Ecological Networks over the Edge: Hypergraph Trait-Mediated Indirect Interaction (TMII) Structure

Analyses of ecological network structure have yielded important insights into the functioning of complex ecological systems. However, such analyses almost universally omit non-pairwise interactions, many classes of which are crucial for system structure, function, and resilience. Hypergraphs are mathematical constructs capable of considering such interactions: we discuss their utility for studying ecological networks containing diverse interaction types, and associated challenges and strategies. We demonstrate the approach using a real-world coffee agroecosystem in which resistance to agricultural pests depends upon a large number of TMIIs. A hypergraph representation successfully reflects both the importance of species imposing such effects and the context-dependency of that importance in terms of how it is affected by removal of other species from the system. Hypergraphs allow quantitative analysis of TMII structure in ecological networks.Hypergraph metrics of species importance reflect influence via nontrophic effects.Hypergraph topology captures context-dependency of TMIIs.Hypergraphs offer new avenues for understanding the roles of TMIIs in large communities.