Time scales and species coexistence in chaotic flows

¹ Theoretical Physics, School of Physics and Astronomy, The University of Manchester - Manchester M13 9PL, UK
² Group of Nonlinear Physics, Faculty of Physics, University of Santiago de Compostela E-15782 Santiago de Compostela, Spain

Received: 26 January 2017
Accepted: 10 April 2017

Abstract

Models of species coexistence often involve spatial heterogeneity, generated by an interplay of environmental flow and biological dynamics. To characterise this scenario, we consider a finite community of two different species, advected by a chaotic flow. Intrinsic stochasticity eventually leads to the extinction of one species. Contrary to intuition, however, varying the relative time scales of population dynamics and flow does not interpolate straightforwardly between the no-flow and well-mixed limits; instead we find long-lasting species coexistence at intermediate Damköhler numbers. Our analysis shows that this slowdown is due to spatial organisation on a modularised network. We also find that diffusion can either slow down or speed up fixation, depending on the relative time scales of flow and population dynamics.