Apomixis
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In botany, apomixis is asexual reproduction, without fertilization and without meiosis. An apomict or apomictic plant produces seeds that are genetically identical to the parent plant. Although the evolutionary advantages of sexual reproduction are lost, apomixis does pass along traits fortuitous for individual evolutionary fitness.
As apomictic plants are genetically identical from one generation to the next, each has the characters of a true species, maintaining distinctions from other congeneric apomicts, while having much smaller differences than is normal between species of most genera. They are therefore often called microspecies. In some genera, it is possible to identify and name hundreds or even thousands of microspecies, which may be grouped together as aggregate species, typically listed in Floras with the convention "Genus species agg." (e.g., the bramble, Rubus fruticosus agg.). Good examples of apomixis can be found in the genera Crataegus (hawthorns), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Hieracium (hawkweeds) and Taraxacum (dandelions).
A unique example of male apomixis has recently been discovered in the Saharan Cypress, Cupressus dupreziana, where the seeds are derived entirely from the pollen with no genetic contribution from the female "parent" (Pichot, et al., 2000, 2001).
Parthenogenesis is the animal equivalent of apomixis.
See also:
References
- Gvaladze G.E. Forms of Apomixis in the genus Allium L. In: S.S. Khokhlov (Ed.): Apomixis and Breeding, Amarind Pub., New Delhi-Bombay-Calcutta-New York, 1976, pp. 160-165
- Pichot, C., Fady, B., & Hochu, I. 2000. Lack of mother tree alleles in zymograms of Cupressus dupreziana A. Camus embryos. Ann. For. Sci. 57: 17–22. Full article (pdf file)
- Pichot, C., El Maátaoui, M., Raddi, S. & Raddi, P. 2001. Surrogate mother for endangered Cupressus. Nature 412: 39.da:Apomixis