Flowering Phenology in Relation to Adaptive Radiation

The role of flowering phenology in ecological diversification is poorly understood, even though this variable may be an important determinant of fitness. While flowering schedules are readily evolvable, they also seem to be under phylogenetic constraint. I ask whether phenological change is a partner to adaptive radiation. Using examples from island and continental lineages, I show that habitat diversifications are not necessarily coupled with phenological change, whereas shifts in pollinator typically are so coupled. It all depends on whether alteration in flowering time is required to invade new habitats or exploit new pollinators. The coupling of ecological and temporal shifts is most evident in the evolution of autopolyploids. Stasis in the flowering times of some lineages more likely is due to stabilizing selection than to genetic constraints.