Fig. 4

Saturation in silico mutagenesis results. A Mutational effect sizes approximate a heavy-tailed distribution (log-normal). B The median absolute importance score binned by position. C An example of importance scores for a peak region on chromosome 3L. The maximum importance score for the entire example overlaps a Dref motif. D There is a significant negative correlation between importance scores and phyloP (Spearman’s r =  − .085, p < 1e − 100) in inaccessible regions, indicating that purifying selection is acting to keep inaccessible regions closed. Only the central 200 bp of each example was considered. Outliers have been omitted for clarity