Figure 2.

Illustration of the Wright-Fisher and WF-CM. In the example shown here, we assume that in the Wright-Fisher model a virus v, with original fitness w₀, acquires three mutations in the mutation step, such that its offspring have the fitness w₃; in the selection step these potential offspring compete with those of other viruses in the population. With continuous mutation these mutations arise at some times t₁, t₂, and t₃ leading to the expression, during a generation, of potential offspring with fitnesses w₀, w₁, w₂, and w₃, indicated by the thickness of the different grey lines. In the selection step these potential viruses have fitnesses scaled by the length of time for which they are actively being produced.