Fig. 4: Molecular dating of ST2250 (n = 212 genomes).

A Bayesian maximum clade credibility time-calibrated phylogeny of ST2250 based on non-recombining regions of the core genome alignment. The colored lines emanating from the branches of the tree represent the major geographical regions. genomes were also annotated based on geographical origin and antimicrobial classes, both represented by colored dots next to the branches. Different SCCmec types are indicated by distinct colors of colored bars. Antimicrobial resistance elements present in each genome are indicated by colored dots and their colors represent the antimicrobial classes. The divergence date (median estimate with 95% highest posterior density dates) is indicated as a horizontal blue line on the tree. For visual clarity, only the relevant divergence dates related to the clonal origin and SCCmec acquisition are shown. B Bayesian skygrowth plot showing changes in effective population size (Ne) over time. Median is represented by a solid line, and 95% confidence intervals are represented by the shaded blue area around the median. Details of the molecular dating analyses are presented in Supplementary Fig. 4, Data 10 and Data 11.