three opsins present in snakes (SWS1,LWS, and RH1) have evolved under positive selection in elapids, and in sea snakes they have undergone multiple shifts in spectral sensitivity toward the longer wavelengths that dominate below the sea surface. Several relatively distantly related Hydrophis sea snakes are polymorphic for shortwave sensitive visual pigment encoded by alleles of SWS1. This spectral site polymorphism is expected to confer expanded ‘‘UV-blue’’ spectral sensitivity and is estimated to have persisted twice as long as the predicted survival time for selectively neutral nuclear alleles. We suggest that this polymorphism is adaptively maintained across Hydrophis species via balancing selection, similarly to the LWS polymorphism that confers allelic trichromacy in some primates. Diving sea snakes thus appear to share parallel mechanisms of color vision diversification with fruit-eating primates.
Kunstnerisk udviklingsvirksomhed (KUV)