• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Logo of geneticsGeneticsCurrent IssueInformation for AuthorsEditorial BoardSubscribeSubmit a Manuscript
Genetics. Jun 2003; 164(2): 767–779.
PMCID: PMC1462574

Fixation probability and time in subdivided populations.

Abstract

New alleles arising in a population by mutation ultimately are either fixed or lost. Either is possible, for both beneficial and deleterious alleles, because of stochastic changes in allele frequency due to genetic drift. Spatially structured populations differ from unstructured populations in the probability of fixation and the time that this fixation takes. Previous results have generally made many assumptions: that all demes contribute to the next generation in exact proportion to their current sizes, that new mutations are beneficial, and that new alleles have additive effects. In this article these assumptions are relaxed, allowing for an arbitrary distribution among demes of reproductive success, both beneficial and deleterious effects, and arbitrary dominance. The effects of population structure can be expressed with two summary statistics: the effective population size and a variant of Wright's F(ST). In general, the probability of fixation is strongly affected by population structure, as is the expected time to fixation or loss. Population structure changes the effective size of the species, often strongly downward; smaller effective size increases the probability of fixing deleterious alleles and decreases the probability of fixing beneficial alleles. On the other hand, population structure causes an increase in the homozygosity of alleles, which increases the probability of fixing beneficial alleles but somewhat decreases the probability of fixing deleterious alleles. The probability of fixing new beneficial alleles can be simply described by 2hs(1 - F(ST))N(e)/N(tot), where hs is the change in fitness of heterozygotes relative to the ancestral homozygote, F(ST) is a weighted version of Wright's measure of population subdivision, and N(e) and N(tot) are the effective and census sizes, respectively. These results are verified by simulation for a broad range of population structures, including the island model, the stepping-stone model, and a model with extinction and recolonization.

Full Text

The Full Text of this article is available as a PDF (164K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Caballero A, Hill WG. Effects of partial inbreeding on fixation rates and variation of mutant genes. Genetics. 1992 Jun;131(2):493–507. [PMC free article] [PubMed]
  • Maruyama T, Kimura M. Genetic variability and effective population size when local extinction and recolonization of subpopulations are frequent. Proc Natl Acad Sci U S A. 1980 Nov;77(11):6710–6714. [PMC free article] [PubMed]
  • Nagylaki T. The strong-migration limit in geographically structured populations. J Math Biol. 1980 Apr;9(2):101–114. [PubMed]
  • Nagylaki T. Geographical invariance in population genetics. J Theor Biol. 1982 Nov 7;99(1):159–172. [PubMed]
  • Slatkin M. Gene flow and genetic drift in a species subject to frequent local extinctions. Theor Popul Biol. 1977 Dec;12(3):253–262. [PubMed]
  • Tachida H, Iizuka M. Fixation probability in spatially changing environments. Genet Res. 1991 Dec;58(3):243–251. [PubMed]
  • KIMURA M. On the probability of fixation of mutant genes in a population. Genetics. 1962 Jun;47:713–719. [PMC free article] [PubMed]
  • Kimura M, Ohta T. The Average Number of Generations until Fixation of a Mutant Gene in a Finite Population. Genetics. 1969 Mar;61(3):763–771. [PMC free article] [PubMed]
  • KIMURA M, MARUYAMA T, CROW JF. THE MUTATION LOAD IN SMALL POPULATIONS. Genetics. 1963 Oct;48:1303–1312. [PMC free article] [PubMed]
  • Whitlock MC. Fixation of new alleles and the extinction of small populations: drift load, beneficial alleles, and sexual selection. Evolution. 2000 Dec;54(6):1855–1861. [PubMed]
  • Whitlock Michael C. Selection, load and inbreeding depression in a large metapopulation. Genetics. 2002 Mar;160(3):1191–1202. [PMC free article] [PubMed]
  • Lande R. Risk of population extinction from fixation of deleterious and reverse mutations. Genetica. 1998;102-103(1-6):21–27. [PubMed]
  • Lewontin RC, Krakauer J. Distribution of gene frequency as a test of the theory of the selective neutrality of polymorphisms. Genetics. 1973 May;74(1):175–195. [PMC free article] [PubMed]
  • Whitlock MC, Barton NH. The effective size of a subdivided population. Genetics. 1997 May;146(1):427–441. [PMC free article] [PubMed]
  • Wright S. Evolution in Mendelian Populations. Genetics. 1931 Mar;16(2):97–159. [PMC free article] [PubMed]
  • Maruyama T. On the fixation probability of mutant genes in a subdivided population. Genet Res. 1970 Apr;15(2):221–225. [PubMed]

Articles from Genetics are provided here courtesy of Genetics Society of America

Formats:

Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...

Links

  • PubMed
    PubMed
    PubMed citations for these articles

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...