In D. melanogaster, male-biased genes have been found to show less codon bias than female-biased or unbiased genes (Hambuch and Parsch 2005). The same pattern is seen for the genes classified in the Sebida meta-analysis. Codon bias was measured by two different statistics: FOP (Frequency of optimal codon usage; higher values indicate stronger codon bias) and ENC (Effective number of codons; lower values indicate stronger codon bias). Sex-biased genes were classified using both a FDR of 5% and a 2-fold cutoff.