Time scales and species coexistence in chaotic flows

Models of species coexistence often involve spatial heterogeneity, generated by an interplayof environmental flow and biological dynamics. To characterise this scenario, we consider afinite 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 nd long-lasting species coexistence at intermediate Damkohler 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 fl
ow and population dynamics.