Parthenogenesis

Parthenogenesis is a type of asexual reproduction in which offspring develop from unfertilized eggs. It is particularly common in arthropods and rotifers, but can also be found in species from other phyla. The term is derived from the Greek words parthenos, meaning "virgin", and genesis, meaning "birth".

Overview

Parthenogenesis occurs naturally in many plants, some invertebrate animal species (including nematodes, water fleas, some scorpions, aphids, some mites, 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.

Types of Parthenogenesis

There are several types of parthenogenesis, including obligate parthenogenesis, in which the organism can only reproduce asexually, and cyclical parthenogenesis, where organisms alternate between sexual and asexual reproduction. Another type is haplodiploidy, a sex-determination system in which one sex is haploid and the other diploid.

Mechanisms

The mechanisms of parthenogenesis include automixis, where the two sets of chromosomes come from the same individual, and apomixis, where the chromosomes are identical to the parent's. In some cases, parthenogenesis can result in offspring that are genetically identical to the parent, a process known as cloning.

Evolutionary Implications

Parthenogenesis has important implications for evolution. It allows for rapid population growth and colonization of new areas. However, it also reduces genetic diversity, which can make populations more susceptible to diseases and other threats.

See Also

• Asexual reproduction
• Sexual reproduction
• Hermaphroditism
• Budding
• Fission
• Fragmentation
• Vegetative reproduction

References

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Parthenogenesis

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  Three species of Cnemidophorus lizards

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  Komodo dragon exhibiting parthenogenesis

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  Diagram of central fusion and terminal fusion automixis

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  Parthenogenesis illustration by Steve R. Bischoff

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  Hybridogenesis in water frogs