Fig. 2

Phylogenomic dissection of major prokaryotic groups. All largest possible clades are plotted for each taxonomic group. y-axis: average sequence identity between a clade and its sister group (I _C-S); x-axis: number of taxa (species in bacteria or genomes in archaea). A horizontal reference line is drawn corresponding to the average of the singleton I _C-S greater than or equal to their third quartile. a–f Bacterial groups. g–h Archaeal groups