Spectral Diversification and Trans-Species Allelic Polymorphism during the Land-to-Sea Transition in Snakes.

摘要: Snakes are descended from highly visual lizards [1] but have limited (probably dichromatic) color vision attributed to a dim-light lifestyle of early snakes [2-4]. The living species front-fanged elapids, however, ecologically very diverse, with ∼300 terrestrial (cobras, taipans, etc.) and ∼60 fully marine sea snakes, plus eight independently marine, amphibious kraits [1]. Here, we investigate the evolution spectral sensitivity in elapids by analyzing their opsin genes (which responsible for UV visible light), retinal photoreceptors, ocular lenses. We found that underwent rapid adaptive diversification pigments when compared relatives. three opsins present (SWS1, LWS, RH1) evolved under positive selection they undergone multiple shifts toward longer wavelengths dominate below surface. Several relatively distantly related Hydrophis polymorphic shortwave sensitive pigment encoded alleles SWS1. This site polymorphism is expected confer expanded "UV-blue" estimated persisted twice as long predicted survival time selectively neutral nuclear alleles. suggest this adaptively maintained across via balancing selection, similarly LWS confers allelic trichromacy some primates. Diving thus appear share parallel mechanisms fruit-eating