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van den Berg CP, Endler JA, Papinczak DEJ, Cheney KL. Using colour pattern edge contrast statistics to predict detection speed and success in triggerfish (Rhinecanthus aculeatus). J Exp Biol 2022; 225:285905. [PMID: 36354306 PMCID: PMC9789405 DOI: 10.1242/jeb.244677] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 10/26/2022] [Indexed: 11/12/2022]
Abstract
Edge detection is important for object detection and recognition. However, we do not know whether edge statistics accurately predict the detection of prey by potential predators. This is crucial given the growing availability of image analysis software and their application across non-human visual systems. Here, we investigated whether Boundary Strength Analysis (BSA), Local Edge Intensity Analysis (LEIA) and the Gabor edge disruption ratio (GabRat) could predict the speed and success with which triggerfish (Rhinecanthus aculeatus) detected patterned circular stimuli against a noisy visual background, in both chromatic and achromatic presentations. We found various statistically significant correlations between edge statistics and detection speed depending on treatment and viewing distance; however, individual pattern statistics only explained up to 2% of the variation in detection time, and up to 6% when considering edge statistics simultaneously. We also found changes in fish response over time. While highlighting the importance of spatial acuity and relevant viewing distances in the study of visual signals, our results demonstrate the importance of considering explained variation when interpreting colour pattern statistics in behavioural experiments. We emphasize the need for statistical approaches suitable for investigating task-specific predictive relationships and ecological effects when considering animal behaviour. This is particularly important given the ever-increasing dimensionality and size of datasets in the field of visual ecology.
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Affiliation(s)
- Cedric P. van den Berg
- Visual Ecology Lab, School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia,Author for correspondence ()
| | - John A. Endler
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC 3216, Australia
| | - Daniel E. J. Papinczak
- Visual Ecology Lab, School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Karen L. Cheney
- Visual Ecology Lab, School of Biological Sciences, The University of Queensland, St Lucia, QLD 4072, Australia
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Goiran C, Shine T, Shine R. The banded colour patterns of sea snakes discourage attack by predatory fishes, enabling Batesian mimicry by harmless species. Proc Biol Sci 2022; 289:20221759. [PMID: 36382516 PMCID: PMC9667369 DOI: 10.1098/rspb.2022.1759] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 10/30/2022] [Indexed: 02/26/2024] Open
Abstract
The evolution of bright 'warning' colours in nontoxic animals often is attributed to mimicry of toxic species, but empirical tests of that hypothesis must overcome the logistical challenge of quantifying differential rates of predation in nature. Populations of a harmless sea snake species (Emydocephalus annulatus) in New Caledonia exhibit colour polymorphism, with around 20% of individuals banded rather than melanic. Stability in that proportion over 20 years has been attributed to Batesian mimicry of deadly snake species by banded morphs of the harmless taxon. This hypothesis requires that banded colours reduce a snake's vulnerability to predation. We tested that idea by pulling flexible snake-shaped models through the water and recording responses by predatory fish. Black and banded lures attracted similar numbers of following fish, but attacks were directed almost exclusively to black lures. Our methods overcome several ambiguities associated with experimental studies on mimicry in terrestrial snakes and support the hypothesis that banded colour patterns reduce a non-venomous marine snake's vulnerability to predation.
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Affiliation(s)
- Claire Goiran
- LabEx Corail & ISEA, Université de la Nouvelle-Calédonie, BP R4, 98851 Nouméa cedex, New Caledonia
| | - Terri Shine
- School of Natural Sciences, Macquarie University, New South Wales 2109, Australia
| | - Richard Shine
- School of Natural Sciences, Macquarie University, New South Wales 2109, Australia
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Winsor AM, Pagoti GF, Daye DJ, Cheries EW, Cave KR, Jakob EM. What gaze direction can tell us about cognitive processes in invertebrates. Biochem Biophys Res Commun 2021; 564:43-54. [PMID: 33413978 DOI: 10.1016/j.bbrc.2020.12.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 11/30/2020] [Accepted: 12/01/2020] [Indexed: 01/29/2023]
Abstract
Most visually guided animals shift their gaze using body movements, eye movements, or both to gather information selectively from their environments. Psychological studies of eye movements have advanced our understanding of perceptual and cognitive processes that mediate visual attention in humans and other vertebrates. However, much less is known about how these processes operate in other organisms, particularly invertebrates. We here make the case that studies of invertebrate cognition can benefit by adding precise measures of gaze direction. To accomplish this, we briefly review the human visual attention literature and outline four research themes and several experimental paradigms that could be extended to invertebrates. We briefly review selected studies where the measurement of gaze direction in invertebrates has provided new insights, and we suggest future areas of exploration.
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Affiliation(s)
- Alex M Winsor
- Graduate Program in Organismic and Evolutionary Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA.
| | - Guilherme F Pagoti
- Programa de Pós-Graduação em Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, 321, Travessa 14, Cidade Universitária, São Paulo, SP, 05508-090, Brazil
| | - Daniel J Daye
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA; Graduate Program in Biological and Environmental Sciences, University of Rhode Island, Kingston, RI, 02881, USA
| | - Erik W Cheries
- Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Kyle R Cave
- Department of Psychological and Brain Sciences, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Elizabeth M Jakob
- Department of Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA.
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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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Marshall NJ, Cortesi F, de Busserolles F, Siebeck UE, Cheney KL. Colours and colour vision in reef fishes: Past, present and future research directions. JOURNAL OF FISH BIOLOGY 2019; 95:5-38. [PMID: 30357835 DOI: 10.1111/jfb.13849] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/22/2018] [Indexed: 06/08/2023]
Abstract
Many fishes, both freshwater or marine, have colour vision that may outperform humans. As a result, to understand the behavioural tasks that vision enables; including mate choice, feeding, agonistic behaviour and camouflage, we need to see the world through a fish's eye. This includes quantifying the variable light environment underwater and its various influences on vision. As well as rapid loss of light with depth, light attenuation underwater limits visual interaction to metres at most and in many instances, less than a metre. We also need to characterize visual sensitivities, fish colours and behaviours relative to both these factors. An increasingly large set of techniques over the past few years, including improved photography, submersible spectrophotometers and genetic sequencing, have taken us from intelligent guesswork to something closer to sensible hypotheses. This contribution to the special edition on the Ecology of Fish Senses under a shifting environment first reviews our knowledge of fish colour vision and visual ecology, past, present and very recent, and then goes on to examine how climate change may impinge on fish visual capability. The review is limited to mostly colour vision and to mostly reef fishes. This ignores a large body of work, both from other marine environments and freshwater systems, but the reef contains examples of many of the challenges to vision from the aquatic environment. It is also a concentrate of life, perhaps the most specious and complex on earth, suffering now catastrophically from the consequences of our lack of action on climate change. A clear course of action to prevent destruction of this habitat is the need to spend more time in it, in the study of it and sharing it with those not fortunate enough to see coral reefs first-hand. Sir David Attenborough on The Great Barrier Reef: "Do we really care so little about the Earth upon which we live that we don't wish to protect one of its greatest wonders from the consequences of our behaviours?"
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Affiliation(s)
- N Justin Marshall
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Fanny de Busserolles
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
| | - Uli E Siebeck
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Karen L Cheney
- Queensland Brain Institute, University of Queensland, Brisbane, Queensland, Australia
- School of Biology, University of Queensland, Brisbane, Queensland, Australia
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