Lessons from flower colour evolution on targets of selection.

The genetic basis of flower colour evolution provides a useful system to address the debate over the relative contribution of regulatory vs. functional mutations in evolution. The relative importance of these two categories depends on the type of flower colour transition and the genes involved in those transitions. These differences reflect differences in the degree of deleterious pleiotropy associated with functional inactivation of various anthocyanin pathway genes. Our findings illustrate how generalized statements regarding the contributions of regulatory and functional mutations to broad categories of traits, such as morphological vs. physiological, ignore differences among traits within categories and in doing so overlook important factors determining the relative importance of regulatory and functional mutations.