Scheme showing the serial transfers experienced by bacteriophage Qβ. a) Populations obtained in our previous work  that have also been used in the current work. b) Progression of the transfers series to obtain the new population Qβ-AZC(t90). The procedure describing how transfers were carried out is described in Methods. Populations were named Qβ-AZC(tx) or Qβ-control(tx) , where x indicates the number of transfer at which they were isolated. The mutations fixed and the number of polymorphic mutations at the end of each transfer series are also indicated. Boxes filled in yellow enclose populations where both the mutant spectrum and the consensus sequence have been analyzed. Non-filled boxes enclose populations analyzed only at the level of consensus sequence. Consensus sequences were analyzed from nucleotide 180 to 4180. Sequences from individual viruses spanned from nucleotide 1485 to 4028.