Pollinator and flower morphology interact to influence pollen receipt

Pollinators are important drivers of floral divergence and speciation in plants. Here we investigate the effects of floral trait variation and trait matching on pollen receipt in two different plant species, each visited by different functional pollinator types across their ranges. Using single visits by pollinators to flowers in populations with experimentally increased variance in floral morphology, we demonstrate that distinct functional groups of pollinators affect pollen movement differently through their interactions with floral trait variation. This study provides details of how the mechanical fit between floral and pollinator morphology may drive the evolution of floral traits through its effects on pollen deposition both within and between populations with contrasting pollinators.

Methods
We used single-visit experiments to understand the relationship between a component of female fitness (pollen receipt) and flower morphology, in association with insects that vary in their morphological traits that affect pollination. 

Insect morphology was collected by capture with a butterfly net and measurements were taken with a steel ruler or callipers
Floral morphology was collected by cutting bolting inflorescences at the base from the field, and floral traits were measured to the nearest millimetre using a steel ruler or digital set of callipers
Inflorescences containing flowers with receptive stigmas were used to conduct single visits where virgin flowers were exposed to pollinators and pollinators were allowed to visit a flower only once. After this event, the stigmas were removed and embedded in fuchsin gel from which the pollen grains were counted. With Nerine humilis that have large pollen grains, pollen was counted directly on the stigma after a single visit in the same afternoon under a disection microscope.