Pollinators, herbivores, and the evolution of floral traits

Floral traits, including flower shape, color, nectar, and scent, affect pollination success and mating systems by influencing attractiveness to pollinators and efficiency of cross- and self-pollination. Traditionally, the evolution and maintenance of differences in these traits have been related to selective pressures imposed by pollinators, and pollen and mate limitation. Recent years have seen increasing evidence that antagonists such as grazers and seed predators also mediate selection on floral traits (1–4). On page 193 of this issue, Ramos and Schiestl (5) show that both pollinators and herbivores influence the evolution of floral display and of self-pollination efficiency and that their effects are not necessarily additive. The study provides a proof-of-concept that should inspire investigation of the interactive effects of mutualists and antagonists on the evolution of plant reproductive traits in additional systems.