It has been long recognized that the success of a mating type depends on its frequency in the population. Although a few empirical examples of frequency-dependent selection exist, its general importance in the evolutionary dynamics of plant mating has yet to be documented. The proposed study will use Solanum carolinense, a species that carries both male and hermaphroditic flowers within individuals, as a model system to answer: i) What is the pattern of selection acting through both female and male components of fitness on the relative production of male flowers? ii) Is selection acting on this trait frequency-dependent, as predicted by theory? iii) If so, does this frequencydependent selection explain the maintenance of intermediate proportions of male flowers in natural populations? These questions will be addressed through a combination of field and greenhouse experiments, and genetic fingerprinting of individual plants.
The intellectual merit of this proposal is to test a fundamental prediction in sexual theory, i.e. that selection on male-biased allocation is frequency-dependent, thus contributing information needed for a more thorough understanding of plant mating systems. The broader impact of this project will enhance the academic community by encouraging the participation of diverse groups, particularly undergraduate and Latino students with an interest in science.
