9321790 Antonovics This project is an investigation of the mechanisms governing population dynamics in Cardamine pennsylvanica, a weedy plant. In an earlier study, experimental populations of these plants displayed complex numerical dynamics over fifteen generations, with populations cycling from low to high density in three to four generations. Although simple models of density-dependent population growth predict that the oscillatory dynamics are possible, these models predicted stable (non-cyclic) dynamics when applied to our experimental populations. This project will investigate what factors responsible for the discrepancy between the model predictions and the observed dynamics. From this, the investigators extrapolate to when similar mechanisms might drive complex dynamics in natural populations. The significance of complex dynamics in nature is twofold. First, if these dynamics are the product of deterministic population regulation (as opposed to stochastic fluctuations in resource availability), then attempts to interpret the complexity of nature should focus on understanding the feedback mechanisms that drive these processes. Second, populations that are highly variable in size are prone to extinction due to demographic stochasticity, and may be unable to adapt to a changing environment due to increased probability of random genetic change. Thus, an understanding of population dynamics is crucial to interpreting basic ecological studies, as well as to environmental management. t v v ! ! ! F v v ( Times New Roman Symbol & Arial l " h * eX* eX* e 9 7 Crystal Blackshear Crystal Blackshear
