Figure 1.

The relative proportion of elements overlapping coding exons and their dN/dS. (A) The ratio of the percentage of transposable element bases in coding exons to the percentage of transposable element bases across the whole genome. Values close to one suggest that the presence of elements in coding sequences have not been selected against. SINE Alu elements have a ratio that is much lower than 1. Predicted simple repeats and low complexity regions included as a comparison. (B) The dN/dS for transposable element families overlapping human coding exons for both rare and common allele frequencies. Values below one and lower dN/dS with common allele frequencies than with rare allele frequencies indicate purifying selection, while values close to one suggest that the elements are generally under neutral selection. SINE Alu elements have dN/dS values close to 1.