WALKER, JA; Univ. Southern Maine: A General Model of Functional Constraints on Phenotypic Evolution

A general model of the functional constraints on the rate and direction of phenotypic evolution is developed using Arnold�s decomposition of the multivariate breeder�s equation. The important feature of the model is the F matrix of functional performance coefficients. The structure of the F matrix constrains the rate and direction of phenotypic evolution, which constraint is independent of that determined by the G matrix. The off-diagonal elements of the F-transpose-F matrix summarize trade-offs and facilitations among performance traits. The off-diagonal elements of the F-F-transpose matrix reflect the functional correlation between two morpho-physiological (m-p) traits and an eigenanalysis of this matrix provides a novel definition of functional integration. Simulation data is used to show how the general model biases m-p trait evolution and the structure of both the G matrix and the among-species covariance matrix.