Connecting higher order interactions with ecological stability in experimental aquatic food webs

Abstract

Community ecology is built on theories that represent the strength of interactions between species as pairwise links. Higher order interactions occur when the presence of a third (or more) species changes the pairwise interaction between a focal pair. Recent theoretical work has highlighted the stabilizing role of higher order interactions for large, simulated communities, yet it remains unclear how important higher order effects are in real communities. Here we used experimental communities of aquatic protists to examine the relationship between higher-order interactions and community stability (as measured by the persistence of species in a community). We cultured a focal pair of consumers in the presence of additional competitors and a predator and collected time series data of their abundances. We then fitted competition models with and without HOIs to measure interaction strength between the focal pair across different community compositions. We used survival analysis to measure the persistence of individual species. We found evidence that additional species positively affected persistence of the focal species and that HOIs were present in most of our communities. However, persistence was only linked to HOIs for one of the focal species. Our results vindicate community ecology theory positing that species interactions may deviate from assumptions of pairwise interactions, opening avenues to consider possible consequences for coexistence and community stability.