title: Experimental demonstration of a causal relationship between heterogeneity of selection and genetic differentiation in quantitative traits.
abstract: Comparisons of estimates of genetic differentiation at molecular markers (F(ST)) and at quantitative traits (Q(ST)) are a means of inferring the level and heterogeneity of selection in natural populations. However, such comparisons are questionable because they require that the influence of drift and selection on Q(ST) be detectable over possible background influences of environmental or nonadditive genetic effects on Q(ST)-values. Here we test this using an experimental evolution approach in metapopulations of Arabidopsis thaliana experiencing different levels of drift and selection heterogeneity. We estimated the intensity and heterogeneity of selection on morphological and phenological traits via selection differentials. We demonstrate that Q(ST)-values increased with increasing selection heterogeneity when genetic drift was limited. The effect of selection on Q(ST) was thus detectable despite significant genotype-by-environment interactions that most probably biased the estimates of genetic differentiation. Although they cannot be used as a direct validation of the conclusions of prior studies, our results strongly support both the relevance of Q(ST) as an estimator of genetic differentiation and the role of local selection in shaping the genetic differentiation of natural populations.
authors.affiliation: Laboratoire Ecologie, Systématique et Evolution, UMR Centre National de la Recherche Scientifique 8079, Université Paris-Sud, Bâtiment 360, F-91405 Orsay Cedex, France. eporcher@ucsd.edu
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Porcher
authors.forename: Tatiana
authors.initials: T
authors.lastname: Giraud
authors.forename: Isabelle
authors.initials: I
authors.lastname: Goldringer
authors.forename: Claire
authors.initials: C
authors.lastname: Lavigne
mesh_terms: D000704:Analysis of Variance; D017360:Arabidopsis / Q000235:genetics*; D004777:Environment; D040961:Genetic Drift; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D008957:Models, Genetic; D019655:Quantitative Trait, Heritable; D012641:Selection, Genetic