Genetic variation among females affects paternity in a dioecious plant

Abstract

Flowering plants rely on vectors for pollen transfer, and cannot choose their mates. Although recipient plants are unable to choose which pollen they receive, post‐pollination selection (acting pre‐ or post‐zygotically) may modify the outcome of pollination. Here we show that genetic variation among pollen recipients can predict the outcome of pollen competition (seed paternity) in the dioecious white campion. To investigate whether genetic variation among pollen recipients affects paternity, we applied the same pollen mixture from two males to three females, two of which full sisters and the third one chosen at random (unrelated). To control for maternal environmental effects, the plants used for these crosses were greenhouse‐reared F1. We replicated this in two populations, for a total of 51 crosses, and genotyped a total of 772 offspring to assign paternity. If genetic variation affects paternity, we expected greater similarity of paternity success of the focal male with the sisters, compared to the unrelated female. Paternity of the focal male was significantly more repeatable over sisters, compared to repeatability over the mean of sisters and the unrelated females. When populations were analyzed separately, this was significant in one of the two populations. Paternity was not significantly correlated with stigma size. This provides evidence that in at least one population, genetic variation among individual plants influences the donors’ paternity success, as assessed through genetic analysis of the seedling. Since due to gravity‐dispersed seeds natural patches may often consist of related plants, the observed effect may contribute to variation in male reproductive success.