Meeting Abstract

54.6  Saturday, Jan. 5  The Influence of Functional Architecture on the Rate and Direction of Phenotypic Evolution WALKER, J.A.; Univ. Southern Maine walker@maine.edu

A general model of the functional constraints on the rate and direction of phenotypic evolution is developed using a decomposition of the Lande-Arnold model of multivariate phenotypic evolution. The important feature of the model is the F matrix of performance coefficients reflecting the causal relationship between morphophysiological (m-p) and functional performance traits. The structure of F, which reflects the functional architecture of the organism, constrains the shape of the adaptive landscape and thus the rate and direction of m-p trait evolution. The rate of m-p trait evolution is a function of the pattern of coefficients in a row of F. The sums and variances of these rows influence the selectability of a trait, which is closely related to the population genetic concept of evolvability. The direction of m-p trait evolution through m-p trait space is a function of the functional covariances among m-p traits. The functional covariance between a pair of m-p traits is a measure of how much the traits function together and is computed as the covariance between rows of F. The model can be used both to explore the theoretical dynamics of functional constraints on phenotypic evolution and to empirically test the influence of functional constraints on the rate and direction of phenotypic evolution within evolutionary radiations.