Pollinator declines select for floral traits that facilitate selfing in Impatiens capensis
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Pollinators have been declining worldwide, affecting plants that depend on them for pollination. In order to persist in the presence of declining pollinators, plants may evolve floral traits that facilitate either pollinator-mediated outcrossing or autonomous self pollination. Whether outcrossing or selfing traits are selected can also be affected by herbivory. To determine whether herbivores can affect pollinator-mediated selection for outcrossing or selfing in the mixed-mating plant Impatiens capensis, I measured phenotypic selection on plants in three treatments: ambient pollinator access and ambient herbivory (P/H), reduced pollinator access and ambient herbivory (–P/H), and reduced pollinator access and increased herbivory (–P/+H). When pollinator access was reduced, plants experienced selection for a floral trait that facilitates autonomous selfing. This pollinator-mediated selection was intensified by herbivory. Plant populations may respond to selection by shifting their mating system towards selfing, which may affect their ability to adapt to environmental stressors in the future.