Figure 3.

Reduced genome-wide effectiveness in selection along the Shigella branches. The average dN is plotted against the average dS. Red circles represent branches that lead towards Shigella strains. Blue squares represent branches that lead towards pathogenic E. coli strains. The red line represents the fitted linear model for the Shigella branches. The blue line represents the same for the pathogenic E. coli branches. The yellow diamond represents the branch that leads towards the direct ancestor of the EHEC strains and of S. dysenteriae.