Fig. 1

Co-occurrence network graphs of the cichlid gut microbiota and their node taxonomic composition. a-b Networks for individual lake assemblages (a) and continental datasets (b), where nodes are OTUs color-colored to the phylum level. c Proportion of nodes (OTUs) per phylum found in each geographical dataset (for the overall microbial taxonomic composition, see [24], while for proportion of OTUs per phylum in the input dataset see Additional file 4: Figure S3). All American networks largely resembled in topology and node taxonomic content. Note the dense cluster of Firmicutes nodes present in all lake networks (blue circles, in L. Tanganyika the cluster is highly reduced), encompassing the two families Clostridiaceae and Peptostreptococcaceae (for family level, see Additional file 2: Figure S1). Network interactions were inferred based on concordance among four co-occurrence measures in the ensemble package CoNet [25] and visualized with igraph [26]