Fig. 3.

Potential dosage compensation in the ZAL2/2^m system. (A–C) A potential scenario for dosage compensation. (A) Initially, expression dosage (shown as black waves) is similar between ZAL2 and ZAL2^m and between tan and white. (B) If the expression of ZAL2^m alleles is reduced and there is no dosage compensation, heterozygous (white) individuals should show reduced expression. (C) Dosage between the morphs may be rebalanced via overexpression of the ZAL2 allele in white birds. Consequently, expression of the ZAL2 allele should be greater in white than in tan birds. (D and E) Levels of compensation (white-ZAL2/tan-ZAL2) are significantly elevated for tan ≈ white (dosage-compensated) genes compared with nondosage-compensated genes (tan > white). The definitions of tan ≈ white and tan > white genes are based on P values from DESeq2 (Table 1). Using FDR-corrected Q values yielded similar results (SI Appendix, Fig. S5). Mann–Whitney U test, ***P < 0.001.