Center for Interdisziplinary Research
 
 

Structure and Dynamics of Meta Food Webs

Date: September 16 - 18, 2013

Convenors: Bernd Blasius (Oldenburg, GER), Ulrich Brose (Göttingen, GER), Barbara Drossel (Darmstadt, GER), Thilo Gross (Bristol, GBR)

Land use by humans and other environmental changes lead to the fragmentation of the habitats of many species into smaller and smaller parts. As a consequence, ecological communities occupy several smaller patches of habitats. Understanding the structure and dynamics of such ecosystems that are distributed over several patches is of high relevance for conservation issues. Of particular relevance for the stability of ecosystems are the feeding relationships. For this reason, the workshop focused on meta-food webs, which are food webs in space, bringing together theoretical scientists with a background in physics, biology, or engineering, who can make important contributions to this field.
The main topic of the first day was dispersal and foraging, with a focus on the behavior of individuals and on the influence of body size. We learned about the stabilizing effect of adaptive foraging, about state-of-the-art modelling of individual behavior in complex landscapes, and how movement velocity, attack rates and handling times change with body mass. We discussed how migration success depends on the distance between patches, and how rare, but important instances of long-range dispersal can be modelled.
The focus of the second day was on the structure of food webs and their variation in space, and on how they are shaped by their evolutionary history. The talks explained the statistical analysis of links within and between patches, new approaches to generating and evolving model food webs based purely on body masses, the contribution of small motifs to food web stability, and the conservation of roles of different species in a food web despite ongoing species turnover. The discussion revolved around how evolution rates depend on metabolic rates, how spatial degrees of freedom are best included in evolutionary food-web models, and how patch size affects encounter and feeding rates.
The third day dealt mainly with the dynamics of meta-food webs. The highlight was the talk of UC Berkeley evolutionary biologist Rosemary Gillespie on adaptive radiation and 'island hopping' of species on the Hawaiian archipelago. The other talks dealt with spatial extensions of the so-called 'niche model' for foodweb structure and with theoretical studies of the effect of migration on metacommunities and meta-food webs, using populations dynamics equations or generalized modelling based on linear stability analysis of fixed points. The discussions after the talks dealt with the difference between the range of species and of individuals, with the influence of noise, and with the relation between the Hawaii data and the evolutionary food-web models.
During the entire workshop, there was also plenty of time for discussions in smaller groups and for planning or continuing joint projects. One group of researchers made plans for a joint study of the influence of different migration rules on the stability of large meta-food webs, another group, which analyses different versions of evolutionary food-web models, discussed how to compare their results and how to design further investigations. Plans were made for future meetings and mutual visits, and everybody left the workshop with a lot of new ideas and with renewed enthusiasm for this exciting field of research in which we have the privilege to participate.

Participants

Korinna Allhoff (Darmstadt, GER), Anna Eklöf (Linköping, SWE), Rosemary G. Gillespie (Berkeley, USA), Christian Guill (Amsterdam, NED), Yuanheng Li (Göttingen, GER), Nicolas Loeuille (Paris, FRA), Neo Martinez (Berkeley, USA), Katrin M. Meyer (Göttingen, GER), Pavel Paulau (Oldenburg, GER), Sebastian Plitzko (Darmstadt, GER), Daniel Ritterskamp (Oldenburg, GER), Lars Rudolf (Dresden, GER), Florian Schwarzmüller (Göttingen, GER), Daniel B. Stouffer (Christchurch, NZL), Eric Tromeur (Paris, FRA), Fernanda Valdovinos (Berkeley, USA)



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