Floral function: effects of traits on pollinators, male and female pollination success, and female fitness across three species of milkweeds (Asclepias)

PREMISE OF THE STUDY: Central questions in plant reproductive ecology are whether the functions of floral traits in hermaphrodites create conflict between sexes that could slow evolution, and whether individual floral traits function in pollinator attraction, efficiency, or both. We studied how floral traits affect pollinator visitation and efficiency, and how they affect male and female function and female fitness within and across three Asclepias species that differ in floral morphology.

METHODS: Using separate multiple regressions, we regressed pollen removal, deposition, and fruit number onto six floral traits. We also used path analyses integrating these variables with pollinator visitation data for two of the species to further explore floral function and its effects on fruit production.

KEY RESULTS: Most traits affected male pollination success only, and these effects often differed between species. The exception was increased slit length, which increased pollinia insertion...