Visual adaptation of opsin genes to the aquatic environment in sea snakes

BMC Evolutionary Biology

article

Seiko, Takashi¹  Kishida, Takushi²  Toyama, Mina³  Hariyama, Takahiko³  Okitsu, Takashi⁴  Wada, Akimori⁴  Toda, Mamoru⁵  Satta, Yoko¹  Terai, Yohey¹ 

[1] Department of Evolutionary Studies of Biosystems, SOKENDAI (The Graduate University for Advanced Studies);Wildlife Research Center, Kyoto University;Department of Biology, Faculty of Medicine, Hamamatsu University School of Medicine;Laboratory of Organic Chemistry for Life Science, Kobe Pharmaceutical University;Tropical Biosphere Research Center, University of the Ryukyus

关键词: Visual adaptation;    Opsin genes;    Sea snakes;    Visual pigments;    Aquatic amniotes;   

DOI  :  10.1186/s12862-020-01725-1

学科分类：护理学

来源: BioMed Central

【 摘 要 】

Evolutionary transitions from terrestrial to aquatic life history cause drastic changes in sensory systems. Indeed, the drastic changes in vision have been reported in many aquatic amniotes, convergently. Recently, the opsin genes of the full-aquatic sea snakes have been reported. However, those of the amphibious sea snakes have not been examined in detail. Here, we investigated opsin genes and visual pigments of sea snakes. We determined the sequences of SWS1, LWS, and RH1 genes from one terrestrial, three amphibious and four fully-aquatic elapids. Amino acid replacements at four and one spectra-tuning positions were found in LWS and RH1, respectively. We measured or predicted absorption of LWS and RH1 pigments with A1-derived retinal. During their evolution, blue shifts of LWS pigments have occurred stepwise in amphibious sea snakes and convergently in both amphibious and fully-aquatic species. Blue shifted LWS pigments may have adapted to deep water or open water environments dominated by blue light. The evolution of opsins differs between marine mammals (cetaceans and pinnipeds) and sea snakes in two fundamental ways: (1) pseudogenization of opsins in marine mammals; and (2) large blue shifts of LWS pigments in sea snakes. It may be possible to explain these two differences at the level of photoreceptor cell composition given that cone and rod cells both exist in mammals whereas only cone cells exist in fully-aquatic sea snakes. We hypothesize that the differences in photoreceptor cell compositions may have differentially affected the evolution of opsins in divergent amniote lineages.

【 授权许可】

CC BY|CC0