Meeting Abstract

71.5  Tuesday, Jan. 6  Correlated evolution of feeding morphology in piscivorous versus non-piscivorous centrarchid fishes COLLAR, D.*; REVELL, L.; Harvard University; Harvard University dcollar@oeb.harvard.edu

We used a new phylogenetic comparative method to test whether an inferred shift in selective regime associated with the evolution of piscivory in centrachid fishes has led to changes in the pattern of diversification of feeding morphology in this group. The new method is based on maximum likelihood and allows the fitting of multiple evolutionary rate matrices to species values for two or more continuous characters and a phylogenetic tree for the included taxa. The evolutionary rate matrix is a square symmetric matrix containing the evolutionary rates for individual characters on its diagonal and the evolutionary covariances elsewhere. The evolutionary correlation between two characters is a function of their evolutionary variances (rates) and covariance, and, as such, our method is the first to allow for the estimation of different evolutionary correlations on different parts of a phylogenetic tree. We found that a two rate matrix model, where different evolutionary rate matrices were assigned to lineages that differed in the binary diet condition of piscivorous versus non-piscivorous, fit the evolution of gape width and buccal length better than did the single matrix model, in which a single rate matrix was assumed to prevail for all centrarchid lineages. The two rate matrix model suggests very strong correlation between the two characters in piscivorous lineages, implying that the demands of a piscivorous trophic strategy impose severe constraints on the evolution of buccal cavity shape in centrachids.