Dataset Information

Variable vision in variable environments: the visual system of an invasive cichlid (Cichla monoculus) in Lake Gatun, Panama.

ABSTRACT: An adaptive visual system is essential for organisms inhabiting new or changing light environments. The Panama Canal exhibits such variable environments owing to its anthropogenic origin and current human activities. Within the Panama Canal, Lake Gatun harbors several exotic fish species including the invasive peacock bass (Cichla monoculus), a predatory Amazonian cichlid. In this research, through spectral measurements and molecular and physiological experiments, we studied the visual system of C. monoculus and its adaptive capabilities. Our results suggest that (1) Lake Gatun is a highly variable environment, where light transmission changes throughout the canal waterway, and that (2) C. monoculus has several visual adaptations suited for this red-shifted light environment. Cichla monoculus filters short wavelengths (?400?nm) from the environment through its ocular media and tunes its visual sensitivities to the available light through opsin gene expression. More importantly, based on shifts in spectral sensitivities of photoreceptors alone, and on transcriptome analysis, C. monoculus exhibits extreme intraspecific variation in the use of vitamin A1/A2 chromophore in their photoreceptors. Fish living in turbid water had higher proportions of vitamin A2, shifting sensitivities to longer wavelengths, than fish living in clear water. Furthermore, we also found variation in retinal transcriptomes, where fish from turbid and clear waters exhibited differentially expressed genes that vary greatly in their function. We suggest that this phenotypic plasticity has been key in the invasion success of C. monoculus.

SUBMITTER: Escobar-Camacho D

PROVIDER: S-EPMC6451412 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Variable vision in variable environments: the visual system of an invasive cichlid (<i>Cichla monoculus</i>) in Lake Gatun, Panama.

Escobar-Camacho Daniel D Pierotti Michele E R MER Ferenc Viktoria V Sharpe Diana M T DMT Ramos Erica E Martins Cesar C Carleton Karen L KL

The Journal of experimental biology 20190318 Pt 6

An adaptive visual system is essential for organisms inhabiting new or changing light environments. The Panama Canal exhibits such variable environments owing to its anthropogenic origin and current human activities. Within the Panama Canal, Lake Gatun harbors several exotic fish species including the invasive peacock bass (<i>Cichla monoculus</i>), a predatory Amazonian cichlid. In this research, through spectral measurements and molecular and physiological experiments, we studied the visual sy ...[more]

PMID: 30787138

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Project description:BackgroundPhenotypic evolution may occur through mutations that affect either the structure or expression of protein-coding genes. Although the evolution of color vision has historically been attributed to structural mutations within the opsin genes, recent research has shown that opsin regulatory mutations can also tune photoreceptor sensitivity and color vision. Visual sensitivity in African cichlid fishes varies as a result of the differential expression of seven opsin genes. We crossed cichlid species that express different opsin gene sets and scanned their genome for expression Quantitative Trait Loci (eQTL) responsible for these differences. Our results shed light on the role that different structural, cis-, and trans-regulatory mutations play in the evolution of color vision.ResultsWe identified 11 eQTL that contribute to the divergent expression of five opsin genes. On three linkage groups, several eQTL formed regulatory "hotspots" associated with the expression of multiple opsins. Importantly, however, the majority of the eQTL we identified (8/11 or 73%) occur on linkage groups located trans to the opsin genes, suggesting that cichlid color vision has evolved primarily via trans-regulatory divergence. By modeling the impact of just two of these trans-regulatory eQTL, we show that opsin regulatory mutations can alter cichlid photoreceptor sensitivity and color vision at least as much as opsin structural mutations can.ConclusionsCombined with previous work, we demonstrate that the evolution of cichlid color vision results from the interplay of structural, cis-, and especially trans-regulatory loci. Although there are numerous examples of structural and cis-regulatory mutations that contribute to phenotypic evolution, our results suggest that trans-regulatory mutations could contribute to phenotypic divergence more commonly than previously expected, especially in systems like color vision, where compensatory changes in the expression of multiple genes are required in order to produce functional phenotypes.

Dataset Information

Variable vision in variable environments: the visual system of an invasive cichlid (Cichla monoculus) in Lake Gatun, Panama.

Publications

Variable vision in variable environments: the visual system of an invasive cichlid (<i>Cichla monoculus</i>) in Lake Gatun, Panama.

Similar Datasets

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