Parthenogenesis Of Asexual Reproduction
Parthenogenesis /ˌpɑrθənoʊˈdʒɛnəsɨs/
 is a form of asexual reproduction in which growth and development of 
embryos occur without fertilization. In animals, parthenogenesis means 
development of an embryo from an unfertilized egg cell and is a 
component process of apomixis.
Gynogenesis
 and pseudogamy are closely related phenomena in which a sperm or pollen
 triggers the development of the egg cell into an embryo but makes no 
genetic contribution to the embryo. The rest of the cytology and 
genetics of these phenomena are mostly identical to that of 
parthenogenesis.
The word parthenogenesis comes from the Greek παρθένος, parthenos, 
meaning "virgin" and γένεσις, genesis, meaning "birth". The term is 
sometimes used inaccurately to describe reproduction modes in 
hermaphroditic species that can reproduce by themselves because they 
contain reproductive organs of both sexes in a single individual's body.
Parthenogenesis occurs naturally in many plants, some invertebrate 
animal species (including nematodes, water fleas, some scorpions, 
aphids, some bees, some Phasmida and parasitic wasps) and a few 
vertebrates (such as some fish, amphibians, reptiles and very rarely 
birds). This type of reproduction has been induced artificially in a few
 species including fish and amphibians.
Normal egg cells form after meiosis and are haploid, with half as many 
chromosomes as their mother's body cells. Haploid individuals, however, 
are usually non-viable, and parthenogenetic offspring usually have the 
diploid chromosome number. Depending on the mechanism involved in 
restoring the diploid number of chromosomes, parthenogenetic offspring 
may have anywhere between all and half of the mother's alleles. The 
offspring having all of the mother's genetic material are called full 
clones and those having only half are called "half clones". Full clones 
are usually formed without meiosis. If meiosis occurs, the offspring 
will get only a fraction of the mother's alleles.
arthenogenesis is a form of agamogenesis in which 
an unfertilized egg develops into a new individual. Parthenogenesis 
occurs naturally in many plants, invertebrates (e.g. water fleas, 
rotifers, aphids, stick insects, some ants, bees and parasitic wasps), 
and vertebrates (e.g. some reptiles, amphibians,rarely birds). In 
plants, apomixis may or may not involve parthenogenesis.


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