Neutral Substitutions Occur at a Faster Rate in Exons Than in Noncoding DNA in Primate Genomes

Table 1.

Relative Rates of Evolutionary Divergence Between Synonymous Sites in Coding DNA and Different Types of Noncoding Regions

Coding DNA (#genes, #bp) Noncoding DNA (#segments, #bp) Relative rate ratio
All sites CpG sites excluded
Human–Chimpanzee
 Coding genes (81,14790) Pseudogenes (19,21003) 1.3 1.0
 Coding genes (81,14790) Intergenic regions (4,141322) 1.6 1.0
 Coding genes (48,8464) Intronic regions (48,327344) 1.4 1.0
Human–Orangutan
 Coding genes (38,5634) Intergenic regions (1,9772) 1.5 1.1
Human–Baboon
 Coding genes (31,6512) Intergenic regions (1,37937) 1.6 1.0
 Coding genes (25,5264) Intronic regions (25,260186) 1.4 0.9
  • Relative rate ratio is the ratio between the synonymous divergence at the fourfold-degenerate sites of the exons and the sequence divergence in the noncoding DNA.

  • Difference in evolutionary distances between synonymous sites of coding genes and noncoding DNA is significant at least at a 0.2% level using a Z-test.

  • Difference in evolutionary distances (excluding CpG sites) between the synonymous sites of coding genes and noncoding DNA is not significant at the 5% level in each comparison.

  • Neutral evolutionary divergence from the exons and introns of the same genes.

  • Count refers to the number of genes from which the introns were obtained.

This Article

  1. Genome Res. 13: 838-844

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