High complexity of aquatic irradiance may have driven the evolution of four-dimensional colour vision in shallow-water fish

摘要: Humans use three cone photoreceptor classes for colour vision, yet many birds, reptiles and shallow-water fish are tetrachromatic four classes. Screening pigments, which narrow the spectrum of photoreceptors in birds diurnal reptiles, render visual systems with more efficient. To date, however, question tetrachromacy that, like humans, lack screening is still unsolved. We raise possibility that has evolved response to higher spectral complexity underwater light. compared dimensionality vision humans by examining signal reflected from objects into their eyes. show require six reconstruct aquatic at accuracy level achieved viewing terrestrial objects. This because environmental light, alters signals, complex contains fluctuations than on land. further cones better suited human detect these fluctuations, suggesting capability high-frequency confers an advantage. Taken together, we propose enhance reconstruction signals shallow environments. Of course, might possess fewer classes; this would come inevitable loss reconstruction.