Back نظرية التطور الجزيئي المحايدة Arabic Неутрална теория за молекулярната еволюция Bulgarian Teoria neutral de l'evolució molecular Catalan Den neutrale teori om molekylær evolution Danish Neutrale Theorie der molekularen Evolution German Teoría neutralista de la evolución molecular Spanish Théorie neutraliste de l'évolution French Teoría neutralista da evolución molecular GL התאוריה הנייטרלית של אבולוציה מולקולרית HE Teori evolusi molekuler netral ID
The neutral theory of molecular evolution holds that most evolutionary changes occur at the molecular level, and most of the variation within and between species are due to random genetic drift of mutant alleles that are selectively neutral. The theory applies only for evolution at the molecular level, and is compatible with phenotypic evolution being shaped by natural selection as postulated by Charles Darwin.
The neutral theory allows for the possibility that most mutations are deleterious, but holds that because these are rapidly removed by natural selection, they do not make significant contributions to variation within and between species at the molecular level. A neutral mutation is one that does not affect an organism's ability to survive and reproduce.
The neutral theory assumes that most mutations that are not deleterious are neutral rather than beneficial. Because only a fraction of gametes are sampled in each generation of a species, the neutral theory suggests that a mutant allele can arise within a population and reach fixation by chance, rather than by selective advantage.[1]
The theory was introduced by the Japanese biologist Motoo Kimura in 1968, and independently by two American biologists Jack Lester King and Thomas Hughes Jukes in 1969, and described in detail by Kimura in his 1983 monograph The Neutral Theory of Molecular Evolution. The proposal of the neutral theory was followed by an extensive "neutralist–selectionist" controversy over the interpretation of patterns of molecular divergence and gene polymorphism, peaking in the 1970s and 1980s.
Neutral theory is frequently used as the null hypothesis, as opposed to adaptive explanations, for describing the emergence of morphological or genetic features in organisms and populations. This has been suggested in a number of areas, including in explaining genetic variation between populations of one nominal species,[2] the emergence of complex subcellular machinery,[3] and the convergent emergence of several typical microbial morphologies.[4]
- ^ Kimura, Motoo (1983). The neutral theory of molecular evolution. Cambridge University Press. ISBN 978-0-521-31793-1.
- ^ Fenchel, Tom (2005-11-11). "Cosmopolitan microbes and their 'cryptic' species". Aquatic Microbial Ecology. 41 (1): 49–54. doi:10.3354/ame041049. ISSN 0948-3055.
- ^ Cite error: The named reference
:2was invoked but never defined (see the help page). - ^ Lahr, Daniel J. G.; Laughinghouse, Haywood Dail; Oliverio, Angela M.; Gao, Feng; Katz, Laura A. (2014). "How discordant morphological and molecular evolution among microorganisms can revise our notions of biodiversity on Earth: Prospects & Overviews". BioEssays. 36 (10): 950–959. doi:10.1002/bies.201400056. PMC 4288574. PMID 25156897.