Asexual reproduction

Encyclopedia : A : AS : ASE : Asexual reproduction

Asexual reproduction in liverworts: a caducuous phylloid germinating

Asexual reproduction (also known as agamogenesis) is a form of reproduction which does not involve meiosis, gamete formation, or fertilization. In laymen's terms, there is only one "parent" involved. This form of reproduction is common among simple organisms such as amoeba and other single-celled organisms, although most plants produce asexually as well (see vegetative reproduction).

Because it does not require male and female participation, asexual reproduction occurs faster than sexual reproduction and requires less energy. Additionally, asexual reproduction produces an exact replica of the parent due to the lack of genetic recombination. From an evolutionary standpoint, one could thus argue that asexual reproduction is inferior because it stifles the potential for change. However, there is also a significantly reduced chance of mutation or other complications that can result from the mixing of genes.

Many, but not all, single-celled organisms produce asexually through binary fission. Some single-celled organisms rely on one or more host organisms in order to reproduce, but most literally divide into two organisms. An exception to the rule are ciliates, which reproduce both sexually and asexually. All prokaryotes (the vast majority of which are unicellular) reproduce asexually. ^{[[Citing sources citation needed]]}

There are three types of asexual reproduction utilized by plants: regeneration, vegetative reproduction, and spore formation. The last type, spore formation, involves the production of reproductive cells called spores that contain DNA and develop into a new organism after dispersal. This method of reproduction is found in the ferns, and involves sporogenesis without meiosis. Thus the chromosome number of the spore cell is the same as that of the parent producing the spores.

Examples of asexual reproduction in higher organisms

The cape bee Apis mellifera capensis is known to sometimes reproduce asexually through a process called thelytoky.

References

• Graham, L., J. Graham, & L. Wilcox. 2003. Plant Biology. Pearson Education, Inc., Upper Saddle River, N.J.: pp. 258-259.
• [tiscali.reference] Asexual reproduction
• [Intestinal Protozoa]

See also

• Alternation of generation
• Bacterial conjugation
• Reproduction
• Sex

From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.