Coexistence mediates the effect of competition on species’ distributions

Abstract

There is substantial controversy on whether species interactions (particularly competition) shape species’ distributions at large spatial scales. This controversy is difficult to resolve using empirical work alone due to the challenge of large-scale experimental manipulations of species’ interactions. Here we argue that another branch of ecology (coexistence theory) provides powerful, underexploited tools to resolve the effect of competition on species’ distributions. We show why conditions that promote coexistence reduce the effect of competition on species’ distributions, we argue that experiments designed to study coexistence can be modified to anticipate the effect of competition on range limits and show how these insights can be used to effects of species’ interactions across spatial scales. We use this work to argue that our ability to predict species’ distributions will depend on our ability to assess largescale coexistence mechanisms.