Noise induced phenomena in ecological models

Abstract

Understanding population dynamics, and in particular, population cycles is one of the central issues in ecology. In this work we study noise induced phenomena in generalized Lotka-Volterra ecological models and we show how a stochastic model for population dynamics can give rise to periodic cyclic behaviour in the presence of intrinsic noise. We will show how the intrinsic noise in a prey-predator dynamics including intra-specific, or logistic auto-regulatory, interactions gives rise to a resonant frequency in the power spectrum characterizing the system evolution, but at the same time, we show that there are other types of interactions among species where a resonant frequency does not appear. Furthermore, we analyze the effects of random transport between different ecological patches or metapopulations and see that cyclic behaviours can appear, if a prey-predator dynamics is imposed, or disappear