Fig. 3

Multivariate analysis of COG profiles of the 66 MAGs of this study. Principal components analysis (PCA) was performed using the Euclidean distance matrix calculated from Hellinger-transformed abundance data. The ordination is shown in Eigenvalue scale. MAGs from healthy octocoral samples are represented by circles, MAGs from necrotic octocoral samples by triangles, and MAGs from seawater by asterisks. Symbols are colored according to the family-level, taxonomic affiliation of the MAGs with family names written next to them. Black arrows represent the top ten COG functions (i.e., COG0666, COG0515, COG3119, COG1629, COG1960, COG0673, COG0583, COG0697, COG1028, COG3839, in that order) which contributed most to the dissimilarities between these MAGs at order level, as revealed by a SIMPER test. Note the highly distinct clustering of the Endozoicomonadaceae MAGs, statistically supported by a one-way PERMANOVA test (P < 0.001) with 999 permutations and driven by the high copy number of genes encoding for ankyrin repeat proteins (COG0666) and serine/threonine protein kinases (COG0515). See also Tables S3 and S4 (Additional file 2) for complete COG profiles and SIMPER results