Effect of PCR cycle on (a) recombination and (b) mutation rates. RNA was extracted and transcribed as described in Figure 2. Resulting cDNA was diluted as described and amplified using a 2-step PCR and either 27 cycles (white bars) or 35 cycles (black bars). Recombination and mutation rates are expressed as rate per 1000 nucleotides and the confidence intervals, as estimated via bootstrapping, are shown. Significant differences (at 95%CI) are indicated.