The phrase "pigment genes" refers to the specific genes responsible for determining the color or pigment in an organism's skin, hair, or eyes. Full definition
The team discovered that visual pigment genes have changed substantially during snake evolution, including many changes to the wavelengths of light that the pigments are sensitive to. (nhm.ac.uk)
Neitz's new work rests on a detailed molecular analysis of pigment genes that encode proteins responsible for the eye's sensitivity to various wavelengths of visible light. (sciencemag.org)
The next step, he said, is to demonstrate the same results among those called protananamolous, who suffer from a less common form of color blindness involving an overabundance of red pigment genes. (sciencemag.org)