9701311 Raven Gynodioecy is the co-occurrence of female and hermaphrodite individuals in a population of a given species. There has been much debate about the factors influencing the maintenance of this breeding system in plants. The aim of this study is to understand how various ecological processes and growth habits may act as constraints or releases on the maintenance of females in populations. In particular, the PIs are looking at how plant-insect interactions including pollen limitation and floral herbivory may differentially affect females and hermaphrodites. In addition, we are studying how clonal spread and the spatial distribution of females and hermaphrodites in a population may affect pollen limitation. The PIs' study species is Sidalcea malviflora, a gynodioecious perennial with 2 contrasting and sympatric clonal and aclonal subspecies (ssp. laciniata and ssp. malviflora, respectively). A combination of field observations, experimental manipulations and genetical greenhouse studies will be used to look at the above processes. Gynodioecy is often considered to be an intermediate step in the development of dioecy, or completely separate male and female individuals within plant species. Because of this, investigation into the factors influencing the maintenance of females in gynodioecious plant populations is crucial to our broader understanding of the development of breeding systems throughout the flowering plants. Though many studies have investigated genetic mechanisms and aspects of resource allocation which act to maintain females in gynodioecious populations, very few studies have looked at the roles of ecological factors or clonal growth in selecting for females. This study is important because it investigates the effects of several interacting ecological factors and will thus enable us to evaluate the overall importance of ecology and growth form in the maintenance of gynodioecy in Sidalcea malviflora.
