BACKGROUND AND AIMS: Gynodioecy, the co-occurrence of female and hermaphroditic individuals, is thought to be an intermediate step between @entity4998 and separate sexes, a major transition in flowering plants. Because retaining females in a population requires that they have increased seed @entity410 (to compensate for the lack of pollen @entity410 ), factors that affect seed @entity410 are of great importance to the evolution of this mating system and have often been studied. However, factors negatively affecting female @entity410 are equally important and have been largely neglected. One such factor stems from female flowers being less attractive to insects than hermaphrodite flowers, thereby decreasing their relative @entity410 . METHODS: To test the severity and consequences of this type of pollinator discrimination in @entity27043 maculatum, experimental populations with the range of sex ratios observed in nature were created, ranging from 13 % to 42 % females. Pollinators were observed in order to measure the strength of discrimination, and pollen deposition and seed production of both sexes were measured to determine the @entity410 consequences of this discrimination. Additionally a comparison was made across the sex ratios to determine whether discrimination was frequency-dependent. KEY RESULTS: It was found that female flowers, on average, were visited at half of the rate of hermaphrodite flowers, which decreased their pollen receipt and seed production. Additionally, females were most discriminated against when rare, due to both changes in the pollinators' behaviour and a shift in pollinator composition. CONCLUSIONS: The results suggest that pollinator discrimination negatively affects females' relative @entity410 when they are rare. Thus, the initial spread of females in a population, the first step in the evolution of gynodioecy, may be made more difficult due to pollinator discrimination.

Frequency-dependent pollinator discrimination acts against female plants in the gynodioecious XXXX maculatum.

@entity27043 :: ('4031', 'Species') :: ['Geranium'] @entity410 :: ('MESH:D012640', 'Disease') :: ['fitness'] @entity4998 :: ('MESH:D012734', 'Disease') :: ['hermaphroditism']
@entity27043 :: (4031,Species) :: ['Geranium']
