Figure 2

Genotype changes over the course of the selection. A phylogeny of the two lines, along with associated mutations, is shown. Evolution on W is in black, while selection carried out on 6fW is indicated in red; the number of cycles of selection are indicated beside the lines. Mutations are color coordinated as indicated at the bottom of the figure; mutations in green are in A2, black is the coat protein, orange indicates a mutation in A1, and green in the replicase; genotypes with no mutations are indicated by 'wt.' Lower case mutations correspond to base changes; upper case indicates protein substitutions.