A major gap in our understanding of floral evolution, especially micro-evolutionaryprocesses, is the role of pollinators in generating patterns of natural selection onfloral traits. Here we explicitly tested the role of pollinators in selecting floral traitsin a herbaceous perennial,Penstemon digitalis.•We manipulated the effect of pollinators on fitness through hand pollinationsand compared phenotypic selection in open- and hand-pollinated plants.•Despite the lack of pollen limitation in our population, pollinators mediatedselection on floral size and floral display. Hand pollinations removed directionalselection for larger flowers and stabilizing selection on flower number, suggestingthat pollinators were the agents of selection on both of these traits.•We reviewed studies that measured natural selection on floral traits by bioticagents and generally found stronger signatures of selection imposed by pollinatorsthan by herbivores and co-flowering plant species.
