1
|
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.
Collapse
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
| |
Collapse
|
2
|
Boycott TJ, Sherrard MG, Gall MD, Ronald KL. Deer management influences perception of avian plumage in temperate deciduous forests. Vision Res 2023; 213:108312. [PMID: 37703599 DOI: 10.1016/j.visres.2023.108312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 08/07/2023] [Accepted: 08/17/2023] [Indexed: 09/15/2023]
Abstract
Many animals use visual signals to communicate; birds use colorful plumage to attract mates and repel intruders. Visual signal conspicuousness is influenced by the lighting environment, which can be altered by human-induced changes. For example, deer-management efforts can affect vegetation structure and light availability. Whether these changes alter animal communication is still unknown. We investigated the effect of deer management on forest light and the contrast of understory birds against the forest background. We modeled visual perception using: (1) an ultraviolet-sensitive (UVS) avian model and plumage parameters representative of red, yellow, and blue birds (2) species-specific turkey visual and plumage parameters, and (3) individual-specific brown-headed cowbird visual and plumage parameters. Deer management led to greater light irradiance and lowered forest background reflectance. Management increased chromatic contrasts in the UVS model, primarily in deciduous forests and low understory, and across all habitat types in turkey and cowbird models. Deer management did not affect achromatic contrasts in the UVS model, but was associated with lower contrast in mixed forests for turkeys and across habitats for cowbirds. Together, this suggests that management of deer browsing is likely to impact visual signaling for a wide range of avian species. However, we also suspect that species- and individual-specific parameters increased the resolution of models, warranting consideration in future studies. Further work should determine if differences in visual perception translate to biologically relevant consequences. Our results suggest that, at least for some species, deer browsing and anthropogenic change may impose an evolutionary driver on visual communication.
Collapse
Affiliation(s)
- Timothy J Boycott
- Department of Biology, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604, USA; New York Cooperative Fish and Wildlife Research Unit, Department of Natural Resources and the Environment, Cornell University, 226 Mann Drive, Ithaca, NY 14853, USA
| | - Morgan G Sherrard
- Department of Biology, Hope College, 35 East 12th Street, Holland, MI 49423, USA; University of Detroit Mercy School of Dentistry, 2700 Martin Luther King Jr. Blvd. Detroit, MI 48208-2576, USA
| | - Megan D Gall
- Department of Biology, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604, USA; Neuroscience and Behavior Program, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604, USA
| | - Kelly L Ronald
- Department of Biology, Hope College, 35 East 12th Street, Holland, MI 49423, USA.
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
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.
Collapse
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
| |
Collapse
|
5
|
Tosetto L, Williamson JE, White TE, Hart NS. Can the Dynamic Colouration and Patterning of Bluelined Goatfish (Mullidae; Upeneichthys lineatus) Be Perceived by Conspecifics? BRAIN, BEHAVIOR AND EVOLUTION 2021; 96:103-123. [PMID: 34856558 DOI: 10.1159/000519894] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/17/2021] [Indexed: 06/13/2023]
Abstract
Bluelined goatfish (Upeneichthys lineatus) exhibit dynamic body colour changes and transform rapidly from a pale, buff/white, horizontally banded pattern to a conspicuous, vertically striped, red pattern when foraging. This red pattern is potentially an important foraging signal for communication with conspecifics, provided that U. lineatus can detect and discriminate the pattern. Using both physiological and behavioural experiments, we first examined whether U. lineatus possess visual pigments with sensitivity to long ("red") wavelengths of light, and whether they can discriminate the colour red. Microspectrophotometric measurements of retinal photoreceptors showed that while U. lineatuslack visual pigments dedicated to the red part of the spectrum, their pigments likely confer some sensitivity in this spectral band. Behavioural colour discrimination experiments suggested that U. lineatuscan distinguish a red reward stimulus from a grey distractor stimulus of variable brightness. Furthermore, when presented with red stimuli of varying brightness they could mostly discriminate the darker and lighter reds from the grey distractor. We also obtained anatomical estimates of visual acuity, which suggest that U. lineatus can resolve the contrasting bands of conspecifics approximately 7 m away in clear waters. Finally, we measured the spectral reflectance of the red and white colouration on the goatfish body. Visual models suggest that U. lineatus can discriminate both chromatic and achromatic differences in body colouration where longer wavelength light is available. This study demonstrates that U. lineatus have the capacity for colour vision and can likely discriminate colours in the long-wavelength region of the spectrum where the red body pattern reflects light strongly. The ability to see red may therefore provide an advantage in recognising visual signals from conspecifics. This research furthers our understanding of how visual signals have co-evolved with visual abilities, and the role of visual communication in the marine environment.
Collapse
Affiliation(s)
- Louise Tosetto
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Jane E Williamson
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
- Sydney Institute of Marine Science, Mosman, New South Wales, Australia
| | - Thomas E White
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - Nathan S Hart
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| |
Collapse
|
6
|
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.
Collapse
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
| |
Collapse
|
7
|
Yong L, Croft DP, Troscianko J, Ramnarine IW, Wilson AJ. Sensory-based quantification of male colour patterns in Trinidadian guppies reveals no support for parallel phenotypic evolution in multivariate trait space. Mol Ecol 2021; 31:1337-1357. [PMID: 34170592 DOI: 10.1111/mec.16039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/29/2021] [Accepted: 06/16/2021] [Indexed: 12/01/2022]
Abstract
Parallel evolution, in which independent populations evolve along similar phenotypic trajectories, offers insights into the repeatability of adaptive evolution. Here, we revisit a classic example of parallelism, that of repeated evolution of brighter males in the Trinidadian guppy (Poecilia reticulata). In guppies, colonisation of low predation habitats is associated with emergence of 'more colourful' phenotypes since predator-induced viability selection for crypsis weakens while sexual selection by female preference for conspicuousness remains strong. Our study differs from previous investigations in three respects. First, we adopted a multivariate phenotyping approach to characterise parallelism in multitrait space. Second, we used ecologically-relevant colour traits defined by the visual systems of the two selective agents (i.e., guppy, predatory cichlid). Third, we estimated population genetic structure to test for adaptive (parallel) evolution against a model of neutral phenotypic divergence. We find strong phenotypic differentiation that is inconsistent with a neutral model but very limited support for the predicted pattern of greater conspicuousness at low predation. Effects of predation regime on each trait were in the expected direction, but weak, largely nonsignificant, and explained little among-population variation. In multitrait space, phenotypic trajectories of lineages colonising low from high predation regimes were not parallel. Our results are consistent with reduced predation risk facilitating adaptive differentiation, potentially by female choice, but suggest that this proceeds in independent directions of multitrait space across lineages. Pool-sequencing data also revealed SNPs showing greater differentiation than expected under neutrality, among which some are found in genes contributing to colour pattern variation, presenting opportunities for future genetic study.
Collapse
Affiliation(s)
- Lengxob Yong
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK
| | - Darren P Croft
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Jolyon Troscianko
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK
| | - Indar W Ramnarine
- Department of Life Sciences, The University of The West Indies, St Augustine, Trinidad and Tobago
| | - Alastair J Wilson
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, UK
| |
Collapse
|
8
|
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
| |
Collapse
|
9
|
Sibeaux A, Camduras T, Endler JA. The role of boundary length and adjacent patch contrast in guppy mate choice. Behav Ecol 2020. [DOI: 10.1093/beheco/araa097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
The presence of various combinations of adjacent colors within polymorphic species’ color pattern could have a major impact on mate choice. We studied the role of pattern geometry in predicting mate choice in guppies using boundary strength analysis (BSA). BSA estimates the visual contrast intensity between two adjacent color patches (ΔS) weighted by the lengths of the boundaries between these adjacent color patches. We measured both the chromatic (hue and saturation) and achromatic (luminance) ΔS for each pair of adjacent patches. For each male’s color pattern, we measured BSA as both mean (mΔS) and coefficient of variation (cvΔS) of all ΔS weighted by their corresponding boundary lengths. We also determined if specific color patch boundaries had an impact on female preferences and whether these predicted overall male contrast (mΔS). We found that males with a higher mΔS were more attractive to females and that six boundaries containing either fuzzy black or black as one of the pair colors significantly affected female preferences, indicating that 1) females favored highly conspicuous males and 2) melanin-based patches could be used as a signal amplifier, not only for orange but for other colors.
Collapse
Affiliation(s)
- Adélaïde Sibeaux
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, Australia
| | - Thomas Camduras
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, Australia
| | - John A Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, Australia
| |
Collapse
|
10
|
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.
Collapse
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
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Fleishman LJ, Wadman CS, Maximov KJ. The interacting effects of total light intensity and chromatic contrast on visual signal visibility in an Anolis lizard. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
13
|
van den Berg CP, Troscianko J, Endler JA, Marshall NJ, Cheney KL. Quantitative Colour Pattern Analysis (QCPA): A comprehensive framework for the analysis of colour patterns in nature. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13328] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - John A. Endler
- School of Life & Environmental Sciences Deakin University Geelong Australia
| | - N. Justin Marshall
- Queensland Brain Institute The University of Queensland St Lucia QLD Australia
| | - Karen L. Cheney
- The School of Biological Sciences The University of Queensland St Lucia QLD Australia
- Queensland Brain Institute The University of Queensland St Lucia QLD Australia
| |
Collapse
|