Fig. 3

a: A founder effect dominates the history of the Q80K clade. The branches in the HCV1a MCC tree are colored according to the inferred amino acid at NS3 position 80 (see legend). All except five Q80K variants descend from a common ancestor that is inferred to have existed around 1957 (95% HPD: 1947–1959). Posterior root node support is visualized in a selection of deeper nodes. Amino acids other than Q or K were found in only 13 lineages. b: Histogram of the size of the (second) largest clade with an independent origin of Q80K among the plausible trees. The size of the largest clade remains more or less constant, and the limited size of the second largest clade shows that most contemporaneous Q80K lineages reside in the major Q80K clade. c: Histogram of the number of independent origins of a Q80K lineage in the plausible trees. This shows that in the most plausible trees three to four de novo appearances of the Q80K variant appear