Visual system plasticity is differently mediated by cone opsin expression and chromophore composition in closely related cichlid species

Abstract

AbstractPhenotypic plasticity allows organisms to rapidly adjust to environmental changes. Cichlid fish inhabit a wide range of light environments and show a large diversity in visual system properties, which makes them a good model system to address the role of phenotypic plasticity in visual adaptation. Cichlid retinal cone pigments consist of opsin proteins bound to Vitamin A1or A2-derived chromophores. Plasticity in expression has been shown for cichlidopsingenes, but less is known about the contribution ofcyp27c1,the enzyme that converts Vitamin A1into A2,. Here, we studied bothopsinandcyp27c1expression patterns for three closely related cichlid species from different visual habitats in Lake Victoria, across different light treatments. We found differences incyp27c1as well as inopsinexpression patterns between the three species. Experimental light treatments affected the developmental trajectory ofcyp27c1expression in one species andopsinexpression in all three species. Within each species, we found large individual variation incyp27c1expression levels and no consistent association withopsinexpression levels. These results indicate that visual system plasticity of even closely related species can be differentially mediated byopsinandcyp27c1expression, possibly associated with species differences in visual niche.