Importance of internal pattern contrast and contrast against the background in aposematic signals

Aronsson, Marianne; Gamberale‐Stille, Gabriella

doi:10.1093/beheco/arp141

Cited by 69 publications

(59 citation statements)

References 41 publications

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“…As an outcome of decades of research on visual aposematic signals we currently understand relatively well the mechanisms involved in the avoidance learning processes. The properties of the color signals that cause enhanced avoidance learning in predators include their high contrast against background (Osorio et al, 1999;Gamberale-Stille, 2001;Aronsson and Gamberale-Stille, 2009), novelty to the predators (Mappes and Alatalo, 1997), distinctiveness relative to the non-aposematic prey (Merilaita and Ruxton, 2007), or the color itself (Gaberale-Stille and Guilford, 2003). Many of the learning effects of various aposematic features are consistent with the classical psychology of learning, particularly with the idea that more salient stimuli cause faster associative learning (Mackintosh, 1983).…”

Section: Introductionmentioning

confidence: 83%

Post-attack Aposematic Display in Prey Facilitates Predator Avoidance Learning

et al. 2016

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Warning signals protect unpalatable prey from predation because predators who learn the association between the warning signal and prey unprofitability decrease attacks on the prey. Most of the research have focused on visual aposematic signals that are constantly presented and visible to the predators. But a variety of chemically defended insects are rather cryptic when resting, and only in response to predator attacks (post-attack) they perform displays of conspicuous abdomens or hindwings normally hidden under forewings. The function of those displays in unpalatable insects is not well understood. We examined two adaptive hypotheses on this facultative aposematic display using wild-caught oriental tits (Parus minor) as predators. First, we tested whether the display increases the rejection of the prey by predators upon seeing the display (i.e., at the moment of attack) through learning trials (aposematic signaling hypothesis). Second, we tested whether the display facilitates the memory formation between cryptic visible form of the prey and prey defense so that it prevents the predators initiate an attack upon seeing the cryptic form (facilitation hypothesis). We found that predators learned to avoid attacking the prey which supports the facilitation hypothesis. However, the support for the aposematic signaling hypothesis was equivocal. Our results open new directions of research by highlighting the possibility that similar facilitation effects may contribute to the evolution of various forms of post-attack visual displays in chemically, or otherwise, defended animals.

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Section: Introductionmentioning

confidence: 83%

Post-attack Aposematic Display in Prey Facilitates Predator Avoidance Learning

et al. 2016

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“…Contrasts between prey and background can be important in perception and predator avoidance learning (Gittleman and Harvey, 1980;Roper and Wistow, 1986;Roper and Redston, 1987;Aronsson and Gamberale-Stille, 2009;Llandres et al, 2011). The pixel intensity variance (PIV) is a measure of the distribution of brightness contrast within an image.…”

Section: Assessment Of Color Pattern Differencementioning

confidence: 99%

The Role of Life-History and Ecology in the Evolution of Color Patterns in Australian Chrysomeline Beetles

et al. 2017

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The variation in animal coloration patterns has evolved in response to different visual strategies for reducing the risk of predation. However, the perception of animal coloration by enemies is affected by a variety of factors, including morphology and habitat. We use the diversity of Australian chrysomeline leaf beetles to explore relationships of visual ecology to beetle morphology and color patterns. There is impressive color pattern variation within the Chrysomelinae, which is likely to reflect anti-predatory strategies. Our phylogenetic comparative analyses reveal strong selection for beetles to be less distinct from their host plants, suggesting that the beetle color patterns have a camouflage effect, rather than the widely assumed aposematic function. Beetles in dark habitats were significantly larger than beetles in bright habitats, potentially to avoid detection by predators because it is harder for large animals to be cryptic in bright habitats. Polyphagous species have greater brightness contrast against their host plants than monophagous species, highlighting the conflict between a generalist foraging strategy and the detection costs of potential predators. Host plant taxa-Eucalyptus and Acacia-interacted differently with beetle shape to predict blue pattern differences between beetle and host plant, possibly an outcome of different predator complexes on these host plants. The variety of anti-predator strategies in chrysomelines may explain their successful radiation into a variety of habitats and, ultimately, their speciation.

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“…Experiments are needed holding colour constant but manipulating contrast. There is good evidence showing that contrast of the overall prey coloration with the background is important in aposematism (reviewed by Ruxton et al [2]), and some recent evidence in studies with chicks suggest that contrast with the background is more important than contrast within the prey [15]. However, most experiments investigating internal contrast simply produce prey with and without patterns (e.g.…”

Section: What Makes An Effective Warning Signal?mentioning

confidence: 99%

Linking the evolution and form of warning coloration in nature

2011

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Many animals are toxic or unpalatable and signal this to predators with warning signals (aposematism). Aposematic appearance has long been a classical system to study predator-prey interactions, communication and signalling, and animal behaviour and learning. The area has received considerable empirical and theoretical investigation. However, most research has centred on understanding the initial evolution of aposematism, despite the fact that these studies often tell us little about the form and diversity of real warning signals in nature. In contrast, less attention has been given to the mechanistic basis of aposematic markings; that is, 'what makes an effective warning signal?', and the efficacy of warning signals has been neglected. Furthermore, unlike other areas of adaptive coloration research (such as camouflage and mate choice), studies of warning coloration have often been slow to address predator vision and psychology. Here, we review the current understanding of warning signal form, with an aim to comprehend the diversity of warning signals in nature. We present hypotheses and suggestions for future work regarding our current understanding of several inter-related questions covering the form of warning signals and their relationship with predator vision, learning, and links to broader issues in evolutionary ecology such as mate choice and speciation.

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Importance of internal pattern contrast and contrast against the background in aposematic signals

Cited by 69 publications

References 41 publications

Post-attack Aposematic Display in Prey Facilitates Predator Avoidance Learning

Post-attack Aposematic Display in Prey Facilitates Predator Avoidance Learning

The Role of Life-History and Ecology in the Evolution of Color Patterns in Australian Chrysomeline Beetles

Linking the evolution and form of warning coloration in nature

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