Sexual dimorphism in the dioecious grass Distichlis spicata: testing hypotheses for the evolution of intraspecific niche divergence

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PROJECT ABSTRACTSpatial separation of males and females should be a significant disadvantage in organisms that are not mobile. However, spatial separation is common in plants with separate sexes. This project will integrate field, greenhouse, and molecular approaches to rigorously test hypotheses for mechanisms causing spatial separation of the sexes in the wetland grass Distichlis spicata (saltgrass). The study takes advantage of novel molecular techniques to identify saltgrass seedlings as male or female, then follows the fates of both genders in an integrated set of experiments that will evaluate the mechanisms and consequences of competition for limited resources by males and females of the same species in a variety of habitats. Additionally, the experiments will test whether the soil biota plays a significant role in the different plant-soil associations of males and females. The proposed research will have significant impacts on wetland conservation, resource management, and student training. Sea levels are projected to rise for the foreseeable future. Understanding how male and female plants of saltgrass compete will allow researchers to anticipate the effects of rising sea levels on this important salt marsh species. The proposed research also has applied value, because saltgrass and related species are used in agronomy and environmental restoration. The project will also provide support for two graduate and 12 undergraduate students. Undergraduates will be recruited through outreach to local community colleges to increase recruitment of underrepresented groups via targeted internships.