Analysis of the genetic diversity of the opsin of an Amazonian fish species, the sailfin tetra

Differences in underwater lighting conditions usually drive divergence in the visual system, especially in color sensitivity. Amazon small forest streams, locally named igarapes, can be classified into black and clear water types. These water types are remarkable differences in relation to light transmission. Black waters are red-biased environments, while clear waters do not show any apparent bias, being mostly transparent. The sailfin tetra Crenuchus spilurus is a sexually dimorphic Amazon fish species that lives in black and clear water types. In this project, we investigated the genetic divergence of the LWS (Long Wavelength Sensitivity) gene, which is responsible for sensing red color, among populations exposed to black and clear water igarapes. We also estimated the maximum light peak absorption among individuals living in clear and black water types.