Fig. 5.

Temporal distribution of the Scotland emm89 strains. (a) Reconstructed phylogeny of the 122 Scotland strains inferred by neighbour-joining based on 1410 core SNPs is shown. Strains are coloured by the year of isolation as indicated in the index. In general, strains isolated in earlier years are more proximal and in later years are more distal on the tree branches. (b) A scatter plot of root-to-tip genetic distances for the adjacent 122 Scotland strain tree is shown. The weighted fit shows an overall upward trend and a consistent yearly increase in the root-to-tip distances over 2010–2015.