Sex allocation and reproductive success in the andromonoecious perennial Solanum carolinense (Solanaceae). II. Paternity and functional gender

According to Bateman's principle, male fitness in entomophilous plant speci es should be limited by mating opportunity, which is influenced by the size or number of flowers. We determined male-specific fitness consequences of floral phenotype in andromonoecious Solanum carolinense, examined the relat ionship between male and female reproductive success within plants, and eva luated the distribution of functional gender among plants. A maximum likeli hood-based paternity analysis, based on multilocus allozyme phenotypes of p arents and offspring from four experimental plots, was used to determine ma le reproductive success and its relationship to floral phenotype. Male succ ess was enhanced by an increase in the proportion of male flowers produced but not by an increase in total flower number, even though all flowers cont ain male parts. Larger flower size increased male success in only one plot. Male and female reproductive success were negatively correlated, and plant s varied in functional gender from completely female to completely male. Th is gender specialization may occur because hermaphroditic and male flowers differ in their ability to contribute to male and female success. Although sex allocation theory predicts a positive relationship between the size or number of plant parts and reproductive success, this study indicates that a spects of floral morphology that affect gender specialization should also b e considered.