Yersinia whole-genome phylogeny. The phylogeny of the Yersinia genus was constructed from a dataset of 681 concatenated, conserved protein sequences using the Neighbor-Joining (NJ) algorithm implemented by PHYLIP . The tree was rooted using E. coli. The scale measures number of substitutions per residue. Tree topologies computed using maximum likelihood and parsimony estimates are identical with each other and the NJ tree (Additional file 20). The only branches not supported in more than 99% of the 1,000 bootstrap replicates using both methods are marked with asterisks. Both these branches were supported by >57% of replicates.