Simulated pollinator decline has similar effects on seed production of female and hermaphrodite Lobelia siphilitica, but different effects on selection on floral traits

PREMISE: Pollinator decline, by reducing seed production, is predicted to
strengthen natural selection on floral traits. However, the effect of
pollinator decline on gender dimorphic species (such as gynodioecious
species, where plants produce female or hermaphrodite flowers) may differ
between the sex morphs: if pollinator decline reduces the seed production
of females more than hermaphrodites, then it should also have a larger
effect on selection on floral traits in females than in hermaphrodites.
RESULTS: Experimentally reducing pollination decreased seed production of
both females and hermaphrodites by ~21%. Reducing pollination also
strengthened selection on floral traits, but this effect was not larger in
females than in hermaphrodites. Instead, reducing pollination intensified
selection for taller inflorescences in hermaphrodites, but did not
intensify selection on any floral trait in females. CONCLUSIONS: Our
results suggest that pollinator decline will not have a larger effect on
either seed production or selection on floral traits of female plants. As
such, any effect of pollinator decline on seed production may be similar
for gender dimorphic and monomorphic species. However, the potential for
floral traits of females (and thus of gender dimorphic species) to evolve
in response to pollinator decline could be limited.