Food webs versus interaction networks: principles, pitfalls and perspectives

“Ecological network” and “food web” are summary terms covering a continuum from speciesassociation based networks to quantified-links networks to interaction-specified ecosystem models. In particular “classical” one-mode (“unipartite”) food webs and bipartite (two-mode) interaction networks are two very active research fields. While often aiming to tackle similar topics (such as community stability and species coexistence) their data, methods and approaches often differ substantially. In this chapter we shall review the continuum of food web approaches along a set of questions: • Which kind of data form the basis of the network? Are interactions observed or inferred? • What do network nodes and links represent? • What is the focus of scientific questions, which key features and topics are being investigated? • Which methods are employed, and what are their potential pitfalls? We find that the literature on food webs and bipartite networks reveals very different challenges, although the questions addressed are often very similar. For example, sampling artifacts and ecological interpretation of link strength are issues of vigorous discussion in many studies of bipartite networks, while being accepted largely unquestioned in classical food webs. In contrast, dynamic analyses and their mathematical challenges are behind many food webs papers, while being marginal to bipartite network research. In fact, several substantial criticisms leveled at one type of network are absent from the other for purely historic reasons. We identify challenges common to all network types and suggest avenues for a potentially fruitful transfer of approaches as well as applications between them.