Figure 3.—
Longer exons experience more background selection. Mean values of B = Ne/N0 for a gene are shown, assuming no neighboring genes, no introns, and rg = 2.5 × 10−6. The thickness of the curves denotes the crossing-over rate (thick, 3 × 10−8; medium, 1 × 10−8; thin, 1 × 10−9), line type represents the mutation rate (dotted, 2 × 10−9; dashed, 4 × 10−9; solid, 8 × 10−9), and the highlighted curve indicates a typical gene (dashed line with medium thickness). (A) Fixed selection coefficient is as in Figure 1. (B) Average of 100 samples from the DDME. The bottom three curves belong to the scale on the right.