SUMMARY

Population sex ratios are generally thought to be 1:1, but can vary in many species. Using the dioecious, saltmarsh grass Distichlis spicata, which exhibits extremely skewed sex ratios as well as spatial segregation of the sexes, we tested the hypothesis that females would be more competitive than males due to females of this species having a higher rate of infection by mycorrhizal fungi. In the greenhouse, we grew D. spicata seedlings in competition and alone to determine the effects of competition. Additionally, in a fully crossed design, we added treatments with and without mycorrhizal fungi, a potential third player in intersexual competition in this species. We, then, calculated chlorophyll fluorescence and chlorophyll meter readings. Our results indicate that little size difference exists between male and female D. spicata despite the finding that females exhibit higher mycorrhizal infection rates.