Geographic variation in plant-pollinator interactions

A widely distributed plant species will experience variable selection pressures across its range, which include ecological interactions such as pollination. Across a landscape, varying plant-pollinator interactions may drive differences in floral traits on a population scale. Penstemon deustus var. pedicellatus is a bee-pollinated species found throughout the Intermountain Great Basin, a region with high diversity of native bees. Seeds from six widely dispersed P. deustus populations were collected from different mountain ranges and raised in two common gardens. The resulting plants were assessed for genetically based differences in floral morphology. Significant differences in floral characteristics were detected at the level of population origin. Further assessment of plants growing at original collection sites revealed equivalent differences in floral morphology.  A survey of potential pollinator communities and visitation rates also revealed site-level differences. These results, in combination, indicate possible pollinator-mediated selection. This study highlights the importance of considering local pollinators in restoration of plant communities.