Clusters of genes identified by patterns of orthology. The patterns presented in Figure 5 were used for the identification of two clusters of genes potentially displaying cases of LGT. Dendrograms on the left are derived from Figure 3a (branch lengths do not represent inferred distances). Detected orthologs are only present in the genomes in bold. Arrows in black represent genes in an OG of the highlighted pattern and grey arrows represent other genes nearby in the genome. Blue lines linking genes indicate inferred orthology. Gene numbers correspond to the last part of the original gene names. Numbers in colours other than black indicate genes with products putatively secreted (red) or with transmembrane domains (green). The clusters are (a) one including a wrongly annotated pathogenicity-related gene (yapH) and a phage gene (Φ-hk97); and (b) one possibly related to the type IV secretion system.