PARENT SESSION
Contributed Oral Session 72: Trophic Systems: Communities; Predator Behavior
Tuesday, August 9, 1:30 PM - 5:00 PM, Meeting Room 524 C, Level 5, Palais des congrès de Montréal

Network motifs present in food webs reveal mechanism for prey selection.

Stouffer, Daniel^*,1, Camacho, Juan^{*,1, 2}, Nunes Amaral, Luis¹, ¹ Department of Chemical and Biological Engineering, Evanston, Illinois, USA² Departament de Fisica (Fisica Estadistica), Bellaterra, Catalonia, Spain

ABSTRACT- Food webs provide a graphic representation of the trophic interactions found in an ecosystem. The food webs reported in the literature appear increasingly complex. This complexity, however, masks a number of robust statistical properties, including the existence of universal forms for the distributions of numbers of prey and predators. Much research to date has concentrated upon predicting and testing the existence of such patterns rather than on the factors giving rise to them. In particular, little is known about the way in which predators select their prey. We hypothesize that the network motifs present in food webs depend on how predators select their prey and investigate the network motifs found in twelve empirical food webs from a variety of environments. Remarkably, we find regularities common to all webs studied. We determine that predators typically consume prey with a "characteristic" mass. This is a fundamental result if one is to build a dynamic model for, for example, the effect of exotic species on an ecosystem.

Key words: food webs, networks, predator-prey, motifs