Figure 1From: Extensive purifying selection acting on synonymous sites in HIV-1 Group M sequencesHIV-1 genome-wide plot of mean nonsynonymous substitution rates. A 30 codon sliding window was used. Regions coding for proteins in more than one frame are shaded in pink. The frames that were used in each region are shown in grey rectangles, with frame 1 at the top and frame 3 at the bottom.Back to article page