Frequency of genes with sex-biased expression on each chromosomal arm of Drosophila genomes. The percentages of genes on each chromosome arm that have female-biased (white), male-biased (black), or unbiased (gray) expression are indicated by the height of the bars. (Dashed lines) Genome-wide percent of genes in each sex-bias class. (*) Significant deviations between observed and expected frequencies (as determined by a permutation test); (*) P < 0.05, (**) P < 0.01, (***) P < 0.001. Chromosome arms are sorted such that homologous arms are in the same order for each species with the dot chromosome (Muller element F) omitted: (Dmel) D. melanogaster; (Dpse) D. pseudoobscura; (Dwil) D. willistoni; (Dmoj) D. mojavensis. Expression was measured with RNA-seq using RNA from whole flies (Dmel, Dpse, and Dmoj) or abdomen (Dwil) (A), microarrays or RNA-seq from head (B), RNA-seq from thorax (C), and microarrays using RNA from third instar larva (D). In the case of the RNA-seq data, reads were aligned to the genome using BWA, and differential expression was determined using edgeR (see Methods). Species in panels A and B are sorted by increasing evolutionary distance from D. melanogaster.
