SGER: Real-Population Data for Evaluating Chaos-Detection Methods

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9505343 Hairston Dr. Hairston requests funding for a Small Grant for Exploratory Research (SGER) for a project which has great potential to move research on chaos to a new arena: real experimental validation of methods for detecting nonlinearity and chaos. The ultimate goal is the development of methods for determining whether chaos underlies the dynamics of natural populations. In this project, real organisms will be used to create data sets that demonstrably exhibit complex nonlinear dynamics (either chaos or complicated periodic oscillations). These data will be used to experimentally test existing and new methods for characterizing complex dynamics. The experimental system is a single-state chemostat culturing rotifers and their algal food with variable supply rate of the nutrient limiting algal growth. There is experimental evidence that this system can exhibit predator-prey oscillation. Mathematical theory suggests that such oscillations can be driven into complex mode-locking oscillations, and eventually into chaos, by pulsed or periodically varying nutrient supply rate. SGER funding will be used for a one-year pilot study to demonstrate the feasibility to: construct and maintain the experimental system; vary conditions to obtain useful population dynamics; and conduct experiments. These will be the first studies in which statistical methods, intended for use on natural populations, are validated through experiments on real organisms. This represents a major step towards reality, compared with conventional tests using simulated data.