For example, in experimental set-upj=A for isolate #2, at passage p =12 (see Fig. 1A) we took into account both the phenotypic effects of q1=M???184 V, which arose earlier at passage 4, as well as q2= N???67 S, see eq. (1)-(3).Passage TimesIn the experiments (see Virological Methods), viral growth which exceeded a threshold was recorded, i.e. the time required for a viral population to exceed a p2