Genetic drift

Genetic drift, also known as allelic drift or the Wright effect,[1] is the change in the frequency of an existing gene variant (allele) in a population due to random chance.[2]

Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation.[3] It can also cause initially rare alleles to become much more frequent and even fixed.

When few copies of an allele exist, the effect of genetic drift is more notable, and when many copies exist, the effect is less notable. In the middle of the 20th century, vigorous debates occurred over the relative importance of natural selection versus neutral processes, including genetic drift. Ronald Fisher, who explained natural selection using Mendelian genetics,[4] held the view that genetic drift plays at most a minor role in evolution, and this remained the dominant view for several decades. In 1968, population geneticist Motoo Kimura rekindled the debate with his neutral theory of molecular evolution, which claims that most instances where a genetic change spreads across a population (although not necessarily changes in phenotypes) are caused by genetic drift acting on neutral mutations.[5][6] In the 1990s, constructive neutral evolution was proposed which seeks to explain how complex systems emerge through neutral transitions.[7][8]

  1. ^ Gould SJ (2002). "Chapter 7, section "Synthesis as Hardening"". The Structure of Evolutionary Theory.
  2. ^ Masel J (October 2011). "Genetic drift". Current Biology. Cell Press. 21 (20): R837-8. doi:10.1016/j.cub.2011.08.007. PMID 22032182.
  3. ^ Star B, Spencer HG (May 2013). "Effects of genetic drift and gene flow on the selective maintenance of genetic variation". Genetics. 194 (1): 235–44. doi:10.1534/genetics.113.149781. PMC 3632471. PMID 23457235.
  4. ^ Miller 2000, p. 54
  5. ^ Kimura M (February 1968). "Evolutionary rate at the molecular level". Nature. Nature Publishing Group. 217 (5129): 624–6. Bibcode:1968Natur.217..624K. doi:10.1038/217624a0. PMID 5637732. S2CID 4161261.
  6. ^ Futuyma 1998, p. 320
  7. ^ Stoltzfus, Arlin (1999). "On the Possibility of Constructive Neutral Evolution". Journal of Molecular Evolution. 49 (2): 169–181. Bibcode:1999JMolE..49..169S. doi:10.1007/PL00006540. ISSN 0022-2844. PMID 10441669. S2CID 1743092.
  8. ^ Muñoz-Gómez, Sergio A.; Bilolikar, Gaurav; Wideman, Jeremy G.; Geiler-Samerotte, Kerry (1 April 2021). "Constructive Neutral Evolution 20 Years Later". Journal of Molecular Evolution. 89 (3): 172–182. Bibcode:2021JMolE..89..172M. doi:10.1007/s00239-021-09996-y. ISSN 1432-1432. PMC 7982386. PMID 33604782.

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