Figure 4: Linear regression plots of root-to-tip distances according to Path-O-Gen (http://tree.bio.ed.ac.uk/software/pathogen/).

(a) All 165 genotypes in Lineage 4, including four high-coverage eighteenth-century genomes. (b) Only the 161 modern isolates. (c) Genotypes from sub-lineage 4.1. (d) Genotypes from sub-lineage 4.a.