Some Models for Development, Growth, and Morphometric Correlation

Genetic and phenotypic correlations between morphometric traits can be a direct consequence of shared developmental history and common systems of growth regulation. Correlation between traits, therefore, need not imply direct functional or adaptive constraints on those traits. Useful models of the developmental origins of correlations will consider mechanisms that can reduce initially high correlation of traits that arise from a single developmental precursor. Several models presented here predict such correlations for different modes of fission of a precursor. Timing of developmental events may also affect correlations and respond to selection on adult traits. The models may apply to development of the tetrapod limb bud, including variance and covariance induced by known developmental mutants.