Tip-dated phylogeny of the 27 S. Cerro isolates sequenced in this study with stepwise deletion of a D-alanine transporter encoding gene cluster mapped onto the phylogeny. Values on the branches represent posterior probabilities. Genes adjacent to the D-alanine transporter encoding gene cluster are represented as black arrows, genes in the cluster are represented as red arrows. Numbers in the arrows refer to STM gene tags as used in the genome sequence of S. Typhimurium LT2. Labels on the tips indicate isolate accession numbers, isolate date (month/year) and source.