Inferring evolutionary pathways and directed genotype networks of foodborne pathogens
Fig 7
Evidence for an evolutionary drive within the STM population.
The 1,020 edges in the genotype network yield 6,897 potential evolutionary paths. The subfigures show the proportion and number of paths evolving in a certain direction in the centrality-prevalence state space from Fig 3. This direction depends on the start and end-points of the path: right-to-left (RL), left-to-right (LR), top-to-bottom (TB), and bottom-to-top (BT). For instance, the first case study (magenta) is categorised as RL-BT (with ten edges), while the second case study (blue) follows the RL-TB direction (with eight edges). The absolute majority of paths (66%, or 4,532 paths) are shown to travel from the right-to-left (RL, decrease in centrality) and the bottom-to-top (BT, increase in prevalence), as shown in the figure legends. Further, the correlation between the path length and the change in prevalence is r = 0.497 (M = 6,897, p < 0.00001). A: as the path length increases, a higher number of paths are associated with this dominant direction. B: a majority of these paths are within the range of 6–12 edges; the smaller set of longer paths (above 12 edges) all decrease in centrality, mostly capturing exploitative adaptation (RL-BT) with a minority attributed to unsuccessful exploration (RL-TB).