Male-to-female ratio of gene expression by chromosome. Male-to-female ratio (m:f) of gene expression in sub-adult crow brains grouped by orthologous chromosomal position in zebra finch. The m:f ratio is significantly elevated on the Z chromosome (***) while there is no significant deviation from expected equity in expression for any of the autosomes. Number of sampled genes per chromosome is indicated below (only chromosomes with more than 40 genes are shown). Boxes include the 2nd and 3rd quantile; whiskers extend to the most extreme data points that lie within 1.5 times the interquartile range from the box; points depict extreme values beyond that boundary.