scholarly journals Prey with hidden colour defences benefit from their similarity to aposematic signals

2020 ◽  
Vol 287 (1934) ◽  
pp. 20201894
Author(s):  
Yongsu Kim ◽  
Yerin Hwang ◽  
Sangryong Bae ◽  
Thomas N. Sherratt ◽  
Jeongseop An ◽  
...  
Keyword(s):  
Avoidance Learning ◽  
Predator Avoidance ◽  
Lepidopteran Species ◽  
Aposematic Signals ◽  
Colour Patterns ◽  
Colour Signals

Some camouflaged animals hide colour signals and display them only transiently. These hidden colour signals are often conspicuous and are used as a secondary defence to warn or startle predators (deimatic displays) and/or to confuse them (flash displays). The hidden signals used in these displays frequently resemble typical aposematic signals, so it is possible that prey with hidden signals have evolved to employ colour patterns of a form that predators have previously learned to associate with unprofitability. Here, we tested this hypothesis by conducting two experiments that examined the effect of predator avoidance learning on the efficacy of deimatic and flash displays. We found that the survival benefits of both deimatic and flash displays were substantially higher against predators that had previously learned to associate the hidden colours with unprofitability than against naive predators. These findings help explain the phenological patterns we found in 1568 macro-lepidopteran species on three continents: species with hidden signals tend to occur later in the season than species without hidden signals.

The effect of predator appetite, prey warning coloration and luminance on predator foraging decisions

Behaviour ◽  
2010 ◽  
Vol 147 (9) ◽  
pp. 1121-1143 ◽  
Author(s):  
Martin Stevens ◽  
Johanna Mappes ◽  
Siiri-Lii Sandre
Keyword(s):  
Methodological Approach ◽  
Luminance Contrast ◽  
Colour Pattern ◽  
Species Variation ◽  
Insect Larvae ◽  
Predator Attack ◽  
Aposematic Signals ◽  
Predator Foraging ◽  
Colour Patterns ◽  
Visual Properties

AbstractAposematic prey advertise their defence to visually hunting predators using conspicuous warning colouration. Established theory predicts that aposematic signals should evolve towards increased conspicuousness and similarity to enhance predator education. Contrary to theoretical expectations, there is often considerable within- and between-species variation in aposematic signals of animals sharing the same ecological niche, phylogeny and predators. This may be explained by varying responses of predators that weaken the selection pressure for a consistent signal. By presenting painted mealworm larvae as prey to great tits as predators we tested if different aposematic colour patterns have different values as a means of initial protection and learnt avoidance from predators, and how widely birds generalise their learnt avoidance to other colour patterns. We also investigated how the colour and luminance of the pattern elements affect predator attack decisions. Finally, we studied if hunger affects the predators' reaction to differently coloured prey. We found that similarity in colour was not crucial to the survival of aposematic prey, since learnt avoidance was not influenced by colour, and predators remembered and generalised widely in their learnt avoidance to other colours. We found that initial avoidance was, however, apparently influenced by luminance contrast. Interestingly, the predators' level of hunger was more important than the colour of the aposematic signal in determining birds' decisions to attack chemically-defended insect larvae. We discuss the implications of visual properties of prey colour pattern and predator appetite for the evolution of insect defences and warning signals. In addition we propose a methodological approach to effectively control for predator appetite in laboratory experiments.

scholarly journals Distance-dependent pattern blending can camouflage salient aposematic signals

2017 ◽  
Vol 284 (1858) ◽  
pp. 20170128 ◽  
Author(s):  
James B. Barnett ◽  
Innes C. Cuthill ◽  
Nicholas E. Scott-Samuel
Keyword(s):  
Spatial Frequency ◽  
Relative Rate ◽  
Colour Pattern ◽  
Viewing Distance ◽  
Resolution Limit ◽  
Avian Predation ◽  
Spatial Frequencies ◽  
Close Range ◽  
Aposematic Signals ◽  
Colour Patterns

The effect of viewing distance on the perception of visual texture is well known: spatial frequencies higher than the resolution limit of an observer's visual system will be summed and perceived as a single combined colour. In animal defensive colour patterns, distance-dependent pattern blending may allow aposematic patterns, salient at close range, to match the background to distant observers. Indeed, recent research has indicated that reducing the distance from which a salient signal can be detected can increase survival over camouflage or conspicuous aposematism alone. We investigated whether the spatial frequency of conspicuous and cryptically coloured stripes affects the rate of avian predation. Our results are consistent with pattern blending acting to camouflage salient aposematic signals effectively at a distance. Experiments into the relative rate of avian predation on edible model caterpillars found that increasing spatial frequency (thinner stripes) increased survival. Similarly, visual modelling of avian predators showed that pattern blending increased the similarity between caterpillar and background. These results show how a colour pattern can be tuned to reveal or conceal different information at different distances, and produce tangible survival benefits.

scholarly journals Variation in colour signals among Sarracenia pitcher plants and the potential role of areoles in the attraction of flying Hymenoptera

2021 ◽  
Author(s):  
Corentin Dupont ◽  
Claire Villemant ◽  
Tom Hattermann ◽  
Jeremie Pratviel ◽  
Laurence Gaume ◽  
...  
Keyword(s):  
Potential Role ◽  
Prey Capture ◽  
Visual Signal ◽  
Visual Features ◽  
Prey Composition ◽  
Insectivorous Plants ◽  
Visual Characteristics ◽  
Colour Patterns ◽  
Colour Signals

Sarracenia insectivorous plants show a diversity of visual features in their pitchers but their perception by insects and their role in attraction, have received little attention. They also vary in prey composition, with some species trapping more flying Hymenoptera, such as bees. To test the hypothesis of a link between visual signal variability and prey segregation ability, and to identify which signal could attract flying Hymenoptera, we characterised, the colour patterns of 32 pitchers belonging to four taxa, modelled their perception by flying Hymenoptera, and examined the prey they trapped. The pitchers of the four taxa differed in colour patterns, with notably two long-leaved taxa displaying clear areoles, which contrasted strongly in colour and brightness with the vegetative background and with other pitcher areas in the eyes of flying Hymenoptera. These taxa trapped high proportion of flying hymenoptera. This suggests that contrasting areoles may act as a visual lure for flying Hymenoptera, making plants particularly visible to these insects. Prey capture also differed according to pitcher stage, morphology, season and visual characteristics. Further studies on prey visitation are needed to better understand the link between prey capture and attraction feature.

scholarly journals Aposematism: balancing salience and camouflage

2016 ◽  
Vol 12 (8) ◽  
pp. 20160335 ◽  
Author(s):  
James B. Barnett ◽  
Nicholas E. Scott-Samuel ◽  
Innes C. Cuthill
Keyword(s):  
Avoidance Learning ◽  
Survival Benefit ◽  
Ecological Validity ◽  
Field Conditions ◽  
Evolutionary Models ◽  
Natural Conditions ◽  
Honest Signalling ◽  
Encounter Rates ◽  
Low Levels ◽  
Aposematic Signals

Aposematic signals are often characterized by high conspicuousness. Larger and brighter signals reinforce avoidance learning, distinguish defended from palatable prey and are more easily memorized by predators. Conspicuous signalling, however, has costs: encounter rates with naive, specialized or nutritionally stressed predators are likely to increase. It has been suggested that intermediate levels of aposematic conspicuousness can evolve to balance deterrence and detectability, especially for moderately defended species. The effectiveness of such signals, however, has not yet been experimentally tested under field conditions. We used dough caterpillar-like baits to test whether reduced levels of aposematic conspicuousness can have survival benefits when predated by wild birds in natural conditions. Our results suggest that, when controlling for the number and intensity of internal contrast boundaries (stripes), a reduced-conspicuousness aposematic pattern can have a survival advantage over more conspicuous signals, as well as cryptic colours. Furthermore, we find a survival benefit from the addition of internal contrast for both high and low levels of conspicuousness. This adds ecological validity to evolutionary models of aposematic saliency and the evolution of honest signalling.

scholarly journals Post-attack Aposematic Display in Prey Facilitates Predator Avoidance Learning

2016 ◽  
Vol 4 ◽  
Author(s):  
Changku Kang ◽  
Hyun-Joon Cho ◽  
Sang-Im Lee ◽  
Piotr G. Jablonski
Keyword(s):  
Avoidance Learning ◽  
Predator Avoidance

scholarly journals A tale of 2 signals: signal mimicry between aposematic species enhances predator avoidance learning

2010 ◽  
Vol 21 (4) ◽  
pp. 851-860 ◽  
Author(s):  
Hannah M. Rowland ◽  
Tom Hoogesteger ◽  
Graeme D. Ruxton ◽  
Michael P. Speed ◽  
Johanna Mappes
Keyword(s):  
Avoidance Learning ◽  
Predator Avoidance

scholarly journals Inter-Individual Differences in Ornamental Colouration in a Mediterranean Lizard in Relation to Altitude, Season, Sex, Age, and Body Traits

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 158
Author(s):  
Gregorio Moreno-Rueda ◽  
Senda Reguera ◽  
Francisco J. Zamora-Camacho ◽  
Mar Comas
Keyword(s):  
Elevational Gradient ◽  
Head Size ◽  
Long Distance ◽  
Altitudinal Variation ◽  
Light Yellow ◽  
Psammodromus Algirus ◽  
Colour Saturation ◽  
Colour Patterns ◽  
Different Sources ◽  
Colour Signals

Animals frequently show complex colour patterns involved in social communication, which attracts great interest in evolutionary and behavioural ecology. Most researchers interpret that each colour in animals with multiple patches may either signal a different bearer’s trait or redundantly convey the same information. Colour signals, moreover, may vary geographically and according to bearer qualities. In this study, we analyse different sources of colour variation in the eastern clade of the lizard Psammodromus algirus. Sexual dichromatism markedly differs between clades; both possess lateral blue eyespots, but whereas males in the western populations display strikingly colourful orange-red throats during the breeding season, eastern lizards only show some commissure pigmentation and light yellow throats. We analyse how different colour traits (commissure and throat colouration, and the number of blue eyespots) vary according to body size, head size (an indicator of fighting ability), and sex along an elevational gradient. Our findings show that blue eyespots function independently from colour patches in the commissure and throat, which were interrelated. Males had more eyespots and orange commissures (which were yellow or colourless in females). Throat colour saturation and the presence of coloured commissures increased in older lizards. The number of eyespots, presence of a coloured commissure, and throat colour saturation positively related to head size. However, while the number of eyespots was maximal at lowlands, throat colour saturation increased with altitude. Overall, our results suggest that this lizard harbours several colour signals, which altitudinally differ in their importance, but generally provide redundant information. The relevance of each signal may depend on the context. For example, all signals indicate head size, but commissure colouration may work well at a short distance and when the lizard opens the mouth, while both throat and eyespots might work better at long distance. Meanwhile, throat colouration and eyespots probably work better in different light conditions, which might explain the altitudinal variation in the relative importance of each colour component.

Sign in / Sign up

Export Citation Format

Share Document