Human CNE-enhancers duplication history and their genomic range of action. (A) This pie chart shows the extent of duplication events in our selected subset of CNE-enhancers (192 enhancers in total). The majority of our selected enhancers are unduplicated. About 10% of the enhancers have duplicated copies only in teleost fishes, 9% are duplicated before teleost-tetrapod split and 3% enhancers have duplicated copies only in human/tetrapod. (B) This pie chart represents the distribution of distances between CNE-enhancers and target gene bodies to estimate the optimal distance at which an enhancer can access its concerned promoter. About 19% of enhancers are within the introns of their predicted target gene bodies, 24% are within a range of 0-200 kb, 17% are at a distance of 201-400 bp, 10% lie in the range of 401-600 kb, 14% in the range of 601-999 kb and 16% of the enhancers are located at distance of >1 Mb from their target genes.