Differential self-fertilization rates in response to variation in floral traits within inflorescences of Aquilegia buergeriana var. oxysepala (Ranunculaceae)

To assess variation in the proportion of self-fertilized seeds among flowers within inflorescences and the relationship between floral traits and the rate of self-fertilization, the proportion of self-fertilized seeds among individual flowers was estimated using ten microsatellite markers in self-compatible plants of Aquilegia buergeriana var. oxysepala. Within-inflorescence variation in floral traits, such as the duration of the male and female phases, flower size, herkogamy and the number of pollen grains and ovules in two natural populations, were investigated. The first flower in an inflorescence produced more seeds and a higher proportion of self-fertilized seeds than the second flower. The higher proportion of self-fertilized seeds in the first flowers was accompanied by a higher number of pollen grains and ovules in the bud stage and the female phase. These results indicate that the high proportion of self-fertilized seeds in the first flowers in an inflorescence may be due to the high number of remaining pollen grains in the female phase. This suggests that variation in floral traits within inflorescences affects seed quality and quantity among flowers within inflorescences.