The topology of ecological interaction networks:The state of the art

This chapter considers topology, i.e. the shape and structure of networks of interacting organisms in ecological systems. Species often form the nodes of such networks, though life stages, age classes or functional groups are sometimes equally applicable. The links between nodes in ecological networks can have a variety of meanings, in particular they can represent transfer of energy or material, they can represent the net effect on fitness or population size (direct and/or indirect) of one species on another, or represent the exchange of information. These differences create at least three types of interaction networks: competition networks, mutualistic networks and food webs (consumption networks), all of which are subsets of the full network of interactions in any community.