Per lineage root to tip plot. Lineages were rooted using their topology in the entire maximum likelihood tree, and the number of SNPs accumulated from the root was plotted against date of isolation. Correlation is poor for all lineages, with r squared values of 0.002,0.03,0.006 and 0.06 for Euro American, East African.
Bryant et al. BMC Infectious Diseases 2013 13:110 doi:10.1186/1471-2334-13-110