9306393 The major goal of this research is to determine the extent of nonrandom fertilization in natural populations of a native rose mallow (Hisbiscus moscheutos). These results will be used to test the hypothesis that male fertility is influenced by the outcome of pollen tube competition within styles. Our previous work suggests that pollen tube growth rates differ among individuals, and this trait may affect how many seeds a plant sires. Controlled crosses and genetic markers will be used to test this hypothesis. This research represents the first thorough investigation of the potential for sexual selection due to post-pollination events in plants. %%% Although our work addresses basic evolutionary theory, it also has practical applications. Pollen tube competition has been proposed as a mechanism by which superior genotypes can be identified in commercially important species. This research will improve our understanding of whether pollen competitive ability has a genetic basis, and whether there is a positive correlation between the growth rates of pollen tubes and their sporophytic progeny. In addition, seed companies need more information about the extent to which seed paternity varies due to characteristics of particular pollen donors. Our results have general implications for insect- pollinated crops in which pollinators deliver a mixture of pollen from several plants to receptive stigmas.
