Rhodopsin Gene Polymorphism Associated with Divergent Light Environments in Atlantic Cod
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The spectral sensitivity of visual pigments in vertebrate eyes is optimized for specific light conditions. One of such pigments, rhodopsin (RH1), mediates dim-light vision. Amino acid replacements at tuning sites may alter spectral sensitivity, providing a mechanism to adapt to ambient light conditions and depth of habitat in fish. Here we present a first investigation of RH1 gene polymorphism among two ecotypes of Atlantic cod in Icelandic waters, which experience divergent light environments throughout the year due to alternative foraging behaviour. We identified one synonymous single nucleotide polymorphism (SNP) in the RH1 protein coding region and one in the 3′ untranslated region (3′-UTR) that are strongly divergent between these two ecotypes. Moreover, these polymorphisms coincided with the well-known panthophysin (Pan I) polymorphism that differentiates coastal and frontal (migratory) populations of Atlantic cod. While the RH1 SNPs do not provide direct inference for a specific molecular mechanism, their association with this dim-sensitive pigment indicates the involvement of the visual system in local adaptation of Atlantic cod.
KeywordsAtlantic cod Rhodopsin Pantophysin Behaviour type Ecotype Divergence
We acknowledge funding from the EU-project CODYSSEY (Q5RS-2002-00813) for the tagging experiment and from the Icelandic Ministry of Innovation and Fisheries (Verkefnasjóður Sjávarútvegsins grant, 2011–2014) for the genetic work.
Conflict of Interest
Christophe Pampoulie, Sigurlaug Skirnisdottir, Bastiaan Star, Sissel Jentoft, Ingibjörg G. Jónsdóttir, Einar Hjörleifsson, Vilhjálmur Thorsteinsson, Ólafur K. Pálsson, Paul R. Berg, Øivind Andersen, Steinunn Magnusdottir, Sarah J. Helyar, and Anna K. Daníelsdóttir declare that they have no conflict of interest.
Human and Animal Rights and Informed Consent
The tagging was carried out in strict accordance with the recommendations by the Icelandic Committee for Welfare of Experimental Animals, Chief Veterinary Office at the Ministry of Agriculture, Reykjavik Iceland, under a surgery permit license (No. 0304-1901) issued to V. Thorsteinsson. Informed consent was obtained from all individual participants included in the present study.
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