Figure 5.

Different polymorphisms arose multiple, independent times. Polymorphism analysis identified that several strains in different branches of the phylogenetic tree present either a nucleotide deletion (del T83) resulting in premature termination of the translation of the global regulator covS (indicated in red) and/or a SNP (A601C) resulting in a nonsynonymous amino acid replacement (His201Arg) in the stand alone regulator Mga (indicated in light blue). These polymorphisms could not have been inherited by descent. Their multiple, independent acquisition within the host suggests that they confer a selective advantage.