Crossing the Hopf bifurcation in a live predator-prey system

Population biologists have Long been interested in the oscillations in popu lation size displayed by many organisms in the field and Laboratory. A wide range of deterministic mathematical models predict that these fluctuations can be generated internally by nonlinear interactions among species and, i f correct, would provide important insights for understanding and predictin g the dynamics of interacting populations. We studied the dynamical behavio r of a two-species aquatic Laboratory community encompassing the interactio ns between a demographically structured herbivore population, a primary pro ducer, and a mineral resource, yet still amenable to description and parame terization using a mathematical model. The qualitative dynamical behavior o f our experimental system, that is, cycles, equilibria, and extinction, is highly predictable by a simple nonlinear model.