Meeting Abstract

P2.94  Monday, Jan. 5  Using artificial selection to determine how sexual size dimorphism affects within-sex size variation TIGREROS, Natasha*; LEWIS, Sara; Tufts University; Tufts University natasha.tigreros@tufts.edu

An important issue concerning the evolution of sexual size dimorphism is that strong genetic correlations between the sexes constitute a genetic constraint. Although females may be subject to fecundity selection for larger body size and males for small body size, the evolution of sexual size dimorphism could be constrained by genetic correlations between the sexes. Thus, selection for sexual size dimorphism coupled with genetic correlations between the sexes may help maintain body size variation within each sex. Using artificial selection on red flour beetles (Tribolium castaneum), we tested the prediction that selection for extreme sexual size dimorphism will broaden within-sex variation in body size. We established 3 replicated selection lines: a) increased female-biased sexual size dimorphism b) reduced sexual size dimorphism and c) control line. We assessed T. castaneum body size via a multivariate approach based on principal component analysis of five linear measures: head width, pronotum width, tibia length, prosternum width and third abdominal sternite length. After three generations of selection, we compared the effect that increasing or decreasing sexual size dimorphism had on intrasexual variation in body size. These results provide new insight into the evolutionary significance of sexual size dimorphism.