Parthenogenesis in animals: mechanisms, occurrence, and applications

Parthenogenesis is the development or growth of an organism in which fertilization does not occur between complimentary sex cells. It is a form of asexual reproduction where an unfertilized gamete begins to develop into the full-grown organism. It is fairly common in the less complex forms of species in the animal kingdom up through the Insect class, but becomes much less common thereafter. While the mechanisms involved in the process are not completely understood, parthenogenesis develops an offspring with almost identical genetic markers as the parent, very similar to the development of a clone, but with only one sex producing the phenomena. While certain worms and insects have this trait in common, a few kinds of amphibians, reptiles, and birds can also reproduce parthenogenetically. ("Parthenogenesis") However, mammalian embryos derived experimentally in this manner have thus far died within a period of days. (Kim, et.al. 483)

Parthenogenesis is used by organisms to exploit certain environmental circumstance. In the case of aphids they often use parthenogenesis to reproduce in larger numbers when supplies of food are abundant. Many organisms that use this method of reproduction are also capable of typical sexual reproduction as well. One of the more interesting cases is that of the Komodo Dragon. The females in this more complex species are able to spontaneously reproduce parthenogenetically when there are no males available for sexual reproduction. While allowing for the survival of the species through a few generations, prolonged use of the method will eventually reduce the gene pool and effectively eliminate any variation in the lineage of the species. (Watts, et.al 1021-1022)