The timing of food-deceptive flowers: a commentary on Internicola et al. (2008)

A recent article presents a study of pollinator visitation behaviour that is used to evaluate the selective pressure that pollinator visitation rate might have on the timing of the production of nonrewarding flowers. Here we take issue with the conclusions of the paper that there should be selection pressure for nonrewarding flowers to be available earlier in the season in order to avoid dissimilar sympatric rewarding species. Consideration of selection pressure must take into account temporal variation in total pollinator availability, pollinator longevity and unlearned response, and the stability of plant communities over time, as well as the learned responses of individual pollinators that the original study focused on. Learning alone would not necessarily select for early flowering by nonrewarders if temporal variation in pollinator numbers is strong or naive pollinators consistently appear throughout the flowering season. Further, we argue that early flowering could simply be a natural corollary of longevity of flowers needed to combat negative frequency-dependent selection and low overall visitation rates by pollinators, rather than a trait that has been specifically selected to reduce temporal overlap with competing rewarding species.