QEIB: Extended multitrophic diversity maintenance theory

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Understanding the forces that maintain biodiversity in natural communities has eluded ecologists for centuries. Much of the progress made to date has come from development of theory that provides specific predictions that can be tested experimentally or observationally. This project will extend existing biodiversity theory in new and important, though challenging, ways. The investigator will develop theoretical predictions for how and when two fundamental ecological interactions - competition and predation - interact to influence species diversity. These predictions will advance basic ecological research as well as conservation and management efforts to preserve biodiversity in the face of species invasion and increasing anthropogenic disturbance. The project will provide strong training in quantitative theory development and modeling, further enhancing our ability to predict the effects of future challenges to biodiversity. Current diversity theory suggests that the effects of competition and predation commonly counteract one another, predicting that coexistence is weaker in the presence of both than when only one of these mechanisms is present. When will adding a predator to a community make coexistence more likely, and how will substituting one predator for another affect their influence on community diversity? The investigators will begin with a model that can be linear or nonlinear, allowing the effects of different interactions (competition within a trophic level, effects from higher and lower levels) to be separated and to understand how nonlinearities affect the ways in which these processes combine. They will examine the roots of nonlinearities in biological factors such as life-history traits and behavior. They will also examine food web structure to predict how the numerous indirect interactions in complex food webs alter the relative strengths and joint action of predation-based and competition-based mechanisms. Models will be developed to predict the consequences of species extinctions on other members of food webs and communities. Finally, models will be developed to examine how trophic cascades and the roles of competition-based and predation-based coexistence mechanisms are affected by the relationship between trophic position and the spatial and temporal dynamics of key species. The value of the resulting extended theory will have considerable value to basic ecology and to diverse applications aimed at preserving biodiversity. Quantitative training of graduate students and postdoctoral researchers will be extended to secondary education through collaboration with high school teachers. The prospect of developing these ties to strengthen biomathematics is novel, and may strengthen several areas of ecology and biology.