The dissimilarity of species interaction networks

TLDR

Global change and shifting community structures make it essential to quantify how species interactions vary across space and time, yet this has been limited by the difficulty of measuring interaction network dissimilarity. The authors propose a general framework to assess species interaction network dissimilarity across time, space, or environments using both quantitative and qualitative data, and outline a research agenda for a biogeographical theory of interactions. The framework decomposes dissimilarity into interaction and species turnover components, enabling direct comparison with standard β‑diversity metrics. Applying the method to a large host–parasite dataset shows that scaling community β‑diversity to interaction β‑diversity requires only a minor methodological adjustment, and the approach can be extended to other ecological contexts.

Abstract

Abstract In a context of global changes, and amidst the perpetual modification of community structure undergone by most natural ecosystems, it is more important than ever to understand how species interactions vary through space and time. The integration of biogeography and network theory will yield important results and further our understanding of species interactions. It has, however, been hampered so far by the difficulty to quantify variation among interaction networks. Here, we propose a general framework to study the dissimilarity of species interaction networks over time, space or environments, allowing both the use of quantitative and qualitative data. We decompose network dissimilarity into interactions and species turnover components, so that it is immediately comparable to common measures of β ‐diversity. We emphasise that scaling up β ‐diversity of community composition to the β ‐diversity of interactions requires only a small methodological step, which we foresee will help empiricists adopt this method. We illustrate the framework with a large dataset of hosts and parasites interactions and highlight other possible usages. We discuss a research agenda towards a biogeographical theory of species interactions.