Energy Storage and the Evolution of Population Dynamics

We explore the mutual dependence of life history evolution and population dynamics by modeling a structured rotifer population that preys on a dynamic food supply. We focus on the ecological role of energy storage. A physiologically based submodel describes how individual predators allocate assimilated energy among growth, reproduction, and storage. We use invasibility analyses to predict evolutionary stable strategies for energy allocation. Various proxy measures of fitness based on measurable biological quantities, such as average population size or average per-capita fecundity, fail to predict evolutionary stable strategies. The predicted strategies indicate that selection strongly favors storage allocation for juveniles, but only for adults when prey densities are high. With the evolution of energy storage, population dynamics can shift from aperiodic to stable cycles without any need to invoke group selection.