In botany, apomixis is asexual reproduction, without fertilization. Apomixis mainly occurs in two forms: In agamogenesis, the embryo arises from an unfertilized egg via a modified meiosis. In agamospermy (also called apogamy), a nucellar embryo is formed from the surrounding embryo sac tissue. Apomictically produced seeds 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. Pinguicula grandiflora Example of a Cross Section of a Stem [1] Botany is the scientific study of plant life. ... It has been suggested that Parthenogenesis be merged into this article or section. ... For other uses, see Embryo (disambiguation). ... Most commercial citrus varieties produce mainly nucellar seedlings. ... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... This article is about evolution in biology. ... Sexual reproduction is a union that results in increasing genetic diversity of the offspring. ...

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). For other uses, see Species (disambiguation). ... A congener (from Latin roots meaning born together or within the same race or kind) has several different meanings depending on the field in which it is used. ... For other uses, see Genus (disambiguation). ... Flora is a collective term for plant life. ... The blackberry is a bramble fruit Bramble refers to thorny plants of the Genus Rubus, in the Rose family (Rosaceae). ... Species See text Crataegus (Hawthorn) is a large genus of in the family Rosaceae, native to temperate regions of the Northern Hemisphere in Europe, Asia and North America. ... Subgenera Sorbus Aria Micromeles Cormus Torminaria Chamaemespilus The genus Sorbus is a genus of about 100-200 species of trees and shrubs in the subfamily Maloideae of the Rose family Rosaceae. ... Species Sorbus subgenus Sorbus Sorbus aucuparia - European Rowan Sorbus americana - American mountain ash Sorbus cashmeriana - Kashmir Rowan Sorbus commixta - Japanese Rowan Sorbus decora - Showy mountain ash Sorbus glabrescens - White-fruited Rowan Sorbus hupehensis - Hubei Rowan Sorbus matsumurana Sorbus sargentiana - Sargents Rowan Sorbus scalaris - Ladder Rowan Sorbus sitchensis - Sitka mountain... Species Sorbus subgenus Aria Sorbus alnifolia - Korean Whitebeam Sorbus aria - Common Whitebeam Sorbus arranensis - Arran Whitebeam Sorbus bristoliensis - Bristol Gorge Whitebeam Sorbus devoniensis - Devon Whitebeam Sorbus folgneri - Folgners Whitebeam Sorbus intermedia - Swedish Whitebeam Sorbus latifolia - Service Tree of Fontainebleau Sorbus mougeotii - Vosges Whitebeam Sorbus rupicola - Rock Whitebeam Sorbus thibetica... Species See text. ... Genera Hieracium Pilosella Hawkweed refers to any species in the very large genus Hieracium and its segregate genus Pilosella, in the sunflower family (Asteraceae). ... For other uses, see Dandelion (disambiguation). ...

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). Binomial name Cupressus dupreziana A. Camus Cupressus dupreziana, the Saharan Cypress, is a very rare coniferous tree native to the Tassili nAjjer mountains in the central Sahara Desert, southeast Algeria, where it forms a unique population of trees hundreds of kilometres from any other trees. ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ...

In zoology parthenogenesis is the animal equivalent of apomixis. Recently, Matthew Meselson won the Lasker Award 2004. He and his students are probing why sex is necessary for evolution. Some small aquatic animals, bdelloid rotifers, are apomictic and have survived for millions of years without sex. They serve as an experimental model system. Meselson assumes that the advantage of sex may lie in its ability to reduce what he calls "genetic parasites" (i.e.transposable elements). These are pieces of DNA that multiply on their own and can cause genetic damage. Bdelloid rotifers don't appear to have such parasites. Zoology (from Greek: ζῴον, zoion, animal; and λόγος, logos, knowledge) is the biological discipline which involves the study of animals. ... For the religious belief, see Virgin Birth. ... For other uses, see Animal (disambiguation). ... Dr. Matthew Stanley Meselson (born 1930) is an American geneticist and molecular biologist whose research was important in showing how DNA replicates, recombines and is repaired in cells. ... The Albert Lasker Medical Research Awards have been awarded annually since 1946 to living persons who have made major contributions to medical science. ... The bdelloids (Bdelloidea) are a class of rotifers, found in freshwater and moist soil. ... Transposons are sequences of DNA that can move around to different positions within the genome of a single cell, a process called Transposition. ...

See also

• Parthenocarpy

In botany and horticulture, parthenocarpic literally means virgin fruit; the fruit develops without fertilization of ovules, therefore it is seedless. ...

References in Popular Culture

The patenting of apomixis is the MacGuffin at the core of British journalist Peter Pringle's thriller The Day of the Dandelion (Simon & Shuster, 2007). A MacGuffin (sometimes McGuffin or Maguffin) is a plot device that motivates the characters and/or advances the story, but has little other relevance to the story. ...

Further reading

• Arkhipova I. & Meselson M. (2000). Transposable elements in sexual and ancient asexual taxa. Proceedings of the National Academy of Sciences of the United States of America. 97:14473-14477
• Arkhipova I. & Meselson M. (2005). Deleterious transposable elements and the extinction of asexuals. BioEssays. 27:76-85
• Normark BB, Judson OP, & Moran NA (2003). Genomic signatures of ancient asexual lineages. Biological Journal of the Linnean Society. 79:69-84.

References

• Gvaladze G.E. (1976). Forms of Apomixis in the genus Allium L. In: S.S. Khokhlov (Ed.): Apomixis and Breeding, Amarind Pub., New Delhi-Bombay-Calcutta-New York 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.