Floral phenotypes may be as much the result of selection for avoidance of some animal visitors as selection for improving the interaction with better pollinators. When specializing on hummingbird‐pollination, Penstemon flowers may have evolved to impr . . .

Male-male competition in plants is thought to exert selection on flower morphology and on the temporal presentation of pollen. Theory suggests that a plant’s pollen dosing strategy should evolve to match the abundance and pollen transfer efficiency of . . .

Male-male competition in plants is thought to exert selection on flower morphology and on the temporal presentation of pollen. Theory suggests that a plant's pollen dosing strategy should evolve to match the abundance and pollen transfer efficiency of . . .

I outline the criteria for choosing flower species to study in terms of how selection acts on characters affecting pollination success.

We compared pollen removal and deposition by hummingbirds and bumblebees visiting bird-syndrome Penstemon barbatus and bee-syndrome P. strictus flowers. One model for evolutionary shifts from bee pollination to bird pollination has assumed that, mostl . . .