Lotka re-loaded: Modeling trophic interactions under stoichiometric constraints

Nearly a century ago A.J. Lotka provided fundamental formulations for population modeling; less appreciated are his explorations of the underlying material (elemental) basis of life and its implications for ecology and evolution. This paper describes recent developments in ecological and biological stoichiometry that unify these aspects of Lotka's work. Stoichiometrically explicit versions of the Lotka–Volterra equations capture key missing aspects of food web interactions, such as the effects of food quality and nutrient recycling feedbacks, and encompass a richer, and potentially more realistic, set of dynamics than non-stoichiometric models. These stoichiometric models are now being further extended to include the recently discovered effects of excess dietary nutrient content on consumer performance. The multi-dimensional capacity of stoichiometric models is likely to be of particular value given the pressing need to anticipate the ecological effects of globally dynamic perturbations of multiple chemical elements (e.g. C, N, and P) due to human actions.

► The development of modified, “stoichiometrically explicit”, versions of the classic Lotka–Volterra equations is reviewed. ► Unique features of these models include the possibility of multiple stable states and food-quality induced species coexistence among consumers. ► Two new frontiers for stoichiometric models are described, including effects of “excess” food nutrient content and of stoichiometrically heterogeneous prey.