Editing Genetic drift (section)

{{Short description|Concept in genetics}}
{{Distinguish|Genetic draft|Antigenic drift|Antigenic shift|Genetic Drift (video game)}}
{{Use dmy dates|date=September 2020}}
{{Good article}}
{{Evolutionary biology}}

'''Genetic drift''', also known as '''random genetic drift''', '''allelic drift''' or the''' Wright effect''',<ref>{{cite book | title = [[The Structure of Evolutionary Theory]] | year = 2002 | vauthors = Gould SJ | author-link = Stephen Jay Gould | chapter = Chapter 7, section "Synthesis as Hardening" }}</ref> is the change in the [[Allele frequency|frequency]] of an existing [[gene]] variant ([[allele]]) in a population due to random chance.<ref name="Masel 2011">{{cite journal | vauthors = Masel J | title = Genetic drift | journal = Current Biology | volume = 21 | issue = 20 | pages = R837-8 | date = October 2011 | pmid = 22032182 | doi = 10.1016/j.cub.2011.08.007 | publisher = [[Cell Press]] | author-link = Joanna Masel | doi-access = free | bibcode = 2011CBio...21.R837M }}</ref>

Genetic drift may cause gene variants to disappear completely and thereby reduce [[genetic variation]].<ref name="Star_2013">{{cite journal | vauthors = Star B, Spencer HG | title = Effects of genetic drift and gene flow on the selective maintenance of genetic variation | journal = Genetics | volume = 194 | issue = 1 | pages = 235–44 | date = May 2013 | pmid = 23457235 | pmc = 3632471 | doi = 10.1534/genetics.113.149781 }}</ref> 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 (due to the [[law of large numbers]]). 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 inheritance|Mendelian genetics]],<ref>{{harvnb|Miller|2000|p=54}}</ref> 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 [[Fixation (population genetics)|spreads across a population]] (although not necessarily changes in [[phenotype]]s) are caused by genetic drift acting on neutral [[mutation]]s.<ref name="Kimura_1968">{{cite journal | vauthors = Kimura M | title = Evolutionary rate at the molecular level | journal = Nature | volume = 217 | issue = 5129 | pages = 624–6 | date = February 1968 | pmid = 5637732 | doi = 10.1038/217624a0 | publisher = Nature Publishing Group | author-link = Motoo Kimura | bibcode = 1968Natur.217..624K | s2cid = 4161261 }}</ref><ref name="Futuyma 1998 320">{{harvnb|Futuyma|1998|p=320}}</ref> In the 1990s, [[constructive neutral evolution]] was proposed which seeks to explain how complex systems emerge through neutral transitions.<ref name=":0">{{Cite journal|vauthors=Stoltzfus A|date=1999|title=On the Possibility of Constructive Neutral Evolution|url=http://link.springer.com/10.1007/PL00006540|journal=Journal of Molecular Evolution|language=en|volume=49|issue=2|pages=169–181|doi=10.1007/PL00006540|pmid=10441669|bibcode=1999JMolE..49..169S|s2cid=1743092|issn=0022-2844|access-date=20 January 2022|archive-date=30 July 2022|archive-url=https://web.archive.org/web/20220730090616/https://link.springer.com/article/10.1007/PL00006540|url-status=live}}</ref><ref name=":1">{{cite journal | vauthors = Muñoz-Gómez SA, Bilolikar G, Wideman JG, Geiler-Samerotte K | title = Constructive Neutral Evolution 20 Years Later | journal = Journal of Molecular Evolution | volume = 89 | issue = 3 | pages = 172–182 | date = April 2021 | pmid = 33604782 | pmc = 7982386 | doi = 10.1007/s00239-021-09996-y | bibcode = 2021JMolE..89..172M }}</ref>