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Keywords:

  • anti-predator defences;
  • Batesian mimicry;
  • camouflage;
  • crypsis

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

Many organisms appear to mimic inanimate objects such as twigs, leaves, stones, and bird droppings. Such adaptations are considered to have evolved because their bearers are misidentified as either inedible objects by their predators, or as innocuous objects by their prey. In the past, this phenomenon has been classified by some as Batesian mimicry and by others as crypsis, but now is considered to be conceptually different from both, and has been termed ‘masquerade’. Despite the debate over how to classify masquerade, this phenomenon has received little attention from evolutionary biologists. Here, we discuss the limited empirical evidence supporting the idea that masquerade functions to cause misidentification of organisms, provide a testable definition of masquerade, and suggest how masquerade evolved and under what ecological conditions. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99, 1–8.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

Many species of plants and animals have evolved striking visual resemblances to inanimate objects found in the same locality. Examples can be found in a diverse array of taxa. Plants from the genus Lithops look remarkably like stones; stick insects are easily mistaken for the twigs of the branches on which they sit; the spider Ornithoscatoides decipiens closely resembles bird-droppings; the leafy sea dragon Phyllopteryx eques is often misidentified as seaweed; the Amazon fish Monocirrhus polycanthus is visually almost indistinguishable from leaves, and birds from the family Nyctibiidae bear an uncanny likeness to tree stumps. These resemblances appear to be particularly common among insects, we estimate that at least 50 of the 950 species of British macrolepidoptera resemble inanimate objects at some point during their development, as do most of the 2500 species in the group Phasmatodea (stick and leaf insects) and a large number of the Mantodea (mantises).

The classification of these visual signals is controversial (Vane-Wright, 1980; Cloudsley-Thompson, 1981; Edmunds, 1981; Endler, 1981; Robinson, 1981; Rothschild, 1981; Vane-Wright, 1981; Allen & Cooper, 1985). Some researchers argue that these animals are cryptic (i.e. they avoid being detected, by predators or prey, by resembling the background against which they are viewed) (Vane-Wright, 1980; Edmunds, 1981). Others argue that they are Batesian mimics (Edmunds, 1972, 1974), gaining protection from predators or access to prey, by mimicking the appearance of another species. The consensus of opinion now appears to be that this phenomenon is logically different from both crypsis and Batesian mimicry (Allen & Cooper, 1985; Ruxton, Sherratt & Speed, 2004a), and is termed ‘masquerade’ (Endler, 1981). Masquerade now replaces previous terminology, including ‘special resemblance’ (Cott, 1940), ‘procryptic resemblance’ (Carrick, 1936), and ‘concealing imitation’ (Hailman, 1977)). Despite its widespread taxonomic occurrence, and the recent resurgence of interest in both crypsis (Ruxton, Speed & Kelly, 2004b; Cuthill et al., 2005; Merilaita & Lind, 2006; Schaefer & Stobbe, 2006; Stevens et al., 2006) and mimicry (Rowe, Lindström & Lyytinen, 2004; Skelhorn & Rowe, 2005, Darst & Cummings, 2006, 2006; Rowland et al., 2007; 2007), masquerade has received very little attention from evolutionary biologists (Carrick, 1936; De Ruiter, 1952; Tinbergen, 1960). In this review, we argue how masquerade differs from both Batesian mimicry and crypsis, present a testable definition of masquerade, and discuss how masquerade could have evolved and under what ecological conditions we would expect to find it.

DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

Existing definition

Although conceptually similar, masquerade is different from both Batesian mimicry and crypsis. Endler (1981) was the first to propose a testable difference between masquerade and Batesian mimicry. He stated that although both Batesian mimics and masquerading species are cosidered to benefit from predators misclassifying them as things that they would rather not eat, the species that Batesian mimics resemble may experience demographic or evolutionary change as a result of the presence of the mimic, whereas the presence of a masquerading species will have no affect on its model. For example, if a palatable insect evolves to resemble a chemically defended insect (Batesian mimicry), the presence of the palatable mimic is likely to cause predators to increase their attack rates on both palatable mimics and defended models, which in turn is likely to influence the population/evolutionary dynamics of the model. However, if a palatable insect evolves to resemble a stone (masquerade), even if predators increase their attack rates on stones, stones are unlikely to suffer a change in their density in the local environment as a result of these attacks.

Masquerade is also thought to differ from crypsis because cryptic individuals are mistaken for the background on which they rest, whereas masquerading individuals are mistaken for specific objects. As a result, crypsis relies on the relationship between the individual and the background, but the benefit of masquerade is thought to be independent of the background against which the masquerading individual is viewed (Endler, 1981).

Exceptions to this definition

Endler (1981) recognized that, by using this definition, some species that we might think of as displaying masquerade are excluded. For example, many predacious mimics of flowers will fall outside this definition because predacious insects can either increase or decrease the number of viable seeds that their host plants produce by consuming seed-eating insects and pollinators, respectively (Louda, 1982; Suttle, 2003; Romero & Vasconcellos-Neto, 2004; Knight et al., 2006). Furthermore, because a mimic's resemblance to a flower is likely to afford it protection from predation, the mimic has more opportunity to influence the reproductive success of its host plant than if it did not resemble its host plant's flower. Additionally, predacious leaf and twig mimics may actually protect a plant by being more efficient predators of the herbivores that feed on it. Consquently, when predacious insects affect their host plant's fitness, they must be classed as examples of mimicry.

We would add that Endler's definition also excludes many herbivorous species that resemble leaves or twigs. This is because the resemblance of such species to parts of their host plants confers protection from predation, allowing them to damage their host plant more extensively than if they did not resemble parts of the host plants. In some circumstances this could reduce the reproductive success of the plant on which the masqueraders feed. One extreme example of this is the defoliation of large areas of forest by stick insects, which results in the death of many trees, and the surviving trees utilizing all their resources to produce new crowns rather than to reproduce (Bedford, 1978).

Proposed refinements to this definition

We would therefore, suggest that it might be useful to refine Endler's definition. This can be achieved by considering that the difference between Batesian mimicry and masquerade lies in ‘how’ Batesian mimics and masquerading species influence the population or evolutionary dynamics of their models. Clearly, masquerading species that resemble nonliving objects have no effect on their models. However, in the situations where masquerading species do influence the population or evolutionary dynamics of their models, they do so directly either by damaging the models themselves (e.g. stick insect eating their host plants), or by removing animals that directly influence the reproductive success of the model (e.g. flower mantids eating seed-eating pests and/or pollinators). By contrast, Batesian mimics cause the signal receiver's behaviour towards the model to change in a way that influences the population or evolutionary dynamics of the model (e.g. experience with palatable Batesian mimics causes avian predators to attack more defended models). Thus, Batesian mimics influence their models indirectly, through the actions of a third party (e.g. potential predators). Using this definition, twig-mimics that damage their host plants would be classified as benefiting from masquerade. Flower-mimicking spiders would also be considered to benefit from masquerade if they directly influenced the fitness of their host plants (e.g. preying on potential pollinators). However, if the spiders cause pollinators to change their behaviour in a way that influenced the fitness of the plant (Ings & Chittka, 2009), then they would be considered to be Batesian mimics rather than masqueraders.

We now clarify how masquerade differs from crypsis. The visual appearance of a cryptic species hinders its detection, whereas the visual appearance of a masquerading species hinders its correct identification. If the observer (the individual's predator or prey) fails to detect a cryptic organism, then it does not form the conclusion that there is a specific entity at the site where the cryptic organism is. By contrast, masquerade is not thought to hinder the viewers' ability to detect that there is an entity in the spatial position of the focal organism but, instead, the viewer is thought to misclassify the identity of the focal organism as something in which it has no interest (i.e. something which is not a profitable food source or a threat). Misclassification can occur either because naïve predators/prey are unaware that there is a masquerading species in the environment, or because the cost of discrimination between the masquerader and the model (i.e. in lost foraging time) makes discrimination unprofitable to educated predators/prey. It is also important to note that masquerading species may, in some cases, benefit from both masquerade and crypsis. For example, species such as twig-mimicking caterpillars are probably both misidentified as twigs (masquerade), and difficult to detect as discrete entities against a background of other twigs (crypsis).

The importance of context

We also disagree with the assumption that the benefits of masquerade must be independent of the background against which the species is seen (Endler, 1981) because it does not allow for the possibility that classification is context dependent. This is important because a number of studies have demonstrated that the context in which prey are viewed influences how both naïve (Gamberale-Stille & Tullberg, 2001) and educated (Skow & Jakob, 2006) predators perceive the value of prey items. It therefore is likely that the context in which a prey item is found may influence whether predators identify it as a model or a masquerader.

Hailman (1977) also failed to consider the possibility that identification could be context dependent. He divided masquerade (although he used the term ‘concealment imitation’) into two separate phenomena: ‘element imitation’ and ‘object imitation’. He stated that element imitators resemble some specific and common object that is one element of the environmental pattern (e.g. twigs or leaves), whereas object imitators resemble some specific object that is not necessarily common and is not an element of a regular environmental pattern (e.g. stones or bird droppings). The essential difference is that element imitators tend to be seen against a background of the items that they mimic, whereas object imitators tend to be viewed in isolation from examples of the object that they mimic. He stated that element imitators benefit from blending into the background pattern (crypsis), and object imitators benefit from being misclassified as the object which they resemble (masquerade).

We do not agree that element imitators benefit from crypsis whereas object imitators benefit from masquerade. We predict that both element and object imitators will benefit from being misclassified as the item that they resemble, and therefore that both use masquerade. However, we agree that making the distinction between element and object imitation is useful. Object imitators are likely to be misclassified as their models over a wider range of backgrounds than element imitators. This is simply because objects such as stones and bird-droppings are found over a range of different backgrounds (such that they are widespread across many microhabitats), whereas elements such as twigs and leaves are most often found amongst backgrounds of similar elements. For element imitators, predators or prey could learn that elements found out of context are more likely to be masqueraders than those found in the correct context. By contrast, predators could not use this simple rule of thumb to distinguish between object imitators and their models because there is no specific context in which the models are found.

We would also predict that whilst both element and object imitators benefit from masquerade, element imitators are more likely to gain additional benefits from crypsis (being difficult to detect) than object imitators simply because they are likely to be seen against a background of the elements that they are mimicking. Finally, we would add that misclassification could potentially occur in two ways; by being misidentified, or by being miscategorized. For example, if a caterpillar has evolved to resemble the twigs of a beech tree (Fagus sylvatica), birds that have learned that beech twigs are not a food source may misidentify the twig mimic as a beech twig and conclude that it is not a prey item; alternatively, birds may not have experienced beech twigs, but may have formed twig and caterpillar categories (by experiencing several other species of twig and caterpillar) and may miscategorize the twig-mimic as a twig rather than a caterpillar. If birds learn about their environment in this way, both object and element imitators will benefit from miscategorization. However, only element imitators will benefit from misidentification, since this type of mis-classification requires the signal receiver to have experience with a specific model.

Our definition of masquerade

Given our objections to the existing definition of masquerade, we would define a masquerading species as one whose appearance causes its predators or prey to misclassify it as a specific object found in the environment, causing the observer to change its behaviour in a way that enhances the survival of the masquerader. Any change in the population/evolutionary dynamics of the model caused by the presence of the masquerader will not be as a result of the signal receiver changing its behaviour towards the model. We would also add that masquerade can be subdivided into protective masquerade when the resemblance functions to protect prey from their predators, and aggressive masquerade when the resemblance functions to increase predators' access to prey.

EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

We know of only two empirical studies that have attempted to directly test the efficacy and function of masquerade (De Ruiter, 1952; Tinbergen, 1960), and both are difficult to interpret. In a series of experiments carried out by De Ruiter (1952), twig-like geometrid caterpillars (Ennomos alniaria L., Biston hirtaria, and Biston strataria) and twigs that resembled the larvae, were scattered over the floor of an aviary. Seven jays (Garrulus glandarius) were then allowed to forage individually. Despite usually taking less than 10 s to find cryptic prey, the birds took between 1 and 40 min to attack the first twig-mimicking caterpillars (two birds were given live caterpillars and appeared to detect the first caterpillar after it moved; the other birds were given dead caterpillars, and, in an unspecified number of cases, the birds were lured to the first caterpillar by the experimenter). After finding the first caterpillar, however, the birds immediately went on to find most, if not all, of the caterpillars present. Four of the birds picked up twigs and caterpillars indiscriminately, one bird picked up fewer twigs than caterpillars and handled twigs (but not caterpillars) hesitantly, and two birds discriminated perfectly, picking up only caterpillars.

The fact that four of the birds did not discriminate between twigs and caterpillars may indicate that birds found it difficult to discriminate between them. However, two of the birds were clearly able to perform this discrimination. The initial ‘reluctance’ to attack the caterpillars is consistent with the idea that birds initially saw them and misclassified them as twigs, but, on closer inspection, found them to be caterpillars. However, because the birds' reactions to twig-mimicking caterpillars were not directly compared to their reactions to any other prey type, these findings could also be explained by assuming that birds were not motivated to eat.

Tinbergen (1960) extended the experiments performed by de Ruiter, by investigating whether birds' predation rates on masquerading prey were influenced by the relative frequency of models to masqueraders. Such an influence might be expected when masqueraders are common in comparison to their models; birds would be more likely to be rewarded with a masquerader when they attack an individual of the model-masquerader complex. As a result, birds receive a larger net energy gain when masqueraders are common, and educated birds should be more likely to spend time searching for masquerading individuals. Tinbergen (1960) demonstrated that when caterpillars were common in comparison to twigs, birds continued to hunt caterpillars, but if twigs were common in comparison to caterpillars, they gave up searching. One explanation for these findings is that birds were misclassifying the caterpillars as twigs, and, at low caterpillar densities, they did not benefit from attacking both twigs and mimics because the net energy gain was low. Alternatively, adding twigs into the environment may have increased the complexity of the visual landscape, such that birds had to search through more items before they found a caterpillar. If this is true, then the caterpillars were not necessarily benefitting from masquerade because adding any items into the environment (even ones that were visually very different from twigs) would have given the same results.

Therefore, although these experiments provide some suggestive evidence that masquerading species gain protection from their coloration, there is no evidence that they are benefiting from masquerade (i.e. being misclassified as their models). To demonstrate that organisms benefit from masquerade, we need to show that:

  • 1
    The species is misidentified or misclassified by either its predators, its prey or both.
  • 2
    Being misidentified confers fitness benefits on the masquerading species.
  • 3
    The presence of the masquerader does not change the behaviour of the signal receiver in a way that influences the population or evolutionary dynamics of the model (if the object is not a living species then this is self evident).

Perhaps one reason for the lack of empirical evidence in this area is the methodological challenge of studying masquerade. It is difficult to determine whether a predator has detected and misclassified a masquerading individual, or whether it has simply failed to detect the prey item. For predators to misclassify a masquerading prey item as the object that it mimics, the predator must have experience of that object. By manipulating a predator's experience of the model, it should be possible to determine whether birds are misclassifying masquerading prey or simply not detecting them. For example, if birds misidentify beech (Fagus sylvatica) twig-mimicking insects as beech twigs, we would expect birds with experience of beech twigs to be more reluctant to attack the mimics than birds that have never seen beech twigs.

It may also be possible to test whether birds miscategorize beech twig-mimicking insects as twigs rather than insects. If naïve birds were taught to form twig and insect categories by giving them experience with several species of twig (that are dissimilar to beech twigs) and insects (although not the beech twig mimics). Then, if birds form twig and insect categories, and miscategorize beech twig mimics as twigs, we would expect birds to ignore novel twigs and insects that resemble novel twigs, but accept other novel insects. Using a representative sample of twigs and insects found in the same environment as twig-mimicking insects during training would give an ecologically realistic idea about how birds form natural categories, and how masquerading insects fit into these categories.

Finally, although it is unclear whether the contexts in which masquerading prey are found influences the way in which predators misclassify prey, and hence the benefit of masquerade, there is some evidence that this could be the case. For example, the twig-like caterpillars of both the early thorn moth (Selenia dentaria) and the brindled beauty (Lycia hirtaria) suffer less from predation when presented on their own host plant compared to when they are presented on either other plant species or feeding trays (Carrick, 1936). This could be because these species are benefiting from crypsis as well as/instead of masquerade, and the differences in predation may simply reflect differences in detection. It is also possible that these species survive better on their own host plants because they are misclassified as twigs more often when found in the ‘correct’ context. Again, this could be tested by comparing the behaviour of predators that have never experienced twigs with those that have: if differential crypsis alone is responsible for this finding, then there should be no difference between the behaviour of naïve and experienced predators. However, if misclassification is context dependent, then the benefit of being positioned on the correct host plant should be greater when predators have experience with the models than when they are naïve.

THE ECOLOGY OF MASQUERADE

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

There may be opportunity costs associated with masquerading as an inanimate object. For example, there is some evidence that masquerading prey may benefit from restricted movement (De Ruiter, 1952), perhaps because movement provides a cue that allows individuals to discriminate between masqueraders and their models. As a result, we might expect masquerade to be more common among species whose foraging and/or mating patterns are not strongly movement dependent (e.g. sit and wait predators and species that reproduce asexually). Masquerade may also be costly in terms of the restrictions it places on body structure: Edmunds (1972) describes the conflict between the requirement for a slender profile in stick-mimicking mantids and the requirement for separation of the eyes to give binocular vision for effective prey capture.

Finally, if misclassification is context dependent, masquerading insects will benefit more from masquerade when found on specific backgrounds. As a result, we would expect masquerade to be associated with species with specialized feeding habits because they are already restricted to particular foraging areas. Alternatively, masquerading species could overcome this problem by evolving a more general resemblance to several models, or by developing polyphenisms (Noor, Parnell & Grant, 2008) or polymorphisms (Greene, 1989).

Examples of both polymorphisms and polyphenisms can be found in masquerading species. For example, the caterpillar Nemoria arizonaria mimics oak twigs when fed on oak leaves, or oak catkins when fed on oak catkins (Greene, 1989). Although it is unlikely that these caterpillars can change from one morph to another when their diet is changed, there are species in which visual appearance is plastic. The appearance of the American peppered moth caterpillar Biston betularia cognataria is influenced by the colour of light in the feeding environment, and changes in light colour correspond with changes in appearance (Noor et al., 2008), thus allowing individuals to adapt to the background on which they find themselves. As a result, caterpillars found on birch trees, Betula nigra, bear a striking resemblance to birch twigs, and caterpillars found on weeping willow trees, Salix babylonica, bear a striking resemblance to willow twigs.

THE EVOLUTION OF MASQUERADE

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

Because masquerading species are found across a number of diverse taxa, and the physiological mechanisms through which masquerade are achieved differ greatly, it is likely that masquerade has evolved independently several times. Although the mechanisms underlying the initial evolution of masquerade remain unclear, it is reasonable to assume that masquerading species evolved from cryptic ancestors. Mutants with a superficial resemblance to an appropriate model probably benefited from being misclassified as an object that predators were unmotivated to eat, or that prey did not perceive to be a threat. Even if such mutants were only misclassified when seen at a distance, this may have been enough to prevent predators inspecting them more closely, or may have allowed them to get slightly closer to their prey before being detected. However, such a mutation may also have been associated with a loss of crypsis and thus an increased rate of being detected. If the benefit of being misidentified outweighed any costs associated with masquerade, selection would have favoured the masquerading mutants. The accuracy of the resemblance would then have gradually improved over successive generations as the individuals that most closely resembled the model were misidentified by predators or prey at ever closer distances (assuming that the benefits associated with being misidentified continue to outweigh any costs). Clearly, this evolutionary pathway relies on the assumption that the cryptic ancestors were sometimes detected because if prey cannot be detected they cannot be misclassified, although this does not appear to be unreasonable because many apparently cryptic prey are known to suffer heavily from predation (Philpott et al., 2004).

Because masquerading species are thought to gain protection/foraging success by being mistaken for the object/species that they resemble, one may expect masquerade to show a frequency-dependent advantage, such that masquerading species benefit more from their appearance when they are rare in comparison with their models. Although there is some limited evidence that the benefit of protective masquerade may be frequency dependent (Tinbergen, 1960), Ruxton et al. (2004a) argue that because masquerading prey mimic objects that are common in the environment, factors other than predation will regulate the population size of masquerading prey long before they reach densities at which it pays predators to attack (or even closely inspect) them and the things they resemble. However, there is some evidence suggesting that predators may influence the population dynamics of masquerading prey. Many species of visually hunting predators prey on masquerading species (spiders: Nentwig, 1990; mantids: Reitze & Nentwig, 1991; birds: Sandoval, 1993), and, in one exclusion experiment, the number of stick insect nymphs in areas from which predators had been excluded for just 2 weeks was 54% higher compared to control areas (Berger & Wirth, 2004).

There is also some evidence from natural populations that predation on masquerading prey may be frequency dependent. Predation by birds is known to have severe effects on stick insect populations that are moderately abundant locally (Bedford, 1978). Furthermore, during periodic population explosions, avian predators migrate to outbreak areas, releasing stick insect populations in abandoned areas from predation pressure, and causing their numbers to rocket in the subsequent year (Bedford, 1978). However, predation by birds was found to have no measurable effect on stick insect numbers during periodic population explosions, demonstrating that frequency-dependent predation is not the only factor influencing the population dynamics of masquerading prey.

If the benefit of masquerade is frequency dependent, then general resemblances to more than one model, large variations among individuals in visual appearance, polyphenisms, and polymorphisms may also be favoured by selection. Essentially, these adaptations would overcome the costs associated with masquerading species becoming abundant relative to their models because, if more than one species is mimicked, there are more models in the environment. Such adaptations also prevent predators restricting their searching for masquerading species to a single host plant (or, more generally, microhabitat), or prevent prey avoiding certain species of plants that are more likely to contain flower-mimicking predatory mantids.

CONCLUSIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

We have provided a testable definition of masquerade and have suggested ways in which a benefit of masquerade might be demonstrated. Experiments in which predators' experience with models and masquerading prey is carefully controlled could potentially allow us to understand how predators classify masquerading prey. Whether context is important when making a decision about how to classify prey, and how both prey frequency and predator experience influence the evolutionary dynamics of such prey, are important avenues to explore. Finally, we have made predictions about the ecological conditions under which we would expect masquerade to evolve. We hope that this review highlights how understudied the evolution and ecology of masquerading species are, and that it will promote empirical work in this neglected area of anti-predator defences.

ACKNOWLEDGEMENTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES

We would like to thank Andrew Higginson, Candy Rowe, and two anonymous referees for their comments on previous drafts of the manuscript.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. DIFFERENCES BETWEEN MASQUERADE, BATESIAN MIMICRY, AND CRYPSIS
  5. EVIDENCE THAT ORGANISMS BENEFIT FROM MASQUERADE
  6. THE ECOLOGY OF MASQUERADE
  7. THE EVOLUTION OF MASQUERADE
  8. CONCLUSIONS
  9. ACKNOWLEDGEMENTS
  10. REFERENCES