Editing F-statistics (section)

{{short description|Statistically expected level of heterozygosity in a population}}
{{distinguish|text=the "F-test" statistic as used in general statistical inference. See [[F-test]] and [[F-distribution]]}}
{{DISPLAYTITLE:''F''-statistics}}
In [[population genetics]], '''''F''-statistics''' (also known as '''fixation indices''') describe the statistically expected level of [[Zygosity|heterozygosity]] in a population; more specifically the expected degree of (usually) a reduction in heterozygosity when compared to [[Hardy–Weinberg law|Hardy–Weinberg expectation]].

''F''-statistics can also be thought of as a measure of the correlation between genes drawn at different levels of a (hierarchically) subdivided population. This correlation is influenced by several [[evolution]]ary processes, such as [[genetic drift]], [[founder effect]], [[population bottleneck|bottleneck]], [[genetic hitchhiking]], [[meiotic drive]], [[mutation]], [[gene flow]], [[inbreeding]], [[natural selection]], or the [[Wahlund effect]], but it was originally designed to measure the amount of allelic fixation owing to [[genetic drift]].

The concept of ''F''-statistics was developed during the 1920s by the  American geneticist [[Sewall Wright]],<ref>{{cite journal |pmid=15439261 |year=1950 |last1=Wright |first1=S |title=Genetical structure of populations |volume=166 |issue=4215 |pages=247–9 |journal=Nature |doi=10.1038/166247a0|bibcode = 1950Natur.166..247W |s2cid=36311175 }}</ref><ref>{{cite journal |pmid=4063030 |lccn=67025533 |year=1985 |last1=Kulig |first1=K |title=Utilization of emergency toxicology screens |volume=3 |issue=6 |pages=573–4 |journal=The American Journal of Emergency Medicine |doi=10.1016/0735-6757(85)90177-9}}</ref> who was interested in inbreeding in [[cattle]].  However, because [[complete dominance]] causes the [[phenotype]]s of [[Zygosity|homozygote]] dominants and heterozygotes to be the same, it was not until the advent of [[molecular genetics]] from the 1960s onwards that heterozygosity in populations could be measured.

''F'' can be used to define [[effective population size]].{{elucidate|date=August 2014}}