gynogenesis

Gynogenesis is a form of asexual reproduction in which an egg develops into an embryo after being activated by sperm from a male of a related species, but the paternal genetic material generally does not contribute to the offspring. In many gynogenetic lineages the offspring inherit only the maternal genome, effectively producing clones of the mother, although in some cases paternal DNA may be incorporated occasionally, leading to polyploid or hybrid offspring.

Mechanistically, a female produces a gamete that, upon fertilization by a sperm cell, triggers embryonic development. The paternal genome is typically excluded from the zygote or later eliminated, so the resulting individual is genetically derived from the mother. In some systems, unreduced eggs or rare genetic exchanges can allow paternal DNA to persist, producing offspring with mixed or increased ploidy.

Gynogenesis occurs in several vertebrate groups, most prominently in certain fishes and salamanders. The best-known example is the Amazon molly (Poecilia formosa), an all-female species that requires sperm from related Poecilia species to activate development but usually passes on only maternal genes. Other instances are documented in some unisexual salamander lineages and related fish, where the presence of sperm ties reproduction to nearby males while paternal genes are not reliably transmitted.

Ecologically and evolutionarily, gynogenesis yields clonal lineages with limited genetic variation, which can be advantageous in stable environments but may hinder adaptation to change. The reliance on males for activation also influences population dynamics and the potential for genetic exchange, hybridization, and occasional shifts toward sexual reproduction in some lineages.