Resilience Analysis for Competing Populations.

Abstract

Ecological resilience refers to the ability of a system to retain its state when subject to state variables perturbations or parameter changes. While understanding and quantifying resilience is crucial to anticipate the possible regime shifts, characterizing the influence of the system parameters on resilience is the first step toward controlling the system to avoid undesirable critical transitions. In this paper, we apply tools of qualitative theory of differential equations to study the resilience of competing populations as modeled by the classical Lotka-Volterra system. Within the high interspecific competition regime, such model exhibits bistability, and the boundary between the basins of attraction corresponding to exclusive survival of each population is the stable manifold of a saddle point. Studying such manifold and its behavior in terms of the model parameters, we characterized the populations resilience: While increasing competitiveness leads to higher resilience, it is not always the case with respect to reproduction. Within a pioneering context where both populations initiate with few individuals, increasing reproduction of one population leads to an increase in its resilience; however, within an environment previously dominated by one population and then invaded by the other, an increase in the resilience of a population is obtained by decreasing its reproduction rate. Besides providing interesting insights for the dynamics of competing populations, this work brings near to each other the concepts of ecological resilience and the methods of differential equations and stimulates the development and application of new tools for ecological resilience.