1
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van den Berg CP, Santon M, Endler JA, Cheney KL. Highly defended nudibranchs "escape" to visually distinct background habitats. Behav Ecol 2024; 35:arae053. [PMID: 39086666 PMCID: PMC11289952 DOI: 10.1093/beheco/arae053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 06/06/2024] [Accepted: 07/03/2024] [Indexed: 08/02/2024] Open
Abstract
The "escape and radiate" hypothesis predicts that once species have evolved aposematism, defended species can utilize more visually diverse visual backgrounds as they "escape" the need to be well camouflaged. This enables species to explore new ecological niches, resulting in increased diversification rates. To test this hypothesis "escape" component, we examined whether the background habitats of 12 nudibranch mollusk species differed among species depending on the presence and strength of chemical defenses. We obtained a rich array of color pattern statistics using quantitative color pattern analysis to analyze backgrounds viewed through the eyes of a potential predator (triggerfish, Rhinecanthus aculeatus). Color pattern analysis was done at viewing distances simulating an escalating predation sequence. We identified 4 latent factors comprising 17 noncorrelated color pattern parameters, which captured the among-species variability associated with differences in chemical defenses. We found that chemically defended species, indeed, were found on visually distinct backgrounds with increased color and luminance contrast, independent of viewing distance. However, we found no evidence for increased among-species background diversity coinciding with the presence and strength of chemical defenses. Our results agree with the "escape and radiate" hypothesis, suggesting that potent chemical defenses in Dorid nudibranchs coincide with spatiochromatic differences of visual background habitats perceived by potential predators.
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Affiliation(s)
- Cedric P van den Berg
- School of the Environment, The University of Queensland, University Drive, St. Lucia, QLD 4072, Australia
- School of Biological Sciences, University of Bristol, 24 Tyndall Ave, Bristol, BS8 1TQ, United Kingdom
| | - Matteo Santon
- School of Biological Sciences, University of Bristol, 24 Tyndall Ave, Bristol, BS8 1TQ, United Kingdom
| | - John A Endler
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC 3216, Australia
| | - Karen L Cheney
- School of the Environment, The University of Queensland, University Drive, St. Lucia, QLD 4072, Australia
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2
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van den Berg CP, Santon M, Endler JA, Drummond L, Dawson BR, Santiago C, Weber N, Cheney KL. Chemical defences indicate bold colour patterns with reduced variability in aposematic nudibranchs. Proc Biol Sci 2024; 291:20240953. [PMID: 39013421 PMCID: PMC11251778 DOI: 10.1098/rspb.2024.0953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 05/31/2024] [Accepted: 05/31/2024] [Indexed: 07/18/2024] Open
Abstract
The selective factors that shape phenotypic diversity in prey communities with aposematic animals are diverse and coincide with similar diversity in the strength of underlying secondary defences. However, quantitative assessments of colour pattern variation and the strength of chemical defences in assemblages of aposematic species are lacking. We quantified colour pattern diversity using quantitative colour pattern analysis (QCPA) in 13 dorid nudibranch species (Infraorder: Doridoidei) that varied in the strength of their chemical defences. We accounted for the physiological properties of a potential predator's visual system (a triggerfish, Rhinecanthus aculeatus) and modelled the appearance of nudibranchs from multiple viewing distances (2 and 10 cm). We identified distinct colour pattern properties associated with the presence and strength of chemical defences. Specifically, increases in chemical defences indicated increases in colour pattern boldness (i.e. visual contrast elicited via either or potentially coinciding chromatic, achromatic and/or spatial contrast). Colour patterns were also less variable among species with chemical defences when compared to undefended species. Our results indicate correlations between secondary defences and diverse, bold colouration while showing that chemical defences coincide with decreased colour pattern variability among species. Our study suggests that complex spatiochromatic properties of colour patterns perceived by potential predators can be used to make inferences on the presence and strength of chemical defences.
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Affiliation(s)
- Cedric P. van den Berg
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
- Ecology of Vision Laboratory, School of Biological Sciences, University of Bristol, BristolBS8 1TQ, UK
| | - Matteo Santon
- Ecology of Vision Laboratory, School of Biological Sciences, University of Bristol, BristolBS8 1TQ, UK
| | - John A. Endler
- Zoology and Ecology, Tropical Environments Sciences, College of Science & Engineering, James Cook University, Cairns, QLD4878, Australia
| | - Leon Drummond
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
| | - Bethany R. Dawson
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
| | - Carl Santiago
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
| | - Nathalie Weber
- Faculty of Biology and Medicine, School of Biological Sciences, The University of Lausanne, Lausanne1015, Switzerland
| | - Karen L. Cheney
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
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3
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Mitchell LJ, Phelan A, Cortesi F, Marshall NJ, Chung WS, Osorio DC, Cheney KL. Ultraviolet vision in anemonefish improves colour discrimination. J Exp Biol 2024; 227:jeb247425. [PMID: 38586934 PMCID: PMC11057877 DOI: 10.1242/jeb.247425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 02/19/2024] [Indexed: 04/09/2024]
Abstract
In many animals, ultraviolet (UV) vision guides navigation, foraging, and communication, but few studies have addressed the contribution of UV signals to colour vision, or measured UV discrimination thresholds using behavioural experiments. Here, we tested UV colour vision in an anemonefish (Amphiprion ocellaris) using a five-channel (RGB-V-UV) LED display. We first determined that the maximal sensitivity of the A. ocellaris UV cone was ∼386 nm using microspectrophotometry. Three additional cone spectral sensitivities had maxima at ∼497, 515 and ∼535 nm. We then behaviourally measured colour discrimination thresholds by training anemonefish to distinguish a coloured target pixel from grey distractor pixels of varying intensity. Thresholds were calculated for nine sets of colours with and without UV signals. Using a tetrachromatic vision model, we found that anemonefish were better (i.e. discrimination thresholds were lower) at discriminating colours when target pixels had higher UV chromatic contrast. These colours caused a greater stimulation of the UV cone relative to other cone types. These findings imply that a UV component of colour signals and cues improves their detectability, which likely increases the prominence of anemonefish body patterns for communication and the silhouette of zooplankton prey.
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Affiliation(s)
- Laurie J. Mitchell
- School of the Environment, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
- Marine Eco-Evo-Devo Unit, Okinawa Institute of Science and Technology, Onna son, Okinawa 904-0495, Japan
| | - Amelia Phelan
- School of the Environment, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fabio Cortesi
- School of the Environment, The University of Queensland, Brisbane, QLD 4072, Australia
- 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
| | - Wen-sung Chung
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Daniel C. Osorio
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - Karen L. Cheney
- School of the Environment, The University of Queensland, Brisbane, QLD 4072, Australia
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4
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Stieb SM, Cortesi F, de Queiroz LJ, Carleton KL, Seehausen O, Marshall NJ. Long-wavelength-sensitive (lws) opsin gene expression, foraging and visual communication in coral reef fishes. Mol Ecol 2023; 32:1656-1672. [PMID: 36560895 PMCID: PMC10065935 DOI: 10.1111/mec.16831] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 11/25/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
Coral reef fishes are diverse in ecology and behaviour and show remarkable colour variability. Investigating the visual pigment gene (opsin) expression in these fishes makes it possible to associate their visual genotype and phenotype (spectral sensitivities) to visual tasks, such as feeding strategy or conspecific detection. By studying all major damselfish clades (Pomacentridae) and representatives from five other coral reef fish families, we show that the long-wavelength-sensitive (lws) opsin is highly expressed in algivorous and less or not expressed in zooplanktivorous species. Lws is also upregulated in species with orange/red colours (reflectance >520 nm) and expression is highest in orange/red-coloured algivores. Visual models from the perspective of a typical damselfish indicate that sensitivity to longer wavelengths does enhance the ability to detect the red to far-red component of algae and orange/red-coloured conspecifics, possibly enabling social signalling. Character state reconstructions indicate that in the early evolutionary history of damselfishes, there was no lws expression and no orange/red coloration. Omnivory was most often the dominant state. Although herbivory was sometimes dominant, zooplanktivory was never dominant. Sensitivity to long wavelength (increased lws expression) only emerged in association with algivory but never with zooplanktivory. Higher lws expression is also exploited by social signalling in orange/red, which emerged after the transition to algivory. Although the relative timing of traits may deviate by different reconstructions and alternative explanations are possible, our results are consistent with sensory bias whereby social signals evolve as a correlated response to natural selection on sensory system properties in other contexts.
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Affiliation(s)
- Sara M. Stieb
- Centre for Ecology, Evolution and Biogeochemistry (CEEB), EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, Switzerland
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Luiz Jardim de Queiroz
- Centre for Ecology, Evolution and Biogeochemistry (CEEB), EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, Switzerland
| | - Karen L. Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ole Seehausen
- Centre for Ecology, Evolution and Biogeochemistry (CEEB), EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, Switzerland
| | - N. Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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5
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Yilmaz A, Hempel de Ibarra N, Kelber A. High diversity of arthropod colour vision: from genes to ecology. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210273. [PMID: 36058249 PMCID: PMC9441235 DOI: 10.1098/rstb.2021.0273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/17/2022] [Indexed: 11/16/2022] Open
Abstract
Colour vision allows animals to use the information contained in the spectrum of light to control important behavioural decisions such as selection of habitats, food or mates. Among arthropods, the largest animal phylum, we find completely colour-blind species as well as species with up to 40 different opsin genes or more than 10 spectral types of photoreceptors, we find a large diversity of optical methods shaping spectral sensitivity, we find eyes with different colour vision systems looking into the dorsal and ventral hemisphere, and species in which males and females see the world in different colours. The behavioural use of colour vision shows an equally astonishing diversity. Only the neural mechanisms underlying this sensory ability seems surprisingly conserved-not only within the phylum, but even between arthropods and the other well-studied phylum, chordates. The papers in this special issue allow a glimpse into the colourful world of arthropod colour vision, and besides giving an overview this introduction highlights how much more research is needed to fill in the many missing pieces of this large puzzle. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'.
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Affiliation(s)
- Ayse Yilmaz
- Department of Biology - Functional Zoology, Lund University, Lund 22362, Sweden
| | | | - Almut Kelber
- Department of Biology - Functional Zoology, Lund University, Lund 22362, Sweden
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6
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Hempel de Ibarra N, Holtze S, Bäucker C, Sprau P, Vorobyev M. The role of colour patterns for the recognition of flowers by bees. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210284. [PMID: 36058248 PMCID: PMC9441241 DOI: 10.1098/rstb.2021.0284] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/28/2022] [Indexed: 11/26/2022] Open
Abstract
Bees discriminate between many different colours of flower petals, but it is not well understood how they perceive and learn patterns frequently found in flowers with colourful structures. We used multi-spectral imaging to explore chromatic cues in concentric flower patterns as they are seen through the low-resolution eyes of the honeybee. We find a diversity of colour combinations, which suggests that plants might exploit the sensory capabilities of pollinators, like bees, that learn colours easily. A consistent feature is that the surround of the pattern has a stronger chromatic contrast to the foliage background than the centre. This can potentially facilitate the fast identification of floral objects within colourful scenes when a foraging bee moves through a flower patch. In behavioural experiments we trained and tested bees with three types of concentric patterns. They recognized and discriminated patterns accurately in most tests, relying flexibly on both chromatic and spatial cues. Only rarely, depending on the training stimulus, chromatic cues determined their choices whilst pattern cues were ignored. The variability of floral designs and the bees' flexibility in recalling colour and spatial information suggest a role for colour vision in pattern processing. Implications for the signalling strategies of flowers are discussed. This article is part of the theme issue 'Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods'.
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Affiliation(s)
- Natalie Hempel de Ibarra
- Centre for Research in Animal Behaviour, Department of Psychology, University of Exeter, Exeter, UK
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Susanne Holtze
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Cornelia Bäucker
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Philipp Sprau
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Misha Vorobyev
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
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7
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Cheney KL, Hudson J, de Busserolles F, Luehrmann M, Shaughnessy A, van den Berg C, Green NF, Marshall NJ, Cortesi F. Seeing Picasso: an investigation into the visual system of the triggerfish Rhinecanthus aculeatus. J Exp Biol 2022; 225:jeb243907. [PMID: 35244167 PMCID: PMC9080752 DOI: 10.1242/jeb.243907] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 02/25/2022] [Indexed: 11/20/2022]
Abstract
Vision is used by animals to find food and mates, avoid predators, defend resources and navigate through complex habitats. Behavioural experiments are essential for understanding animals' perception but are often challenging and time-consuming; therefore, using species that can be trained easily for complex tasks is advantageous. Picasso triggerfish, Rhinecanthus aculeatus, have been used in many behavioural studies investigating vision and navigation. However, little is known about the molecular and anatomical basis of their visual system. We addressed this knowledge gap here and behaviourally tested achromatic and chromatic acuity. In terms of visual opsins, R. aculeatus possessed one rod opsin gene (RH1) and at least nine cone opsins: one violet-sensitive SWS2B gene, seven duplicates of the blue-green-sensitive RH2 gene (RH2A, RH2B, RH2C1-5) and one red-sensitive LWS gene. However, only five cone opsins were expressed: SWS2B expression was consistent, while RH2A, RH2C-1 and RH2C-2 expression varied depending on whether fish were sampled from the field or aquaria. Levels of LWS expression were very low. Using fluorescence in situ hybridisation, we found SWS2B was expressed exclusively in single cones, whereas RH2A and RH2Cs were expressed in opposite double cone members. Anatomical resolution estimated from ganglion cell densities was 6.8 cycles per degree (cpd), which was significantly higher than values obtained from behavioural testing for black-and-white achromatic stimuli (3.9 cpd) and chromatic stimuli (1.7-1.8 cpd). These measures were twice as high as previously reported. This detailed information on their visual system will help inform future studies with this emerging focal species.
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Affiliation(s)
- Karen L. Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jemma Hudson
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Martin Luehrmann
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Abigail Shaughnessy
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Cedric van den Berg
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Naomi F. Green
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - N. Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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8
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Green NF, Guevara E, Osorio DC, Endler JA, Marshall NJ, Vorobyev M, Cheney KL. Color discrimination thresholds vary throughout color space in a reef fish (Rhinecanthus aculeatus). J Exp Biol 2022; 225:274644. [PMID: 35258087 PMCID: PMC9080749 DOI: 10.1242/jeb.243533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 03/02/2022] [Indexed: 11/20/2022]
Abstract
Animal use color vision in a range of behaviours. Visual performance is limited by thresholds, which are set by noise in photoreceptors and subsequent neural processing. The receptor noise limited (RNL) model of color discrimination is widely used for modelling color vision and accounts well for experimental data from many species. In one of the most comprehensive tests yet of color discrimination in a non-human species, we using Ishihara-style stimulus patterns to examine thresholds for 21 directions at five locations in color space for the fish Rhineacanthus aculeatus. Thresholds matched RNL model predictions most closely for stimuli near to the the achromatic point, but exceeded predictions (indicating a decline in sensitivity) with distance from this point. Thresholds were also usually higher for saturation than for hue differences. These changes in color threshold with color space location and direction may give insight into photoreceptor non-linearities and post-receptoral mechanisms of color vision in fish. Our results highlight the need for a cautious interpretation of the RNL model - especially for modelling colours that differ from one another in saturation (rather than hue), and especially for highly saturated colours distant from the achromatic point in colour space.
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Affiliation(s)
- Naomi F Green
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Emily Guevara
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Daniel C Osorio
- School of Life Sciences, The University of Sussex, Falmer, Brighton, BN1 9QG, UK
| | - John A Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Victoria, 3216, Australia
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Misha Vorobyev
- Department of Optometry and Vision Science, The University of Auckland, Auckland 1142, New Zealand
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, 4072, Australia
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9
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González Bardeci N, Lagorio MG. A mathematical approach to assess the ability of light filters to improve color discriminability of color vision deficient persons. Heliyon 2021; 7:e08058. [PMID: 34622063 PMCID: PMC8482439 DOI: 10.1016/j.heliyon.2021.e08058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 06/26/2021] [Accepted: 09/20/2021] [Indexed: 11/25/2022] Open
Abstract
Color vision deficiency (CVD) is a frequent condition that alters color perception to such an extent that many people encounter serious difficulties on their everyday lives. In this work, we present a strategy to analyze the effectiveness of light filters aimed to improve color discriminability of persons with CVD. The calculations are based on a simple model of color discrimination which has been successfully applied to several animal species. We first tested the calculations on three well-known commercial lenses designed for persons with CVD. In agreement with results of clinical studies, the calculations show that the highly colored lenses (VINO® and X-Chrom®) enhance chromaticity contrasts between problematic colors, whereas the more neutral Enchroma® do not provide any benefit. Also, we predict that two light filters proposed in recent works for novel lenses would not improve the performance of the commercial ones. Since the mathematical approach presented in this work enables predictive filter assessment, it opens the door to future research on the design of more effective lenses to improve color discriminability of persons with CVD. The calculations allow for large-scale screening of numerous light filters and different colored stimuli, CVD conditions, light sources, etc.
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Affiliation(s)
- Nicolás González Bardeci
- CONICET, Universidad de Buenos Aires, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria. Pabellón II, 1er piso, C1428EHA, Buenos Aires, Argentina
| | - María Gabriela Lagorio
- CONICET, Universidad de Buenos Aires, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Buenos Aires, Argentina.,Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria. Pabellón II, 1er piso, C1428EHA, Buenos Aires, Argentina
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10
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Toomey MB, Ronald KL. Avian color expression and perception: is there a carotenoid link? J Exp Biol 2021; 224:269205. [PMID: 34142139 DOI: 10.1242/jeb.203844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Carotenoids color many of the red, orange and yellow ornaments of birds and also shape avian vision. The carotenoid-pigmented oil droplets in cone photoreceptors filter incoming light and are predicted to aid in color discrimination. Carotenoid use in both avian coloration and color vision raises an intriguing question: is the evolution of visual signals and signal perception linked through these pigments? Here, we explore the genetic, physiological and functional connections between these traits. Carotenoid color and droplet pigmentation share common mechanisms of metabolic conversion and are both affected by diet and immune system challenges. Yet, the time scale and magnitude of these effects differ greatly between plumage and the visual system. Recent observations suggest a link between retinal carotenoid levels and color discrimination performance, but the mechanisms underlying these associations remain unclear. Therefore, we performed a modeling exercise to ask whether and how changes in droplet carotenoid content could alter the perception of carotenoid-based plumage. This exercise revealed that changing oil droplet carotenoid concentration does not substantially affect the discrimination of carotenoid-based colors, but might change how reliably a receiver can predict the carotenoid content of an ornament. These findings suggest that, if present, a carotenoid link between signal and perception is subtle. Deconstructing this relationship will require a deeper understanding of avian visual perception and the mechanisms of color production. We highlight several areas where we see opportunities to gain new insights, including comparative genomic studies of shared mechanisms of carotenoid processing and alternative approaches to investigating color vision.
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Affiliation(s)
- Matthew B Toomey
- Department of Biological Science, University of Tulsa, 800 S Tucker Dr., Tulsa, OK 74104, USA
| | - Kelly L Ronald
- Department of Biology, Hope College, 35 East 12th Street, Holland, MI 49422, USA
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11
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Silvasti SA, Valkonen JK, Nokelainen O. Behavioural thresholds of blue tit colour vision and the effect of background chromatic complexity. Vision Res 2021; 182:46-57. [PMID: 33596523 DOI: 10.1016/j.visres.2020.11.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 10/23/2020] [Accepted: 11/04/2020] [Indexed: 01/09/2023]
Abstract
Vision is a vital attribute to foraging, navigation, mate selection and social signalling in animals, which often have a very different colour perception in comparison to humans. For understanding how animal colour perception works, vision models provide the smallest colour difference that animals of a given species are assumed to detect. To determine the just-noticeable-difference, or JND, vision models use Weber fractions that set discrimination thresholds of a stimulus compared to its background. However, although vision models are widely used, they rely on assumptions of Weber fractions since the exact fractions are unknown for most species. Here, we test; i) which Weber fractions in long-, middle- and shortwave (i.e. L, M, S) colour channels best describe the blue tit (Cyanistes caeruleus) colour discrimination, ii) how changes in hue of saturated colours and iii) chromatic background noise impair search behaviour in blue tits. We show that the behaviourally verified Weber fractions on achromatic backgrounds were L: 0.05, M: 0.03 and S: 0.03, indicating a high colour sensitivity. In contrast, on saturated chromatic backgrounds, the correct Weber fractions were considerably higher for L: 0.20, M: 0.17 and S: 0.15, indicating a less detailed colour perception. Chromatic complexity of backgrounds affected the longwave channel, while middle- and shortwave channels were mostly unaffected. We caution that using a vision model whereby colour discrimination is determined in achromatic viewing conditions, as they often are, can lead to misleading interpretations of biological interactions in natural - colourful - environments.
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Affiliation(s)
- Sanni A Silvasti
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland.
| | - Janne K Valkonen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
| | - Ossi Nokelainen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
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12
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Powell SB, Mitchell LJ, Phelan AM, Cortesi F, Marshall J, Cheney KL. A five‐channel LED display to investigate UV perception. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13555] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Samuel B. Powell
- Queensland Brain Institute The University of Queensland St Lucia Qld Australia
| | - Laurie J. Mitchell
- School of Biological Sciences The University of Queensland St Lucia Qld Australia
| | - Amelia M. Phelan
- School of Biological Sciences The University of Queensland St Lucia Qld Australia
| | - Fabio Cortesi
- Queensland Brain Institute The University of Queensland St Lucia Qld Australia
| | - Justin Marshall
- Queensland Brain Institute The University of Queensland St Lucia Qld Australia
| | - Karen L. Cheney
- School of Biological Sciences The University of Queensland St Lucia Qld Australia
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13
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Caves EM, Green PA, Zipple MN, Bharath D, Peters S, Johnsen S, Nowicki S. Comparison of Categorical Color Perception in Two Estrildid Finches. Am Nat 2020; 197:190-202. [PMID: 33523788 DOI: 10.1086/712379] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractSensory systems are predicted to be adapted to the perception of important stimuli, such as signals used in communication. Prior work has shown that female zebra finches perceive the carotenoid-based orange-red coloration of male beaks-a mate choice signal-categorically. Specifically, females exhibited an increased ability to discriminate between colors from opposite sides of a perceptual category boundary than equally different colors from the same side of the boundary. The Bengalese finch, an estrildid finch related to the zebra finch, is black, brown, and white, lacking carotenoid coloration. To explore the relationship between categorical color perception and signal use, we tested Bengalese finches using the same orange-red continuum as in zebra finches, and we also tested how both species discriminated among colors differing systematically in hue and brightness. Unlike in zebra finches, we found no evidence of categorical perception of an orange-red continuum in Bengalese finches. Instead, we found that the combination of chromatic distance (hue difference) and Michelson contrast (difference in brightness) strongly correlated with color discrimination ability on all tested color pairs in Bengalese finches. The pattern was different in zebra finches: this strong correlation held when discriminating between colors from different categories but not when discriminating between colors from within the same category. These experiments suggest that categorical perception is not a universal feature of avian-or even estrildid finch-vision. Our findings also provide further insights into the mechanism underlying categorical perception and are consistent with the hypothesis that categorical perception is adapted for signal perception.
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14
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van den Berg CP, Hollenkamp M, Mitchell LJ, Watson EJ, Green NF, Marshall NJ, Cheney KL. More than noise: context-dependent luminance contrast discrimination in a coral reef fish ( Rhinecanthus aculeatus). J Exp Biol 2020; 223:jeb232090. [PMID: 32967998 DOI: 10.1242/jeb.232090] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/11/2020] [Indexed: 01/19/2023]
Abstract
Achromatic (luminance) vision is used by animals to perceive motion, pattern, space and texture. Luminance contrast sensitivity thresholds are often poorly characterised for individual species and are applied across a diverse range of perceptual contexts using over-simplified assumptions of an animal's visual system. Such thresholds are often estimated using the receptor noise limited model (RNL). However, the suitability of the RNL model to describe luminance contrast perception remains poorly tested. Here, we investigated context-dependent luminance discrimination using triggerfish (Rhinecanthus aculeatus) presented with large achromatic stimuli (spots) against uniform achromatic backgrounds of varying absolute and relative contrasts. 'Dark' and 'bright' spots were presented against relatively dark and bright backgrounds. We found significant differences in luminance discrimination thresholds across treatments. When measured using Michelson contrast, thresholds for bright spots on a bright background were significantly higher than for other scenarios, and the lowest threshold was found when dark spots were presented on dark backgrounds. Thresholds expressed in Weber contrast revealed lower thresholds for spots darker than their backgrounds, which is consistent with the literature. The RNL model was unable to estimate threshold scaling across scenarios as predicted by the Weber-Fechner law, highlighting limitations in the current use of the RNL model to quantify luminance contrast perception. Our study confirms that luminance contrast discrimination thresholds are context dependent and should therefore be interpreted with caution.
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Affiliation(s)
- Cedric P van den Berg
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Michelle Hollenkamp
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Laurie J Mitchell
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Erin J Watson
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Naomi F Green
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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15
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Tietbohl MD, Hardenstine RS, Tanabe LK, Hulver AM, Berumen ML. Intentional partial beaching in a coral reef fish: a newly recorded hunting behaviour of titan triggerfish, Balistoides viridescens. JOURNAL OF FISH BIOLOGY 2020; 97:1569-1572. [PMID: 32864738 DOI: 10.1111/jfb.14513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/17/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
Coral reef fishes use a multitude of diverse feeding behaviours to increase their ability to successfully capture a wide range of prey. Here, this study reports a novel hunting behaviour in a coral reef fish, the titan triggerfish, Balistoides viridescens, where an individual was seen partially beaching itself while attempting to catch a Red Sea ghost crab, Ocypode saratan. This is the first report of this behaviour in the order Tetraodontiformes and represents an astonishing capability of this species to exploit food resources outside their typical assumed ecological niche.
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Affiliation(s)
- Matthew D Tietbohl
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Royale S Hardenstine
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Lyndsey K Tanabe
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Ann Marie Hulver
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Michael L Berumen
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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16
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Carleton KL, Yourick MR. Axes of visual adaptation in the ecologically diverse family Cichlidae. Semin Cell Dev Biol 2020; 106:43-52. [PMID: 32439270 PMCID: PMC7486233 DOI: 10.1016/j.semcdb.2020.04.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 04/21/2020] [Accepted: 04/21/2020] [Indexed: 02/07/2023]
Abstract
The family Cichlidae contains approximately 2000 species that live in diverse freshwater habitats including murky lakes, turbid rivers, and clear lakes from both the Old and New Worlds. Their visual systems are similarly diverse and have evolved specific sensitivities that differ along several axes of variation. Variation in cornea and lens transmission affect which wavelengths reach the retina. Variation in photoreceptor number and distribution affect brightness sensitivity, spectral sensitivity and resolution. Probably their most dynamic characteristic is the variation in visual pigment peak sensitivities. Visual pigments can be altered through changes in chromophore, opsin sequence and opsin expression. Opsin expression varies by altering which of the seven available cone opsins in their genomes are turned on. These opsins can even be coexpressed to produce seemingly infinitely tunable cone sensitivities. Both chromophore and opsin expression can vary on either rapid (hours or days), slower (seasonal or ontogenetic) or evolutionary timescales. Such visual system shifts have enabled cichlids to adapt to different habitats and foraging styles. Through both short term plasticity and longer evolutionary adaptations, cichlids have proven to be ecologically successful and an excellent model for studying organismal adaptation.
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Affiliation(s)
- Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Miranda R Yourick
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
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17
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Santiago C, Green NF, Hamilton N, Endler JA, Osorio DC, Marshall NJ, Cheney KL. Does conspicuousness scale linearly with colour distance? A test using reef fish. Proc Biol Sci 2020; 287:20201456. [PMID: 32933449 DOI: 10.1098/rspb.2020.1456] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To be effective, animal colour signals must attract attention-and therefore need to be conspicuous. To understand the signal function, it is useful to evaluate their conspicuousness to relevant viewers under various environmental conditions, including when visual scenes are cluttered by objects of varying colour. A widely used metric of colour difference (ΔS) is based on the receptor noise limited (RNL) model, which was originally proposed to determine when two similar colours appear different from one another, termed the discrimination threshold (or just noticeable difference). Estimates of the perceptual distances between colours that exceed this threshold-termed 'suprathreshold' colour differences-often assume that a colour's conspicuousness scales linearly with colour distance, and that this scale is independent of the direction in colour space. Currently, there is little behavioural evidence to support these assumptions. This study evaluated the relationship between ΔS and conspicuousness in suprathreshold colours using an Ishihara-style test with a coral reef fish, Rhinecanthus aculeatus. As our measure of conspicuousness, we tested whether fish, when presented with two colourful targets, preferred to peck at the one with a greater ΔS - from the average distractor colour. We found the relationship between ΔS and conspicuousness followed-- a sigmoidal function, with high ΔS colours perceived as equally conspicuous. We found that the relationship between ΔS and conspicuousness varied across colour space (i.e. for different hues). The sigmoidal detectability curve was little affected by colour variation in the background or when colour distance was calculated using a model that does not incorporate receptor noise. These results suggest that the RNL model may provide accurate estimates for perceptual distance for small suprathreshold distance colours, even in complex viewing environments, but must be used with caution with perceptual distances exceeding- -10 ΔS.
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Affiliation(s)
- Carl Santiago
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Naomi F Green
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072 Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Nadia Hamilton
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - John A Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Daniel C Osorio
- School of Life Sciences, The University of Sussex, Brighton BN1 9QG, UK
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072 Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, Queensland 4072 Australia
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18
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Cortesi F, Mitchell LJ, Tettamanti V, Fogg LG, de Busserolles F, Cheney KL, Marshall NJ. Visual system diversity in coral reef fishes. Semin Cell Dev Biol 2020; 106:31-42. [PMID: 32593517 DOI: 10.1016/j.semcdb.2020.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 06/12/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023]
Abstract
Coral reefs are one of the most species rich and colourful habitats on earth and for many coral reef teleosts, vision is central to their survival and reproduction. The diversity of reef fish visual systems arises from variations in ocular and retinal anatomy, neural processing and, perhaps most easily revealed by, the peak spectral absorbance of visual pigments. This review examines the interplay between retinal morphology and light environment across a number of reef fish species, but mainly focusses on visual adaptations at the molecular level (i.e. visual pigment structure). Generally, visual pigments tend to match the overall light environment or micro-habitat, with fish inhabiting greener, inshore waters possessing longer wavelength-shifted visual pigments than open water blue-shifted species. In marine fishes, particularly those that live on the reef, most species have between two (likely dichromatic) to four (possible tetrachromatic) cone spectral sensitivities and a single rod for crepuscular vision; however, most are trichromatic with three spectral sensitivities. In addition to variation in spectral sensitivity number, spectral placement of the absorbance maximum (λmax) also has a surprising degree of variability. Variation in ocular and retinal anatomy is also observed at several levels in reef fishes but is best represented by differences in arrangement, density and distribution of neural cell types across the retina (i.e. retinal topography). Here, we focus on the seven reef fish families most comprehensively studied to date to examine and compare how behaviour, environment, activity period, ontogeny and phylogeny might interact to generate the exceptional diversity in visual system design that we observe.
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Affiliation(s)
- Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia.
| | - Laurie J Mitchell
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia; School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Valerio Tettamanti
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Lily G Fogg
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, St Lucia, Queensland 4072, Australia
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19
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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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20
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Caves EM, Nowicki S, Johnsen S. Von Uexküll Revisited: Addressing Human Biases in the Study of Animal Perception. Integr Comp Biol 2020; 59:1451-1462. [PMID: 31127268 DOI: 10.1093/icb/icz073] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
More than 100 years ago, the biologist Jakob von Uexküll suggested that, because sensory systems are diverse, animals likely inhabit different sensory worlds (umwelten) than we do. Since von Uexküll, work across sensory modalities has confirmed that animals sometimes perceive sensory information that humans cannot, and it is now well-established that one must account for this fact when studying an animal's behavior. We are less adept, however, at recognizing cases in which non-human animals may not detect or perceive stimuli the same way we do, which is our focus here. In particular, we discuss three ways in which our own perception can result in misinformed hypotheses about the function of various stimuli. In particular, we may (1) make untested assumptions about how sensory information is perceived, based on how we perceive or measure it, (2) attribute undue significance to stimuli that we perceive as complex or striking, and (3) assume that animals divide the sensory world in the same way that we as scientists do. We discuss each of these biases and provide examples of cases where animals cannot perceive or are not attending to stimuli in the same way that we do, and how this may lead us to mistaken assumptions. Because what an animal perceives affects its behavior, we argue that these biases are especially important for researchers in sensory ecology, cognition, and animal behavior and communication to consider. We suggest that studying animal umwelten requires integrative approaches that combine knowledge of sensory physiology with behavioral assays.
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Affiliation(s)
| | | | - Sönke Johnsen
- Biology Department, Duke University, Durham, NC, USA
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21
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22
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Escobar-Camacho D, Taylor MA, Cheney KL, Green NF, Marshall NJ, Carleton KL. Color discrimination thresholds in a cichlid fish: Metriaclima benetos. J Exp Biol 2019; 222:jeb201160. [PMID: 31399486 PMCID: PMC6765173 DOI: 10.1242/jeb.201160] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 08/05/2019] [Indexed: 01/31/2023]
Abstract
Color vision is essential for animals as it allows them to detect, recognize and discriminate between colored objects. Studies analyzing color vision require an integrative approach, combining behavioral experiments, physiological models and quantitative analyses of photoreceptor stimulation. Here, we demonstrate, for the first time, the limits of chromatic discrimination in Metriaclima benetos, a rock-dwelling cichlid from Lake Malawi, using behavioral experiments and visual modeling. Fish were trained to discriminate between colored stimuli. Color discrimination thresholds were quantified by testing fish chromatic discrimination between the rewarded stimulus and distracter stimuli that varied in chromatic distance (ΔS). This was done under fluorescent lights alone and with additional violet lights. Our results provide two main outcomes. First, cichlid color discrimination thresholds correspond with predictions from the receptor noise limited (RNL) model but only if we assume a Weber fraction higher than the typical value of 5%. Second, cichlids may exhibit limited color constancy under certain lighting conditions as most individuals failed to discriminate colors when violet light was added. We further used the color discrimination thresholds obtained from these experiments to model color discrimination of actual fish colors and backgrounds under natural lighting for Lake Malawi. We found that, for M. benetos, blue is most chromatically contrasting against yellows and space-light, which might be important for discriminating male nuptial colorations and detecting males against the background. This study highlights the importance of lab-based behavioral experiments in understanding color vision and in parameterizing the assumptions of the RNL vision model for different species.
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Affiliation(s)
| | - Michaela A Taylor
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia
| | - Naomi F Green
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - N Justin Marshall
- Queensland Brain Institute, University of Queensland, Brisbane, QLD 4072, Australia
| | - Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
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23
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Knight K. Colour blindness test gets submerged. J Exp Biol 2019. [DOI: 10.1242/jeb.195818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Tettamanti V, de Busserolles F, Lecchini D, Marshall NJ, Cortesi F. Visual system development of the spotted unicornfish, Naso brevirostris (Acanthuridae). J Exp Biol 2019; 222:jeb.209916. [DOI: 10.1242/jeb.209916] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 11/22/2019] [Indexed: 12/28/2022]
Abstract
Ontogenetic changes of the visual system are often correlated to shifts in habitat and feeding behaviour of animals. Coral reef fishes begin their lives in the pelagic zone and then migrate to the reef. This habitat transition frequently involves a change in diet and light environment as well as major morphological modifications. The spotted unicornfish, Naso brevirostris, is known to shift diet from zooplankton to algae and back to mainly zooplankton when transitioning from larval to juvenile and then to adult stages. Concurrently, N. brevirostris also moves from an open pelagic to a coral-associated habitat before migrating up in the water column when reaching adulthood. Using retinal mapping techniques, we discovered that the distribution and density of ganglion and photoreceptor cells in N. brevirostris mostly changes during the transition from the larval to the juvenile stage, with only minor modifications thereafter. Similarly, visual gene (opsin) expression based on RNA sequencing, although qualitatively similar between stages (all fishes mainly expressed the same three cone opsins; SWS2B, RH2B, RH2A), also showed the biggest quantitative difference when transitioning from larvae to juveniles. The juvenile stage in particular seems mismatched with its reef-associated ecology, which may be due to this stage only lasting a fraction of the lifespan of these fishes. Hence, the visual ontogeny found in N. brevirostris is very different from the progressive changes found in other reef fishes calling for a thorough analysis of visual system development of the reef fish community.
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Affiliation(s)
- Valerio Tettamanti
- Queensland Brain Institute, The University of Queensland, 4072 Brisbane, Australia
- Swiss Federal Institute of Technology Zurich, 8092 Zurich, Switzerland
| | - Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, 4072 Brisbane, Australia
| | - David Lecchini
- PSL Research University: EPHE-UPVD-CNRS, USR3278 CRIOBE, BP 1013, 98729 Papetoai, Moorea, French Polynesia
- Laboratoire d'Excellence “CORAIL”, Paris, France
| | - N. Justin Marshall
- Queensland Brain Institute, The University of Queensland, 4072 Brisbane, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, 4072 Brisbane, Australia
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