scholarly journals The conspicuousness of the toxic Heliconius butterflies across time and habitat

2019 ◽  
Author(s):  
Denise Dalbosco Dell’Aglio ◽  
Jolyon Troscianko ◽  
Martin Stevens ◽  
W Owen McMillan ◽  
Chris D Jiggins
Keyword(s):  
Signal Transmission ◽  
Warning Signal ◽  
Microhabitat Use ◽  
Natural Habitats ◽  
Signal Stability ◽  
Light Spectra ◽  
Green Background ◽  
Avian Visual System ◽  
Colour Patterns ◽  
Colour Signals

AbstractForests are a mosaic of light spectra, and colour signal efficiency might change in different light environments. Local adaptation in Heliconius butterflies is linked to microhabitat use and the colourful wing colour patterns may be adapted for signalling in different light environments. These toxic butterflies exhibit conspicuous colours as a warning to predators that they should be avoided, but also find and choose potential mates based on colour signals. The two selection pressures of predation and mate preference are therefore acting together. Colour conspicuousness should show habitat-specific contrast for the butterflies, which would facilitate detection and species identification. On the other hand, selection for signal stability would be stronger in the avian visual system. In this study we analysed the contrast of two Heliconius mimicry rings in their natural habitats under varying degrees of forest fragmentation and light conditions. We used digital image analyses and mapped the bird and butterfly vision colour space in order to examine whether warning colours have greater contrast and if they transmit a consistent signal across time of the day and habitat in a tropical forest. We tested conspicuousness using opponent colour channels against a natural green background. For avian vision, colours are generally very stable through time and habitat. For butterfly vision, there is some evidence that species are more contrasting in their own habitats, where conspicuousness is higher for red and yellow bands in the border and for white in the forest. Light environment affects Heliconius butterflies’ warning signal transmission to a higher degree through their own vision, but to a lesser degree through avian predator vision. This work provides insight into the use of colour signals in sexual and natural selection in the light of ecological adaptation.

scholarly journals Simulations with Australian dragon lizards suggest movement-based signal effectiveness is dependent on display structure and environmental conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xue Bian ◽  
Angela Pinilla ◽  
Tom Chandler ◽  
Richard Peters
Keyword(s):  
Research Methods ◽  
Environmental Conditions ◽  
Comparative Studies ◽  
Habitat Structure ◽  
Signal Transmission ◽  
Lizard Species ◽  
Local Adaptations ◽  
Signal Divergence ◽  
Colour Signals ◽  
Optimal Signal

AbstractHabitat-specific characteristics can affect signal transmission such that different habitats dictate the optimal signal. One way to examine how the environment influences signals is by comparing changes in signal effectiveness in different habitats. Examinations of signal effectiveness between different habitats has helped to explain signal divergence/convergence between populations and species using acoustic and colour signals. Although previous research has provided evidence for local adaptations and signal divergence in many species of lizards, comparative studies in movement-based signals are rare due to technical difficulties in quantifying movements in nature and ethical restrictions in translocating animals between habitats. We demonstrate herein that these issues can be addressed using 3D animations, and compared the relative performance of the displays of four Australian lizard species in the habitats of each species under varying environmental conditions. Our simulations show that habitats differentially affect signal performance, and an interaction between display and habitat structure. Interestingly, our results are consistent with the hypothesis that the signal adapted to the noisier environment does not show an advantage in signal effectiveness, but the noisy habitat was detrimental to the performance of all displays. Our study is one of the first studies for movement-based signals that directly compares signal performance in multiple habitats, and our approach has laid the foundation for future investigations in motion ecology that have been intractable to conventional research methods.

scholarly journals Locomotor mimicry in Heliconius butterflies: contrast analyses of flight morphology and kinematics

1999 ◽  
Vol 354 (1380) ◽  
pp. 203-214 ◽  
Author(s):  
Robert B. Srygley
Keyword(s):  
Wing Length ◽  
Beat Frequency ◽  
Warning Signal ◽  
Wing Shape ◽  
The Body ◽  
Colour Pattern ◽  
Müllerian Mimicry ◽  
Flight Morphology ◽  
Mullerian Mimicry ◽  
Colour Patterns

Müllerian mimicry is a mutualism involving the evolutionary convergence of colour patterns of prey on a warning signal to predators. Behavioural mimicry presumably adds complexity to the signal and makes it more difficult for Batesian mimics to parasitize it. To date, no one has quantified behavioural mimicry in Müllerian mimicry groups. However, morphological similarities among members of mimicry groups suggested that pitching oscillations of the body and wing–beat frequency (WBF) might converge with colour pattern. I compared the morphology and kinematics of four Heliconius species, which comprised two mimicry pairs. Because the mimics arose from two distinct lineages, the relative contributions of mimicry and phylogeny to variation in the species' morphologies and kinematics were examined. The positions of the centre of body mass and centre of wing mass and wing shape diverged among species within lineages, and converged among species within mimicry groups. WBF converged within mimicry groups, and it was coupled with body pitching frequency. However, body–pitching frequency was too variable to distinguish mimicry groups. Convergence in WBF may be due, at least in part, to biomechanical consequences of similarities in wing length, wing shape or the centre of wing mass among co–mimics. Nevertheless, convergence in WBF among passion–vine butterflies serves as the first evidence of behavioural mimicry in a mutualistic context.

scholarly journals The Ecomechanics of Gecko Adhesion: Natural Surface Topography, Evolution, and Biomimetics

2019 ◽  
Vol 59 (1) ◽  
pp. 148-167 ◽  
Author(s):  
Timothy E Higham ◽  
Anthony P Russell ◽  
Peter H Niewiarowski ◽  
Amber Wright ◽  
Thomas Speck
Keyword(s):  
Sand Dunes ◽  
Science Research ◽  
Adhesive System ◽  
Microhabitat Use ◽  
Natural Habitats ◽  
Complex Interactions ◽  
Wide Range ◽  
Hierarchical Nature ◽  
Gecko Adhesion ◽  
Adhesive Performance

Abstract The study of gecko adhesion is necessarily interdisciplinary due to the hierarchical nature of the adhesive system and the complexity of interactions between the animals and their habitats. In nature, geckos move on a wide range of surfaces including soft sand dunes, trees, and rocks, but much of the research over the past two decades has focused on their adhesive performance on artificial surfaces. Exploring the complex interactions between geckos and their natural habitats will reveal aspects of the adhesive system that can be applied to biomimetic research, such as the factors that facilitate movement on dirty and rough surfaces with varying microtopography. Additionally, contrasting suites of constraints and topographies are found on rocks and plants, likely driving differences in locomotion and morphology. Our overarching goals are to bring to light several aspects of ecology that are important for gecko–habitat interactions, and to propose a framework for how they can inspire material scientists and functional ecologists. We also present new data on surface roughness and topography of a variety of surfaces, and adhesive performance of Phelsuma geckos on surfaces of varying roughness. We address the following key questions: (1) why and how should ecology be incorporated into the study of gecko adhesion? (2) What topographical features of rocks and plants likely drive adhesive performance? (3) How can ecological studies inform material science research? Recent advances in surface replication techniques that eliminate confounding factors among surface types facilitate the ability to address some of these questions. We pinpoint gaps in our understanding and identify key initiatives that should be adopted as we move forward. Most importantly, fine details of locomotor microhabitat use of both diurnal and nocturnal geckos are needed.

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 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.

scholarly journals The "Hyper-Visible World" hypothesis for the dazzling colours of coral reef fish

F1000Research ◽  
2015 ◽  
Vol 4 ◽  
pp. 115
Author(s):  
Wladimir J. Alonso
Keyword(s):  
Coral Reef ◽  
Reef Fish ◽  
Coral Reef Fish ◽  
Signal Transmission ◽  
Visual Complexity ◽  
Predator Prey ◽  
Selective Pressures ◽  
Visual Exposure ◽  
Colour Patterns ◽  
World Hypothesis

No evolutionary explanation for the striking colouration of coral reef fish has been established to date. Here I present the "Hyper-Visible World” hypothesis, which proposes that coral reef habitats impose special conditions on the evolution of body-colour communication for mobile fish – that is, fish that roam across coral reef formations. The special conditions are: 1) the high clarity of water during daylight hours, and 2) the unpredictable pattern/ visual complexity of the coral habitat itself. The hypothesis suggests that, in a signal transmission framework, the visual exposure (signal) of mobile fish cannot be effectively reduced so as to make a difference to predator-prey interactions. This negates the possibility of effective colour-based camouflage. In contrast, the selective pressures that usually come secondary to camouflage (such as sexual, aposematic or territorial display) benefit from these same conditions, driving the evolution of the colour patterns in this environment – the conspicuousness and dazzling colour diversity that we commonly associate with coral reef fish.

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.

scholarly journals Persistence of multiple patterns and intraspecific polymorphism in multi-species Müllerian communities of net-winged beetles

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Matej Bocek ◽  
Dominik Kusy ◽  
Michal Motyka ◽  
Ladislav Bocak
Keyword(s):  
Environmental Conditions ◽  
Body Shape ◽  
Purifying Selection ◽  
Warning Signal ◽  
Relative Effect ◽  
The Body ◽  
Intraspecific Polymorphism ◽  
Low Contrast ◽  
Phenotypic Differences ◽  
Colour Patterns

Abstract Background In contrast to traditional models of purifying selection and a single aposematic signal in Müllerian complexes, some communities of unprofitable prey contain members with multiple aposematic patterns. Processes responsible for diversity in aposematic signaling are poorly understood and large multi-species communities are seldom considered. Results We analyzed the phylogeny and aposematic patterns of closely related Eniclases net-winged beetles in New Guinea using mtDNA and nextRAD data. We suggest three clades of closely related and incompletely reproductively isolated lineages, detail the extent of polymorphism among Eniclases, and categorize their low-contrast aposematic patterns. The warning signal of Eniclases consists of body shape and color, with ambiguous color perception under some circumstances, i.e., when resting on the undersides of leaves. Field observations suggest that perception of the aposematic signal is affected by beetle behavior and environmental conditions. Local communities containing Eniclases consisted of 7–85 metriorrhynchine species assigned to 3–10 colour patterns. Conclusion As a result, we suggest that under certain light conditions the aposematic colour signal is less apparent than the body shape in net-winged beetle communities. We document variable environmental factors in our study area and highly diverse multi-species communities of other net-winged beetles. Which implies dynamically changing community structure in space and time. Variable environmental conditions and diverse community composition are suggested to be favorable for the persistence of multiple aposematic patterns, imperfect mimics, and intraspecific polymorphism. Further research should identify the relative effect of these factors on purifying selection and the alleles which are responsible for phenotypic differences.

scholarly journals Effectiveness of movement-based animal signals is a function of display structure and habitat characteristics: simulations of Australian dragons

2020 ◽  
Author(s):  
Xue Bian ◽  
Angela Pinilla ◽  
Tom Chandler ◽  
Richard Peters
Keyword(s):  
Environmental Conditions ◽  
Habitat Structure ◽  
Signal Transmission ◽  
Habitat Characteristics ◽  
Lizard Species ◽  
Local Adaptations ◽  
Signal Efficacy ◽  
Signal Divergence ◽  
Colour Signals ◽  
Optimal Signal

Abstract Habitat-specific characteristics can affect signal transmission such that different habitats dictate the optimal signal. One way to examine how the environment influences signals is by comparing changes in signal efficacy in different habitats. Examinations of signal efficacy between different habitats has helped to explain signal divergence/convergence between populations and species utilising acoustic and colour signals. Although previous research has provided evidence for local adaptations and signal divergence in many species of lizards, comparative studies in movement-based signals are rare due to technical difficulties in quantifying movements in nature and ethical restrictions in translocating animals between habitats. We demonstrate herein that these issues can be addressed using 3D animations, and compared the relative performance of the displays of four Australian lizard species in the habitats of each species under varying environmental conditions. Our simulations show that habitats differentially affect signal performance, and an interaction between display and habitat structure. Interestingly, the signal adapted to the noisier environment did not show an advantage in signal efficacy, but the noisy habitat was detrimental to the performance of all displays. Our study is one of the first studies for movement-based signals that directly compares signal performance in multiple habitats, and our approach has laid the foundation for future investigations in motion ecology that have been intractable to conventional research methods.

Microhabitat use and body size drive the evolution of colour patterns in snapping shrimps (Decapoda: Alpheidae: Alpheus)

2019 ◽  
Author(s):  
Marco A M Elias ◽  
Arthur Anker ◽  
Felipe M Gawryszewski
Keyword(s):  
Body Size ◽  
Luminance Contrast ◽  
Microhabitat Use ◽  
Generalist Species ◽  
Categorical Analysis ◽  
Background Matching ◽  
Disruptive Coloration ◽  
Motion Dazzle ◽  
Colour Patterns ◽  
Snapping Shrimps

Abstract Background matching and disruptive coloration are common strategies used by animals to increase concealment, whereas motion-dazzle may prevent capture after recognition. Studies have related background matching to habitat dependency and survival success, whereas for animals with highly contrasting patterns it has been shown that they are able to explore a broader range of habitats due to disruptive coloration, and possibly via motion-dazzle. However, the effects of these strategies are likely to be influenced by body size and to work better for smaller species. We applied phylogenetic comparative methods to test the hypothesis that smaller snapping shrimps (genus Alpheus) with high-contrast stripes would be able to utilize more microhabitats than non-striped and larger species. We used a published phylogeny of the American species of Alpheus, studies that have described alpheid microhabitats and size, and high-resolution photographs of each species in the phylogeny. Our categorical analysis suggested that generalist snapping shrimps are more likely to have stripes than specialist shrimps, and this effect was stronger in smaller species. Similarly, we found an interacting effect of body size and habitat use on the degree of luminance contrast: smaller generalist species had higher contrast values than average-sized and habitat-specialist species. Therefore, predators, body size and frequency of microhabitats are likely to have influenced the evolution of colour patterns in Alpheus.

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