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Pushing the switch: functional responses and prey switching by invasive lionfish may mediate their ecological impact. Biol Invasions 2021. [DOI: 10.1007/s10530-021-02487-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AbstractBiodiversity is declining on a global scale and the spread of invasive alien species (IAS) is a major driver, particularly through predatory impacts. Thus, effective means of assessing and predicting the consequences of IAS predation on native prey population stability remains a vital goal for conservation. Here, we applied two classic ecological concepts, consumer functional response (FR) and prey switching, to predict and understand the ecological impacts of juveniles of the lionfish (Pterois volitans), a notorious and widespread marine invader. Functional responses and prey switching propensities were quantified towards three representative prey species: Artemia salina, Palaemonetes varians, and Gammarus oceanicus. Lionfish exhibited potentially destabilising Type II FRs towards individual prey species, owing to high consumption rates at low prey densities, whilst FR magnitudes differed among prey species. Functional response attack rates (a) were highest, and handling times (h) lowest, towards A. salina, followed by P. varians and then G. oceanicus. Maximum feeding rates (1/h) and functional response ratios (FRR; a/h) also followed this impact gradient for the three prey species. Lionfish, however, displayed a potentially population stabilising prey switching propensity (i.e. frequency-dependent predation) when multiple prey species were presented simultaneously, where disproportionately less of rare prey, and more of abundant prey, were consumed. Whilst FR and FRR magnitudes indicate marked per capita lionfish predatory impacts towards prey species, a strong prey switching propensity may reduce in-field impacts by offering low density prey refuge in biodiverse communities. Our results thus corroborate field patterns documenting variable impacts of lionfish, with prey extirpations less likely in diverse communities owing to frequency-dependent predation.
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Chang CH, Fuller RC. The Eye Size of the Bluefin Killifish (Lucania goodei) Varies from Springs to Swamps. COPEIA 2020. [DOI: 10.1643/ci-19-330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Chia-Hao Chang
- TIGP, Biodiversity Program, Tunghai University, No. 181, Sec. 4, Taiwan Blvd., Taichung City 407224, Taiwan; . Send reprint requests to this address
| | - Rebecca C. Fuller
- Department of Animal Biology, School of Integrative Biology, University of Illinois, 104 Shelford Vivarium, 606 E. Healey St., Champaign, Illinois 61820;
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Carleton KL, Escobar-Camacho D, Stieb SM, Cortesi F, Marshall NJ. Seeing the rainbow: mechanisms underlying spectral sensitivity in teleost fishes. J Exp Biol 2020; 223:jeb193334. [PMID: 32327561 PMCID: PMC7188444 DOI: 10.1242/jeb.193334] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among vertebrates, teleost eye diversity exceeds that found in all other groups. Their spectral sensitivities range from ultraviolet to red, and the number of visual pigments varies from 1 to over 40. This variation is correlated with the different ecologies and life histories of fish species, including their variable aquatic habitats: murky lakes, clear oceans, deep seas and turbulent rivers. These ecotopes often change with the season, but fish may also migrate between ecotopes diurnally, seasonally or ontogenetically. To survive in these variable light habitats, fish visual systems have evolved a suite of mechanisms that modulate spectral sensitivities on a range of timescales. These mechanisms include: (1) optical media that filter light, (2) variations in photoreceptor type and size to vary absorbance and sensitivity, and (3) changes in photoreceptor visual pigments to optimize peak sensitivity. The visual pigment changes can result from changes in chromophore or changes to the opsin. Opsin variation results from changes in opsin sequence, opsin expression or co-expression, and opsin gene duplications and losses. Here, we review visual diversity in a number of teleost groups where the structural and molecular mechanisms underlying their spectral sensitivities have been relatively well determined. Although we document considerable variability, this alone does not imply functional difference per se. We therefore highlight the need for more studies that examine species with known sensitivity differences, emphasizing behavioral experiments to test whether such differences actually matter in the execution of visual tasks that are relevant to the fish.
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Affiliation(s)
- Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | | | - Sara M Stieb
- Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
| | - N Justin Marshall
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
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Yan H, Liu Q, Shen X, Liu W, Cui X, Hu P, Yuan Z, Zhang L, Song C, Liu L, Liu Y. Effects of different light conditions on the retinal microstructure and ultrastructure of Dicentrarchus labrax larvae. FISH PHYSIOLOGY AND BIOCHEMISTRY 2020; 46:613-628. [PMID: 31797174 DOI: 10.1007/s10695-019-00735-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Accepted: 11/12/2019] [Indexed: 06/10/2023]
Abstract
Light is a key environmental parameter known to influence fish throughout various stages of their life, from embryonic development to sexually mature adults. In a recent study, the effects of different light conditions on the growth of Dicentrarchus labrax larvae were investigated using light-emitting diodes (LEDs) as a light source. Here, pathological examinations were carried out to assess whether variations in light affected the visual system of the larvae, including any negative impacts on the retina or the growth rate. Although light did not affect the total thickness (TT) of the retina, the thickness of the retinal pigment epithelium layer (PRE), photoreceptor layer (PRos/is), outer nuclear layer (ONL), and inner nuclear layer (INL), and the PRE/TT and ONL/TT ratios were all significantly higher in larvae exposed to blue light than in larvae exposed to white light. Additionally, the thickness of PRE and the outer nuclear layer and the RPE/TT and ONL/TT ratios of larvae exposed to 2.0 W m-2 were significantly lower than in larvae exposed to 0.3 W m-2. By contrast, the INL/TT ratio in larvae exposed to 2.0 W m-2 was significantly higher than in larvae exposed to 0.3 W m-2. Additionally, the INL and ganglion cell layer nuclei density of larvae exposed to 2.0 W m-2 were significantly higher than in those exposed to 0.3 W m-2 (p < 0.05). Transmission electron microscopy revealed different levels of abnormalities in the photoreceptor layers in all treatment groups. Considering the growth of the larvae, the results of the study suggest that continuous LED exposure induced damage to photoreceptor cells but was not relevant to the growth performance of D. labrax larvae. Moreover, the results obtained here also support the high plasticity of retinal development in response to altered environmental light conditions.
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Affiliation(s)
- Hongwei Yan
- College of Fisheries and life Science, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Qi Liu
- College of Marine Science and Environment Engineering, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Xufang Shen
- College of Fisheries and life Science, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Wenlei Liu
- College of Marine Science and Environment Engineering, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Xin Cui
- College of Fisheries and life Science, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Pengfei Hu
- College of Marine Science and Environment Engineering, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Zhen Yuan
- College of Fisheries and life Science, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Lei Zhang
- College of Marine Science and Environment Engineering, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China
| | - Changbin Song
- Institute of Semiconductors, Chinese Academy of Sciences, No.35, Qinghua East Road, Haidian District, Beijing, 10083, China
| | - Lili Liu
- Institute of Semiconductors, Chinese Academy of Sciences, No.35, Qinghua East Road, Haidian District, Beijing, 10083, China
| | - Ying Liu
- College of Marine Science and Environment Engineering, Dalian Ocean University, No. 52 Heishijiao Street, Shahekou District, Dalian, 116023, China.
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5
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Schweikert LE, Grace MS. Altered environmental light drives retinal change in the Atlantic Tarpon (Megalops atlanticus) over timescales relevant to marine environmental disturbance. BMC Ecol 2018; 18:1. [PMID: 29347979 PMCID: PMC5774114 DOI: 10.1186/s12898-018-0157-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 01/09/2018] [Indexed: 12/13/2022] Open
Abstract
Background For many fish species, retinal function changes between life history stages as part of an encoded developmental program. Retinal change is also known to exhibit plasticity because retinal form and function can be influenced by light exposure over the course of development. Aside from studies of gene expression, it remains largely unknown whether retinal plasticity can provide functional responses to short-term changes in environmental light quality. The aim of this study was to determine whether the structure and function of the fish retina can change in response to altered light intensity and spectrum—not over the course of a developmental regime, but over shorter time periods relevant to marine habitat disturbance. Results The effects of light environment on sensitivity of the retina, as well as on cone photoreceptor distribution were examined in the Atlantic tarpon (Megalops atlanticus) on 2- and 4-month timescales. In a spectral experiment, juvenile M. atlanticus were placed in either ‘red’ or ‘blue’ light conditions (with near identical irradiance), and in an intensity experiment, juveniles were placed in either ‘bright’ or ‘dim’ light conditions (with near identical spectra). Analysis of the retina by electroretinography and anti-opsin immunofluorescence revealed that relative to fish held in the blue condition, those in the red condition exhibited longer-wavelength peak sensitivity and greater abundance of long-wavelength-sensitive (LWS) cone photoreceptors over time. Following pre-test dark adaption of the retina, fish held in the dim light required less irradiance to produce a standard retinal response than fish held in bright light, developing a greater sensitivity to white light over time. Conclusions The results show that structure and function of the M. atlanticus retina can rapidly adjust to changes in environmental light within a given developmental stage, and that such changes are dependent on light quality and the length of exposure. These findings suggest that the fish retina may be resilient to disturbances in environmental light, using retinal plasticity to compensate for changes in light quality over short timescales. Electronic supplementary material The online version of this article (10.1186/s12898-018-0157-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lorian E Schweikert
- Department of Biological Sciences, Florida Institute of Technology, 150 W. University Boulevard, Melbourne, FL, 32901, USA.,Department of Biology, Duke University, 130 Science Dr. Durham, Durham, NC, 27583, USA
| | - Michael S Grace
- Department of Biological Sciences, Florida Institute of Technology, 150 W. University Boulevard, Melbourne, FL, 32901, USA.
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Luehrmann M, Stieb SM, Carleton KL, Pietzker A, Cheney KL, Marshall NJ. Short term colour vision plasticity on the reef: Changes in opsin expression under varying light conditions differ between ecologically distinct reef fish species. J Exp Biol 2018; 221:jeb.175281. [DOI: 10.1242/jeb.175281] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 08/21/2018] [Indexed: 12/17/2022]
Abstract
Vision mediates important behavioural tasks such as mate choice, escape from predators and foraging. In fish, photoreceptors are generally tuned to specific visual tasks and/or to their light environment according to depth or water colour to ensure optimal performance. Evolutionary mechanisms acting on opsin genes, the protein component of the photopigment, can influence the spectral sensitivity of photoreceptors. Opsin genes are known to respond to environmental conditions on a number of time scales including shorter time frames due to seasonal variation, or through longer term evolutionary tuning. There is also evidence for ‘on-the-fly’ adaptations in adult fish in response to rapidly changing environmental conditions, however, results are contradictory. Here we investigated the ability of three reef fish species that belong to two ecologically distinct families, Yellow-striped cardinalfish, Ostorhinchus cyanosoma, Ambon damselfish, Pomacentrus amboinensis, and Lemon damselfish, Pomacentrus moluccensis, to alter opsin-gene expression as an adaptation to short-term (weeks to months) changes of environmental light conditions, and attempted to characterize the underlying expression regulation principles. We report the ability for all species to alter opsin gene expression within months and even a few weeks, suggesting that opsin expression in adult reef fish is not static. Furthermore, we found that opsin expression changes in single cones generally occurred more rapidly than in double cones, and identified different responses of RH2 opsin gene expression between the ecologically distinct reef fish families. Quantum catch correlation analysis suggested different regulation mechanisms for opsin expression dependent on gene class.
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Affiliation(s)
- Martin Luehrmann
- Queensland Brain Institute, The University of Queensland, Sensory Neurobiology Group, 4072, Brisbane, QLD, Australia
| | - Sara M. Stieb
- Queensland Brain Institute, The University of Queensland, Sensory Neurobiology Group, 4072, Brisbane, QLD, Australia
| | - Karen L. Carleton
- Department of Biology, The University of Maryland, College Park, MD, 20742, USA
| | - Alisa Pietzker
- Queensland Brain Institute, The University of Queensland, Sensory Neurobiology Group, 4072, Brisbane, QLD, Australia
| | - Karen L. Cheney
- Queensland Brain Institute, The University of Queensland, Sensory Neurobiology Group, 4072, Brisbane, QLD, Australia
- School of Biological Sciences, The University of Queensland, 4072, Brisbane, QLD, Australia
| | - N. Justin Marshall
- Queensland Brain Institute, The University of Queensland, Sensory Neurobiology Group, 4072, Brisbane, QLD, Australia
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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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Kopperud KL, Grace MS. Circadian Rhythms of Retinomotor Movement in a Marine Megapredator, the Atlantic Tarpon, Megalops atlanticus. Int J Mol Sci 2017; 18:E2068. [PMID: 28956858 PMCID: PMC5666750 DOI: 10.3390/ijms18102068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/21/2017] [Accepted: 09/21/2017] [Indexed: 11/16/2022] Open
Abstract
Many ecologically and economically important marine fish species worldwide spend portions of their lives in coastal regions that are increasingly inundated by artificial light at night. However, while extensive research illustrates the harmful effects of inappropriate light exposure on biological timing in humans, rodents and birds, comparable studies on marine fish are virtually nonexistent. This study aimed to assess the effects of light on biological clock function in the marine fish retina using the Atlantic tarpon (Megalops atlanticus) as a model. Using anti-opsin immunofluorescence, we observed robust rhythms of photoreceptor outer segment position (retinomotor movement) over the course of the daily light-dark cycle: cone outer segments were contracted toward the inner retina and rods were elongated during the day; the opposite occurred at night. Phase shifting the daily light-dark cycle caused a corresponding shift of retinomotor movement timing, and cone retinomotor movement persisted in constant darkness, indicating control by a circadian clock. Constant light abolished retinomotor movements of both photoreceptor types. Thus, abnormally-timed light exposure may disrupt normal M. atlanticus clock function and harm vision, which in turn may affect prey capture and predator avoidance. These results should help inform efforts to mitigate the effects of coastal light pollution on organisms in marine ecosystems.
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Affiliation(s)
- Kristin L Kopperud
- College of Science, Florida Institute of Technology, 150 West University Blvd, Melbourne, FL 32901, USA.
| | - Michael S Grace
- College of Science, Florida Institute of Technology, 150 West University Blvd, Melbourne, FL 32901, USA.
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9
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Schweikert LE, Grace MS. Spectral Sensitivity Change May Precede Habitat Shift in the Developing Retina of the Atlantic Tarpon (Megalops atlanticus). Physiol Biochem Zool 2017; 90:553-563. [PMID: 28665184 DOI: 10.1086/692993] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Fish that undergo ontogenetic migrations between habitats often encounter new light environments that require changes in the spectral sensitivity of the retina. For many fish, sensitivity of the retina changes to match the environmental spectrum, but the timing of retinal change relative to habitat shift remains unknown. Does retinal change in fish precede habitat shift, or is it a response to encountered changes in environmental light? Spectral sensitivity changes were examined over the development of the Atlantic tarpon (Megalops atlanticus) retina relative to ontogenetic shifts in habitat light. Opsin gene isoform expression and inferred chromophore use of visual pigments were examined over the course of M. atlanticus development. Spectral sensitivity of the retina was then determined by electroretinography and compared to the spectroradiometric measurements of habitat light encountered by M. atlanticus from juveniles to adults. These data, along with previously known microspectrophotometric measurements of sensitivity in M. atlanticus, indicate retinal spectral sensitivity that matches the dominant wavelengths of environmental light for juvenile and adult fish. For the intervening subadult stage, however, spectral sensitivity does not match the dominant wavelength of light it occupies but better matches the dominant wavelengths of light in the habitat of its forthcoming migration. These results first indicate that the relationship between environmental light spectrum and spectral sensitivity of the retina changes during M. atlanticus development and then suggest that such changes may be programmed to support visual anticipation of new photic environments.
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10
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Secondi J, Martin M, Goven D, Mège P, Sourice S, Théry M. Habitat-related variation in the plasticity of a UV-sensitive photoreceptor over a small spatial scale in the palmate newt. J Evol Biol 2017; 30:1229-1235. [PMID: 28370602 DOI: 10.1111/jeb.13076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2016] [Revised: 03/10/2017] [Accepted: 03/17/2017] [Indexed: 11/26/2022]
Abstract
Plastic phenotypes are expected to be favoured in heterogeneous environments compared with stable environments. Sensory systems are interesting to test this theory because they are costly to produce and support, and strong fitness costs are expected if they are not tuned to the local environment. Consistently, the visual system of several species changes with the conditions experienced during early development. However, there is little information on whether the amplitude of the change, that is the reaction norm, differs between visual environments. Given the rapid change of many ecosystems, especially eutrophication for aquatic habitats, it is crucial to determine down to which spatial scale, change in the reaction norm occurs. We addressed this issue by quantifying the between-habitat variation in the expression of a UV-sensitive opsin in a newt. In western France, this species breeds in ponds of small forest patches, where water filters out UV, and in agricultural ponds where UV transmission is variable. We raised larvae from both habitats with or without exposure to UV. Opsin expression was reduced in larvae from agricultural habitats when raised without UV, whereas it was low in larvae from forest ponds under all lighting conditions. Thus, the variation in the reaction norm of opsin expression was lower in stable filtering environments and higher in heterogeneous environments. Its variation occurred between habitats across a small spatial scale. We discuss the hypotheses for this pattern and for the maintenance of residual opsin expression in forest populations.
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Affiliation(s)
- J Secondi
- UMR 5023 Écologie des Hydrosystèmes Naturels et Anthropisés, Université Lyon 1, ENTPE, CNRS, Université de Lyon, Villeurbanne, France.,UMR CNRS 6554 LETG-LEESA, Université d'Angers, Angers, France
| | - M Martin
- UMR 7179 CNRS-MNHN, Mécanismes Adaptatifs et Evolution, Brunoy, France
| | - D Goven
- UPRES EA 2647/USC INRA 1330 SIFCIR, Université d'Angers, Angers, France
| | - P Mège
- UMR CNRS 6554 LETG-LEESA, Université d'Angers, Angers, France
| | - S Sourice
- UMR CNRS 6554 LETG-LEESA, Université d'Angers, Angers, France
| | - M Théry
- UMR 7179 CNRS-MNHN, Mécanismes Adaptatifs et Evolution, Brunoy, France
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Stieb SM, Carleton KL, Cortesi F, Marshall NJ, Salzburger W. Depth-dependent plasticity in opsin gene expression varies between damselfish (Pomacentridae) species. Mol Ecol 2016; 25:3645-61. [DOI: 10.1111/mec.13712] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 05/10/2016] [Accepted: 05/31/2016] [Indexed: 01/02/2023]
Affiliation(s)
- Sara M. Stieb
- Zoological Institute; University of Basel; Basel 4051 Switzerland
- Queensland Brain Institute; The University of Queensland; Brisbane QLD 4072 Australia
| | - Karen L. Carleton
- Department of Biology; University of Maryland; College Park MD 20742 USA
| | - Fabio Cortesi
- Zoological Institute; University of Basel; Basel 4051 Switzerland
- Queensland Brain Institute; The University of Queensland; Brisbane QLD 4072 Australia
| | - N. Justin Marshall
- Queensland Brain Institute; The University of Queensland; Brisbane QLD 4072 Australia
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12
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Abstract
Predation is an important but often fluctuating selection factor for prey animals. Accordingly, individuals plastically adopt antipredator strategies in response to current predation risk. Recently, it was proposed that predation risk also plastically induces neophobia (an antipredator response towards novel cues). Previous studies, however, do not allow a differentiation between general neophobia and sensory channel-specific neophobic responses. Therefore, we tested the neophobia hypothesis focusing on adjustment in shoaling behavior in response to a novel cue addressing a different sensory channel than the one from which predation risk was initially perceived. From hatching onwards, juveniles of the cichlid Pelvicachromis taeniatus were exposed to different chemical cues in a split-clutch design: conspecific alarm cues which signal predation risk and heterospecific alarm cues or distilled water as controls. At 2 months of age, their shoaling behavior was examined prior and subsequent to a tactical disturbance cue. We found that fish previously exposed to predation risk formed more compact shoals relative to the control groups in response to the novel disturbance cue. Moreover, the relationship between shoal density and shoal homogeneity was also affected by experienced predation risk. Our findings indicate predator-induced, increased cross-sensory sensitivity towards novel cues making neophobia an effective antipredator mechanism.
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13
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Guinea pigs reared in a monochromatic environment exhibit changes in cone density and opsin expression. Exp Eye Res 2011; 93:804-9. [PMID: 21978951 DOI: 10.1016/j.exer.2011.09.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 09/20/2011] [Accepted: 09/22/2011] [Indexed: 11/23/2022]
Abstract
This study aimed to determine if a monochromatic environment will affect the development of cones in a guinea pig model. Thirty 3-day-old guinea pigs were randomized into three groups and exposed to green, violet, and white light (control) for 8 weeks. The animals were sacrificed and the density of middle-wavelength cones (M cones) and short-wavelength sensitive (S cones) and expression of M-opsin and S-opsin were determined. The density of M cones was increased in the green light group as compared to the control group, and decreased in the violet light group as compared to the control group (both, p < 0.05). There was no significant difference in the density of the S cones among the groups (all, p > 0.05). The density of coexpressing cones in the middle retina was significantly increased in the green light group in comparison to the violet light group (p < 0.01). In addition, there was a significant increase in the level of M-opsin as determined by Western blotting and M-opsin mRNA expression as determined by PCR analysis in the green light group as compared to the control group and a significant decrease in violet light group as compared to the control group (all, p < 0.05). No significant difference in S-opsin level or S-opsin mRNA expression was noted among the groups. We concluded that monochromatic lighting affected the density of cones and expression of opsins in a guinea pig model, and this indicates that the retinal color visual system of the guinea pig possess developmental plasticity.
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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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15
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Hofmann CM, O'Quin KE, Marshall NJ, Cronin TW, Seehausen O, Carleton KL. The eyes have it: regulatory and structural changes both underlie cichlid visual pigment diversity. PLoS Biol 2009; 7:e1000266. [PMID: 20027211 PMCID: PMC2790343 DOI: 10.1371/journal.pbio.1000266] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 11/12/2009] [Indexed: 11/18/2022] Open
Abstract
A major goal of evolutionary biology is to unravel the molecular genetic mechanisms that underlie functional diversification and adaptation. We investigated how changes in gene regulation and coding sequence contribute to sensory diversification in two replicate radiations of cichlid fishes. In the clear waters of Lake Malawi, differential opsin expression generates diverse visual systems, with sensitivities extending from the ultraviolet to the red regions of the spectrum. These sensitivities fall into three distinct clusters and are correlated with foraging habits. In the turbid waters of Lake Victoria, visual sensitivity is constrained to longer wavelengths, and opsin expression is correlated with ambient light. In addition to regulatory changes, we found that the opsins coding for the shortest- and longest-wavelength visual pigments have elevated numbers of potentially functional substitutions. Thus, we present a model of sensory evolution in which both molecular genetic mechanisms work in concert. Changes in gene expression generate large shifts in visual pigment sensitivity across the collective opsin spectral range, but changes in coding sequence appear to fine-tune visual pigment sensitivity at the short- and long-wavelength ends of this range, where differential opsin expression can no longer extend visual pigment sensitivity.
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Affiliation(s)
- Christopher M Hofmann
- Department of Biology, University of Maryland, College Park, Maryland, United States of America.
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Shand J, Davies WL, Thomas N, Balmer L, Cowing JA, Pointer M, Carvalho LS, Trezise AEO, Collin SP, Beazley LD, Hunt DM. The influence of ontogeny and light environment on the expression of visual pigment opsins in the retina of the black bream, Acanthopagrus butcheri. ACTA ACUST UNITED AC 2008; 211:1495-503. [PMID: 18424684 DOI: 10.1242/jeb.012047] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The correlation between ontogenetic changes in the spectral absorption characteristics of retinal photoreceptors and expression of visual pigment opsins was investigated in the black bream, Acanthopagrus butcheri. To establish whether the spectral qualities of environmental light affected the complement of visual pigments during ontogeny, comparisons were made between fishes reared in: (1) broad spectrum aquarium conditions; (2) short wavelength-reduced conditions similar to the natural environment; or (3) the natural environment (wild-caught). Microspectrophotometry was used to determine the wavelengths of spectral sensitivity of the photoreceptors at four developmental stages: larval, post-settlement, juvenile and adult. The molecular sequences of the rod (Rh1) and six cone (SWS1, SWS2A and B, Rh2Aalpha and beta, and LWS) opsins were obtained and their expression levels in larval and adult stages examined using quantitative RT-PCR. The changes in spectral sensitivity of the cones were related to the differing levels of opsin expression during ontogeny. During the larval stage the predominantly expressed opsin classes were SWS1, SWS2B and Rh2Aalpha, contrasting with SWS2A, Rh2Abeta and LWS in the adult. An increased proportion of long wavelength-sensitive double cones was found in fishes reared in the short wavelength-reduced conditions and in wild-caught animals, indicating that the expression of cone opsin genes is also regulated by environmental light.
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Affiliation(s)
- Julia Shand
- School of Animal Biology, University of Western Australia, Crawley, WA 6009, Australia
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Malkki PE, Kröger RHH. Visualization of chromatic correction of fish lenses by multiple focal lengths. ACTA ACUST UNITED AC 2005. [DOI: 10.1088/1464-4258/7/11/012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
Colour vision greatly enhances the discriminatory and cognitive capabilities of visual systems and is found in a great majority of vertebrates and many invertebrates. However, colour coding visual systems are confronted with the fact that the external stimuli are ambiguous because they are subject to constant variations of luminance and spectral composition. Furthermore, the transmittance of the ocular media, the spectral sensitivity of visual pigments and the ratio of spectral cone types are also variable. This results in a situation where there is no fixed relationship between a stimulus and a colour percept. Colour constancy has been identified as a powerful mechanism to deal with this set of problems; however, it is active only in a short-term time range. Changes covering longer periods of time require additional tuning mechanisms at the photoreceptor level or at postreceptoral stages of chromatic processing. We have used the trichromatic blue acara (Aequidens pulcher, Cichlidae) as a model system and studied retinal morphology and physiology, and visually evoked behaviour after rearing fish for 1-2 years under various conditions including near monochromatic lights (spectral deprivation) and two intensities of white light (controls). In general, long-term exposure to long wavelengths light had lesser effects than light of middle and short wavelengths. Within the cone photoreceptors, spectral deprivation did not change the absorption characteristics of the visual pigments. By contrast, the outer segment length of middle and long-wave-sensitive cones was markedly increased in the blue rearing group. Furthermore, in the same group, we observed a loss of 65% short-wave-sensitive cones after 2 years. These changes may be interpreted as manifestations of compensatory mechanisms aimed at restoring the balance between the chromatic channels. At the horizontal cell level, the connectivity between short-wave-sensitive cones and the H2 cone horizontal cells, and the spinule dynamics were both affected in the blue light group. This observation rules out the role of spinules as sites of chromatic feedback synapses. The light-evoked responses of H2 horizontal cells were also sensitive to spectral deprivation showing a shift of the neutral point towards short wavelengths in the blue rearing group. Interestingly, we also found an intensity effect because in the group reared in bright white light the neutral point was more towards longer wavelength than in the dim light group. Like the changes in the cones, the reactions of horizontal cells to spectral deprivation in the long wave domain can be characterised as compensatory. We also tested the spectral sensitivity of the various experimental groups of blue acara in visually evoked behaviour using the optomotor response paradigm. In this case, the changes in the relative spectral sensitivity were more complex and could not be explained by a simple extrapolation of the adaptive and compensatory processes in the outer retina. We conclude that the inner retina, and/or the optic tectum are also involved and react to the changes of the spectral environment. In summary, we have shown a considerable developmental plasticity in the colour vision system of the blue acara, where epigenetic adaptive processes at various levels of the visual system respond to the specific spectral composition of the surroundings and provide a powerful mechanism to ensure functional colour vision in different visual environments. We suggest that processes involving an active fine-tuning of the photoreceptors and the postreceptoral processing of chromatic information during ontogenetic development are a general feature of all colour vision systems. Such mechanisms would establish a functional balance between the various chromatic channels. This appears to be an essential condition for the cognitive systems to extract the relevant and stable information from the unstable and changing stimulus situation.
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Affiliation(s)
- Hans-Joachim Wagner
- Eberhard-Karls Universität Tübingen, Graduate School of Neural and Behavioural Sciences and Max Planck Research School, Anatomisches Institut, Osterbergstrasse 3, 72074 Tübingen, Germany.
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Fuller RC, Carleton KL, Fadool JM, Spady TC, Travis J. Genetic and environmental variation in the visual properties of bluefin killifish, Lucania goodei. J Evol Biol 2005; 18:516-23. [PMID: 15842481 DOI: 10.1111/j.1420-9101.2005.00886.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Animals use their sensory systems to detect information about the external environment in order to find mates, locate food and habitat and avoid predators. Yet, there is little understanding of the relative amounts of genetic and/or environmental variation in sensory system properties. In this paper, we demonstrate genetic and environmental variation in opsin expression in a population of bluefin killifish. We measured expression of five opsins (which correlates with relative frequency of corresponding cones) using quantitative, real-time polymerase chain reaction for offspring from a breeding study where offspring were raised under different lighting conditions. Sire (i.e. genetic) effects were present for opsin found in yellow photopigment. Dam effects were present for opsins that create violet, blue and red photopigment. Lighting conditions affected expression of all opsins except SWS2A and mimicked the pattern found among populations. These results highlight the fact that sensory systems are both plastic and yet readily evolvable traits.
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Affiliation(s)
- R C Fuller
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4340, USA.
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Kröger RHH, Knoblauch B, Wagner HJ. Rearing in different photic and spectral environments changes the optomotor response to chromatic stimuli in the cichlid fish Aequidens pulcher. J Exp Biol 2003; 206:1643-8. [PMID: 12682096 DOI: 10.1242/jeb.00337] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Developmental plasticity of spectral processing in vertebrates was investigated in fish by using an innate behavior, the optomotor response. Rearing blue acara (Aequidens pulcher; Cichlidae) under white lights of different intensities as well as deprivation of long wavelengths induced significant changes in the animals' responses to chromatic stimuli. Deprivation of short wavelengths had no effect. With this and previous studies on animals reared under similar conditions, we have demonstrated that developmental plasticity in spectral processing is present at a wide range of neural levels, spanning from photoreceptors to behavior. We hypothesize that earlier studies did not reveal such effects because of the rearing and testing conditions used.
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Affiliation(s)
- Ronald H H Kröger
- Eberhard-Karls University Tübingen, Institute of Anatomy, Osterbergstrasse 3, 72074 Tübingen, Germany.
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Cheroske AG, Cronin TW, Caldwell RL. Adaptive color vision in Pullosquilla litoralis (Stomatopoda, Lysiosquilloidea) associated with spectral and intensity changes in light environment. J Exp Biol 2003; 206:373-9. [PMID: 12477907 DOI: 10.1242/jeb.00084] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Some stomatopod crustacean species that inhabit a range of habitat depths have color vision systems that adapt to changes in ambient light conditions. To date, this change in retinal function has been demonstrated in species within the superfamily Gonodactyloidea in response to varying the spectral range of light. Intrarhabdomal filters in certain ommatidia within the specialized midband of the eye change spectrally, modifying the sensitivity of underlying photoreceptors to match the spectrum of available light. In the present study, we utilized Pullosquilla litoralis, a member of the superfamily Lysiosquilloidea that also has a wide depth range. Individuals were placed within one of three light treatments: (1) full-spectrum, high-intensity 'white' light, (2) narrow-spectrum 'blue' light and (3) full-spectrum, reduced-intensity 'gray' light. After 3 months, the intrarhabdomal filters in Row 3 ommatidia of the midband in blue- and gray-light-treated animals were short-wavelength shifted by 10-20 nm compared with homologous filters in animals in white-light treatments. These spectral changes increase the relative sensitivity of associated photoreceptors in animals that inhabit environments where light spectral range or intensity is reduced. The adaptable color vision system of stomatopods may allow animals to make the best use of the ambient light occurring at their habitat regardless of depth. The major controlling element of the plasticity in lysiosquilloid stomatopod color vision appears to be light intensity rather than spectral distribution.
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Affiliation(s)
- Alexander G Cheroske
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA.
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