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ad ty dark over bright stimuli, in agreement with the pre- from bipolar cells (Breuninger et al., 2011) and retinal ganglion cells (Chang et al., 2013; Ekesten and Gouras, 2005; Wanging from above (Gouras and Ekesten, 2004; Nikonov et al., 2006). Presumably as an evolutionary consequence, a broad range of different vertebrates and invertebrates, including diverse spe-proposed that the match in opsin spectral sensitivity and pre-dominant ‘‘color’ ’ distributionmay be beneficial for visual coding, in particular, with respect to ecological niches and naturalcies, such as guinea pigs, rabbits, hyenas, guppies, dragonflies, or honey bee drones, possess unequal distributions of photore-behaviors (reviewed in Peichl, 2005). Indeed, it is tempting to draw a simple connection between ‘‘green’ ’ and ‘‘blue’ ’ visiondominance of dark contrasts in the sky but not on the ground. Therefore, the different cone types do not only form the basis of ‘‘color vision,’ ’ but in addi-tion represent distinct (achromatic) contrast-selec-tive channels