Many complex networks are extended in space and have therefore two types of connections, namely local connections between network nodes and spatial connections between different locations. A typical example are ecological food webs in a heterogeneous environment. The network nodes represent ecological populations interacting through predation. In addition to this (non-spatial) food-web stucture, the species live on a spatial network, since they occupy habitats embedded in physical space, with the possibility to migrate between different habitats. Using food webs as example systems, we will investigate the structure and dynamics of such “networks on networks” and explore how the local trophic network structure, the structure of space, the distribution of species in space, and the population dynamics mutually influence each other. Important goals of this study consist in characterizing the structure of such networks on networks, in obtaining the correct spatial scaling of the dynamical terms, in generating realistic networks on the computer, and in identifying criteria for the dynamical stability of such food webs and the persistence of species.

The group leaders participating in this Research Unit are Bernd Blasius in Oldenburg, Ulrich Brose in Leipzig, Barbara Drossel in Darmstadt, Christian Guill in Potsdam, Björn Rall in Leipzig, and our cooperation partner Thilo Gross in Bristol.