Dresden 2009 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 21: Population Dynamics and Evolution

BP 21.1: Vortrag

Donnerstag, 26. März 2009, 17:30–17:45, HÜL 186

Determinants of food-web stability — •Lars Rudolf and Thilo Gross — Max Planck Institute for the Physics of Complex System, Nöthnitzer Str.28, 01187 Dresden, Germany

Since the publication of Robert May's seminal work the stability of ecological food webs is a topic of intense research and hot debate. Contrary to many field observations, May showed that large, densely connected food webs are in general unstable. The only way to reconcile May's proof with observation is to find the special properties that lend natural food webs their unusual stability. It has been pointed out that the identification of such stabilizing network properties could have broad implications beyond the field of ecology. Most recent theoretical work focuses on numerical models based on explicit rate equations. These and empirical studies have revealed that weak trophic links may play an important role for stability. However, in contrast to May's abstract random matrix model, numerical constraints limit most simulative studies to the investigation of relatively few instances (approx. 10000) of relatively small food webs (approx. 10 species). Recently, generalized modeling, a novel numerical approach for the analysis of stability in families of nonlinear rate equations, has been proposed. Here we utilize this approach to study several billion instances of food webs of up to 50 species with nonlinear interactions. While we find a stabilizing effect of weak links in small food webs, this stabilization is absent in larger webs. Instead, we identify a universal feature in the distribution of links that is important for stability.