The strength of phenotypic selection on floral traits (Visiting Scholar)
Floral trait evolution has interested biologists since Darwin because divergence in floral traits can limit the movement of pollen between populations and thus contribute to reproductive isolation. One approach to studying whether divergence in floral traits contributes to the evolution of reproductive isolation is to measure phenotypic selection on these traits. I propose to assemble and analyze a database of estimates of phenotypic selection on floral traits. If divergence in floral traits contributes to the evolution of reproductive isolation, then (1) pollinators should exert strong selection on floral traits, (2) the strength and direction of selection on floral traits should depend on pollinator identity, and (3) there should be strong selection on floral traits that restrict the movement of pollen between populations. In addition to testing these predictions, I will explore how selection on floral traits differs among trait types (e.g. pollinator attraction vs. pollination efficiency) and fitness components (e.g. fecundity vs. mating success).