DISSERTATION RESEARCH: A Spatial Theory of Trophic Cascades in Omnivory Systems

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Identifying the characteristics of communities that affect their responses to perturbations is a primary goal of both fundamental and applied ecology. Trophic cascades occur when predators reduce their prey, indirectly affecting lower trophic levels such as plants. This project combines mathematical models and their predictions with experiments to determine why trophic cascades vary across diverse communities. The investigators propose that omnivores - organisms that eat both animals and plants - will stabilize communities based on convincing preliminary data. This hypothesis will be tested using experimental food webs consisting of mixed bacteria as resources, a single-celled prey species, a protist predator, and a protist omnivore. The investigators will manipulate colonization rates across experimental communities and measure changes in the mathematical stability of each community in response to these manipulations. Models will be fit to time series of data to provide new insights into the causes underlying change in the structure and stability of omnivorous food webs. Support for this project will significantly improve an ongoing doctoral dissertation project that has combined mathematical models with field experiments to suggest that colonization rates result in consistent changes in trophic cascades. The training of a promising young scientist will be enhanced as a result. The project will involve a diverse assemblage of undergraduates who will perform research at the interface of biology and mathematics. Through participation in the United States Department of Education RISE program, the investigators integrate deserving students underrepresented in science fields into research labs when they transfer from local community colleges. These students will receive training in microscopy, experimental design, mathematical modeling, statistical analyses and basic usage of several computer programming environments. Results from the research will improve efforts to curb human alteration of habitats, production of commercially-valuable crops, and control of animal vectors that spread human disease.