Interspecific divergence in opsin gene expression among African cichlids and their hybrid progeny. [A] A. baenschi and T. intermedius differ qualitatively in their patterns of opsin gene expressiona. [B] Box-and-whisker plots of opsin expression in the hybrid F2 progeny (n=115). The notched line defines the location of the median; the boxes define the upper and lower interquartile range (IQR); and the whiskers define observations within the 1.5 IQR. [C] Heatmap of correlation coefficients for F2 opsin expression show that the expression of the SWS2B/SWS2A and RH2A/LWS opsins are highly correlated. Numbers indicate r2 values for pairwise comparisons with P < 0.05. a Images of A. baenschi and T. intermeidus by Ad Konings, used with permission.