The scent of a male: The role of floral volatiles in pollination of a gender dimorphic plant

Most flowering plants rely on animal pollinators to transfer mate gametes between individuals, and thus a significant problem for gender dimorphic plants is that pollinators often avoid female flowers. Here we show for the first time that one important reason pollinators shun female flowers is because they do not smell like males. We compared emission rates and floral scent composition in a gynodioecious wild strawberry (Fragaria virginiana) where females receive half as many visits by generalist pollinators as conspecific hermaphrodites. We used floral extracts to determine the Source of sexually dimorphic odor and pollinator responses. Specifically, we used extracts of whole flowers and specific floral parts in choice tests to determine that pollinators preferred the scent of hermaphrodite flowers over those of females and that this discrimination was-due primarily to the scent of hermaphrodite anthers. These data conclusively show that scent can be a major driver of pollinator behavior in gender dimorphic plants. Our results also indicate that scent is an important modulator of pollinator behavior even in a small flowered, weakly scented species visited by generalist pollinators, and not just peculiar to intensely scented, deceptive, or specialized pollination systems.