Figure 4

Relative entropies of 12 substitution categories. On the X-axis, the substitution site is labelled as 0, the 5' flank as negative and the 3' flank as positive. The horizontal reference line represents a threshold value. If the observed relative entropy is greater than or equal to the threshold value, its occurrence probability is lower than 0.001 by chance. Black solid lines (with squares) indicate results in human genes and red broken lines (with circles) indicate those in chimpanzee genes. To clarify fluctuations of small entropies, we did not show the entropy at site 0 (i.e., the substitution site), which approximates 2 bits (see methods).