineum, a unisexual mole salamander, is hybrid of sexually reproducing A. jeffersonianum and A. laterale. A. platineum individuals normally live in proximity to either of these parent species, so as to access their sperm.