Distribution of gene expression levels for 12 RNA-seq data sets from seven fungal species. Histograms of normalized, log2-transformed coverage for each locus tag (grey bars), and estimated frequency distributions. Locus tags without coverage were not included in this analysis. The distribution function (red line) for each data set was dissected into components (blue, green, yellow, orange, and black lines) that are normal distributions with varying means and variances that make up different proportions of the observed distribution (Additional file 3: Table S1). Histograms and frequency distributions for the other data sets that were analyzed in this study can be found in Figures S1-S11 in Additional file 3.