Gynogenesis

Gynogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. This form of reproduction is found in certain fish, amphibians, and insects. Gynogenesis is a type of parthenogenesis, but unlike other forms of parthenogenesis, gynogenesis requires the presence of sperm to stimulate the egg into development.

Mechanism

In gynogenesis, the sperm does not contribute any genetic material to the offspring. Instead, the sperm merely triggers the egg's development. The egg cell can be either haploid or diploid, depending on the species. In some cases, the sperm cell may penetrate the egg cell but its nucleus is not incorporated into the egg's genetic material. This is known as "sperm-dependent gynogenesis".

Species

Gynogenesis has been observed in several species of fish, including the Amazon molly and the European bitterling. In these species, the females reproduce by gynogenesis but require the presence of males for sperm, which triggers the development of the eggs.

In insects, gynogenesis occurs in some species of aphids and bees. In these species, the females are able to reproduce without males, but the presence of males can stimulate the production of more females.

Implications

Gynogenesis has significant implications for the study of evolution and genetics. Because gynogenetic offspring are genetically identical to their mothers, they provide a unique opportunity to study the effects of environment on phenotype without the confounding factor of genetic variation.

See also

• Parthenogenesis
• Sexual reproduction
• Asexual reproduction