English: A network path for four informative substitutions shows that New World subsp. pertenue, or yaws-causing strains, are the closest relatives of modern subsp. pallidum strains.

The geographical distribution of the endemic treponemal diseases circa 1900 is shown, based on a map created by Hackett [62]. Each polymorphism pattern is linked to the sites where the strains that contain it were gathered. Arrows convey the directionality of change, determined from the previously built phylogenetic tree as described in the text. The four substitutions were located in two genes located on separate sides of the genome, tprI and gpd. The locations from which subsp. pallidum strains were gathered are listed in Table 1.

doi:10.1371/journal.pntd.0000148.g004