Predictability in the assembly of microbial communities

Multispecies microbial communities are essential for the health of the planet as well as the human body. A major challenge is to develop a predictive understanding of which species will be able to coexist in a given environment. This task is potentially made even more difficult if there are strong higher-order interactions between species, in which the presence of a third species changes the nature of the interaction between two other species. In a series of laboratory experiments we have demonstrated that pairwise competitive outcomes are typically sufficient to predict the composition of simple communities containing three species. These results argue that higher-order interactions, while undoubtedly present, are typically not so strong as to make prediction impossible.