Figure 2

Observed and predicted relative entropies over flanking nucleotide positions. On the X-axis, the substitution site is labelled as 0, the 5' flank as negative and the 3' flank as positive. Equation 2 was employed to fit the relative entropies, given that the region between sites ±2 was excluded. The black solid squares represent observed relative entropies over neighbouring-nucleotide positions. The red circles represent the best-fit curve for the data. 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.