Fig. 3.

Distribution of genomic distances to the closest known gene start site. We calculated the distribution of the distances to the closest TSS for three sets: all exapted CNE elements (red), all mobile element subfamilies predating the human–dog split of which the exapted CNEs are a subset (dark gray), and the set of all sequenced bases in the human genome (light gray). Although the set of all repeats is seen to be roughly distributed uniformly across the genome, the functional set departs from this null distribution by exhibiting a substantial overabundance at the distal range of 100 kb–1 Mb from the TSS. Error bars show the 95% confidence intervals for all three sets, but only the exapted elements have confidence intervals large enough to visualize. We calculated the confidence intervals by treating these data sets as samples from a multinomial distribution, and the confidence intervals are representative of the true proportions from which we were sampling.