title: Sex chromosome linked genetic variance and the evolution of sexual dimorphism of quantitative traits.
abstract: Theory predicts that sex chromsome linkage should reduce intersexual genetic correlations thereby allowing the evolution of sexual dimorphism. Empirical evidence for sex linkage has come largely from crosses and few studies have examined how sexual dimorphism and sex linkage are related within outbred populations. Here, we use data on an array of different traits measured on over 10,000 individuals from two pedigreed populations of birds (collared flycatcher and zebra finch) to estimate the amount of sex-linked genetic variance (h(2)z ). Of 17 traits examined, eight showed a nonzero h(2)Z estimate but only four were significantly different from zero (wing patch size and tarsus length in collared flycatchers, wing length and beak color in zebra finches). We further tested how sexual dimorphism and the mode of selection operating on the trait relate to the proportion of sex-linked genetic variance. Sexually selected traits did not show higher h(2)Z than morphological traits and there was only a weak positive relationship between h(2)Z and sexual dimorphism. However, given the relative scarcity of empirical studies, it is premature to make conclusions about the role of sex chromosome linkage in the evolution of sexual dimorphism.
authors: Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden. arild.husby@ebc.uu.se
authors: Arild
authors: A
authors: Husby
authors: Holger
authors: H
authors: Schielzeth
authors: Wolfgang
authors: W
authors: Forstmeier
authors: Lars
authors: L
authors: Gustafsson
authors: Anna
authors: A
authors: Qvarnström
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005260:Female; D046369:Finches / Q000235:genetics*; D008040:Genetic Linkage; D014644:Genetic Variation; D008297:Male; D012641:Selection, Genetic; D012727:Sex Characteristics; D012730:Sex Chromosomes