Figure 4From: Measuring the prevalence of regional mutation rates: an analysis of silent substitutions in mammals, fungi, and insectsGraphs of Codon Adaptation Index (CAI) vs. normalized substitution rates. Data for the sensu stricto yeasts (S. cerevisiae, S. bayanus, S. mikatae, S. paradoxus) (right) and for N. crassa-C. globosum (left) are both shown. Although the r distribution for N. crassa-C. globosum (Fig 1c) is wider than a Normal distribution, this appears to be due to a large number of genes under codon usage selection, rather than regional mutational biases. Genes under codon usage bias tend to have low z-scores and high CAI values (red ellipse), while the remaining genes have low CAI values and r values centered around zero (yellow ellipse). N. crassa has a much larger number of genes in the cluster likely to be under codon usage selection (949 genes with CAI≥0.70, red ellipse) than does S. cerevisiae (121 genes with CAI≥0.40), suggesting that more genes are under codon usage selection in N. crassa.Back to article page