Expression levels of W/Z gametologue pairs. Expression of W-linked genes (red) compared to their Z-linked gametologues (blue), for blastoderms (A) and gonads (B). The total combined expression of gametologue pairs is shown for females (red - W/blue - Z, left bar in pair) and males (ZZ -blue only, right bar in pair). The shaded data are shown on an adjusted FPKM scale (inset). Genes with significantly different expression between the sexes are identified (* P <0.01).