Joint Dynamics of Prey Size Spectra and Predator Population Structure

The size spectrum has been used as a meaningful representation of the structure of aquatic communities. Recent theoretical developments permit the overall spectrum to be derived from its component populations. The dynamical behavior of the spectrum then becomes a function of the traits of the species making up those populations, and extrinsic factors such as fishing mortality, assuming simple representations of trophic transfers and individual energy budgets.  However, current models do not take into account two important features. First, activity costs may be the limiting component of energy budgets – and these costs vary with the size distribution of prey. Second, species’ traits should be emergent features of community dynamics, and the selective advantage these traits embody will depend on how energy budgets scale with body size. Our objective is to explore this mutual dependence by coupling a community size spectrum model with a size structured predator population with varying traits, using an assembly approach. Simulations will be carried out to evaluate: (i) how a predator’s traits respond to the characteristics of the prey spectrum, (ii) how population structure relates to emergent traits, and (iii) how these relationships depend on whether the energy budget is limited by consumption or activity costs.