Figure 1.

Sources of co-occurrence in microbial interaction networks. (A) Co-occurrence relationships can be driven by microbial interactions. Cross-feeding between species can be detected as co-occurrence relationships, while competition can cause mutual exclusion. (B) Organisms that share niches are more likely to co-occur. If samples were taken from a heterogeneous environment, differing niche specialization may induce spurious interactions. (C) Not all interacting species are detected in a 16S rRNA dataset. (D) The final inferred network contains both spurious and true interactions.