Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 16: Poster Session I

BP 16.11: Poster

Tuesday, March 27, 2007, 17:00–19:30, Poster D

Evolutionary emergence of complexity in model food webs — •Christian Guill and Barbara Drossel — Institut für Festkörperphysik, Technische Universität Darmstadt, Deutschland

Explaining the amazing diversity of ecological communities remains one of the greatest challenges in theoretical ecology. We investigate various mechanisms that promote the emergence of large and complex food webs in an evolutionary model that also includes population dynamics. Networks are created by starting from one species and external resources, followed by an iterated process of adding new species that are obtained by modifying existing species. Species are ordered on a one-dimensional niche axis, and links between them that represent feeding relationships are assigned according to the rules of the niche model (R.J. Williams, N.D. Martinez, 2000, Nature 404, 180-183). The average body size (or mass) of the species is assumed to increase with their position on the niche axis. The tested hypotheses for the promotion of complexity are the influence of different functional responses, adaptive behaviour, and body size effects that relate the metabolic rate of a species to its position on the niche axis. Adaptive foraging behaviour is found to be the key mechanism for the emergence of complex networks, while body size effects only determine the degree of complexity.