Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog

Maan, Martine E.; Cummings, Molly E.

doi:10.1073/pnas.0903327106

Cited by 172 publications

(204 citation statements)

References 53 publications

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“…We might expect that sexual and social signals would benefit from being reliable under a wide range of signaling conditions, especially if they provide information about quality or condition. Studies on species with aposematic coloration show that females of several species prefer to mate with brightly colored males (Summers et al, 1999;Maan and Cummings, 2009). In the butterfly genus Heliconius and the ladybird genus Adalia, females preferentially mate with males having their own color patterns (Muggleton, 1979;Majerus et al, 1982;Jiggins et al, 2001).…”

Section: Discussionmentioning

confidence: 99%

Color contrast and stability as key elements for effective warning signals

2014

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Vivid warning signals (aposematism) have evolved repeatedly throughout the animal kingdom. However, relatively few studies consider what makes an effective signal, in terms of preventing attack and promoting avoidance learning by predators. Signal form varies substantially among and sometimes within species, but there has also been apparent convergence on relatively few main color types. We aimed to determine why warning signals often combine red, orange, yellow, and black colors, and specifically to determine whether these colors provide highly salient and reliable visual signals under a range of environmental conditions. Using digital image analysis, we modeled ladybird (ladybug) coloration to an avian visual system. We calculated the contrast of several different ladybird species against an average green background, based on predicted opponent color channel responses in bird vision. Our results suggest that longwave colors (i.e., red, orange) are more contrasting than colors such as blue, against green natural backgrounds. Moreover, these colors yield relatively unchanging (stable) signals throughout the day and under different weather conditions. These analyses show how aposematic signals have evolved under selection to be more effective by being more conspicuous and reliable to the visual system of their potential avian predators.

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Section: Discussionmentioning

confidence: 99%

Color contrast and stability as key elements for effective warning signals

2014

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“…Paradoxically, withinpopulation variation exists in some aposematic species [5,6]. Despite studies suggesting a natural-sexual selection interaction as a cause [5,7], the mechanisms by which within-population variation is maintained, and its ecological and behavioural correlates, are poorly understood. Attempts to explain the maintenance of variable aposematic signals have primarily addressed among-population variation [8,9] or involved laboratory studies with artificial prey or computer games.…”

Section: Introductionmentioning

confidence: 99%

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

2014

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Aposematic signal variation is a paradox: predators are better at learning and retaining the association between conspicuousness and unprofitability when signal variation is low. Movement patterns and variable colour patterns are linked in non-aposematic species: striped patterns generate illusions of altered speed and direction when moving linearly, affecting predators' tracking ability; blotched patterns benefit instead from unpredictable pauses and random movement. We tested whether the extensive colour-pattern variation in an aposematic frog is linked to movement, and found that individuals moving directionally and faster have more elongated patterns than individuals moving randomly and slowly. This may help explain the paradox of polymorphic aposematism: variable warning signals may reduce protection, but predator defence might still be effective if specific behaviours are tuned to specific signals. The interacting effects of behavioural and morphological traits may be a key to the evolution of warning signals.

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“…For chemically defended frogs, bright coloration in males serves a dual purpose to attract females and as aposematic signals to potential predators (e.g. Bufonidae and Dedrobatidae); therefore, both sexual and natural selection may act in concert in these species to produce brighter coloration in males [47].…”

Section: Evolutionary Mechanisms For Ontogenetic Sexual Dichromatismmentioning

confidence: 99%

Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity

2012

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Sexual dichromatism, a form of sexual dimorphism in which males and females differ in colour, is widespread in animals but has been predominantly studied in birds, fishes and butterflies. Moreover, although there are several proposed evolutionary mechanisms for sexual dichromatism in vertebrates, few studies have examined this phenomenon outside the context of sexual selection. Here, we describe unexpectedly high diversity of sexual dichromatism in frogs and create a comparative framework to guide future analyses of the evolution of these sexual colour differences. We review what is known about evolution of colour dimorphism in frogs, highlight alternative mechanisms that may contribute to the evolution of sexual colour differences, and compare them to mechanisms active in other major groups of vertebrates. In frogs, sexual dichromatism can be dynamic (temporary colour change in males) or ontogenetic (permanent colour change in males or females). The degree and the duration of sexual colour differences vary greatly across lineages, and we do not detect phylogenetic signal in the distribution of this trait, therefore frogs provide an opportunity to investigate the roles of natural and sexual selection across multiple independent derivations of sexual dichromatism.

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Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog

Cited by 172 publications

References 53 publications

Color contrast and stability as key elements for effective warning signals

Color contrast and stability as key elements for effective warning signals

Paradox lost: variable colour-pattern geometry is associated with differences in movement in aposematic frogs

Sexual dichromatism in frogs: natural selection, sexual selection and unexpected diversity

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