Visual predators select for crypticity and polymorphism in virtual prey

Bond, Alan B.; Kamil, Alan C.

doi:10.1038/415609a

Cited by 297 publications

(223 citation statements)

References 36 publications

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“…Common morphs thereafter suffer from more intensive male-mating harassment, causing both their fitness and future frequency to decline (Fincke 2004). This latter mechanism is thus a form of apostatic selection, similar to the frequencydependent visual mechanism that causes the fitness of common prey to decline, due to the development among predators of search images towards common prey morphs Kamil 1998, Bond andKamil 2002). Evidence for apostatic selection in terms of frequencydependent female fecundities comes from our longitudinal study of four generations, involving a dozen populations .…”

Section: Sexually Antagonistic Selection and Female Polymorphismmentioning

confidence: 93%

Female polymorphisms, sexual conflict and limits to speciation processes in animals

et al. 2007

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Heritable and visually detectable polymorphisms, such as trophic polymorphisms, ecotypes, or colour morphs, have become classical model systems among ecological geneticists and evolutionary biologists. The relatively simple genetic basis of many such polymorphisms (one or a few loci) makes such species well-suited to study evolutionary processes in natural settings. More recently, polymorphic systems have become popular when studying the early stages of the speciation process and mechanisms facilitating or constraining the evolution of reproductive isolation. Although colour polymorphisms have been studied extensively in the past, we argue that they have been underutilized as model systems of constraints on speciation processes. Colouration traits may function as signalling characters in sexual selection contexts, and the maintenance of colour polymorphisms is often due to frequency-dependent selection.One important issue is why there are so few described cases of female polymorphisms. Here we present a synthetic overview of female sexual polymorphisms, drawing from our previous work on female colour polymorphisms in lizards and damselflies. We argue that female sexual polymorphisms have probably been overlooked in the past, since workers have mainly focused on male-male competition over mates and have not realized the ecological sources of genetic variation in female fitness. Recent experimental evolution studies on fruit flies (Drosophila melanogaster) have demonstrated significant heritable variation among female genotypes in the fitness costs of resistance or tolerance to male mating harassment. In addition, femalefemale competition over resources could also generate genetic variation in female fitness and promote the maintenance of female sexual polymorphisms. Female sexual polymorphisms could subsequently either be maintained as intrapopulational polymorphisms or provide the raw material for the formation of new species.

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Section: Sexually Antagonistic Selection and Female Polymorphismmentioning

confidence: 93%

Female polymorphisms, sexual conflict and limits to speciation processes in animals

et al. 2007

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“…Future work might address whether disruptive patterning allows its carrier to exploit a greater range of habitats than an organism with only background matching, and whether search images for disruptively patterned prey can be developed by predators. A computer-based system such as the one employed here not only enables close control over the foraging environment, but it also potentially allows camouflage solutions to evolve when subjected to selection (see also Bond & Kamil 2002, 2006Sherratt et al 2007). If disruptive pattern solutions were introduced to this general approach, then we would have a unique set of tools for designing and identifying effective camouflage strategies in a wide range of contexts.…”

Section: Discussionmentioning

confidence: 99%

Empirical tests of the role of disruptive coloration in reducing detectability

et al. 2007

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Disruptive patterning is a potentially universal camouflage technique that is thought to enhance concealment by rendering the detection of body shapes more difficult. In a recent series of field experiments, artificial moths with markings that extended to the edges of their 'wings' survived at higher rates than moths with the same edge patterns inwardly displaced. While this result seemingly indicates a benefit to obscuring edges, it is possible that the higher density markings of the inwardly displaced patterns concomitantly reduced their extent of background matching. Likewise, it has been suggested that the mealworm baits placed on the artificial moths could have created differential contrasts with different moth patterns. To address these concerns, we conducted controlled trials in which human subjects searched for computer-generated moth images presented against images of oak trees. Moths with edge-extended disruptive markings survived at higher rates, and took longer to find, than all other moth types, whether presented sequentially or simultaneously. However, moths with no edge markings and reduced interior pattern density survived better than their high-density counterparts, indicating that background matching may have played a so-far unrecognized role in the earlier experiments. Our disruptively patterned nonbackground-matching moths also had the lowest overall survivorship, indicating that disruptive coloration alone may not provide significant protection from predators. Collectively, our results provide independent support for the survival value of disruptive markings and demonstrate that there are common features in human and avian perception of camouflage.

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“…Search image formation is thought to result from limited attention in predators; it can generate frequency-dependent predation and maintain polymorphism, as shown in experiments using artificial prey 27,28 . If selective predation were responsible for the frequency-dependent survival we observed, our results suggest that predators were attuned to small elements of colour patterns, as we manipulated the frequency of only a small part of the overall pattern.…”

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confidence: 99%

Frequency-dependent survival in natural guppy populations

Olendorf

Rodd

Punzalan

et al. 2006

Nature

227

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The maintenance of genetic variation in traits under natural selection is a long-standing paradox in evolutionary biology [1][2][3] . Of the processes capable of maintaining variation, negative frequency-dependent selection (where rare types are favoured by selection) is the most powerful, at least in theory 1 ; however, few experimental studies have confirmed that this process operates in nature. One of the most extreme, unexplained genetic polymorphisms is seen in the colour patterns of male guppies (Poecilia reticulata) 4,5 . Here we manipulated the frequencies of males with different colour patterns in three natural populations to estimate survival rates, and found that rare phenotypes had a highly significant survival advantage compared to common phenotypes. Evidence from humans 6,7 and other species 8,9 implicates frequency-dependent survival in the maintenance of molecular, morphological and health-related polymorphisms. As a controlled manipulation in nature, this study provides unequivocal support for frequency-dependent survival-an evolutionary process capable of maintaining extreme polymorphism.Colour-pattern polymorphism in guppies is limited to males and consists of irregular spots of several different structural (blue, green and purple) and pigment-based (yellow, orange, red and black) colours that occur on the body, caudal fin and dorsal fin (Fig. 1). The position, number, size and hue of the spots are highly heritable 5,10 , although the colour saturation (chroma) of orange spots can be influenced by diet 11,12 . Male colouration is highly polymorphic despite being subject to sexual and ecological selection. Female mating preferences usually favour males with the greatest area of orange, although the strength of that preference varies among populations 10,12,13 . Predators also exert selection on colour patterns; they preferentially prey upon males with brighter or more conspicuous colours 14,15 . Despite the apparently strong and directional selection within populations, colour patterns are so variable that any two males are easily distinguishable based on colour pattern alone, unless they are closely related 10 .Several mechanisms have been proposed to explain the maintenance of this extreme polymorphism 10,14 . Mate-choice experiments indicate that females preferentially mate with males bearing rare or novel colour patterns 16,17 . A trade-off (antagonistic pleiotropy) between male sexual attractiveness and offspring viability has also been reported 18 . Both processes could contribute to the maintenance of genetic variation in nature. However, experiments demonstrating these processes were conducted in laboratory environments, and it is not clear whether either process occurs in nature. Another process capable of maintaining polymorphism is a rare-morph survival advantage. This process has been implicated in the maintenance of colour polymorphism in some invertebrates 19,20 and vertebrates 21 , but it has not been tested in the highly polymorphic guppy system. We tested the hypothesis that ma...

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Visual predators select for crypticity and polymorphism in virtual prey

Cited by 297 publications

References 36 publications

Female polymorphisms, sexual conflict and limits to speciation processes in animals

Female polymorphisms, sexual conflict and limits to speciation processes in animals

Empirical tests of the role of disruptive coloration in reducing detectability

Frequency-dependent survival in natural guppy populations

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