Floral traits may evolve when pollinators select among variant forms of flowers. The behavior of animal pollinators can directly influence plant fitness through preferential visitation. Also, the sequence of pollinator visitation to the floral morphs in part determines gene flow and the mating structure of the plant population. Analysis of pollinator behavior in natural populations is complex, as is extrapolation of the implications of the behavior for the main-tenance or elimination of the floral polymorphism, and would be greatly facilitated by an experimental approach with an uncomplex system. The behavioral response of bee pollinators to a discrete floral pigmentation polymorphism found in a natural population of Clarkia gracilis subsp. sonomensis will be examined. The evolutionary implications of this response will be investgated; through genetic studies of the floral poly-morphism, by computer simulation of the interaction and resultant changes in floral allele frequencies through time, and with long-term studies of experimental polymorphic populations. This combined approach, applied to a system with discrete variation under simple genetic control, should yield new insights into plant-pollinator interactions and their evolutionary consequences.
