Meeting Abstract

94.3  Monday, Jan. 6 14:00  Developmental erosion of between-sex genetic correlations in a sexually dimorphic lizard COX, R.M.*; MCGLOTHLIN, J.W.; University of Virginia; Virginia Tech rmc3u@virginia.edu

Selection often favors dramatically different phenotypes in males and females, but quantitative-genetic theory predicts that the subsequent evolution of sexual dimorphism is potentially constrained by between-sex genetic correlations for shared traits. However, these correlations are not fixed constraints, but evolving features of the genomic architecture that can respond to selection. Moreover, estimates of between-sex genetic correlations often vary across ontogeny, suggesting that sex-biased developmental changes in gene expression may contribute to the relaxation of genetic constraint. Here, we present a comparative study of the quantitative genetics underlying body size and shape in two island populations of a highly dimorphic lizard, Anolis sagrei. Although selection favors extreme sexual size dimorphism in both populations, the extent to which males exceed females in body size varies significantly between populations, even under controlled laboratory conditions. Using a paternal half-sib breeding design, we show that the between-sex genetic correlation for body size decreases sharply as ontogeny progresses, and that the magnitude of this effect is greater in the population with greater sexual size dimorphism. We discuss this result in light of similar ontogentic patterns for sexually dimorphic shape traits, and with respect to the potential for maturational changes in gene expression to facilitate the developmental erosion of genetic constraint between the sexes.