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Experimental layout. The longitudinally striped, unicolored, and vertically striped objects are shown on the left. During the experiment, objects appeared on the left side of the screen at varying heights. The cursor (black circle) marks the position of the cursor at the beginning of a trial. The arrows above and below indicate the direction of the cursor movement. The dotted lines indicate possible paths of the objects and where they can be intercepted with the cursor. The brackets indicate the duration of the time interval during which objects would disappear. doi:10.1371/journal.pone.0061173.g001
Source publication
In the animal kingdom, camouflage refers to patterns that help potential prey avoid detection. Mostly camouflage is thought of as helping prey blend in with their background. In contrast, disruptive or dazzle patterns protect moving targets and have been suggested as an evolutionary force in shaping the dorsal patterns of animals. Dazzle patterns,...
Contexts in source publication
Context 1
... could be hit by moving a cursor over the object with a joystick and pressing the fire button while the object was under the cursor. The cursor was positioned at L of the width of the screen and could only be moved vertically (see Figure 1). Thus the task was to move the cursor to the vertical location of the object on the screen and to press the fire button when the object reached the target zone. ...
Context 2
... hit an object, participants had to move the cursor over the object and press the fire button. The cursor was positioned at L of the width of the screen and could only be moved vertically (see Figure 1). Because objects disappeared shortly before they reached the point where they could be hit (see [11] for a similar design), participants had to press the fire button when they thought the object would be under the cursor without seeing the object. ...
Context 3
... vertically striped object had 11 black stripes (0.7 mm67 mm, 0.0760.67 degrees of visual angle) equidistantly distributed over the object (see Figure 1). The unicolored object was black (RGB color code: 0,0,0). ...
Context 4
... Task. The hitting task was similar to the setup in Experiment 1 (see Figure 1). After a short practice period, participants played 180 trials of a hitting task. ...
Context 5
... reduced the long disappearance duration in comparison to Experiment 1 to investigate if the effect was reliable at different disappearance durations and to ensure that the objects were visible long enough to allow participants to form an accurate perception of speed. There were three types of patterns: the objects were unicolored, vertically striped, or longitudinally striped (see Figure 1). In each condition participants performed 30 trials. ...
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... Only 4 of the 11 published studies yielded measures of effect size (Scott-Samuel et al., 2011;von Helversen et al., 2013;Murali & Kodandaramaiah, 2016;Kodandaramaiah et al., 2020). All involved computerbased tasks with simple geometric shapes and human participants (for sample stimuli, see Fig. 1B,D and E) . ...
... In the context of a signal-to-noise framework (Merilaita et al., 2017), the relationship between the target (signal) and the background (noise) matters; therefore, if these both vary across different experiments, it is challenging to make meaningful comparisons. For example, the backgrounds used by both von Helversen et al. (2013) and Kodandaramaiah et al. (2020) were considerably more complex than those used by Scott-Samuel et al. (2011) and Murali & Kodandaramaiah (2016), which could have implications for the signal-to-noise ratio in these studies, hence the different effect of dazzle found in each pair of papers (see Fig. 3A). It is also worth noting that these experiments compared one stimulus with another, so all the data were relative; it is impossible to determine which pattern, if any, had its speed reported veridically. ...
... 'Dazzle camouflage' (e.g. see Scott-Samuel et al., 2011;von Helversen et al., 2013), by virtue of the second word, carries with it the baggage of crypsis: avoiding detection or recognition (Cuthill, 2019). However, the term dazzle was coined specifically to differentiate it from the many 'low-visibility' schemes in use at the time (Williams, 2001;Taylor, 2016: p. 29). ...
‘Dazzle coloration’ describes a wide variety of high-contrast patterns allegedly providing protection against attack during motion. Previous research falls into three broad groups. First, studies using humans demonstrate that certain surface patterns can cause significant misperceptions in controlled laboratory conditions, although the effects are inconsistent in both direction and magnitude. Second, experiments on target capture or tracking also show effects that are strongly dependent upon the test paradigm. It has not been established that these laboratory findings generalize to other species, or to the real world. Third, mainly comparative studies build a case for longitudinal striping being involved in escape strategies in some squamate reptiles. We suggest that: (1) the concept of dazzle conflates a description of appearance with presumed function; (2) some effects attributed to dazzle have not been distinguished clearly from other mechanisms of protective coloration; and (3) confusion persists over the evidence necessary to attribute a dazzle function to markings. We refine the definition of dazzle to exclude appearance: dazzle is coloration that interferes with target interception, as a result of misperception of its speed, trajectory and/or range. Our review clarifies discussion of dazzle, and sets out a coherent and practical framework for future research.
... There is an intense debate about the protective function of eyespots and motion camouflage, and our meta-analysis highlight that such mechanisms are not effective to increase searching time by predators [18,[46][47][48][49]. However, this does not mean that these camouflage strategies are not adaptive. ...
Although numerous studies about camouflage have been conducted in the last few decades, there is still a significant gap in our knowledge about the magnitude of protective value of different camouflage strategies in prey detection and survival. Furthermore, the functional significance of several camouflage strategies remains controversial. Here we carried out a comprehensive meta-analysis including comparisons of different camouflage strategies as well as predator and prey types, considering two response variables: mean predator search time (ST) (63 studies) and predator attack rate (AR) of camouflaged prey (28 studies). Overall, camouflage increased the predator ST by 62.56% and decreased the AR of prey by 27.34%. Masquerade was the camouflage strategy that most increased predator ST (295.43%). Background matching and disruptive coloration did not differ from each other. Motion camouflage did not increase ST but decreases AR on prey. We found no evidence that eyespot increases ST and decreases AR by predators. The different types of predators did not differ from each other, but caterpillars were the type of prey that most influenced the magnitude of camouflage's effect. We highlight the potential evolutionary mechanisms that led camouflage to be a highly effective anti-predatory adaptation, as well as potential discrepancies or redundancies among strategies, predator and prey types.
... This special type of camouflage is called motion dazzle as it prevents successful capture during motion by causing predators to misjudge the direction or speed of prey movement. Several studies showed that such motion dazzle patterns might be involved in hampering a predator's ability to intercept a moving prey (Allen et al., 2013;Brodie, 1992;von Helversen et al., 2013;Jackson et al., 1976;Kelley & Kelley, 2014;Rojas et al., 2014). It is generally accepted that motion dazzle patterns are advantageous for mobile species that are highly detectable against the stationary background, while cryptic pigmentation patterns are advantageous for less-mobile species that rely on camouflage to reduce detection (Halperin et al., 2016). ...
... A beneficial trait correlation of stripe patterns with body length was first shown for several reptile species (Allen et al., 2013;Murali & Kodandaramaiah, 2017). This trait correlation redirects predator attacks to the tail and thereby reduces the probability of individuals being captured (von Helversen et al., 2013) suggesting that the effectiveness of dazzle patterns depends on body shape (Murali & Kodandaramaiah, 2017). ...
... Notably, different elongation optima are supported for striped species than for nonstriped species (Table 1). In reptiles, a combination of body length and stripes reduces the probability with which moving prey is captured by affecting the predators' perception of speed (von Helversen et al., 2013). This motion dazzle effect of stripes is a form of defensive color pattern suggested to prevent successful capture during motion by causing predators to misjudge the direction or speed of prey movement. ...
Color patterns are often linked to the behavioral and morphological characteristics of an animal, contributing to the effectiveness of such patterns as antipredatory strategies. Species-rich adaptive radiations, such as the freshwater fish family Cichlidae, provide an exciting opportunity to study trait correlations at a macroevolutionary scale. Cichlids are also well known for their diversity and repeated evolution of color patterns and body morphology. To study the evolutionary dynamics between color patterns and body morphology, we used an extensive dataset of 461 species. A phylogenetic supertree of these species shows that stripe patterns evolved ~70 times independently and were lost again ~30 times. Moreover, stripe patterns show strong signs of correlated evolution with body elongation, suggesting that the stripes' effectiveness as antipredatory strategy might differ depending on the body shape. Using pedigree-based analyses, we show that stripes and body elongation segregate independently, indicating that the two traits are not genetically linked. Their correlation in nature is therefore likely maintained by correlational selection. Lastly, by performing a mate preference assay using a striped CRISPR-Cas9 mutant of a nonstriped species, we show that females do not differentiate between striped CRISPR mutant males and nonstriped wild-type males, suggesting that these patterns might be less important for species recognition and mate choice. In summary, our study suggests that the massive rates of repeated evolution of stripe patterns are shaped by correlational selection with body elongation, but not by sexual selection.
... Motion dazzle, where the contrasting markings of the moving prey, such as stripes or zig-zag patterns, can compromise the predator's judgement of its speed and trajectory, and thus reduces the likelihood of prey capture (Elias et al., 2019;Hämäläinen et al., 2015;Hughes et al., 2014;Kodandaramaiah et al., 2020;Murali et al., 2019;Stevens, 2007;Stevens et al., 2008;Valkonen et al., 2020). Several studies refer to this phenomenon as 'dazzle camouflage' (von Helversen et al., 2013;Hogan et al., 2016aHogan et al., ,b, 2017aLingel, 2020). However, as camouflage is not necessarily the underlying mechanism reducing the risk of predation during motion dazzle , we prefer 'motion dazzle' over 'dazzle camouflage' to avoid any confusion. ...
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.
... Despite these findings, not all research has supported the motion dazzle hypothesis. Some studies on humans have found that striped targets are easier to capture than non-patterned targets [20,21], and moving cuttlefish have been shown to preferentially display low contrast patterns [22]. Similarly, a recent study using natural predators hunting patterned prey found no evidence for a benefit of motion dazzle patterning compared to uniform colouration [23]. ...
... 17.6, and 11.7 deg s −1 ). These speeds were similar to those used in previous studies [11,[13][14][15]20,21]. Each participant was presented with a random mix of targets of all three speeds. ...
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.
... In addition to reducing the chance of visual detection by predators through camouflage, plumage patterning can reduce the chance of predation by disorienting or deceiving the signaler's escape velocity (Stevens et al. 2008, Scott-Samuel et al. 2011, von Helversen et al. 2013. In particular, high-contrast patterns, such as adjacent black and white patches, bars, or stripes, can produce visual illusions that interfere with visual assessments of motion and reduce the chance of successful capture (Brodie 1992). ...
Birds exhibit remarkable variation in plumage patterns, both within individual feathers and among plumage patches. Differences in the size, shape, and location of pigments and structural colors comprise important visual signals involved in mate choice, social signaling, camouflage, and many other functions. While ornithologists have studied plumage patterns for centuries, recent technological advances in digital image acquisition and processing have transformed pattern quantification methods, enabling comprehensive, detailed datasets of pattern phenotypes that were heretofore inaccessible. In this review, we synthesize recent and classic studies of plumage patterns at different evolutionary and organismal scales and discuss the various roles that plumage patterns play in avian biology. We dissect the role of plumage patches as signals within and among species. We also consider the evolutionary history of plumage patterns, including phylogenetic comparative studies and evolutionary developmental research of the genetic architecture underlying plumage patterns. We also survey an expanding toolbox of new methods that characterize and quantify the size, shape, and distribution of plumage patches. Finally, we provide a worked example to illustrate a potential workflow with dorsal plumage patterns among subspecies of the Horned Lark (Eremophila alpestris) in western North America. Studies of plumage patterning and coloration have played a prominent role in ornithology thus far, and recent methodological and conceptual advances have opened new avenues of research on the ecological functions and evolutionary origins of plumage patterns in birds.
... Here, we explore a different possible advantage that occurs when prey movement occurs in peripheral vision: gaze may be 'anchored' upon the initial location by a highly salient but transient display, and subsequent movement masked due to a flash-lag effect [20] or sensory overload [21]. Instead of exploring the effectiveness of motion camouflage strategies with regards to impeding capture, as in motion dazzle experiments [22][23][24][25][26][27][28], we aim to explore the phenotype's effects on localization. ...
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.
... Yet, it is important to note that the effect of this strategy can be influenced by species size, it seems to work better for smaller ones, at least for lizards (Murali & Kodandaramaiah, 2017). The authors argued that: (1) stripes may increase detectability of larger prey; (2) in smaller prey, the benefits of stripes may overcome the costs due to enhanced conspicuousness; (3) the effect of perceived speed disruption may be lower in larger individuals; (4) smaller prey are known to have greater ability to suddenly change their escape trajectory (Witter et al., 1994), and therefore motion-dazzle may work better for them; and (5) if smaller prey have higher sprint speed (Bauwens et al., 1995), and motion-dazzle has a larger effect for rapidly moving individuals (von Helversen et al., 2013), then smaller striped species may be favoured. Therefore, motion-dazzle differs from disruptive camouflage by presenting regular patterns and by preventing capture after detection. ...
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.
... For instance, it is unclear whether the orientation of stripes in relation to the direction of prey motion affects prey capture success. Previous studies suggest that perpendicular stripes are more beneficial than parallel ones (von Helversen et al. 2013;Hughes et al. 2015). Stevens et al. (2008), however, found no influence of stripe orientation on capture success. ...
... A SCRATCH task similar to that used by Murali and Kodandaramaiah (2016) in their speed perception experiment (their Experiment 4) was used to test whether perceived speed differed between a pair of objects. The task was based on an adaptive staircase paradigm (Leek 2001;von Helversen et al. 2013). Multiple sets of experiments were performed using selected pairs of object types to test the effect of different attributes (i.e., stripe orientation, contrast, object size, and object speed) on speed perception by participants. ...
Motion dazzle markings comprise patterns such as stripes and zigzags 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.
... We showed that models with stripes were less attacked than its uniform counterpart. As pointed out by Helversen et al. (2013), from an evolutionary point of view, a slight increase in survival rate can result in a great selective pressure, referring to Haldane's mathematical theory of natural selection (Haldane, 1927). ...
Disruptive coloration, such as striped pelage, is a form of camouflage that breaks out the animal outline and makes it hard to be visually detected in the background. As consequence, it diminishes the chances of being caught by predators and confers adaptive advantage to its possessor, thus being referred as a classic example of natural selection. Monodelphis microdelphys americana and Monodelphis microdelphys iheringi are small Neotropical marsupials that present similar disruptive pelage pattern with dorsal longitudinal black stripes, which are lost only in adult males of M. m. americana when these two species are in sympatry. Here, we investigated the effectiveness of stripes for camouflage in these species following two approaches: (i) visual search test by human volunteers using an Android application; and (ii) natural predation on artificial models made with plasticine. Results showed that presence of stripes decreased detectability of the target when tested by humans and by predators in natural habitat. The predation test also showed that the stripes are more advantageous when combined with a reduced body size. Thus the loss of stripes as a means of camouflage in an adult male of M. m. americana (the larger species) should not have a great impact as it would probably have in smaller individuals, such as youngsters and females of both species, or even adult males of M. m. iheringi (the smallest species). Resumo: Ter ou não ter listras? Seleção natural e coloração disruptiva em duas espécies simpátricas de marsupiais Neotropicais do gênero Monodelphis (Didelphidae, Mammalia). Coloração disruptiva, como presença de listras na pelagem, é uma forma de camuflagem que quebra o contorno da silhueta de um animal, dificultando a sua detecção no ambiente de fundo. Como consequência, diminui as chances de o mesmo ser localizado e atacado por predadores, conferindo vantagem adaptativa ao indivíduo que a possui, sendo, portanto, um exemplo clássico de seleção natural. Monodelphis microdelphys americana e Monodelphis microdelphys iheringi são pequenos marsupiais Neotropicais que apresentam padrões similares de pelagem disruptiva com listras escuras longitudinais, que são perdidas apenas nos machos adultos de M. m. americana quando essas duas espécies estão em simpatria. Neste trabalho, investigamos a efetividade das listras para a camuflagem nestas duas espécies, com duas abordagens: (i) teste de busca visual com humanos voluntários usando um aplicativo para Android; e (ii) predação natural em modelos artificias feitos com plasticina. Os resultados mostraram que a presença de listras diminui a detectabilidade do alvo por humanos e por predadores em ambiente natural. O teste de predação também mostrou que listras são mais vantajosas quando combinadas com tamanho corporal reduzido. Logo, a perda de listras para fins de camuflagem em machos adultos de M. m. americana (a espécies maior) não deve ter um impacto tão grande como teria em indivíduos menores, assim como em jovens e fêmeas de ambas as espécies, e até machos adultos de M. m. iheringi (a menor espécie). Palavras-Chave: Busca visual; Camuflagem; Cripsia; Modelo de plasticina; Predação. ARTiGoS 86 Boletim da Sociedade Brasileira de Mastozoologia, 85: 86-94, 2019
