Effects of intraspecific density-dependence on species richness and species abundance distributions

Abstract Species richness and patterns of abundance result from the interplay between niche differences, realized as intraspecific density-dependence (IDD), and so-called neutral processes that arise when species fitnesses are similar. This paper presents an extension of neutral models that incorporates delays in IDD that could result from resource-mediated competition or through a pathogen pool. These delays reduce standing species richness and qualitatively change the shape of species abundance distributions and render them consistent with the hollow curve shape even in the presence of strong IDD.