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Gerwin J, Torres-Dowdall J, Brown TF, Meyer A. Expansion and Functional Diversification of Long-Wavelength-Sensitive Opsin in Anabantoid Fishes. J Mol Evol 2024:10.1007/s00239-024-10181-0. [PMID: 38861038 DOI: 10.1007/s00239-024-10181-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 05/25/2024] [Indexed: 06/12/2024]
Abstract
Gene duplication is one of the most important sources of novel genotypic diversity and the subsequent evolution of phenotypic diversity. Determining the evolutionary history and functional changes of duplicated genes is crucial for a comprehensive understanding of adaptive evolution. The evolutionary history of visual opsin genes is very dynamic, with repeated duplication events followed by sub- or neofunctionalization. While duplication of the green-sensitive opsins rh2 is common in teleost fish, fewer cases of multiple duplication events of the red-sensitive opsin lws are known. In this study, we investigate the visual opsin gene repertoire of the anabantoid fishes, focusing on the five lws opsin genes found in the genus Betta. We determine the evolutionary history of the lws opsin gene by taking advantage of whole-genome sequences of nine anabantoid species, including the newly assembled genome of Betta imbellis. Our results show that at least two independent duplications of lws occurred in the Betta lineage. The analysis of amino acid sequences of the lws paralogs of Betta revealed high levels of diversification in four of the seven transmembrane regions of the lws protein. Amino acid substitutions at two key-tuning sites are predicted to lead to differentiation of absorption maxima (λmax) between the paralogs within Betta. Finally, eye transcriptomics of B. splendens at different developmental stages revealed expression shifts between paralogs for all cone opsin classes. The lws genes are expressed according to their relative position in the lws opsin cluster throughout ontogeny. We conclude that temporal collinearity of lws expression might have facilitated subfunctionalization of lws in Betta and teleost opsins in general.
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Affiliation(s)
- Jan Gerwin
- Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany
- German Cancer Research Center (DKFZ), Division Signaling and Functional Genomics and Department of Cell and Molecular Biology, Medical Faculty Mannheim, Heidelberg University, Heidelberg, Germany
| | - Julián Torres-Dowdall
- Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany.
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
| | - Thomas F Brown
- Max Planck Institute of Molecular Cellular Biology and Genetics, Dresden, Germany
- Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany
| | - Axel Meyer
- Zoology and Evolutionary Biology, Department of Biology, University of Konstanz, Konstanz, Germany.
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Bertinetti C, Härer A, Karagic N, Meyer A, Torres-Dowdall J. Repeated Divergence in Opsin Gene Expression Mirrors Photic Habitat Changes in Rapidly Evolving Crater Lake Cichlid Fishes. Am Nat 2024; 203:604-617. [PMID: 38635367 DOI: 10.1086/729420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/20/2024]
Abstract
AbstractSelection pressures differ along environmental gradients, and traits tightly linked to fitness (e.g., the visual system) are expected to track such variation. Along gradients, adaptation to local conditions might be due to heritable and nonheritable environmentally induced variation. Disentangling these sources of phenotypic variation requires studying closely related populations in nature and in the laboratory. The Nicaraguan lakes represent an environmental gradient in photic conditions from clear crater lakes to very turbid great lakes. From two old, turbid great lakes, Midas cichlid fish (Amphilophus cf. citrinellus) independently colonized seven isolated crater lakes of varying light conditions, resulting in a small adaptive radiation. We estimated variation in visual sensitivities along this photic gradient by measuring cone opsin gene expression among lake populations. Visual sensitivities observed in all seven derived crater lake populations shifted predictably in direction and magnitude, repeatedly mirroring changes in photic conditions. Comparing wild-caught and laboratory-reared fish revealed that 48% of this phenotypic variation is genetically determined and evolved rapidly. Decreasing intrapopulation variation as environments become spectrally narrower suggests that different selective landscapes operate along the gradient. We conclude that the power to predict phenotypic evolution along gradients depends on both the magnitude of environmental change and the selective landscape shape.
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Ricci V, Ronco F, Boileau N, Salzburger W. Visual opsin gene expression evolution in the adaptive radiation of cichlid fishes of Lake Tanganyika. SCIENCE ADVANCES 2023; 9:eadg6568. [PMID: 37672578 PMCID: PMC10482347 DOI: 10.1126/sciadv.adg6568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 08/07/2023] [Indexed: 09/08/2023]
Abstract
Tuning the visual sensory system to the ambient light is essential for survival in many animal species. This is often achieved through duplication, functional diversification, and/or differential expression of visual opsin genes. Here, we examined 753 new retinal transcriptomes from 112 species of cichlid fishes from Lake Tanganyika to unravel adaptive changes in gene expression at the macro-evolutionary and ecosystem level of one of the largest vertebrate adaptive radiations. We found that, across the radiation, all seven cone opsins-but not the rhodopsin-rank among the most differentially expressed genes in the retina, together with other vision-, circadian rhythm-, and hemoglobin-related genes. We propose two visual palettes characteristic of very shallow- and deep-water living species, respectively, and show that visual system adaptations along two major ecological axes, macro-habitat and diet, occur primarily via gene expression variation in a subset of cone opsin genes.
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Affiliation(s)
- Virginie Ricci
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Fabrizia Ronco
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Nicolas Boileau
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Walter Salzburger
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland
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Shi X, Li J, Liu T, Zhao H, Leng H, Sun K, Feng J. Divergence of cochlear transcriptomics between reference‑based and reference‑free transcriptome analyses among Rhinolophus ferrumequinum populations. PLoS One 2023; 18:e0288404. [PMID: 37432940 DOI: 10.1371/journal.pone.0288404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 06/26/2023] [Indexed: 07/13/2023] Open
Abstract
Differences in gene expression within tissues can lead to differences in tissue function. Understanding the transcriptome of a species helps elucidate the molecular mechanisms underlying phenotypic divergence. According to the presence or absence of a reference genome of for a studied species, transcriptome analyses can be divided into reference‑based and reference‑free methods, respectively. Presently, comparisons of complete transcriptome analysis results between those two methods are still rare. In this study, we compared the cochlear transcriptome analysis results of greater horseshoe bats (Rhinolophus ferrumequinum) from three lineages in China with different acoustic phenotypes using reference‑based and reference‑free methods to explore their differences in subsequent analysis. The results gained by reference-based results had lower false-positive rates and were more accurate because differentially expressed genes among the three populations obtained by this method had greater reliability and a higher annotation rate. Some phenotype-related enrichment terms, including those related to inorganic molecules and proton transmembrane channels, were also obtained only by the reference-based method. However, the reference‑based method might have the limitation of incomplete information acquisition. Thus, we believe that a combination of reference‑free and reference‑based methods is ideal for transcriptome analyses. The results of our study provided a reference for the selection of transcriptome analysis methods in the future.
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Affiliation(s)
- Xiaoxiao Shi
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, Jilin, China
| | - Jun Li
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, Jilin, China
| | - Tong Liu
- Department of Life Science, Jilin Agricultural University, Changchun, Jilin, China
| | - Hanbo Zhao
- Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural, Shenzhen, China
| | - Haixia Leng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, Jilin, China
| | - Keping Sun
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, Jilin, China
- Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, Jilin, China
| | - Jiang Feng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, Jilin, China
- Department of Life Science, Jilin Agricultural University, Changchun, Jilin, China
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Novales Flamarique I, Sayed Ahmed A, Cheng CL, Molday RS, Devlin RH. Growth hormone regulates opsin expression in the retina of a salmonid fish. J Neuroendocrinol 2019; 31:e12804. [PMID: 31630448 DOI: 10.1111/jne.12804] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/07/2019] [Accepted: 10/18/2019] [Indexed: 01/18/2023]
Abstract
Colour vision relies on retinal photoreceptors that express a different predominant visual pigment protein (opsin). In several vertebrates, the primary opsin expressed by a photoreceptor can change throughout ontogeny, although the molecular factors that influence such regulation are poorly understood. One of these factors is thyroid hormone which, together with its receptors, modulates opsin expression in the retinas of multiple vertebrates including rodents and salmonid fishes. In the latter, thyroid hormone induces a switch in opsin expression from SWS1 (ultraviolet light sensitive) to SWS2 (short wavelength or blue light sensitive) in the single cone photoreceptors of the retina. The actions of other hormones on opsin expression have not been investigated. In the present study, we used a transgenic strain of coho salmon (Oncorhynchus kitsutch) with enhanced levels of circulating growth hormone compared to that of wild siblings to assess the effects of this hormone on the SWS1 to SWS2 opsin switch. Transgenic fish showed a developmentally accelerated opsin switch compared to size-matched controls as assessed by immunohistological and in situ hybridisation labelling of photoreceptors and by quantification of transcripts using quantitative polymerase chain reaction. This accelerated switch led to a different spectral sensitivity maximum, under a middle to long wavelength adapting background, from ultraviolet (λmax ~ 380 nm) in controls to short wavelengths (λmax ~ 430 nm) in transgenics, demonstrating altered colour vision. The effects of growth hormone over-expression were independent of circulating levels of thyroid hormone (triiodothyronine), the hormone typically associated with opsin switches in vertebrates.
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Affiliation(s)
- Inigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- Department of Biology, University of Victoria, Victoria, BC, Canada
| | - Ahmed Sayed Ahmed
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Christiana L Cheng
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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Novales Flamarique I. Light exposure during embryonic and yolk-sac alevin development of Chinook salmon Oncorhynchus tshawytscha does not alter the spectral phenotype of photoreceptors. JOURNAL OF FISH BIOLOGY 2019; 95:214-221. [PMID: 30370922 DOI: 10.1111/jfb.13850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 10/16/2018] [Indexed: 06/08/2023]
Abstract
Colour vision is mediated by the expression of different visual pigments in photoreceptors of the vertebrate retina. Each visual pigment is a complex of a protein (opsin) and a vitamin A chromophore; alterations to either component affects visual pigment absorbance and, potentially, the visual capabilities of an animal. Many species of fish undergo changes in opsin expression during retinal development. In the case of salmonid fishes the single cone photoreceptors undergo a switch in opsin expression from SWS1 (ultraviolet sensitive) to SWS2 (blue-light sensitive) starting at the yolk-sac alevin stage, around the time when they first experience light. Whether light may initiate this event or produce a plastic response in the various photoreceptors is unknown. In this study, Chinook salmon Oncorhynchus tshawytscha were exposed to light from the embryonic (5 days prior to hatching) into the yolk sac alevin (25 days post hatching) stage and the spectral phenotype of photoreceptors assessed with respect to that of unexposed controls by in situ hybridization with opsin riboprobes. Light exposure did not change the spectral phenotype of photoreceptors, their overall morphology or spatial arrangement. These results concur with those from a variety of fish species and suggest that plasticity in photoreceptor spectral phenotype via changes in opsin expression may not be a widespread occurrence among teleosts.
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Affiliation(s)
- Inigo Novales Flamarique
- Department of Biological Sciences, Simon Fraser University, Burnaby, Canada
- Department of Biology, University of Victoria, Victoria, Canada
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Nandamuri SP, Conte MA, Carleton KL. Multiple trans QTL and one cis-regulatory deletion are associated with the differential expression of cone opsins in African cichlids. BMC Genomics 2018; 19:945. [PMID: 30563463 PMCID: PMC6299527 DOI: 10.1186/s12864-018-5328-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 11/28/2018] [Indexed: 01/22/2023] Open
Abstract
Background Dissecting the genetic basis of phenotypic diversity is one of the fundamental goals in evolutionary biology. Despite growing evidence for gene expression divergence being responsible for the evolution of complex traits, knowledge about the proximate genetic causes underlying these traits is still limited. African cichlids have diverse visual systems, with different species expressing different combinations of seven cone opsin genes. Using opsin expression variation in African cichlids as a model for gene expression evolution, this study aims to investigate the genetic architecture of opsin expression divergence in this group. Results Results from a genome-wide linkage mapping on the F2 progeny of an intergeneric cross, between two species with differential opsin expression show that opsins in Lake Malawi cichlids are controlled by multiple quantitative trait loci (QTLs). Most of these QTLs are located in trans to the opsins except for one cis-QTL for SWS1 on LG17. A closer look at this major QTL revealed the presence of a 691 bp deletion in the promoter of the SWS1 opsin (located 751 bp upstream of the start site) that is associated with a decrease in its expression. Phylogenetic footprinting indicates that the region spanning the deletion harbors a microRNA miR-729 and a conserved non-coding element (CNE) that also occurs in zebrafish and other teleosts. This suggests that the deletion might contain ancestrally preserved regulators that have been tuned for SWS1 gene expression in Lake Malawi. While this deletion is not common, it does occur in several other species within the lake. Conclusions Differential expression of cichlid opsins is associated with multiple overlapping QTL, with all but one in trans to the opsins they regulate. The one cis-acting factor is a deletion in the promoter of the SWS1 opsin, suggesting that ancestral polymorphic deletions may contribute to cichlid’s visual diversity. In addition to expanding our understanding of the molecular landscape of opsin expression in African cichlids, this study sheds light on the molecular mechanisms underlying phenotypic variation in natural populations. Electronic supplementary material The online version of this article (10.1186/s12864-018-5328-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sri Pratima Nandamuri
- Department of Biology, University of Maryland, 1210 Biology / Psychology Bldg #144, College Park, MD, 20742, USA
| | - Matthew A Conte
- Department of Biology, University of Maryland, 1210 Biology / Psychology Bldg #144, College Park, MD, 20742, USA
| | - Karen L Carleton
- Department of Biology, University of Maryland, 1210 Biology / Psychology Bldg #144, College Park, MD, 20742, USA.
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8
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Härer A, Meyer A, Torres‐Dowdall J. Convergent phenotypic evolution of the visual system via different molecular routes: How Neotropical cichlid fishes adapt to novel light environments. Evol Lett 2018; 2:341-354. [PMID: 30283686 PMCID: PMC6121847 DOI: 10.1002/evl3.71] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 06/21/2018] [Accepted: 06/21/2018] [Indexed: 12/17/2022] Open
Abstract
How predictable is evolution? This remains a fundamental but contested issue in evolutionary biology. When independent lineages colonize the same environment, we are presented with a natural experiment that allows us to ask if genetic and ecological differences promote species-specific evolutionary outcomes or whether species phenotypically evolve in a convergent manner in response to shared selection pressures. If so, are the molecular mechanisms underlying phenotypic convergence the same? In Nicaragua, seven species of cichlid fishes concurrently colonized two novel photic environments. Hence, their visual system represents a compelling model to address these questions, particularly since the adaptive value of phenotypic changes is well-understood. By analyzing retinal transcriptomes, we found that differential expression of genes responsible for color vision (cone opsins and cyp27c1) produced rapid and mostly convergent changes of predicted visual sensitivities. Notably, these changes occurred in the same direction in all species although there were differences in underlying gene expression patterns illustrating nonconvergence at the molecular level. Adaptive phenotypes evolved deterministically, even when species differ substantially in ecology and genetic variation. This provides strong evidence that phenotypic evolution of the visual system occurred in response to similar selective forces of the photic environment.
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Affiliation(s)
- Andreas Härer
- Zoology and Evolutionary Biology, Department of BiologyUniversity of KonstanzGermany
| | - Axel Meyer
- Zoology and Evolutionary Biology, Department of BiologyUniversity of KonstanzGermany
- Radcliffe Institute for Advanced StudyHarvard UniversityCambridgeMassachusetts02138
| | - Julián Torres‐Dowdall
- Zoology and Evolutionary Biology, Department of BiologyUniversity of KonstanzGermany
- Zukunftskolleg, University of KonstanzKonstanzGermany
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Karagic N, Härer A, Meyer A, Torres‐Dowdall J. Heterochronic opsin expression due to early light deprivation results in drastically shifted visual sensitivity in a cichlid fish: Possible role of thyroid hormone signaling. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2018; 330:202-214. [DOI: 10.1002/jez.b.22806] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 04/30/2018] [Accepted: 05/03/2018] [Indexed: 11/07/2022]
Affiliation(s)
- Nidal Karagic
- Zoology and Evolutionary BiologyDepartment of BiologyUniversity of Konstanz Konstanz Germany
| | - Andreas Härer
- Zoology and Evolutionary BiologyDepartment of BiologyUniversity of Konstanz Konstanz Germany
| | - Axel Meyer
- Zoology and Evolutionary BiologyDepartment of BiologyUniversity of Konstanz Konstanz Germany
- Radcliffe Institute for Advanced StudyHarvard University Cambridge Massachusetts
| | - Julián Torres‐Dowdall
- Zoology and Evolutionary BiologyDepartment of BiologyUniversity of Konstanz Konstanz Germany
- ZukunftskollegUniversity of Konstanz Konstanz Germany
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10
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Valen R, Karlsen R, Helvik JV. Environmental, population and life-stage plasticity in the visual system of Atlantic cod. ACTA ACUST UNITED AC 2018; 221:jeb.165191. [PMID: 29146770 DOI: 10.1242/jeb.165191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 11/12/2017] [Indexed: 02/03/2023]
Abstract
The visual system is for many fishes essential in guiding behaviors, such as foraging, predator avoidance and mate choice. The marine environment is characterized by large spatio-temporal fluctuations in light intensity and spectral composition. However, visual capabilities are restricted by both space limitations set by eye size and by the genomic content of light-absorbing opsin genes. The rich array of visual opsins in teleosts may be used differentially to tune vision towards specific needs during ontogeny and to changing light. Yet, to what extent visual plasticity is a pre-programmed developmental event, or is triggered by photic environment, is unclear. Our previous studies on Atlantic cod revealed an evolutionary genomic loss of UV-sensitive sws1 and red-sensitive lws opsin families, while blue-sensitive sws2 and green-sensitive rh2 opsins had duplicated. The current study has taken an opsin expression approach to characterize visual plasticity in cod towards different spectral light during the larval stage, to maturation and extreme seasonal changes in the Barents Sea. Our data suggest that opsin plasticity in cod larvae is controlled by developmental programme rather than immediate light environment. The lack of expressional changes during maturation suggests a less important role for visual modulation related to mate choice. Although no seasonal effects on visual opsins were detected in migratory Northeast Arctic cod, the expressed opsin subset differed from the more stationary Norwegian coastal cod described in previous studies. Interestingly, these data provide the first indications of a population difference in actively used visual opsins associated with cod ecotypes.
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Affiliation(s)
- Ragnhild Valen
- Department of Biology, University of Bergen, NO-5020 Bergen, Norway
| | - Rita Karlsen
- Department of Biology, University of Bergen, NO-5020 Bergen, Norway
| | - Jon Vidar Helvik
- Department of Biology, University of Bergen, NO-5020 Bergen, Norway
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Jacobs GH. Photopigments and the dimensionality of animal color vision. Neurosci Biobehav Rev 2017; 86:108-130. [PMID: 29224775 DOI: 10.1016/j.neubiorev.2017.12.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 12/04/2017] [Accepted: 12/05/2017] [Indexed: 12/31/2022]
Abstract
Early color-matching studies established that normal human color vision is trichromatic. Subsequent research revealed a causal link between trichromacy and the presence in the retina of three classes of cone photopigments. Over the years, measurements of the photopigment complements of other species have expanded greatly and these are frequently used to predict the dimensionality of an animal's color vision. This review provides an account of how the linkage between the number of active photopigments and the dimensions of human color vision developed, summarizes the various mechanisms that can impact photopigment spectra and number, and provides an across-species survey to examine cases where the photopigment link to the dimensionality of color vision has been claimed. The literature reveals numerous instances where the human model fails to account for the ways in which the visual systems of other animals exploit information obtained from the presence of multiple photopigments in support of their behavior.
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Affiliation(s)
- Gerald H Jacobs
- Department of Psychological and Brain Science, University of California, Santa Barbara, CA 93106, USA.
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12
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Nandamuri SP, Yourick MR, Carleton KL. Adult plasticity in African cichlids: Rapid changes in opsin expression in response to environmental light differences. Mol Ecol 2017; 26:6036-6052. [PMID: 28926160 DOI: 10.1111/mec.14357] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 08/01/2017] [Accepted: 08/14/2017] [Indexed: 01/09/2023]
Abstract
Phenotypic plasticity allows organisms to adapt quickly to local environmental conditions and could facilitate adaptive radiations. Cichlids have recently undergone an adaptive radiation in Lake Malawi where they inhabit diverse light environments and tune their visual sensitivity through differences in cone opsin expression. While cichlid opsin expression is known to be plastic over development, whether adults remain plastic is unknown. Adult plasticity in visual tuning could play a role in cichlid radiations by enabling survival in changing environments and facilitating invasion into novel environments. Here we examine the existence of and temporal changes in adult visual plasticity of two closely related species. In complementary experiments, wild adult Metriaclima mbenji from Lake Malawi were moved to the lab under UV-deficient fluorescent lighting; while lab raised M. benetos were placed under UV-rich lighting designed to mimic light conditions in the wild. Surprisingly, adult cichlids in both experiments showed significant changes in the expression of the UV-sensitive single cone opsin, SWS1, in only 3 days. Modeling quantum catches in the light environments revealed a possible link between the light available to the SWS1 visual pigment and SWS1 expression. We conclude that adult cichlids can undergo rapid and significant changes in opsin expression in response to environmental light shifts that are relevant to their habitat and evolutionary history in Lake Malawi. This could have contributed to the rapid divergence characteristic of these fantastic fishes.
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Affiliation(s)
| | - Miranda R Yourick
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD, USA
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13
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Nandamuri SP, Dalton BE, Carleton KL. Determination of the Genetic Architecture Underlying Short Wavelength Sensitivity in Lake Malawi Cichlids. J Hered 2017; 108:379-390. [PMID: 28498989 DOI: 10.1093/jhered/esx020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 02/27/2017] [Indexed: 11/13/2022] Open
Abstract
African cichlids are an exemplary system to study organismal diversity and rapid speciation. Species differ in external morphology including jaw shape and body coloration, but also differ in sensory systems including vision. All cichlids have 7 cone opsin genes with species differing broadly in which opsins are expressed. The differential opsin expression results in closely related species with substantial differences in spectral sensitivity of their photoreceptors. In this work, we take a first step in determining the genetic basis of opsin expression in cichlids. Using a second generation cross between 2 species with different opsin expression patterns, we make a conservative estimate that short wavelength opsin expression is regulated by a few loci. Genetic mapping in 96 F2 hybrids provides clear evidence of a cis-regulatory region for SWS1 opsin that explains 34% of the variation in expression between the 2 species. Additionally, in situ hybridization has shown that SWS1 and SWS2B opsins are coexpressed in individual single cones in the retinas of F2 progeny. Results from this work will contribute to a better understanding of the genetic architecture underlying opsin expression. This knowledge will help answer long-standing questions about the evolutionary processes fundamental to opsin expression variation and how this contributes to adaptive cichlid divergence.
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Affiliation(s)
| | - Brian E Dalton
- National & Environmental Sciences Department, Western State Colorado University, Gunnison, CO 81231
| | - Karen L Carleton
- From the Department of Biology, University of Maryland, College Park, MD 20742
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14
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Fabrin TMC, Prioli SMAP, Prioli AJ. Long-wavelength sensitive opsin (LWS) gene variability in Neotropical cichlids (Teleostei: Cichlidae). AN ACAD BRAS CIENC 2017; 89:213-222. [PMID: 28423081 DOI: 10.1590/0001-3765201720150692] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/22/2016] [Indexed: 11/22/2022] Open
Abstract
Cichlid fishes are an important group in evolutionary biology due to their fast speciation. This group depends widely of vision for feeding and reproduction. During the evolutionary process it plays a significant role in interspecific and intraspecific recognition and in its ecology. The molecular basis of vision is formed by the interaction of the protein opsin and retinal chromophore. Long-wavelength sensitive opsin (LWS) gene is the most variable among the opsin genes and it has an ecological significance. Current assay identifies interspecific variation of Neotropical cichlids that would modify the spectral properties of the LWS opsin protein and codons selected. Neotropical species present more variable sites for LWS gene than those of the African lakes species. The LWS opsin gene in Crenicichla britskii has a higher amino acid similarity when compared to that in the African species, but the variable regions do not overlap. Neotropical cichlids accumulate larger amounts of variable sites for LWS opsin gene, probably because they are spread over a wider area and submitted to a wider range of selective pressures by inhabiting mainly lotic environments. Furthermore, the codons under selection are different when compared to those of the African cichlids.
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Affiliation(s)
- Thomaz M C Fabrin
- Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura/NUPELIA, Universidade Estadual de Maringá. Avenida Colombo, 5790, Bloco G90, Sala 16, Laboratório de Genética, 87020-900 Maringá, PR, Brazil
| | - Sonia Maria A P Prioli
- Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura/NUPELIA, Universidade Estadual de Maringá. Avenida Colombo, 5790, Bloco G90, Sala 16, Laboratório de Genética, 87020-900 Maringá, PR, Brazil.,Departamento de Biotecnologia, Genética e Biologia Celular, Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura/NUPELIA, Universidade Estadual de Maringá. Avenida Colombo, 5790, Bloco G90, Sala 16, Laboratório de Genética, 87020-900 Maringá, PR, Brazil
| | - Alberto José Prioli
- Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura/NUPELIA, Universidade Estadual de Maringá. Avenida Colombo, 5790, Bloco G90, Sala 16, Laboratório de Genética, 87020-900 Maringá, PR, Brazil
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Maan ME, Seehausen O, Groothuis TGG. Differential Survival between Visual Environments Supports a Role of Divergent Sensory Drive in Cichlid Fish Speciation. Am Nat 2017; 189:78-85. [DOI: 10.1086/689605] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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16
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Simões BF, Sampaio FL, Douglas RH, Kodandaramaiah U, Casewell NR, Harrison RA, Hart NS, Partridge JC, Hunt DM, Gower DJ. Visual Pigments, Ocular Filters and the Evolution of Snake Vision. Mol Biol Evol 2016; 33:2483-95. [DOI: 10.1093/molbev/msw148] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
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17
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Carleton KL, Dalton BE, Escobar-Camacho D, Nandamuri SP. Proximate and ultimate causes of variable visual sensitivities: Insights from cichlid fish radiations. Genesis 2016; 54:299-325. [PMID: 27061347 DOI: 10.1002/dvg.22940] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 01/24/2023]
Abstract
Animals vary in their sensitivities to different wavelengths of light. Sensitivity differences can have fitness implications in terms of animals' ability to forage, find mates, and avoid predators. As a result, visual systems are likely selected to operate in particular lighting environments and for specific visual tasks. This review focuses on cichlid vision, as cichlids have diverse visual sensitivities, and considerable progress has been made in determining the genetic basis for this variation. We describe both the proximate and ultimate mechanisms shaping cichlid visual diversity using the structure of Tinbergen's four questions. We describe (1) the molecular mechanisms that tune visual sensitivities including changes in opsin sequence and expression; (2) the evolutionary history of visual sensitivity across the African cichlid flocks; (3) the ontological changes in visual sensitivity and how modifying this developmental program alters sensitivities among species; and (4) the fitness benefits of spectral tuning mechanisms with respect to survival and mating success. We further discuss progress to unravel the gene regulatory networks controlling opsin expression and suggest that a simple genetic architecture contributes to the lability of opsin gene expression. Finally, we identify unanswered questions including whether visual sensitivities are experiencing selection, and whether similar spectral tuning mechanisms shape visual sensitivities of other fishes. genesis 54:299-325, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Karen L Carleton
- Department of Biology, University of Maryland, College Park, Maryland
| | - Brian E Dalton
- Department of Biology, University of Maryland, College Park, Maryland
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18
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Henning F, Lee HJ, Franchini P, Meyer A. Genetic mapping of horizontal stripes in Lake Victoria cichlid fishes: benefits and pitfalls of using RAD markers for dense linkage mapping. Mol Ecol 2014; 23:5224-40. [PMID: 25039588 DOI: 10.1111/mec.12860] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/02/2014] [Accepted: 07/12/2014] [Indexed: 01/25/2023]
Abstract
The genetic dissection of naturally occurring phenotypes sheds light on many fundamental and longstanding questions in speciation and adaptation and is a central research topic in evolutionary biology. Until recently, forward-genetic approaches were virtually impossible to apply to nonmodel organisms, but the development of next-generation sequencing techniques eases this difficulty. Here, we use the ddRAD-seq method to map a colour trait with a known adaptive function in cichlid fishes, well-known textbook examples for rapid rates of speciation and astonishing phenotypic diversification. A suite of phenotypic key innovations is related to speciation and adaptation in cichlids, among which body coloration features prominently. The focal trait of this study, horizontal stripes, evolved in parallel in several cichlid radiations and is associated with piscivorous foraging behaviour. We conducted interspecific crosses between Haplochromis sauvagei and H. nyererei and constructed a linkage map with 867 SNP markers distributed on 22 linkage groups and total size of 1130.63 cM. Lateral stripes are inherited as a Mendelian trait and map to a single genomic interval that harbours a paralog of a gene with known function in stripe patterning. Dorsolateral and mid-lateral stripes were always coinherited and are thus under the same genetic control. Additionally, we directly quantify the genotyping error rates in RAD markers and offer guidelines for identifying and dealing with errors. Uncritical marker selection was found to severely impact linkage map construction. Fortunately, by applying appropriate quality control steps, a genotyping accuracy of >99.9% can be reached, thus allowing for efficient linkage mapping of evolutionarily relevant traits.
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Affiliation(s)
- Frederico Henning
- Lehrstuhl für Zoologie und Evolutionsbiologie, Department of Biology, University of Konstanz, Universitätsstraße 10, Konstanz, 78457, Germany
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Henning F, Meyer A. The evolutionary genomics of cichlid fishes: explosive speciation and adaptation in the postgenomic era. Annu Rev Genomics Hum Genet 2014; 15:417-41. [PMID: 24898042 DOI: 10.1146/annurev-genom-090413-025412] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
With more than 1,500 species, cichlid fishes provide textbook examples of recent and diverse adaptive radiations, rapid rates of speciation, and the parallel evolution of adaptive phenotypes among both recently and distantly related lineages. This extraordinary diversity has attracted considerable interest from researchers across several biological disciplines. Their broad phenotypic variation coupled with recent divergence makes cichlids an ideal model system for understanding speciation, adaptation, and phenotypic diversification. Genetic mapping, genome-wide analyses, and genome projects have flourished in the past decade and have added new insights on the question of why there are so many cichlids. These recent findings also show that the sharing of older DNA polymorphisms is extensive and suggest that linage sorting is incomplete and that adaptive introgression played a role in the African radiation. Here, we review the results of genetic and genomic research on cichlids in the past decade and suggest some potential avenues to further exploit the potential of the cichlid model system to provide a better understanding of the genomics of adaptation and speciation.
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Affiliation(s)
- Frederico Henning
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany;
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O'Quin KE, Schulte JE, Patel Z, Kahn N, Naseer Z, Wang H, Conte MA, Carleton KL. Evolution of cichlid vision via trans-regulatory divergence. BMC Evol Biol 2012; 12:251. [PMID: 23267665 PMCID: PMC3575402 DOI: 10.1186/1471-2148-12-251] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 12/19/2012] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Phenotypic 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. RESULTS We 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. CONCLUSIONS Combined 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.
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Affiliation(s)
- Kelly E O'Quin
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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21
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Mazzuchelli J, Kocher TD, Yang F, Martins C. Integrating cytogenetics and genomics in comparative evolutionary studies of cichlid fish. BMC Genomics 2012; 13:463. [PMID: 22958299 PMCID: PMC3463429 DOI: 10.1186/1471-2164-13-463] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 08/09/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The availability of a large number of recently sequenced vertebrate genomes opens new avenues to integrate cytogenetics and genomics in comparative and evolutionary studies. Cytogenetic mapping can offer alternative means to identify conserved synteny shared by distinct genomes and also to define genome regions that are still not fine characterized even after wide-ranging nucleotide sequence efforts. An efficient way to perform comparative cytogenetic mapping is based on BAC clones mapping by fluorescence in situ hybridization. In this report, to address the knowledge gap on the genome evolution in cichlid fishes, BAC clones of an Oreochromis niloticus library covering the linkage groups (LG) 1, 3, 5, and 7 were mapped onto the chromosomes of 9 African cichlid species. The cytogenetic mapping data were also integrated with BAC-end sequences information of O. niloticus and comparatively analyzed against the genome of other fish species and vertebrates. RESULTS The location of BACs from LG1, 3, 5, and 7 revealed a strong chromosomal conservation among the analyzed cichlid species genomes, which evidenced a synteny of the markers of each LG. Comparative in silico analysis also identified large genomic blocks that were conserved in distantly related fish groups and also in other vertebrates. CONCLUSIONS Although it has been suggested that fishes contain plastic genomes with high rates of chromosomal rearrangements and probably low rates of synteny conservation, our results evidence that large syntenic chromosome segments have been maintained conserved during evolution, at least for the considered markers. Additionally, our current cytogenetic mapping efforts integrated with genomic approaches conduct to a new perspective to address important questions involving chromosome evolution in fishes.
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Affiliation(s)
- Juliana Mazzuchelli
- Department of Morphology, Bioscience Institute, UNESP - São Paulo State University, 18618-970, Botucatu, SP, Brazil
| | | | - Fengtang Yang
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Cesar Martins
- Department of Morphology, Bioscience Institute, UNESP - São Paulo State University, 18618-970, Botucatu, SP, Brazil
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Genetic architecture of variation in the lateral line sensory system of threespine sticklebacks. G3-GENES GENOMES GENETICS 2012; 2:1047-56. [PMID: 22973542 PMCID: PMC3429919 DOI: 10.1534/g3.112.003079] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 06/27/2012] [Indexed: 11/18/2022]
Abstract
Vertebrate sensory systems have evolved remarkable diversity, but little is known about the underlying genetic mechanisms. The lateral line sensory system of aquatic vertebrates is a promising model for genetic investigations of sensory evolution because there is extensive variation within and between species, and this variation is easily quantified. In the present study, we compare the lateral line sensory system of threespine sticklebacks (Gasterosteus aculeatus) from an ancestral marine and a derived benthic lake population. We show that lab-raised individuals from these populations display differences in sensory neuromast number, neuromast patterning, and groove morphology. Using genetic linkage mapping, we identify regions of the genome that influence different aspects of lateral line morphology. Distinct loci independently affect neuromast number on different body regions, suggesting that a modular genetic structure underlies the evolution of peripheral receptor number in this sensory system. Pleiotropy and/or tight linkage are also important, as we identify a region on linkage group 21 that affects multiple aspects of lateral line morphology. Finally, we detect epistasis between a locus on linkage group 4 and a locus on linkage group 21; interactions between these loci contribute to variation in neuromast pattern. Our results reveal a complex genetic architecture underlying the evolution of the stickleback lateral line sensory system. This study further uncovers a genetic relationship between sensory morphology and non-neural traits (bony lateral plates), creating an opportunity to investigate morphological constraints on sensory evolution in a vertebrate model system.
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An evaluation of the role of sensory drive in the evolution of lake Malawi cichlid fishes. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:647420. [PMID: 22779029 PMCID: PMC3388434 DOI: 10.1155/2012/647420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 03/15/2012] [Accepted: 04/05/2012] [Indexed: 11/18/2022]
Abstract
Although the cichlids of Lake Malawi are an important model system for the study of sensory evolution and sexual selection, the evolutionary processes linking these two phenomena remain unclear. Prior works have proposed that evolutionary divergence is driven by sensory drive, particularly as it applies to the visual system. While evidence suggests that sensory drive has played a role in the speciation of Lake Victoria cichlids, the findings from several lines of research on cichlids of Lake Malawi are not consistent with the primary tenets of this hypothesis. More specifically, three observations make the sensory drive model implausible in Malawi: (i) a lack of environmental constraint due to a broad and intense ambient light spectrum in species rich littoral habitats, (ii) pronounced variation in receiver sensory characteristics, and (iii) pronounced variability in male courtship signal characteristics. In the following work, we synthesize the results from recent studies to draw attention to the importance of sensory variation in cichlid evolution and speciation, and we suggest possible avenues of future research.
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Elmer KR, Meyer A. Adaptation in the age of ecological genomics: insights from parallelism and convergence. Trends Ecol Evol 2011; 26:298-306. [PMID: 21459472 DOI: 10.1016/j.tree.2011.02.008] [Citation(s) in RCA: 263] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 02/18/2011] [Accepted: 02/22/2011] [Indexed: 12/19/2022]
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O'Quin KE, Smith D, Naseer Z, Schulte J, Engel SD, Loh YHE, Streelman JT, Boore JL, Carleton KL. Divergence in cis-regulatory sequences surrounding the opsin gene arrays of African cichlid fishes. BMC Evol Biol 2011; 11:120. [PMID: 21554730 PMCID: PMC3116502 DOI: 10.1186/1471-2148-11-120] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 05/09/2011] [Indexed: 11/17/2022] Open
Abstract
Background Divergence within cis-regulatory sequences may contribute to the adaptive evolution of gene expression, but functional alleles in these regions are difficult to identify without abundant genomic resources. Among African cichlid fishes, the differential expression of seven opsin genes has produced adaptive differences in visual sensitivity. Quantitative genetic analysis suggests that cis-regulatory alleles near the SWS2-LWS opsins may contribute to this variation. Here, we sequence BACs containing the opsin genes of two cichlids, Oreochromis niloticus and Metriaclima zebra. We use phylogenetic footprinting and shadowing to examine divergence in conserved non-coding elements, promoter sequences, and 3'-UTRs surrounding each opsin in search of candidate cis-regulatory sequences that influence cichlid opsin expression. Results We identified 20 conserved non-coding elements surrounding the opsins of cichlids and other teleosts, including one known enhancer and a retinal microRNA. Most conserved elements contained computationally-predicted binding sites that correspond to transcription factors that function in vertebrate opsin expression; O. niloticus and M. zebra were significantly divergent in two of these. Similarly, we found a large number of relevant transcription factor binding sites within each opsin's proximal promoter, and identified five opsins that were considerably divergent in both expression and the number of transcription factor binding sites shared between O. niloticus and M. zebra. We also found several microRNA target sites within the 3'-UTR of each opsin, including two 3'-UTRs that differ significantly between O. niloticus and M. zebra. Finally, we examined interspecific divergence among 18 phenotypically diverse cichlids from Lake Malawi for one conserved non-coding element, two 3'-UTRs, and five opsin proximal promoters. We found that all regions were highly conserved with some evidence of CRX transcription factor binding site turnover. We also found three SNPs within two opsin promoters and one non-coding element that had weak association with cichlid opsin expression. Conclusions This study is the first to systematically search the opsins of cichlids for putative cis-regulatory sequences. Although many putative regulatory regions are highly conserved across a large number of phenotypically diverse cichlids, we found at least nine divergent sequences that could contribute to opsin expression differences in cis and stand out as candidates for future functional analyses.
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Affiliation(s)
- Kelly E O'Quin
- Department of Biology, University of Maryland, College Park, MD 20742, USA
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26
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Wang FY, Tang MY, Yan HY. A comparative study on the visual adaptations of four species of moray eel. Vision Res 2011; 51:1099-108. [DOI: 10.1016/j.visres.2011.02.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 02/22/2011] [Accepted: 02/25/2011] [Indexed: 11/16/2022]
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Smith AR, D'Annunzio L, Smith AE, Sharma A, Hofmann CM, Marshall NJ, Carleton KL. Intraspecific cone opsin expression variation in the cichlids of Lake Malawi. Mol Ecol 2010; 20:299-310. [PMID: 21091561 DOI: 10.1111/j.1365-294x.2010.04935.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The expression of cone opsin genes is a primary determinant of the characteristics of colour vision. Interspecific variation in opsin expression is common in African cichlids. It is correlated with foraging among cichlids from Lake Malawi, and with ambient light environment among cichlids from Lake Victoria. In this study, we tested whether gene expression varied within species such that it might be important in contributing to divergence. We hypothesized that light attenuation with depth would be correlated with predictable changes in gene expression in Lake Malawi, and that this variation would tune visual sensitivities to match the ambient light environment. We observed significant differences in cone opsin expression in three different comparisons among populations of the same species. Higher LWS expression was found in shallow versus deep Copadichromis eucinostomus. In Metriaclima zebra, individuals from Zimbawe Rock expressed significantly more SWS2B than those from Thumbi West Island, although these locales have similar ambient light environments. Finally, Tropheops gracilior from deeper water had significantly more variation in expression than their shallow counterparts. These results support that gene expression varies significantly between populations of the same species. Surprisingly, these results could not be explained by predicted visual performance as models predicted that differential expression patterns did not confer sensitivity advantages at different depths. This suggested that expression variation did not confer a local sensitivity advantage. Therefore, our findings were contrary to a primary requirement of the sensory bias hypothesis. As such, other explanations for intraspecific gene expression variation need to be tested.
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Affiliation(s)
- Adam R Smith
- Department of Biology, University of Maryland College Park, College Park, MD 20742, USA.
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Sabbah S, Laria RL, Gray SM, Hawryshyn CW. Functional diversity in the color vision of cichlid fishes. BMC Biol 2010; 8:133. [PMID: 21029409 PMCID: PMC2988715 DOI: 10.1186/1741-7007-8-133] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 10/28/2010] [Indexed: 11/15/2022] Open
Abstract
Background Color vision plays a critical role in visual behavior. An animal's capacity for color vision rests on the presence of differentially sensitive cone photoreceptors. Spectral sensitivity is a measure of the visual responsiveness of these cones at different light wavelengths. Four classes of cone pigments have been identified in vertebrates, but in teleost fishes, opsin genes have undergone gene duplication events and thus can produce a larger number of spectrally distinct cone pigments. In this study, we examine the question of large-scale variation in color vision with respect to individual, sex and species that may result from differential expression of cone pigments. Cichlid fishes are an excellent model system for examining variation in spectral sensitivity because they have seven distinct cone opsin genes that are differentially expressed. Results To examine the variation in the number of cones that participate in cichlid spectral sensitivity, we used whole organism electrophysiology, opsin gene expression and empirical modeling. Examination of over 100 spectral sensitivity curves from 34 individuals of three species revealed that (1) spectral sensitivity of individual cichlids was based on different subsets of four or five cone pigments, (2) spectral sensitivity was shaped by multiple cone interactions and (3) spectral sensitivity differed between species and correlated with foraging mode and the spectral reflectance of conspecifics. Our data also suggest that there may be significant differences in opsin gene expression between the sexes. Conclusions Our study describes complex opponent and nonopponent cone interactions that represent the requisite neural processing for color vision. We present the first comprehensive evidence for pentachromatic color vision in vertebrates, which offers the potential for extraordinary spectral discrimination capabilities. We show that opsin gene expression in cichlids, and possibly also spectral sensitivity, may be sex-dependent. We argue that females and males sample their visual environment differently, providing a neural basis for sexually dimorphic visual behaviour. The diversification of spectral sensitivity likely contributes to sensory adaptations that enhance the contrast of transparent prey and the detection of optical signals from conspecifics, suggesting a role for both natural and sexual selection in tuning color vision.
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Affiliation(s)
- Shai Sabbah
- Department of Biology, Queen's University, Kingston, ON, Canada
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29
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O'Quin KE, Hofmann CM, Hofmann HA, Carleton KL. Parallel Evolution of Opsin Gene Expression in African Cichlid Fishes. Mol Biol Evol 2010; 27:2839-54. [DOI: 10.1093/molbev/msq171] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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30
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HOFMANN CHRISTOPHERM, O’QUIN KELLYE, SMITH ADAMR, CARLETON KARENL. Plasticity of opsin gene expression in cichlids from Lake Malawi. Mol Ecol 2010; 19:2064-74. [DOI: 10.1111/j.1365-294x.2010.04621.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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