Graph theory and food webs

Recently the study of complex networks has received great attention. One of the most interesting applications of these concepts is found in the study of food webs. Food webs provide fascinating examples of biological organization in ecological communities and display characteristic and unexpected statistical properties. In particular, comparison to other complex networks shows that food webs lack the scale-free properties observed in almost all other artificial and natural networks. That is, the frequency distribution for the degree (numer of different predators per species) does not display scale-free behavior. Nevertheless, we show here that self-similiar and universal behavior are still present. By considering food webs as transportation networks (for the flow of resources between species), we can recover scaling properties typical of other transportation system, such as vascular and river networks. The importance of these properties for models of structure in food webs is discussed