Speaker:Frithjof Lutscher,
Department of Mathematics and Statistics,
University of Ottawa

Title:Life in the Flow:Persistence,Invasions and Competition in Rivers

Abstract:The question how populations in rivers can persist despite flow- induced washout, has been termed the "drift paradox". More generally,systems with unidirectional flow include rivers, plug-flow reactors, prevailing wind directions, and climate-change models.A first simple model in the form of a reaction-advection-diffusion equation explored persistence criteria by looking at the minimal domain size (Speirs and Gurney (2001), Ecology). Starting from this simple model, I will report on several extensions, namely: vertical structure in the population (drift and benthic state), spatial heterogeneity and the influence on channel geometry, effects of resource gradients, and competition of two species. I will focus on the minimal domain size, on speeds of upstream invasions, and on spatially mediated coexistence.