Evolutionary scenario for M. ulcerans , basically distinguishing two major lineages, according to the RDs analyzed in this study. All strains with a strain identifier added to the right depict recent isolates. Note that both the M. marinum progenitor and the M. ulcerans MRCA are hypothetical strains. Features differentiating clusters or strains are dedicated to the branches between the nodes. RDs indicated here are all differentiated by features that are also shown in Fig. 4, whereas more RDs bear supporting features between the nodes (Table 1). The lengths of the internodes do not reflect time or genetic distance.