Figure 5.

Unrooted neighbor-joining phylogenetic tree of the RNA polymerase subunit B computed from a Γ-corrected distance matrix. Numbers close to nodes are bootstrap proportions. The scale bar represents the number of changes per position for a unit branch length. In Methanococcus maripaludis, Methanocaldococcus jannaschii, Methanopyrus kandleri, Methanothermobacter thermoautotrophicus, Archaeoglobus fulgidus, Thermoplasmatales, Methanosarcinales and Halobacteriales genomes, the gene for the RNA polymerase subunit B is split in two parts: B' and B". The black and white boxes correspond to the B' and B" parts of the gene, respectively. S and F represent the split and fusion event hypotheses of the B' and B" parts of the gene.