title: F(ST) and Q(ST) under neutrality.
abstract: A commonly used test for natural selection has been to compare population differentiation for neutral molecular loci estimated by F(ST) and for the additive genetic component of quantitative traits estimated by Q(ST). Past analytical and empirical studies have led to the conclusion that when averaged over replicate evolutionary histories, Q(ST) = F(ST) under neutrality. We used analytical and simulation techniques to study the impact of stochastic fluctuation among replicate outcomes of an evolutionary process, or the evolutionary variance, of Q(ST) and F(ST) for a neutral quantitative trait determined by n unlinked diallelic loci with additive gene action. We studied analytical models of two scenarios. In one, a pair of demes has recently been formed through subdivision of a panmictic population; in the other, a pair of demes has been evolving in allopatry for a long time. A rigorous analysis of these two models showed that in general, it is not necessarily true that mean Q(ST) = F(ST) (across evolutionary replicates) for a neutral, additive quantitative trait. In addition, we used finite-island model simulations to show there is a strong positive correlation between Q(ST) and the difference Q(ST) - F(ST) because the evolutionary variance of Q(ST) is much larger than that of F(ST). If traits with relatively large Q(ST) values are preferentially sampled for study, the difference between Q(ST) and F(ST) will also be large and positive because of this correlation. Many recent studies have used tests of the null hypothesis Q(ST) = F(ST) to identify diversifying or uniform selection among subpopulations for quantitative traits. Our findings suggest that the distributions of Q(ST) and F(ST) under the null hypothesis of neutrality will depend on species-specific biology such as the number of subpopulations and the history of subpopulation divergence. In addition, the manner in which researchers select quantitative traits for study may introduce bias into the tests. As a result, researchers must be cautious before concluding that selection is occurring when Q(ST) not equal F(ST).
authors.affiliation: Department of Mathematics, Georgetown University, Washington, DC 20057, USA. jrm32@georgetown.edu
authors.forename: Judith R
authors.initials: JR
authors.lastname: Miller
authors.forename: Bryan P
authors.initials: BP
authors.lastname: Wood
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Hamilton
mesh_terms: D000704:Analysis of Variance; D003198:Computer Simulation; D005828:Genetics, Population; D008957:Models, Genetic; D040641:Quantitative Trait Loci; D012641:Selection, Genetic
references.citation: Mol Ecol. 2003 Feb;12(2):315-30
references.pmid: 12535084
references.citation: Evolution. 2004 Jul;58(7):1434-45
references.pmid: 15341147
references.citation: Mol Ecol. 2008 Apr;17(8):1885-96
references.pmid: 18363667
references.citation: Evolution. 1992 Apr;46(2):381-389
references.pmid: 28564025
references.citation: Mol Ecol. 2007 Jul;16(13):2693-700
references.pmid: 17594440
references.citation: Genet Res. 2006 Feb;87(1):1-12
references.pmid: 16545147
references.citation: J Evol Biol. 2008 Jan;21(1):1-17
references.pmid: 18028355
references.citation: Evolution. 1984 Nov;38(6):1358-1370
references.pmid: 28563791
references.citation: Genetics. 2007 Oct;177(2):1011-22
references.pmid: 17720934
references.citation: Mol Ecol. 2003 Jul;12(7):1963-78
references.pmid: 12803645
references.citation: Genetics. 2003 Aug;164(4):1627-33
references.pmid: 12930766
references.citation: Am Nat. 1998 Mar;151(3):283-92
references.pmid: 18811359
references.citation: Mol Ecol. 2002 Dec;11(12):2583-90
references.pmid: 12453241
references.citation: Proc Natl Acad Sci U S A. 1973 Dec;70(12):3321-3
references.pmid: 4519626
references.citation: Genetics. 2006 Feb;172(2):1337-47
references.pmid: 16322514
references.citation: Genetics. 1983 Dec;105(4):985-1002
references.pmid: 17246186
references.citation: Nature. 2002 Oct 24;419(6909):826-30
references.pmid: 12397355
references.citation: Genetics. 2005 Nov;171(3):1331-9
references.pmid: 16085700
references.citation: Theor Appl Genet. 1995 Jul;91(1):122-30
references.pmid: 24169677
references.citation: Heredity (Edinb). 2005 May;94(5):518-25
references.pmid: 15741999
references.citation: Genet Res. 1999 Dec;74(3):215-21
references.pmid: 10689799
references.citation: Genetics. 2003 Jul;164(3):1205-19
references.pmid: 12871925
references.citation: Ann Eugen. 1951 Mar;15(4):323-54
references.pmid: 24540312
references.citation: Genetics. 1993 Oct;135(2):367-74
references.pmid: 8244001
references.citation: Mol Ecol. 2005 Nov;14(13):4181-92
references.pmid: 16262868