Test for Zipf’s law in distributions of gene expression levels for 12 RNA-seq data sets from seven fungal species. Each data set was sorted independently by normalized log2-transformed coverage, and log2-transformed coverage was plotted against the log2-transformed expression rank for each locus tag. Locus tags without coverage were not used in this analysis. A linear regression line is shown for each analysis, the coefficient (gradient) is given in the right upper corner of each diagram. None of the data sets shown here has a linear distribution, and this was also the case for the other data sets in the analysis (data not shown).