1
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Tan M, Zhang S, Stevens M, Li D, Tan EJ. Antipredator defences in motion: animals reduce predation risks by concealing or misleading motion signals. Biol Rev Camb Philos Soc 2024; 99:778-796. [PMID: 38174819 DOI: 10.1111/brv.13044] [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: 12/06/2022] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024]
Abstract
Motion is a crucial part of the natural world, yet our understanding of how animals avoid predation whilst moving remains rather limited. Although several theories have been proposed for how antipredator defence may be facilitated during motion, there is often a lack of supporting empirical evidence, or conflicting findings. Furthermore, many studies have shown that motion often 'breaks' camouflage, as sudden movement can be detected even before an individual is recognised. Whilst some static camouflage strategies may conceal moving animals to a certain extent, more emphasis should be given to other modes of camouflage and related defences in the context of motion (e.g. flicker fusion camouflage, active motion camouflage, motion dazzle, and protean motion). Furthermore, when motion is involved, defence strategies are not necessarily limited to concealment. An animal can also rely on motion to mislead predators with regards to its trajectory, location, size, colour pattern, or even identity. In this review, we discuss the various underlying antipredator strategies and the mechanisms through which they may be linked to motion, conceptualising existing empirical and theoretical studies from two perspectives - concealing and misleading effects. We also highlight gaps in our understanding of these antipredator strategies, and suggest possible methodologies for experimental designs/test subjects (i.e. prey and/or predators) and future research directions.
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Affiliation(s)
- Min Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Shichang Zhang
- Centre for Behavioural Ecology & Evolution, State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, Hubei, China
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Daiqin Li
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
- Centre for Behavioural Ecology & Evolution, State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, Hubei, China
| | - Eunice J Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
- Division of Science, Yale-NUS College, 16 College Avenue West, Singapore, 138527, Singapore
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2
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Goode CK, Woodrow C, Harrison SL, Deeming DC, Sutton GP. Control of high-speed jumps in muscle and spring actuated systems: a comparative study of take-off energetics in bush-crickets (Mecopoda elongata) and locusts (Schistocerca gregaria). J Comp Physiol B 2023; 193:597-605. [PMID: 37857900 PMCID: PMC10613148 DOI: 10.1007/s00360-023-01524-2] [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: 05/10/2023] [Revised: 09/14/2023] [Accepted: 09/29/2023] [Indexed: 10/21/2023]
Abstract
The Orthoptera are a diverse insect order well known for their locomotive capabilities. To jump, the bush-cricket uses a muscle actuated (MA) system in which leg extension is actuated by contraction of the femoral muscles of the hind legs. In comparison, the locust uses a latch mediated spring actuated (LaMSA) system, in which leg extension is actuated by the recoil of spring-like structure in the femur. The aim of this study was to describe the jumping kinematics of Mecopoda elongata (Tettigoniidae) and compare this to existing data in Schistocerca gregaria (Acrididae), to determine differences in control of rotation during take-off between similarly sized MA and LaMSA jumpers. 269 jumps from 67 individuals of M. elongata with masses from 0.014 g to 3.01 g were recorded with a high-speed camera setup. In M. elongata, linear velocity increased with mass0.18 and the angular velocity (pitch) decreased with mass-0.13. In S. gregaria, linear velocity is constant and angular velocity decreases with mass-0.24. Despite these differences in velocity scaling, the ratio of translational kinetic energy to rotational kinetic energy was similar for both species. On average, the energy distribution of M. elongata was distributed 98.8% to translational kinetic energy and 1.2% to rotational kinetic energy, whilst in S. gregaria it is 98.7% and 1.3%, respectively. This energy distribution was independent of size for both species. Despite having two different jump actuation mechanisms, the ratio of translational and rotational kinetic energy formed during take-off is fixed across these distantly related orthopterans.
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Affiliation(s)
- Chloe K Goode
- School of Life and Environmental Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK
| | - Charlie Woodrow
- School of Life and Environmental Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK
- Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, 752 36, Uppsala, Sweden
| | - Shannon L Harrison
- School of Life and Environmental Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK
| | - D Charles Deeming
- School of Life and Environmental Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK
| | - Gregory P Sutton
- School of Life and Environmental Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln, LN6 7DL, UK.
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3
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Henríquez-Piskulich P, Stuart-Fox D, Elgar M, Marusic I, Franklin AM. Dazzled by shine: gloss as an antipredator strategy in fast moving prey. Behav Ecol 2023; 34:862-871. [PMID: 37744168 PMCID: PMC10516678 DOI: 10.1093/beheco/arad046] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/06/2023] [Accepted: 05/23/2023] [Indexed: 09/26/2023] Open
Abstract
Previous studies on stationary prey have found mixed results for the role of a glossy appearance in predator avoidance-some have found that glossiness can act as warning coloration or improve camouflage, whereas others detected no survival benefit. An alternative untested hypothesis is that glossiness could provide protection in the form of dynamic dazzle. Fast moving animals that are glossy produce flashes of light that increase in frequency at higher speeds, which could make it harder for predators to track and accurately locate prey. We tested this hypothesis by presenting praying mantids with glossy or matte targets moving at slow and fast speed. Mantids were less likely to strike glossy targets, independently of speed. Additionally, mantids were less likely to track glossy targets and more likely to hit the target with one out of the two legs that struck rather than both raptorial legs, but only when targets were moving fast. These results support the hypothesis that a glossy appearance may have a function as an antipredator strategy by reducing the ability of predators to track and accurately target fast moving prey.
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Affiliation(s)
| | - Devi Stuart-Fox
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Mark Elgar
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ivan Marusic
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Amanda M Franklin
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
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4
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Richardson R, Feigin CY, Bano-Otalora B, Johnson MR, Allen AE, Park J, McDowell RJ, Mereby SA, Lin IH, Lucas RJ, Mallarino R. The genomic basis of temporal niche evolution in a diurnal rodent. Curr Biol 2023; 33:3289-3298.e6. [PMID: 37480852 PMCID: PMC10529858 DOI: 10.1016/j.cub.2023.06.068] [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: 08/04/2022] [Revised: 05/05/2023] [Accepted: 06/26/2023] [Indexed: 07/24/2023]
Abstract
Patterns of diel activity-how animals allocate their activity throughout the 24-h daily cycle-play key roles in shaping the internal physiology of an animal and its relationship with the external environment.1,2,3,4,5 Although shifts in diel activity patterns have occurred numerous times over the course of vertebrate evolution,6 the genomic correlates of such transitions remain unknown. Here, we use the African striped mouse (Rhabdomys pumilio), a species that transitioned from the ancestrally nocturnal diel niche of its close relatives to a diurnal one,7,8,9,10,11 to define patterns of naturally occurring molecular variation in diel niche traits. First, to facilitate genomic analyses, we generate a chromosome-level genome assembly of the striped mouse. Next, using transcriptomics, we show that the switch to daytime activity in this species is associated with a realignment of daily rhythms in peripheral tissues with respect to the light:dark cycle and the central circadian clock. To uncover selection pressures associated with this temporal niche shift, we perform comparative genomic analyses with closely related rodent species and find evidence of relaxation of purifying selection on striped mouse genes in the rod phototransduction pathway. In agreement with this, electroretinogram measurements demonstrate that striped mice have functional differences in dim-light visual responses compared with nocturnal rodents. Taken together, our results show that striped mice have undergone a drastic change in circadian organization and provide evidence that the visual system has been a major target of selection as this species transitioned to a novel temporal niche.
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Affiliation(s)
- Rose Richardson
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK; Division of Neuroscience, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Charles Y Feigin
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA; School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Beatriz Bano-Otalora
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK; Division of Neuroscience, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK; Division of Diabetes, Endocrinology, & Gastroenterology, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Matthew R Johnson
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Annette E Allen
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK; Division of Neuroscience, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Jongbeom Park
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Richard J McDowell
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK; Division of Neuroscience, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK
| | - Sarah A Mereby
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - I-Hsuan Lin
- Bioinformatics Core Facility, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PL, UK
| | - Robert J Lucas
- Centre for Biological Timing, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK; Division of Neuroscience, Faculty of Biology Medicine and Health, University of Manchester, Manchester M13 9PT, UK.
| | - Ricardo Mallarino
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA.
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5
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Robledo-Ospina LE, Morehouse N, Escobar F, Tapia-McClung H, Narendra A, Rao D. Visual antipredator effects of web flexing in an orb web spider, with special reference to web decorations. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2023; 110:23. [PMID: 37219696 DOI: 10.1007/s00114-023-01849-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 05/24/2023]
Abstract
Some visual antipredator strategies involve the rapid movement of highly contrasting body patterns to frighten or confuse the predator. Bright body colouration, however, can also be detected by potential predators and used as a cue. Among spiders, Argiope spp. are usually brightly coloured but they are not a common item in the diet of araneophagic wasps. When disturbed, Argiope executes a web-flexing behaviour in which they move rapidly and may be perceived as if they move backwards and towards an observer in front of the web. We studied the mechanisms underlying web-flexing behaviour as a defensive strategy. Using multispectral images and high-speed videos with deep-learning-based tracking techniques, we evaluated body colouration, body pattern, and spider kinematics from the perspective of a potential wasp predator. We show that the spider's abdomen is conspicuous, with a disruptive colouration pattern. We found that the body outline of spiders with web decorations was harder to detect when compared to spiders without decorations. The abdomen was also the body part that moved fastest, and its motion was composed mainly of translational (vertical) vectors in the potential predator's optical flow. In addition, with high contrast colouration, the spider's movement might be perceived as a sudden change in body size (looming effect) as perceived by the predator. These effects alongside the other visual cues may confuse potential wasp predators by breaking the spider body outline and affecting the wasp's flight manoeuvre, thereby deterring the wasp from executing the final attack.
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Affiliation(s)
- Luis E Robledo-Ospina
- Red de Ecoetología, Instituto de Ecología, A.C., Xalapa, Veracruz, México
- Instituto de Biotecnología y Ecología Aplicada, Universidad Veracruzana, Xalapa, Veracruz, México
| | - Nathan Morehouse
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Federico Escobar
- Red de Ecoetología, Instituto de Ecología, A.C., Xalapa, Veracruz, México
| | - Horacio Tapia-McClung
- Instituto de Investigaciones en Inteligencia Artificial, Universidad Veracruzana, Xalapa, Veracruz, México
| | - Ajay Narendra
- School of Natural Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Dinesh Rao
- Instituto de Biotecnología y Ecología Aplicada, Universidad Veracruzana, Xalapa, Veracruz, México.
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6
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Tan EJ, Elgar MA. Motion: enhancing signals and concealing cues. Biol Open 2021; 10:271863. [PMID: 34414408 PMCID: PMC8411570 DOI: 10.1242/bio.058762] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/02/2021] [Indexed: 01/15/2023] Open
Abstract
Animal colour patterns remain a lively focus of evolutionary and behavioural ecology, despite the considerable conceptual and technical developments over the last four decades. Nevertheless, our current understanding of the function and efficacy of animal colour patterns remains largely shaped by a focus on stationary animals, typically in a static background. Yet, this rarely reflects the natural world: most animals are mobile in their search for food and mates, and their surrounding environment is usually dynamic. Thus, visual signalling involves not only animal colour patterns, but also the patterns of animal motion and behaviour, often in the context of a potentially dynamic background. While motion can reveal information about the signaller by attracting attention or revealing signaller attributes, motion can also be a means of concealing cues, by reducing the likelihood of detection (motion camouflage, motion masquerade and flicker-fusion effect) or the likelihood of capture following detection (motion dazzle and confusion effect). The interaction between the colour patterns of the animal and its local environment is further affected by the behaviour of the individual. Our review details how motion is intricately linked to signalling and suggests some avenues for future research. This Review has an associated Future Leader to Watch interview with the first author. Summary: While motion can reveal information about the signaller, motion can also be a means of concealing cues by reducing the likelihood of detection or the likelihood of capture following detection.
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Affiliation(s)
- Eunice J Tan
- Division of Science, Yale-NUS College, Singapore 138527, Singapore
| | - Mark A Elgar
- School of BioSciences, University of Melbourne, Melbourne, Victoria 3010, Australia
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7
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Hughes AE, Griffiths D, Troscianko J, Kelley LA. The evolution of patterning during movement in a large-scale citizen science game. Proc Biol Sci 2021; 288:20202823. [PMID: 33434457 PMCID: PMC7892415 DOI: 10.1098/rspb.2020.2823] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The motion dazzle hypothesis posits that high contrast geometric patterns can cause difficulties in tracking a moving target and has been argued to explain the patterning of animals such as zebras. Research to date has only tested a small number of patterns, offering equivocal support for the hypothesis. Here, we take a genetic programming approach to allow patterns to evolve based on their fitness (time taken to capture) and thus find the optimal strategy for providing protection when moving. Our ‘Dazzle Bug’ citizen science game tested over 1.5 million targets in a touch screen game at a popular visitor attraction. Surprisingly, we found that targets lost pattern elements during evolution and became closely background matching. Modelling results suggested that targets with lower motion energy were harder to catch. Our results indicate that low contrast, featureless targets offer the greatest protection against capture when in motion, challenging the motion dazzle hypothesis.
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Affiliation(s)
- Anna E Hughes
- Department of Psychology, University of Essex, Wivenhoe House, Colchester CO4 3SQ, UK
| | | | - Jolyon Troscianko
- Centre for Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Laura A Kelley
- Centre for Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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8
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Caro T, Koneru M. Towards an ecology of protective coloration. Biol Rev Camb Philos Soc 2020; 96:611-641. [PMID: 33258554 DOI: 10.1111/brv.12670] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 11/05/2020] [Accepted: 11/09/2020] [Indexed: 12/15/2022]
Abstract
The strategies underlying different forms of protective coloration are well understood but little attention has been paid to the ecological, life-history and behavioural circumstances under which they evolve. While some comparative studies have investigated the ecological correlates of aposematism, and background matching, the latter particularly in mammals, few have examined the ecological correlates of other types of protective coloration. Here, we first outline which types of defensive coloration strategies may be exhibited by the same individual; concluding that many protective coloration mechanisms can be employed simultaneously, particularly in conjunction with background matching. Second, we review the ecological predictions that have been made for each sort of protective coloration mechanism before systematically surveying phylogenetically controlled comparative studies linking ecological and social variables to antipredator defences that involve coloration. We find that some a priori predictions based on small-scale empirical studies and logical arguments are indeed supported by comparative data, especially in relation to how illumination affects both background matching and self-shadow concealment through countershading; how body size is associated with countershading, motion dazzle, flash coloration and aposematism, although only in selected taxa; how immobility may promote background matching in ambush predators; and how mobility may facilitate motion dazzle. Examination of nearly 120 comparative tests reveals that many focus on ecological variables that have little to do with predictions derived from antipredator defence theory, and that broad-scale ecological studies of defence strategies that incorporate phylogenetics are still very much in their infancy. We close by making recommendations for future evolutionary ecological research.
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Affiliation(s)
- Tim Caro
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, U.K.,Center for Population Biology, University of California, Davis, CA, 95616, U.S.A
| | - Manisha Koneru
- Department of Evolution and Ecology, University of California, Davis, CA, 95616, U.S.A
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9
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Negro JJ, Doña J, Blázquez MC, Rodríguez A, Herbert-Read JE, Brooke MDL. Contrasting stripes are a widespread feature of group living in birds, mammals and fishes. Proc Biol Sci 2020; 287:20202021. [PMID: 33049169 DOI: 10.1098/rspb.2020.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Grouping is a widespread form of predator defence, with individuals in groups often performing evasive collective movements in response to attack by predators. Individuals in these groups use behavioural rules to coordinate their movements, with visual cues about neighbours' positions and orientations often informing movement decisions. Although the exact visual cues individuals use to coordinate their movements with neighbours have not yet been decoded, some studies have suggested that stripes, lines, or other body patterns may act as conspicuous conveyors of movement information that could promote coordinated group movement, or promote dazzle camouflage, thereby confusing predators. We used phylogenetic logistic regressions to test whether the contrasting achromatic stripes present in four different taxa vulnerable to predation, including species within two orders of birds (Anseriformes and Charadriiformes), a suborder of Artiodactyla (the ruminants), and several orders of marine fishes (predominantly Perciformes) were associated with group living. Contrasting patterns were significantly more prevalent in social species, and tended to be absent in solitary species or species less vulnerable to predation. We suggest that stripes taking the form of light-coloured lines on dark backgrounds, or vice versa, provide a widespread mechanism across taxa that either serves to inform conspecifics of neighbours' movements, or to confuse predators, when moving in groups. Because detection and processing of patterns and of motion in the visual channel is essentially colour-blind, diverse animal taxa with widely different vision systems (including mono-, di-, tri-, and tetrachromats) appear to have converged on a similar use of achromatic patterns, as would be expected given signal-detection theory. This hypothesis would explain the convergent evolution of conspicuous achromatic patterns as an antipredator mechanism in numerous vertebrate species.
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Affiliation(s)
- Juan J Negro
- Estación Biológica de Doñana-CSIC, Avda. Americo Vespucio 26, 41092 Sevilla, Spain
| | - Jorge Doña
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, 1816 S. Oak St., Champaign, IL 61820, USA.,Departamento de Biología Animal, Universidad de Granada, Granada, Spain
| | - M Carmen Blázquez
- Centro de Investigaciones Biológicas del Noroeste (CIBNOR), 23096 La Paz, Baja California Sur, Mexico
| | - Airam Rodríguez
- Estación Biológica de Doñana-CSIC, Avda. Americo Vespucio 26, 41092 Sevilla, Spain.,Grupo de Ornitología e Historia Natural de las Islas Canarias, GOHNIC, Canarias, Spain
| | - James E Herbert-Read
- Department of Zoology, University of Cambridge, Downing St, Cambridge CB2 3EJ, UK.,Department of Biology, Aquatic Ecology Unit, Lund University, Lund 223 62, Sweden
| | - M de L Brooke
- Department of Zoology, University of Cambridge, Downing St, Cambridge CB2 3EJ, UK
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10
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Pembury Smith MQR, Ruxton GD. Camouflage in predators. Biol Rev Camb Philos Soc 2020; 95:1325-1340. [DOI: 10.1111/brv.12612] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 04/24/2020] [Accepted: 04/28/2020] [Indexed: 12/29/2022]
Affiliation(s)
| | - Graeme D. Ruxton
- School of Biology University of St Andrews, Dyers Brae House, St Andrews Fife KY16 9TH U.K
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11
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Allen WL, Moreno N, Gamble T, Chiari Y. Ecological, behavioral, and phylogenetic influences on the evolution of dorsal color pattern in geckos. Evolution 2020; 74:1033-1047. [PMID: 31886521 DOI: 10.1111/evo.13915] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 12/04/2019] [Accepted: 12/15/2019] [Indexed: 12/13/2022]
Abstract
The dorsal surfaces of many taxonomic groups often feature repetitive pattern elements consisting of stripes, spots, or bands. Here, we investigate how distinct categories of camouflage pattern work by relating them to ecological and behavioral traits in 439 species of gecko. We use phylogenetic comparative methods to test outstanding hypotheses based on camouflage theory and research in other taxa. We found that bands are associated with nocturnal activity, suggesting bands provide effective camouflage for motionless geckos resting in refugia during the day. A predicted association between stripes and diurnal activity was not supported, suggesting that stripes do not work via dazzle camouflage mechanisms in geckos. This, along with a lack of support for our prediction that plain patterning should be associated with open habitats, suggests that similar camouflage patterns do not work in consistent ways across taxa. We also found that plain and striped lineages frequently switched between using open or closed habitats, whereas spotted lineages rarely transitioned. This suggests that pattern categories differ in how specialized or generalized their camouflage is. This result has ramifications for theory on how camouflage compromises to background heterogeneity and how camouflage pattern might influence evolutionary trajectories.
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Affiliation(s)
- William L Allen
- Department of Biosciences, Swansea University, Swansea, UK, SA2 8PP
| | - Nickolas Moreno
- Department of Biology, University of South Alabama, Mobile, Alabama, 36688
| | - Tony Gamble
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, 53233.,Bell Museum of Natural History, University of Minnesota, Saint Paul, Minnesota, 55113.,Milwaukee Public Museum, Milwaukee, Wisconsin, 53233
| | - Ylenia Chiari
- Department of Biology, University of South Alabama, Mobile, Alabama, 36688.,Department of Biology, George Mason University, Manassas, Virginia, 20110
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12
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Smart IE, Cuthill IC, Scott-Samuel NE. In the corner of the eye: camouflaging motion in the peripheral visual field. Proc Biol Sci 2020; 287:20192537. [PMID: 31937225 DOI: 10.1098/rspb.2019.2537] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Most animals need to move, and motion will generally break camouflage. In many instances, most of the visual field of a predator does not fall within a high-resolution area of the retina and so, when an undetected prey moves, that motion will often be in peripheral vision. We investigate how this can be exploited by prey, through different patterns of movement, to reduce the accuracy with which the predator can locate a cryptic prey item when it subsequently orients towards a target. The same logic applies for a prey species trying to localize a predatory threat. Using human participants as surrogate predators, tasked with localizing a target on peripherally viewed computer screens, we quantify the effects of movement (duration and speed) and target pattern. We show that, while motion is certainly detrimental to camouflage, should movement be necessary, some behaviours and surface patterns reduce that cost. Our data indicate that the phenotype that minimizes localization accuracy is unpatterned, having the mean luminance of the background, does not use a startle display prior to movement, and has short (below saccadic latency), fast movements.
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Affiliation(s)
- Ioan E Smart
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
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13
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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
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14
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Elias MAM, Anker A, Gawryszewski FM. Microhabitat use and body size drive the evolution of colour patterns in snapping shrimps (Decapoda: Alpheidae: Alpheus). Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz152] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Background matching and disruptive coloration are common strategies used by animals to increase concealment, whereas motion-dazzle may prevent capture after recognition. Studies have related background matching to habitat dependency and survival success, whereas for animals with highly contrasting patterns it has been shown that they are able to explore a broader range of habitats due to disruptive coloration, and possibly via motion-dazzle. However, the effects of these strategies are likely to be influenced by body size and to work better for smaller species. We applied phylogenetic comparative methods to test the hypothesis that smaller snapping shrimps (genus Alpheus) with high-contrast stripes would be able to utilize more microhabitats than non-striped and larger species. We used a published phylogeny of the American species of Alpheus, studies that have described alpheid microhabitats and size, and high-resolution photographs of each species in the phylogeny. Our categorical analysis suggested that generalist snapping shrimps are more likely to have stripes than specialist shrimps, and this effect was stronger in smaller species. Similarly, we found an interacting effect of body size and habitat use on the degree of luminance contrast: smaller generalist species had higher contrast values than average-sized and habitat-specialist species. Therefore, predators, body size and frequency of microhabitats are likely to have influenced the evolution of colour patterns in Alpheus.
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Affiliation(s)
- Marco A M Elias
- Instituto de Ciências Biológicas, Universidade Federal de Goiás, Avenida Esperança, Campus Samambaia, Goiânia, Goiás, Brazil
| | - Arthur Anker
- Instituto de Ciências Biológicas, Universidade Federal de Goiás, Avenida Esperança, Campus Samambaia, Goiânia, Goiás, Brazil
| | - Felipe M Gawryszewski
- Instituto de Ciências Biológicas, Universidade de Brasília, Asa Norte, Campus Darcy Ribeiro, Brasília, Distrito Federal, Brazil
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15
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Kodandaramaiah U, Palathingal S, Bindu Kurup G, Murali G. What makes motion dazzle markings effective against predation? Behav Ecol 2019. [DOI: 10.1093/beheco/arz154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Motion dazzle markings comprise patterns such as stripes and zig-zags that are postulated to protect moving prey by making predators misjudge the prey’s speed or trajectory. Recent experiments have provided conflicting results on their effect on speed perception and attack success. We focus on motion dazzle stripes and investigate the influence of four parameters—stripe orientation, stripe contrast, target size, and target speed—on perceived speed and attack success using a common experimental paradigm involving human “predators” attacking virtual moving targets on a computer touchscreen. We found that high-contrast stripes running parallel or perpendicular to the direction of motion reduce attack success compared to conspicuous uniform targets. Surprisingly, parallel stripes induced underestimation of speed, while perpendicular stripes induced overestimation of speed in relation to uniform black, suggesting that misjudgment of speed per se is sufficient to reduce attack accuracy. Across all the experiments, we found some support for parallel stripes inducing underestimation of target speed but these stripes reduced attack success only when targets were small, moved at an intermediate speed, and had high internal contrast. We suggest that prey features (e.g., size or speed) are an important determinant of capture success and that distortion of speed perception by a color pattern does not necessarily translate to reduced capture success of the prey. Overall, our results support the idea that striped patterns in prey animals can reduce capture in motion but are effective under a limited set of conditions.
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Affiliation(s)
- Ullasa Kodandaramaiah
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
| | - Shuaib Palathingal
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
- Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, India
| | - Gayathri Bindu Kurup
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
| | - Gopal Murali
- IISER-TVM Centre for Research and Education in Ecology and Evolution (ICREEE), School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Thiruvananthapuram, India
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16
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Watson CM, Degon Z, Krogman W, Cox CL. Evolutionary and ecological forces underlying ontogenetic loss of decoy coloration. Biol J Linn Soc Lond 2019. [DOI: 10.1093/biolinnean/blz084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Abstract
Predator-based selection has resulted in the repeated evolution of a variety of antipredator traits. Despite the effectiveness of these traits, some species experience shifts or even complete loss of antipredator traits during development. The evolutionary forces that favour such a transition are poorly understood. We sought to comprehend the role of predator-based selection and organismal factors underlying developmental loss of antipredator traits by focusing on decoy coloration in skink lizards. To this end, we studied the ontogenetic loss of decoy tail coloration in three Nearctic skink species. We performed natural history collection surveys and clay-model studies on predation to determine the organismal determinants of decoy coloration (body size and energy content of the tail) and predation based upon size and decoy coloration. We found that decoy coloration was lost during development at a similar size in all three species. Although predation rates on juvenile models were similar for both uniform brown and decoy models, predation rates on adult models with decoy coloration were much higher than those on non-decoy adult models. Overall, our results suggest that predator-based selection is an important factor driving the ontogenetic loss of decoy coloration at similar sizes across these species and might be generalizable to other antipredator traits.
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Affiliation(s)
- Charles M Watson
- Department of Biology, Midwestern State University, Wichita Falls, TX, USA
| | - Zachariah Degon
- Department of Biology, Georgia Southern University, Statesboro, GA, USA
| | - William Krogman
- Department of Biology, Midwestern State University, Wichita Falls, TX, USA
| | - Christian L Cox
- Department of Biology, Georgia Southern University, Statesboro, GA, USA
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17
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Affiliation(s)
- I. C. Cuthill
- School of Biological Sciences University of Bristol Bristol UK
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18
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Brunyé TT, Martis SB, Kirejczyk JA, Rock K. Camouflage pattern features interact with movement speed to determine human target detectability. APPLIED ERGONOMICS 2019; 77:50-57. [PMID: 30832778 DOI: 10.1016/j.apergo.2019.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 11/19/2018] [Accepted: 01/20/2019] [Indexed: 06/09/2023]
Abstract
Applied ergonomics research examines not only the fit, form and function of military uniforms, but also their ability to effectively camouflage personnel as they perform job-related tasks. Many of these job-related tasks involve moving through environments, but existing literature examining camouflage effectiveness often assumes that movement effectively "breaks" even the best camouflage patterns, rendering them of limited utility for reducing the visual signature of a moving target. However, recent research demonstrates that animals equipped with adaptive camouflage change their patterning in predictable ways during movement and this adaptation decreases detectability, suggesting that uniform patterning may still hold value for reducing conspicuity during movement. The present experiment examined whether three visual pattern characteristics, local contrast, orientation, and spatial frequency, would influence the detectability of a moving human target. Participants attempted to detect and localize a simulated human target moving across a background scene, and a factorial design varied target movement speed, and the local contrast, spatial frequency, and orientation of its camouflage patterning. Results showed that target detectability was strongly influenced by target movement rate, pattern local contrast, and pattern spatial frequency, and these effects persisted even under conditions of very fast movement. Importantly, we found that the effect of local contrast was most robust under conditions of movement, suggesting its importance for reducing detectability of moving personnel. We conclude that movement is not always sufficient to break the concealment offered by a pattern with low contrast and a spatial frequency match with its background. Results are discussed in the context of visual processing theories and the application of these findings to the design and development of static and adaptive camouflage patterns for military personnel.
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Affiliation(s)
- Tad T Brunyé
- Center for Applied Brain and Cognitive Sciences, Medford, MA, USA; U.S. Army Natick Soldier Research, Development, and Engineering Center, Natick, MA, USA; Tufts University, Department of Psychology, Medford, MA, USA.
| | - Shaina B Martis
- Center for Applied Brain and Cognitive Sciences, Medford, MA, USA
| | - John A Kirejczyk
- U.S. Army Natick Soldier Research, Development, and Engineering Center, Natick, MA, USA
| | - Kathryn Rock
- U.S. Army Natick Soldier Research, Development, and Engineering Center, Natick, MA, USA
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19
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Harris RJ, Jenner RA. Evolutionary Ecology of Fish Venom: Adaptations and Consequences of Evolving a Venom System. Toxins (Basel) 2019; 11:E60. [PMID: 30678265 PMCID: PMC6409815 DOI: 10.3390/toxins11020060] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/14/2019] [Accepted: 01/18/2019] [Indexed: 01/21/2023] Open
Abstract
Research on venomous animals has mainly focused on the molecular, biochemical, and pharmacological aspects of venom toxins. However, it is the relatively neglected broader study of evolutionary ecology that is crucial for understanding the biological relevance of venom systems. As fish have convergently evolved venom systems multiple times, it makes them ideal organisms to investigate the evolutionary ecology of venom on a broader scale. This review outlines what is known about how fish venom systems evolved as a result of natural enemy interactions and about the ecological consequences of evolving a venom system. This review will show how research on the evolutionary ecology of venom in fish can aid in understanding the evolutionary ecology of animal venoms more generally. Further, understanding these broad ecological questions can shed more light on the other areas of toxinology, with applications across multiple disciplinary fields.
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Affiliation(s)
- Richard J Harris
- Venom Evolution Lab, School of Biological Sciences, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
| | - Ronald A Jenner
- Department of Life Sciences, the Natural History Museum, Cromwell Road, SW7 5BD London, UK.
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20
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Murali G. Now you see me, now you don't: dynamic flash coloration as an antipredator strategy in motion. Anim Behav 2018. [DOI: 10.1016/j.anbehav.2018.06.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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21
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Zlotnik S, Darnell GM, Bernal XE. Anuran predators overcome visual illusion: dazzle coloration does not protect moving prey. Anim Cogn 2018; 21:729-733. [PMID: 29922864 DOI: 10.1007/s10071-018-1199-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 05/19/2018] [Accepted: 06/13/2018] [Indexed: 10/28/2022]
Abstract
Predators everywhere impose strong selection pressures on the morphology and behavior of their prey, but the resulting antipredator adaptations vary greatly among species. Studies of adaptive coloration in prey species have generally focused on cryptic or aposematic prey, with little consideration of color patterns in palatable mobile prey. Complex color patterns have been proposed to decrease the ability of visual predators to capture moving prey (motion dazzle effect). Most support for this hypothesis, however, comes from experiments with human subjects and simulated prey. We tested the motion dazzle effect using, for the first time, natural predators (cane toads, Rhinella marina) and live prey (house crickets, Acheta domesticus) with altered color patterns. We found no support for the motion dazzle effect as striped crickets did not fare better than solid colored ones. Crickets that spent more time moving, however, were more likely to be eaten. Our results suggest that motion specialized visual predators such as toads overcome the motion dazzle effect and impose stronger selection pressure on prey behavior than on coloration. These findings emphasize the importance of sensory specializations of predators in mediating antipredator strategies.
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Affiliation(s)
- Sara Zlotnik
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
| | - Geena M Darnell
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Ximena E Bernal
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA.,Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Republic of Panama
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22
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Hall JR, Baddeley R, Scott-Samuel NE, Shohet AJ, Cuthill IC. Camouflaging moving objects: crypsis and masquerade. Behav Ecol 2018; 28:1248-1255. [PMID: 29622927 PMCID: PMC5873248 DOI: 10.1093/beheco/arx085] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/07/2017] [Accepted: 05/30/2017] [Indexed: 11/14/2022] Open
Abstract
Motion is generally assumed to “break” camouflage. However, although camouflage cannot conceal a group of moving animals, it may impair a predator’s ability to single one out for attack, even if that discrimination is not based on a color difference. Here, we use a computer-based task in which humans had to detect the odd one out among moving objects, with “oddity” based on shape. All objects were either patterned or plain, and either matched the background or not. We show that there are advantages of matching both group-mates and the background. However, when patterned objects are on a plain background (i.e., no background matching), the advantage of being among similarly patterned distractors is only realized when the group size is larger (10 compared to 5). In a second experiment, we present a paradigm for testing how coloration interferes with target-distractor discrimination, based on an adaptive staircase procedure for establishing the threshold. We show that when the predator only has a short time for decision-making, displaying a similar pattern to the distractors and the background affords protection even when the difference in shape between target and distractors is large. We conclude that, even though motion breaks camouflage, being camouflaged could help group-living animals reduce the risk of being singled out for attack by predators.
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Affiliation(s)
- Joanna R Hall
- School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK.,School of Biological Sciences, University of Bristol, Bristol Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK, and
| | - Roland Baddeley
- School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK
| | - Nicholas E Scott-Samuel
- School of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK
| | - Adam J Shohet
- Stealth Materials Group, QinetiQ, Cody Technology Park, Farnborough GU14 0LX, UK
| | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, Bristol Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK, and
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23
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Merilaita S, Scott-Samuel NE, Cuthill IC. How camouflage works. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0341. [PMID: 28533458 DOI: 10.1098/rstb.2016.0341] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2016] [Indexed: 11/12/2022] Open
Abstract
For camouflage to succeed, an individual has to pass undetected, unrecognized or untargeted, and hence it is the processing of visual information that needs to be deceived. Camouflage is therefore an adaptation to the perception and cognitive mechanisms of another animal. Although this has been acknowledged for a long time, there has been no unitary account of the link between visual perception and camouflage. Viewing camouflage as a suite of adaptations to reduce the signal-to-noise ratio provides the necessary common framework. We review the main processes in visual perception and how animal camouflage exploits these. We connect the function of established camouflage mechanisms to the analysis of primitive features, edges, surfaces, characteristic features and objects (a standard hierarchy of processing in vision science). Compared to the commonly used research approach based on established camouflage mechanisms, we argue that our approach based on perceptual processes targeted by camouflage has several important benefits: specifically, it enables the formulation of more precise hypotheses and addresses questions that cannot even be identified when investigating camouflage only through the classic approach based on the patterns themselves. It also promotes a shift from the appearance to the mechanistic function of animal coloration.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
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Affiliation(s)
- Sami Merilaita
- Department of Biosciences, Åbo Akademi University, Tykistökatu 6, 20520 Turku, Finland
| | - Nicholas E Scott-Samuel
- Department of Experimental Psychology, University of Bristol, 12A Priory Road, Bristol BS8 1TN, UK
| | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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24
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Ireland HM, Ruxton GD. Zebra stripes: an interspecies signal to facilitate mixed-species herding? Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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25
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Hughes AE, Jones C, Joshi K, Tolhurst DJ. Diverted by dazzle: perceived movement direction is biased by target pattern orientation. Proc Biol Sci 2017; 284:20170015. [PMID: 28275144 PMCID: PMC5360933 DOI: 10.1098/rspb.2017.0015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 02/09/2017] [Indexed: 11/12/2022] Open
Abstract
'Motion dazzle' is the hypothesis that predators may misjudge the speed or direction of moving prey which have high-contrast patterning, such as stripes. However, there is currently little experimental evidence that such patterns cause visual illusions. Here, observers binocularly tracked a Gabor target, moving with a linear trajectory randomly chosen within 18° of the horizontal. This target then became occluded, and observers were asked to judge where they thought it would later cross a vertical line to the side. We found that internal motion of the stripes within the Gabor biased judgements as expected: Gabors with upwards internal stripe motion relative to the overall direction of motion were perceived to be crossing above Gabors with downwards internal stripe movement. However, surprisingly, we found a much stronger effect of the rigid pattern orientation. Patches with oblique stripes pointing upwards relative to the direction of motion were perceived to cross above patches with downward-pointing stripes. This effect occurred only at high speeds, suggesting that it may reflect an orientation-dependent effect in which spatial signals are used in direction judgements. These findings have implications for our understanding of motion dazzle mechanisms and how human motion and form processing interact.
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Affiliation(s)
- Anna E Hughes
- Department of Psychology and Language Sciences, University College London, 26 Bedford Way, London WC1H 0AP, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Christian Jones
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - Kaustuv Joshi
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
| | - David J Tolhurst
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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26
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Umeton D, Read JCA, Rowe C. Unravelling the illusion of flicker fusion. Biol Lett 2017; 13:rsbl.2016.0831. [PMID: 28148834 DOI: 10.1098/rsbl.2016.0831] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/09/2017] [Indexed: 11/12/2022] Open
Abstract
For over 150 years, researchers have investigated the anti-predator function of animal patterns. However, this work has mainly focused on when prey remain still, and has only recently started to incorporate motion into the study of defensive coloration. As motion breaks camouflage, a new challenge is to understand how prey avoid predators while moving around their environment, and if a moving prey can ever be camouflaged. We propose that there is a solution to this, in that a 'flicker fusion effect' can change the appearance of the prey in the eyes of their predators to reduce the chances of initial detection. This effect occurs when a high contrast pattern blurs at speed, changing the appearance of the prey, which may help them better match their background. Despite being widely discussed in the literature, the flicker fusion effect is poorly described, there is no clear theoretical framework for testing how it might reduce predation, and the terminology describing it is, at best, rather confusing. Our review addresses these three key issues to enable researchers to formulate precise predictions about when the flicker fusion effect occurs, and to test how it can reduce predation.
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Affiliation(s)
- Diana Umeton
- Department of Biology, Ecology and Earth Sciences, University of Calabria, Cosenza, Italy .,Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle NE2 4HH, UK
| | - Jenny C A Read
- Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle NE2 4HH, UK
| | - Candy Rowe
- Centre for Behaviour and Evolution, Institute of Neuroscience, Newcastle University, Newcastle NE2 4HH, UK
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27
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Hogan BG, Cuthill IC, Scott-Samuel NE. Dazzle camouflage and the confusion effect: the influence of varying speed on target tracking. Anim Behav 2017; 123:349-353. [PMID: 28123185 PMCID: PMC5226095 DOI: 10.1016/j.anbehav.2016.11.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The formation of groups is a common strategy to avoid predation in animals, and recent research has indicated that there may be interactions between some forms of defensive coloration, notably high-contrast ‘dazzle camouflage’, and one of the proposed benefits of grouping: the confusion effect. However, research into the benefits of dazzle camouflage has largely used targets moving with constant speed. This simplification may not generalize well to real animal systems, where a number of factors influence both within- and between-individual variation in speed. Departure from the speed of your neighbours in a group may be predicted to undermine the confusion effect. This is because individual speed may become a parameter through which the observer can individuate otherwise similar targets: an ‘oddity effect’. However, dazzle camouflage patterns are thought to interfere with predator perception of speed and trajectory. The current experiment investigated the possibility that such patterns could ameliorate the oddity effect caused by within-group differences in prey speed. We found that variation in speed increased the ease with which participants could track targets in all conditions. However, we found no evidence that motion dazzle camouflage patterns reduced oddity effects based on this variation in speed, a result that may be informative about the mechanisms behind this form of defensive coloration. In addition, results from those conditions most similar to those of published studies replicated previous results, indicating that targets with stripes parallel to the direction of motion are harder to track, and that this pattern interacts with the confusion effect to a greater degree than background matching or orthogonal-to-motion striped patterns. Variation in speed in groups induces the oddity effect, reducing predator confusion. Dazzle camouflage does not ameliorate this oddity effect. Parallel striped targets in groups are harder to track than other targets.
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Affiliation(s)
- Benedict G Hogan
- Biological Sciences, University of Bristol, Bristol, U.K.; Experimental Psychology, University of Bristol, Bristol, U.K
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28
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Somveille M, Marshall KL, Gluckman TL. A global analysis of bird plumage patterns reveals no association between habitat and camouflage. PeerJ 2016; 4:e2658. [PMID: 27867762 PMCID: PMC5111890 DOI: 10.7717/peerj.2658] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 10/05/2016] [Indexed: 12/03/2022] Open
Abstract
Evidence suggests that animal patterns (motifs) function in camouflage. Irregular mottled patterns can facilitate concealment when stationary in cluttered habitats, whereas regular patterns typically prevent capture during movement in open habitats. Bird plumage patterns have predominantly converged on just four types-mottled (irregular), scales, bars and spots (regular)-and habitat could be driving convergent evolution in avian patterning. Based on sensory ecology, we therefore predict that irregular patterns would be associated with visually noisy closed habitats and that regular patterns would be associated with open habitats. Regular patterns have also been shown to function in communication for sexually competing males to stand-out and attract females, so we predict that male breeding plumage patterns evolved in both open and closed habitats. Here, taking phylogenetic relatedness into account, we investigate ecological selection for bird plumage patterns across the class Aves. We surveyed plumage patterns in 80% of all avian species worldwide. Of these, 2,756 bird species have regular and irregular plumage patterns as well as habitat information. In this subset, we tested whether adult breeding/non-breeding plumages in each sex, and juvenile plumages, were associated with the habitat types found within the species' geographical distributions. We found no evidence for an association between habitat and plumage patterns across the world's birds and little phylogenetic signal. We also found that species with regular and irregular plumage patterns were distributed randomly across the world's eco-regions without being affected by habitat type. These results indicate that at the global spatial and taxonomic scale, habitat does not predict convergent evolution in bird plumage patterns, contrary to the camouflage hypothesis.
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Affiliation(s)
- Marius Somveille
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- The Edward Grey Institute, Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Kate L.A. Marshall
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Thanh-Lan Gluckman
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom
- Center for Interdisciplinary Research in Biology, College de France, Paris, France
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29
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Halperin T, Carmel L, Hawlena D. Movement correlates of lizards’ dorsal pigmentation patterns. Funct Ecol 2016. [DOI: 10.1111/1365-2435.12700] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Topaz Halperin
- Risk‐Management Ecology Lab Department of Ecology, Evolution & Behavior The Alexander Silberman Institute of Life Sciences The Hebrew University of Jerusalem Edmond J. Safra Campus Jerusalem 91904, Israel
- Herpetological Collection National Natural History Collections The Hebrew University of Jerusalem Edmond J. Safra Campus Jerusalem 91904, Israel
| | - Liran Carmel
- Department of Genetics Faculty of Science The Alexander Silberman Institute of Life Sciences The Hebrew University of Jerusalem Edmond J. Safra Campus Givat Ram Jerusalem 91904, Israel
| | - Dror Hawlena
- Risk‐Management Ecology Lab Department of Ecology, Evolution & Behavior The Alexander Silberman Institute of Life Sciences The Hebrew University of Jerusalem Edmond J. Safra Campus Jerusalem 91904, Israel
- Herpetological Collection National Natural History Collections The Hebrew University of Jerusalem Edmond J. Safra Campus Jerusalem 91904, Israel
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30
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Hogan BG, Scott-Samuel NE, Cuthill IC. Contrast, contours and the confusion effect in dazzle camouflage. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160180. [PMID: 27493775 PMCID: PMC4968467 DOI: 10.1098/rsos.160180] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 06/08/2016] [Indexed: 05/16/2023]
Abstract
'Motion dazzle camouflage' is the name for the putative effects of highly conspicuous, often repetitive or complex, patterns on parameters important in prey capture, such as the perception of speed, direction and identity. Research into motion dazzle camouflage is increasing our understanding of the interactions between visual tracking, the confusion effect and defensive coloration. However, there is a paucity of research into the effects of contrast on motion dazzle camouflage: is maximal contrast a prerequisite for effectiveness? If not, this has important implications for our recognition of the phenotype and understanding of the function and mechanisms of potential motion dazzle camouflage patterns. Here we tested human participants' ability to track one moving target among many identical distractors with surface patterns designed to test the influence of these factors. In line with previous evidence, we found that targets with stripes parallel to the object direction of motion were hardest to track. However, reduction in contrast did not significantly influence this result. This finding may bring into question the utility of current definitions of motion dazzle camouflage, and means that some animal patterns, such as aposematic or mimetic stripes, may have previously unrecognized multiple functions.
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Affiliation(s)
- Benedict G. Hogan
- School of Biological Sciences, University of Bristol, Bristol, UK
- School of Experimental Psychology, University of Bristol, Bristol, UK
- Author for correspondence: Benedict G. Hogan e-mail:
| | | | - Innes C. Cuthill
- School of Biological Sciences, University of Bristol, Bristol, UK
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Murali G, Kodandaramaiah U. Deceived by stripes: conspicuous patterning on vital anterior body parts can redirect predatory strikes to expendable posterior organs. ROYAL SOCIETY OPEN SCIENCE 2016; 3:160057. [PMID: 27429765 PMCID: PMC4929900 DOI: 10.1098/rsos.160057] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/10/2016] [Indexed: 06/06/2023]
Abstract
Conspicuous coloration, which presumably makes prey more visible to predators, has intrigued researchers for long. Contrastingly coloured, conspicuous striped patterns are common among lizards and other animals, but their function is not well known. We propose and test a novel hypothesis, the 'redirection hypothesis', wherein longitudinal striped patterns, such as those found on the anterior body parts of most lacertilians, redirect attacks away from themselves during motion towards less vulnerable posterior parts, for example, the autotomous tail. In experiments employing human 'predators' attacking virtual prey on a touchscreen, we show that longitudinal striped patterns on the anterior half of prey decreased attacks to the anterior and increased attacks to the posterior. The position of stripes mattered-they worked best when they were at the anterior. By employing an adaptive psychophysical procedure, we show that prey with striped patterning are perceived to move slower, offering a mechanistic explanation for the redirective effect. In summary, our results suggest that the presence of stripes on the body (i.e. head and trunk) of lizards in combination with caudal autotomy can work as an effective anti-predator strategy during motion.
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Hogan BG, Cuthill IC, Scott-Samuel NE. Dazzle camouflage, target tracking, and the confusion effect. ACTA ACUST UNITED AC 2016; 27:1547-1551. [PMID: 27656087 PMCID: PMC5027625 DOI: 10.1093/beheco/arw081] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 05/09/2016] [Accepted: 05/15/2016] [Indexed: 11/22/2022]
Abstract
The influence of coloration on the ecology and evolution of moving animals in groups is poorly understood. Animals in groups benefit from the “confusion effect,” where predator attack success is reduced with increasing group size or density. This is thought to be due to a sensory bottleneck: an increase in the difficulty of tracking one object among many. Motion dazzle camouflage has been hypothesized to disrupt accurate perception of the trajectory or speed of an object or animal. The current study investigates the suggestion that dazzle camouflage may enhance the confusion effect. Utilizing a computer game style experiment with human predators, we found that when moving in groups, targets with stripes parallel to the targets’ direction of motion interact with the confusion effect to a greater degree, and are harder to track, than those with more conventional background matching patterns. The findings represent empirical evidence that some high-contrast patterns may benefit animals in groups. The results also highlight the possibility that orientation and turning may be more relevant in the mechanisms of dazzle camouflage than previously recognized.
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Affiliation(s)
- Benedict G Hogan
- Biological Sciences, University of Bristol, Bristol Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK and; Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK
| | - Innes C Cuthill
- Biological Sciences, University of Bristol , Bristol Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ , UK and
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Yin J, Gong H, An X, Chen Z, Lu Y, Andolina IM, McLoughlin N, Wang W. Breaking cover: neural responses to slow and fast camouflage-breaking motion. Proc Biol Sci 2016; 282:20151182. [PMID: 26269500 PMCID: PMC4632627 DOI: 10.1098/rspb.2015.1182] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Primates need to detect and recognize camouflaged animals in natural environments. Camouflage-breaking movements are often the only visual cue available to accomplish this. Specifically, sudden movements are often detected before full recognition of the camouflaged animal is made, suggesting that initial processing of motion precedes the recognition of motion-defined contours or shapes. What are the neuronal mechanisms underlying this initial processing of camouflaged motion in the primate visual brain? We investigated this question using intrinsic-signal optical imaging of macaque V1, V2 and V4, along with computer simulations of the neural population responses. We found that camouflaged motion at low speed was processed as a direction signal by both direction- and orientation-selective neurons, whereas at high-speed camouflaged motion was encoded as a motion-streak signal primarily by orientation-selective neurons. No population responses were found to be invariant to the camouflage contours. These results suggest that the initial processing of camouflaged motion at low and high speeds is encoded as direction and motion-streak signals in primate early visual cortices. These processes are consistent with a spatio-temporal filter mechanism that provides for fast processing of motion signals, prior to full recognition of camouflage-breaking animals.
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Affiliation(s)
- Jiapeng Yin
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
| | - Hongliang Gong
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
| | - Xu An
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
| | - Zheyuan Chen
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
| | - Yiliang Lu
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
| | - Ian M Andolina
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
| | - Niall McLoughlin
- Faculty of Life Science, University of Manchester, Manchester M13 9PT, UK
| | - Wei Wang
- Institute of Neuroscience, State Key Laboratory of Neuroscience and Key Laboratory of Primate Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, People's Republic of China
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Hughes AE, Magor-Elliott RS, Stevens M. The role of stripe orientation in target capture success. Front Zool 2015; 12:17. [PMID: 26269704 PMCID: PMC4533824 DOI: 10.1186/s12983-015-0110-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/08/2015] [Indexed: 11/29/2022] Open
Abstract
Introduction ‘Motion dazzle’ refers to the hypothesis that high contrast patterns such as stripes and zigzags may have evolved in a wide range of animals as they make it difficult to judge the trajectory of an animal in motion. Despite recent research into this idea, it is still unclear to what extent stripes interfere with motion judgement and if effects are seen, what visual processes might underlie them. We use human participants performing a touch screen task in which they attempt to ‘catch’ moving targets in order to determine whether stripe orientation affects capture success, as previous research has suggested that different stripe orientations may be processed differently by the visual system. We also ask whether increasing the number of targets presented in a trial can affect capture success, as previous research has suggested that motion dazzle effects may be larger in groups. Results When single targets were presented sequentially within each trial, we find that perpendicular and oblique striped targets are captured at a similar rate to uniform grey targets, but parallel striped targets are significantly easier to capture. However, when multiple targets are present simultaneously during a trial we find that striped targets are captured in fewer attempts and more quickly than grey targets. Conclusions Our results suggest that there may be differences in capture success based on target pattern orientation, perhaps suggesting that different visual mechanisms are involved in processing of parallel stripes compared to perpendicular/oblique stripes. However, these results do not seem to generalise to trials with multiple targets, and contrary to previous predictions, striped targets appear to be easier to capture when multiple targets are present compared to being presented individually. These results suggest that the different orientations of stripes seen on animals in nature (such as in fish and snakes) may serve different purposes, and that it is unclear whether motion dazzle effects may have greater benefits for animals living in groups.
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Affiliation(s)
- Anna E Hughes
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Richard S Magor-Elliott
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall, UK
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Visual illusions in predator–prey interactions: birds find moving patterned prey harder to catch. Anim Cogn 2015; 18:1059-68. [DOI: 10.1007/s10071-015-0874-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 04/29/2015] [Accepted: 04/29/2015] [Indexed: 11/25/2022]
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Marshall KLA, Gluckman TL. The evolution of pattern camouflage strategies in waterfowl and game birds. Ecol Evol 2015; 5:1981-91. [PMID: 26045950 PMCID: PMC4449753 DOI: 10.1002/ece3.1482] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 02/25/2015] [Accepted: 03/10/2015] [Indexed: 11/06/2022] Open
Abstract
Visual patterns are common in animals. A broad survey of the literature has revealed that different patterns have distinct functions. Irregular patterns (e.g., stipples) typically function in static camouflage, whereas regular patterns (e.g., stripes) have a dual function in both motion camouflage and communication. Moreover, irregular and regular patterns located on different body regions ("bimodal" patterning) can provide an effective compromise between camouflage and communication and/or enhanced concealment via both static and motion camouflage. Here, we compared the frequency of these three pattern types and traced their evolutionary history using Bayesian comparative modeling in aquatic waterfowl (Anseriformes: 118 spp.), which typically escape predators by flight, and terrestrial game birds (Galliformes: 170 spp.), which mainly use a "sit and hide" strategy to avoid predation. Given these life histories, we predicted that selection would favor regular patterning in Anseriformes and irregular or bimodal patterning in Galliformes and that pattern function complexity should increase over the course of evolution. Regular patterns were predominant in Anseriformes whereas regular and bimodal patterns were most frequent in Galliformes, suggesting that patterns with multiple functions are broadly favored by selection over patterns with a single function in static camouflage. We found that the first patterns to evolve were either regular or bimodal in Anseriformes and either irregular or regular in Galliformes. In both orders, irregular patterns could evolve into regular patterns but not the reverse. Our hypothesis of increasing complexity in pattern camouflage function was supported in Galliformes but not in Anseriformes. These results reveal a trajectory of pattern evolution linked to increasing function complexity in Galliformes although not in Anseriformes, suggesting that both ecology and function complexity can have a profound influence on pattern evolution.
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Affiliation(s)
- Kate L A Marshall
- Department of Zoology, University of Cambridge Cambridge, CB2 3EJ, UK
| | - Thanh-Lan Gluckman
- Department of Zoology, University of Cambridge Cambridge, CB2 3EJ, UK ; Department of Zoology, University of Melbourne Parkville, Victoria, 3010, Australia ; Department of Animal and Plant Sciences, University of Sheffield Western Bank, S10 2TN, UK
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