Gut microbiota variation across bird phylogeny.

(A) PCoA using weighted UniFrac distances of the 636 birds in the Avian Reference Dataset colored by phylogenetic clades with each dot representing a bird. Legend shows color of each clade and the dendrogram is a reconstruction of the avian phylogenetic tree from [25]. Palaeognathae (maroon), a clade consisting of old-world birds such as ostriches, rheas and kiwis cluster on the left and Australaves (light-green), a clade consisting of recently evolved passerines and parrots, comprised opposite ends of the PCo1 spectrum with the rest of the clades occupying intermediary positions. Ridge plots show positions of phylogenetic clades along each PCo axis. (B) PCoA using weighted UniFrac distances on balanced Avian Reference Dataset (maxN = 50 per clade) retains global structure of gut microbiota variation in birds. Each dot represents a bird and colors represent their respective clusters (CST). Five major clusters were obtained using PAM clustering. (C) Balloon plot showing the phylogenetic distribution of birds among the five clusters inferred from (B). Consistent with the PCoA, the Paleognathae (old-world birds) and Australaves (parrots and passerines) aggregated into distinct clusters (CST 1 and 5 respectively) while the remainder of the birds were spread across the five clusters. Colors and size of the circles represent the number of birds per clade and their proportions, respectively.