1
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Briolat ES, Hancock GRA, Troscianko J. Adapting genetic algorithms for artificial evolution of visual patterns under selection from wild predators. PLoS One 2024; 19:e0295106. [PMID: 38753609 PMCID: PMC11098352 DOI: 10.1371/journal.pone.0295106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 04/26/2024] [Indexed: 05/18/2024] Open
Abstract
Camouflage is a widespread and well-studied anti-predator strategy, yet identifying which patterns provide optimal protection in any given scenario remains challenging. Besides the virtually limitless combinations of colours and patterns available to prey, selection for camouflage strategies will depend on complex interactions between prey appearance, background properties and predator traits, across repeated encounters between co-evolving predators and prey. Experiments in artificial evolution, pairing psychophysics detection tasks with genetic algorithms, offer a promising way to tackle this complexity, but sophisticated genetic algorithms have so far been restricted to screen-based experiments. Here, we present methods to test the evolution of colour patterns on physical prey items, under selection from wild predators in the field. Our techniques expand on a recently-developed open-access pattern generation and genetic algorithm framework, modified to operate alongside artificial predation experiments. In this system, predators freely interact with prey, and the order of attack determines the survival and reproduction of prey patterns into future generations. We demonstrate the feasibility of these methods with a case study, in which free-flying birds feed on artificial prey deployed in semi-natural conditions, against backgrounds differing in three-dimensional complexity. Wild predators reliably participated in this experiment, foraging for 11 to 16 generations of artificial prey and encountering a total of 1,296 evolved prey items. Changes in prey pattern across generations indicated improvements in several metrics of similarity to the background, and greater edge disruption, although effect sizes were relatively small. Computer-based replicates of these trials, with human volunteers, highlighted the importance of starting population parameters for subsequent evolution, a key consideration when applying these methods. Ultimately, these methods provide pathways for integrating complex genetic algorithms into more naturalistic predation trials. Customisable open-access tools should facilitate application of these tools to investigate a wide range of visual pattern types in more ecologically-relevant contexts.
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Affiliation(s)
- Emmanuelle S. Briolat
- Faculty of Environment, Centre for Ecology and Conservation, Science and Economy, University of Exeter, Penryn, Cornwall, United Kingdom
| | - George R. A. Hancock
- Faculty of Environment, Centre for Ecology and Conservation, Science and Economy, University of Exeter, Penryn, Cornwall, United Kingdom
- Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Jolyon Troscianko
- Faculty of Environment, Centre for Ecology and Conservation, Science and Economy, University of Exeter, Penryn, Cornwall, United Kingdom
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2
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Roggero A, Alù D, Laini A, Rolando A, Palestrini C. Color polymorphism and mating trends in a population of the alpine leaf beetle Oreina gloriosa. PLoS One 2024; 19:e0298330. [PMID: 38530852 DOI: 10.1371/journal.pone.0298330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 01/18/2024] [Indexed: 03/28/2024] Open
Abstract
The bright colors of Alpine leaf beetles (Coleoptera, Chrysomelidae) are thought to act as aposematic signals against predation. Within the European Alps, at least six species display a basal color of either blue or green, likely configuring a classic case of müllerian mimicry. In this context, intra-population color polymorphism is paradoxical as the existence of numerous color morphs might hamper the establishment of a search image in visual predators. Assortative mating may be one of the main factors contributing to the maintenance of polymorphic populations. Due to the marked iridescence of these leaf beetles, the perceived color may change as the viewing or illumination angle changes. The present study, conducted over three years, involved intensive sampling of a population of Oreina gloriosa from the Italian Alps and applied colorimetry and a decision tree method to identify the color morphs in an objective manner. The tertiary sex ratio of the population was biased in favor of males, suggesting that viviparous females hide to give birth. Seven color morphs were identified, and their frequencies varied significantly over the course of the study. Three different analyses of mating (JMating, QInfomating, and Montecarlo simulations) recognized a general trend for random mating which coexists with some instances of positive and negative assortative mating. This could help explain the pre-eminence of one morph (which would be favored because of positive selection due to positive assortative mating) in parallel with the persistence of six other morphs (maintained due to negative assortative mating).
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Affiliation(s)
- Angela Roggero
- Department of Life Sciences and Systems Biology, University of Turin, Torino, Italy
| | - Daniele Alù
- Department of Life Sciences and Systems Biology, University of Turin, Torino, Italy
| | - Alex Laini
- Department of Life Sciences and Systems Biology, University of Turin, Torino, Italy
| | - Antonio Rolando
- Department of Life Sciences and Systems Biology, University of Turin, Torino, Italy
| | - Claudia Palestrini
- Department of Life Sciences and Systems Biology, University of Turin, Torino, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
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3
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Polic D, Yıldırım Y, Merilaita S, Franzén M, Forsman A. Genetic structure, UV-vision, wing coloration and size coincide with colour polymorphism in Fabriciana adippe butterflies. Mol Ecol 2024; 33:e17272. [PMID: 38240162 DOI: 10.1111/mec.17272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 12/18/2023] [Accepted: 01/08/2024] [Indexed: 02/22/2024]
Abstract
Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD-sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery-spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet-sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non-random mating might contribute to the differentiation and maintenance of the polymorphism.
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Affiliation(s)
- Daniela Polic
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Yeşerin Yıldırım
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Sami Merilaita
- Department of Biology, University of Turku, Turku, Finland
| | - Markus Franzén
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
| | - Anders Forsman
- Department of Biology and Environmental Science, Linnaeus University, Kalmar, Sweden
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4
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Hemingson CR, Cowman PF, Bellwood DR. Analysing biological colour patterns from digital images: An introduction to the current toolbox. Ecol Evol 2024; 14:e11045. [PMID: 38500859 PMCID: PMC10945235 DOI: 10.1002/ece3.11045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Revised: 02/02/2024] [Accepted: 02/03/2024] [Indexed: 03/20/2024] Open
Abstract
Understanding the numerous roles that colouration serves in the natural world has remained a central focus in many evolutionary and ecological studies. However, to accurately characterise and then compare colours or patterns among individuals or species has been historically challenging. In recent years, there have been a myriad of new resources developed that allow researchers to characterise biological colours and patterns, specifically from digital imagery. However, each resource has its own strengths and weaknesses, answers a specific question and requires a detailed understanding of how it functions to be used properly. These nuances can make navigating this emerging field rather difficult. Herein, we evaluate several new techniques for analysing biological colouration, with a specific focus on digital images. First, we introduce fundamental background knowledge about light and perception to be considered when designing and implementing a study of colouration. We then show how numerous modifications can be made to images to ensure consistent formatting prior to analysis. After, we describe many of the new image analysis approaches and their respective functions, highlighting the type of research questions that they can address. We demonstrate how these various techniques can be brought together to examine novel research questions and test specific hypotheses. Finally, we outline potential future directions in colour pattern studies. Our goal is to provide a starting point and pathway for researchers wanting to study biological colour patterns from digital imagery.
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Affiliation(s)
- Christopher R. Hemingson
- The Research Hub for Coral Reef Ecosystem FunctionsJames Cook UniversityTownsvilleQueenslandAustralia
- College of Science and EngineeringJames Cook UniversityTownsvilleQueenslandAustralia
| | - Peter F. Cowman
- Biodiversity and Geosciences Program, Queensland Museum TropicsTownsvilleQueenslandAustralia
| | - David R. Bellwood
- The Research Hub for Coral Reef Ecosystem FunctionsJames Cook UniversityTownsvilleQueenslandAustralia
- College of Science and EngineeringJames Cook UniversityTownsvilleQueenslandAustralia
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5
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Henríquez-Piskulich P, Stuart-Fox D, Elgar M, Marusic I, Franklin AM. Dazzled by shine: gloss as an antipredator strategy in fast moving prey. Behav Ecol 2023; 34:862-871. [PMID: 37744168 PMCID: PMC10516678 DOI: 10.1093/beheco/arad046] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 03/06/2023] [Accepted: 05/23/2023] [Indexed: 09/26/2023] Open
Abstract
Previous studies on stationary prey have found mixed results for the role of a glossy appearance in predator avoidance-some have found that glossiness can act as warning coloration or improve camouflage, whereas others detected no survival benefit. An alternative untested hypothesis is that glossiness could provide protection in the form of dynamic dazzle. Fast moving animals that are glossy produce flashes of light that increase in frequency at higher speeds, which could make it harder for predators to track and accurately locate prey. We tested this hypothesis by presenting praying mantids with glossy or matte targets moving at slow and fast speed. Mantids were less likely to strike glossy targets, independently of speed. Additionally, mantids were less likely to track glossy targets and more likely to hit the target with one out of the two legs that struck rather than both raptorial legs, but only when targets were moving fast. These results support the hypothesis that a glossy appearance may have a function as an antipredator strategy by reducing the ability of predators to track and accurately target fast moving prey.
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Affiliation(s)
| | - Devi Stuart-Fox
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Mark Elgar
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ivan Marusic
- Department of Mechanical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Amanda M Franklin
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia
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6
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Thomas DHN, Kjernsmo K, Scott-Samuel NE, Whitney HM, Cuthill IC. Interactions between color and gloss in iridescent camouflage. Behav Ecol 2023; 34:751-758. [PMID: 37744171 PMCID: PMC10516679 DOI: 10.1093/beheco/arad050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 05/10/2023] [Accepted: 05/25/2023] [Indexed: 09/26/2023] Open
Abstract
Iridescence is a taxonomically widespread form of structural coloration that produces often intense hues that change with the angle of viewing. Its role as a signal has been investigated in multiple species, but recently, and counter-intuitively, it has been shown that it can function as camouflage. However, the property of iridescence that reduces detectability is, as yet, unclear. As viewing angle changes, iridescent objects change not only in hue but also in intensity, and many iridescent animals are also shiny or glossy; these "specular reflections," both from the target and background, have been implicated in crypsis. Here, we present a field experiment with natural avian predators that separate the relative contributions of color and gloss to the "survival" of iridescent and non-iridescent beetle-like targets. Consistent with previous research, we found that iridescent coloration, and high gloss of the leaves on which targets were placed, enhance survival. However, glossy targets survived less well than matt. We interpret the results in terms of signal-to-noise ratio: specular reflections from the background reduce detectability by increasing visual noise. While a specular reflection from the target attracts attention, a changeable color reduces the signal because, we suggest, normally, the color of an object is a stable feature for detection and identification.
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Affiliation(s)
- Dylan H N Thomas
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Karin Kjernsmo
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Nicholas E Scott-Samuel
- School of Psychological Science, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK
| | - Heather M Whitney
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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7
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van der Kooi CJ, Spaethe J. Visual ecology: How glossy colours shine and confuse. Curr Biol 2023; 33:R865-R867. [PMID: 37607483 DOI: 10.1016/j.cub.2023.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Most colours in nature are matte, but across the tree of life glossiness has evolved numerous times, suggesting that glossiness can be beneficial. Recent research finds that glossiness may confuse observers and protect against predators.
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Affiliation(s)
| | - Johannes Spaethe
- Behavioral Physiology and Sociobiology, University of Würzburg, Würzburg, Germany
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8
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Hughes AE, Briolat ES, Arenas LM, Liggins E, Stevens M. Varying benefits of generalist and specialist camouflage in two versus four background environments. Behav Ecol 2023; 34:426-436. [PMID: 37192921 PMCID: PMC10183209 DOI: 10.1093/beheco/arac114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 11/08/2022] [Accepted: 11/24/2022] [Indexed: 05/18/2023] Open
Abstract
Background-matching camouflage is a well-established strategy to reduce detection, but implementing this on heterogeneous backgrounds is challenging. For prey with fixed color patterns, solutions include specializing on a particular visual microhabitat, or adopting a compromise or generalist appearance, matching multiple backgrounds less well. Existing studies suggest both approaches can succeed, but most consider relatively simple scenarios, where artificial prey appear against two backgrounds differing in a single visual characteristic. Here, we used computer-based search tasks with human participants to test the relative benefits of specializing and generalizing for complex targets, displayed on either two or four types of naturalistic backgrounds. Across two background types, specialization was beneficial on average. However, the success of this strategy varied with search duration, such that generalist targets could outperform specialists over short search durations due to the presence of poorly matched specialists. Over longer searches, the remaining well-matched specialists had greater success than generalists, leading to an overall benefit of specialization at longer search durations. Against four different backgrounds, the initial cost to specialization was greater, so specialists and generalists ultimately experienced similar survival. Generalists performed better when their patterning was a compromise between backgrounds that were more similar to each other than when backgrounds were more different, with similarity in luminance more relevant than pattern differences. Time dependence in the relative success of these strategies suggests that predator search behavior may affect optimal camouflage in real-world situations.
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Affiliation(s)
- Anna E Hughes
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
- Department of Psychology, University of Essex, Wivenhoe House, Colchester CO4 3SQ, UK
| | - Emmanuelle S Briolat
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Lina María Arenas
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Eric Liggins
- QinetiQ, Cody Technology Park, Ively Road, Farnborough, Hampshire GU14 0LX, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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9
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Roth-Nebelsick A, Krause M. The Plant Leaf: A Biomimetic Resource for Multifunctional and Economic Design. Biomimetics (Basel) 2023; 8:biomimetics8020145. [PMID: 37092397 PMCID: PMC10123730 DOI: 10.3390/biomimetics8020145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/29/2023] [Accepted: 03/30/2023] [Indexed: 04/25/2023] Open
Abstract
As organs of photosynthesis, leaves are of vital importance for plants and a source of inspiration for biomimetic developments. Leaves are composed of interconnected functional elements that evolved in concert under high selective pressure, directed toward strategies for improving productivity with limited resources. In this paper, selected basic components of the leaf are described together with biomimetic examples derived from them. The epidermis (the "skin" of leaves) protects the leaf from uncontrolled desiccation and carries functional surface structures such as wax crystals and hairs. The epidermis is pierced by micropore apparatuses, stomata, which allow for regulated gas exchange. Photosynthesis takes place in the internal leaf tissue, while the venation system supplies the leaf with water and nutrients and exports the products of photosynthesis. Identifying the selective forces as well as functional limitations of the single components requires understanding the leaf as an integrated system that was shaped by evolution to maximize carbon gain from limited resource availability. These economic aspects of leaf function manifest themselves as trade-off solutions. Biomimetics is expected to benefit from a more holistic perspective on adaptive strategies and functional contexts of leaf structures.
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Affiliation(s)
| | - Matthias Krause
- State Museum of Natural History, Rosenstein 1, 70191 Stuttgart, Germany
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10
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Fan X, Zheng X, An T, Li X, Leung N, Zhu B, Sui T, Shi N, Fan T, Zhao Q. Light diffraction by sarcomeres produces iridescence in transmission in the transparent ghost catfish. Proc Natl Acad Sci U S A 2023; 120:e2219300120. [PMID: 36913569 PMCID: PMC10041080 DOI: 10.1073/pnas.2219300120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 02/07/2023] [Indexed: 03/15/2023] Open
Abstract
Despite the elaborate varieties of iridescent colors in biological species, most of them are reflective. Here we show the rainbow-like structural colors found in the ghost catfish (Kryptopterus vitreolus), which exist only in transmission. The fish shows flickering iridescence throughout the transparent body. The iridescence originates from the collective diffraction of light after passing through the periodic band structures of the sarcomeres inside the tightly stacked myofibril sheets, and the muscle fibers thus work as transmission gratings. The length of the sarcomeres varies from ~1 μm from the body neutral plane near the skeleton to ~2 μm next to the skin, and the iridescence of a live fish mainly results from the longer sarcomeres. The length of the sarcomere changes by ~80 nm as it relaxes and contracts, and the fish shows a quickly blinking dynamic diffraction pattern as it swims. While similar diffraction colors are also observed in thin slices of muscles from non-transparent species such as the white crucian carps, a transparent skin is required indeed to have such iridescence in live species. The ghost catfish skin is of a plywood structure of collagen fibrils, which allows more than 90% of the incident light to pass directly into the muscles and the diffracted light to exit the body. Our findings could also potentially explain the iridescence in other transparent aquatic species, including the eel larvae (Leptocephalus) and the icefishes (Salangidae).
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Affiliation(s)
- Xiujun Fan
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China
| | - Xuezhi Zheng
- Department of Electrical Engineering, KU Leuven, LeuvenB3001, Belgium
| | - Tong An
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China
| | - Xiuhong Li
- Shanghai Synchrotron Radiation Facility, Shanghai201204, China
| | - Nathanael Leung
- School of Mechanical Engineering Sciences, University of Surrey, SurreyGU2 7XH, UK
| | - Bin Zhu
- School of Mechanical Engineering Sciences, University of Surrey, SurreyGU2 7XH, UK
| | - Tan Sui
- School of Mechanical Engineering Sciences, University of Surrey, SurreyGU2 7XH, UK
| | - Nan Shi
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China
| | - Tongxiang Fan
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China
| | - Qibin Zhao
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai200240, China
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Shiwen L, Morimoto T, Harris JM, Smithson HE. Task-dependent extraction of information from videos of iridescent and glossy samples. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2023; 40:A160-A168. [PMID: 37133033 DOI: 10.1364/josaa.479795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We present an exploratory study on iridescence that revealed systematic differences in the perceptual clustering of glossy and iridescent samples that was driven by instructions to focus on either the material or the color properties of the samples. Participants' similarity ratings of pairs of video stimuli, showing the samples from multiple views, were analyzed using multidimensional scaling (MDS), and differences between the MDS solutions for the two tasks were consistent with flexible weighting of information from different views of the samples. These findings point to ecological implications for how viewers perceive and interact with the color-changing properties of iridescent objects.
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12
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Shavit K, Wagner A, Schertel L, Farstey V, Akkaynak D, Zhang G, Upcher A, Sagi A, Yallapragada VJ, Haataja J, Palmer BA. A tunable reflector enabling crustaceans to see but not be seen. Science 2023; 379:695-700. [PMID: 36795838 DOI: 10.1126/science.add4099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Many oceanic prey animals use transparent bodies to avoid detection. However, conspicuous eye pigments, required for vision, compromise the organisms' ability to remain unseen. We report the discovery of a reflector overlying the eye pigments in larval decapod crustaceans and show how it is tuned to render the organisms inconspicuous against the background. The ultracompact reflector is constructed from a photonic glass of crystalline isoxanthopterin nanospheres. The nanospheres' size and ordering are modulated to tune the reflectance from deep blue to yellow, enabling concealment in different habitats. The reflector may also function to enhance the acuity or sensitivity of the minute eyes by acting as an optical screen between photoreceptors. This multifunctional reflector offers inspiration for constructing tunable artificial photonic materials from biocompatible organic molecules.
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Affiliation(s)
- Keshet Shavit
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Avital Wagner
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Lukas Schertel
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K.,Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Viviana Farstey
- The Interuniversity Institute for Marine Sciences, Eilat 8810302, Israel
| | - Derya Akkaynak
- The Interuniversity Institute for Marine Sciences, Eilat 8810302, Israel.,Hatter Department of Marine Technologies, University of Haifa, Haifa 3498838, Israel
| | - Gan Zhang
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | - Alexander Upcher
- Ilse Katz Institute for Nanoscale Science & Technology, Ben-Gurion University of the Negev, Be'er Sheba 8410501, Israel
| | - Amir Sagi
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.,The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
| | | | - Johannes Haataja
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, U.K
| | - Benjamin A Palmer
- Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel
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13
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Rubin JJ, Martin NW, Sieving KE, Kawahara AY. Testing bird-driven diurnal trade-offs of the moon moth's anti-bat tail. Biol Lett 2023; 19:20220428. [PMID: 36722145 PMCID: PMC9890116 DOI: 10.1098/rsbl.2022.0428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 01/09/2023] [Indexed: 02/02/2023] Open
Abstract
Traits are often caught in a dynamic tension of countervailing evolutionary pressures. Trade-offs can be imposed by predators evolutionarily curtailing the conspicuousness of a sexually selected trait, or acting in opposition to another natural selection pressure, for instance, a different predator with a divergent hunting strategy. Some moon moths (Saturniidae) have long hindwing tails that thwart echolocating bat attacks at night, allowing the moth to escape. These long tails may come at a cost, however, if they make the moth's roosting form more conspicuous to visually foraging predators during the day. To test this potential trade-off, we offered wild-caught Carolina wrens (Thryothorus ludovicianus) pastry dough models with real Actias luna wings that were either intact or had tails experimentally removed. We video recorded wrens foraging on models and found that moth models with tails did not experience increased detection and attack by birds. Thus, this elaborate trait, while obvious to human observers, does not seem to come at a cost of increased avian predator attention. The evolution of long hindwing tails, likely driven by echolocating predators at night, does not seem to be limited by opposing diurnal constraints. This study demonstrates the importance of testing presumed trade-offs and provides hypotheses for future testing.
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Affiliation(s)
- Juliette J. Rubin
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- McGuire Center for Lepidoptera and Biodiversity, Florida museum of Natural History, University of Florida, Gainesville, FL 32611, USA
| | - Nich W. Martin
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA
| | - Kathryn E. Sieving
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32611, USA
| | - Akito Y. Kawahara
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- McGuire Center for Lepidoptera and Biodiversity, Florida museum of Natural History, University of Florida, Gainesville, FL 32611, USA
- Entomology and Nematology Department, University of Florida, Gainesville, FL 32611, USA
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14
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Rao D, Long SM, Tapia-McClung H, Salgado-Espinosa K, Narendra A, Aguilar-Arguello S, Robledo-Ospina L, Rodriguez-Morales D, Jakob EM. Visual signals in the wing display of a tephritid fly deter jumping spider attacks. J Exp Biol 2022; 225:286139. [PMID: 36478243 DOI: 10.1242/jeb.244223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022]
Abstract
Visual animal communication, whether to the same or to other species, is largely conducted through dynamic and colourful signals. For a signal to be effective, the signaller must capture and retain the attention of the receiver. Signal efficacy is also dependent on the sensory limitations of the receiver. However, most signalling studies consider movement and colour separately, resulting in a partial understanding of the signal in question. We explored the structure and function of predator-prey signalling in the jumping spider-tephritid fly system, where the prey performs a wing waving display that deters an attack from the predator. Using a custom-built spider retinal tracker combined with visual modelling, as well as behavioural assays, we studied the effect of fly wing movement and colour on the jumping spider's visual system. We show that jumping spiders track their prey less effectively during wing display and this can be attributed to a series of fluctuations in chromatic and achromatic contrasts arising from the wing movements. These results suggest that displaying flies deter spider attacks by manipulating the movement biases of the spider's visual system. Our results emphasise the importance of receiver attention on the evolution of interspecific communication.
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Affiliation(s)
- Dinesh Rao
- Instituto de Biotecnologia y Ecologia Aplicada, Universidad Veracruzana, 91090 Xalapa, Veracruz, Mexico
| | - Skye M Long
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Horacio Tapia-McClung
- Instituto de Investigacion en Inteligencia Artificial, Universidad Veracruzana, 91097 Xalapa, Veracruz, Mexico
| | - Kevin Salgado-Espinosa
- Instituto de Biotecnologia y Ecologia Aplicada, Universidad Veracruzana, 91090 Xalapa, Veracruz, Mexico
| | - Ajay Narendra
- School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | | | - Luis Robledo-Ospina
- Instituto de Biotecnologia y Ecologia Aplicada, Universidad Veracruzana, 91090 Xalapa, Veracruz, Mexico
| | - Dulce Rodriguez-Morales
- Instituto de Biotecnologia y Ecologia Aplicada, Universidad Veracruzana, 91090 Xalapa, Veracruz, Mexico.,Instituo de Neuroetologia, Universidad Veracruzana, 91190 Xalapa, Veracruz, Mexico
| | - Elizabeth M Jakob
- Department of Biology, University of Massachusetts, Amherst, MA 01003, USA
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15
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Alienopterix santonicus sp. n., a metallic cockroach from the Late Cretaceous ajkaite amber (Bakony Mts, western Hungary) documents Alienopteridae within the Mesozoic Laurasia. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-022-01265-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Abstract
Cockroaches (Blattaria s. str.) were documented from numerous amber localities around the world, representing both extinct and extant families. Alienopteridae is an extinct cockroach family known only from the Cretaceous of Gondwana (Brazil, Botswana, Myanmar amber) and the Cenozoic of North America. Alienopterix santonicus sp. n. from the Late Cretaceous amber of the Ajka Coal Formation (Bakony Mts, western Hungary) extends the rich geographical distribution of the family into Laurasia during the Mesozoic. As a member of the presumably pollinator cohort Alienopteridae, this species could have played an important role in the Ajka Coal ecosystem during the Santonian. The microrectangular structures of the forewing suggest that the new species likely possessed a metallic colouration already known from the group. Combined with the disruptive body pattern this could have served as an advanced camouflage. The microrectangular structures of the forewing were compared to integument microstructures of extant insects with metallic colouration. Various arthropod taxa are already known from ajkaite, and the new discovery further emphasizes the importance of this amber.
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16
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Franklin AM. All camouflage strategies are not equal. Proc Biol Sci 2022; 289:20221869. [PMID: 36382517 PMCID: PMC9667360 DOI: 10.1098/rspb.2022.1869] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Accepted: 10/20/2022] [Indexed: 09/26/2023] Open
Affiliation(s)
- Amanda M. Franklin
- School of BioSciences, The University of Melbourne, Parkville, VIC 3010, Australia
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17
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Female birds disguised as males get extra food. Nature 2022; 610:259-260. [PMID: 36216910 DOI: 10.1038/d41586-022-03177-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Ospina-Rozo L, Roberts A, Stuart-Fox D. A generalized approach to characterize optical properties of natural objects. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
To understand the diversity of ways in which natural materials interact with light, it is important to consider how their reflectance changes with the angle of illumination or viewing and to consider wavelengths beyond the visible. Efforts to characterize these optical properties, however, have been hampered by heterogeneity in measurement techniques, parameters and terminology. Here, we propose a standardized set of measurements, parameters and terminology to describe the optical properties of natural objects based on spectrometry, including angle-dependent effects, such as iridescence and specularity. We select a set of existing measurements and parameters that are generalizable to any wavelength range and spectral shape, and we highlight which subsets of measures are relevant to different biological questions. As a case study, we have applied these measures to 30 species of Christmas beetles, in which we observed previously unrealized diversity in visible and near-infrared reflectance. As expected, reflection of short wavelengths was associated with high spectral purity and angle dependence. In contrast to simple, artificial structures, iridescence and specularity were not strongly correlated, highlighting the complexity and modularity of natural materials. Species did not cluster according to spectral parameters or genus, suggesting high lability of optical properties. The proposed standardization of measures and parameters will improve our understanding of biological adaptations for manipulating light by facilitating the systematic comparison of complex optical properties, such as glossy or metallic appearances and visible or near-infrared iridescence.
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Affiliation(s)
- Laura Ospina-Rozo
- School of Biosciences, University of Melbourne , VIC 3010 , Australia
| | - Ann Roberts
- ARC Centre of Excellence for Transformative Meta-Optical Systems, School of Physics, University of Melbourne , VIC 3010 , Australia
| | - Devi Stuart-Fox
- School of Biosciences, University of Melbourne , VIC 3010 , Australia
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19
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Riley JL, Haff TM, Ryeland J, Drinkwater E, Umbers KDL. The protective value of the colour and shape of the mountain katydid's antipredator defence. J Evol Biol 2022. [PMID: 35960499 DOI: 10.1111/jeb.14067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 06/09/2022] [Accepted: 06/13/2022] [Indexed: 12/12/2022]
Abstract
Deimatic behaviour is performed by prey when attacked by predators as part of an antipredator strategy. The behaviour is part of a sequence that consists of several defences, for example they can be preceded by camouflage and followed by a hidden putatively aposematic signal that is only revealed when the deimatic behaviour is performed. When displaying their hidden signal, mountain katydids (Acripeza reticulata) hold their wings vertically, exposing striking red and black stripes with blue spots and oozing an alkaloid-rich chemical defence derived from its Senecio diet. Understanding differences and interactions between deimatism and aposematism has proven problematic, so in this study we isolated the putative aposematic signal of the mountain katydid's antipredator strategy to measure its survival value in the absence of their deimatic behaviour. We manipulated two aspects of the mountain katydid's signal, colour pattern and whole body shape during display. We deployed five kinds of clay models, one negative control and four katydid-like treatments, in 15 grids across part of the mountain katydid's distribution to test the hypothesis that their hidden signal is aposematic. If this hypothesis holds true, we expected that the models, which most closely resembled real katydids would be attacked the least. Instead, we found that models that most closely resembled real katydids were the most likely to be attacked. We suggest several ideas to explain these results, including that the deimatic phase of the katydid's display, the change from a camouflaged state to exposing its hidden signal, may have important protective value.
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Affiliation(s)
- Julia L Riley
- Department of Biology, Mount Allison University, Sackville, New Brunswick, Canada.,Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Tonya M Haff
- Australian National Wildlife Collection, CSIRO, Acton, Australian Capital Territory, Australia
| | - Julia Ryeland
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia.,School of Science, Western Sydney University, Penrith, New South Wales, Australia
| | - Eleanor Drinkwater
- School of Science, Western Sydney University, Penrith, New South Wales, Australia.,Department of Biology, University of York, York, UK
| | - Kate D L Umbers
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia.,School of Science, Western Sydney University, Penrith, New South Wales, Australia.,School of Biological Sciences, University of Wollongong, Wollongong, New South Wales, Australia
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20
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Kjernsmo K, Lim AM, Middleton R, Hall JR, Costello LM, Whitney HM, Scott-Samuel NE, Cuthill IC. Beetle iridescence induces an avoidance response in naïve avian predators. Anim Behav 2022; 188:45-50. [PMID: 37649469 PMCID: PMC10462570 DOI: 10.1016/j.anbehav.2022.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/11/2021] [Accepted: 03/02/2022] [Indexed: 11/23/2022]
Abstract
It has recently been found that iridescence, a taxonomically widespread form of animal coloration defined by a change in hue with viewing angle, can act as a highly effective form of camouflage. However, little is known about whether iridescence can confer a survival benefit to prey postdetection and, if so, which optical properties of iridescent prey are important for this putative protective function. Here, we tested the effects of both iridescence and surface gloss (i.e. specular reflection) on the attack behaviour of prey-naïve avian predators. Using real and artificial jewel beetle, Sternocera aequisignata, wing cases, we found that iridescence provides initial protection against avian predation by significantly reducing the willingness to attack. Importantly, we found that the main factor explaining this aversion is iridescence, not multiple colours per se, with surface gloss also having an independent effect. Our results are important because they demonstrate that even when prey are presented up close and against a mismatching background, iridescence may confer a survival benefit by inducing hesitation or even, as sometimes observed, an aversion response in attacking birds. Furthermore, this means that even postdetection, prey do not necessarily need to have secondary defences such as sharp spines or toxins for iridescence to have a protective effect. Taken together, our results suggest that reduced avian predation could facilitate the initial evolution of iridescence in many species of insects and that it is the defining feature of iridescence, its colour changeability, that is important for this effect.
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Affiliation(s)
- Karin Kjernsmo
- School of Biological Sciences, University of Bristol, Bristol, U.K
| | - Anna M. Lim
- School of Biological Sciences, University of Bristol, Bristol, U.K
| | - Rox Middleton
- School of Biological Sciences, University of Bristol, Bristol, U.K
| | - Joanna R. Hall
- School of Psychological Science, University of Bristol, Bristol, U.K
| | - Leah M. Costello
- School of Biological Sciences, University of Bristol, Bristol, U.K
| | | | | | - Innes C. Cuthill
- School of Biological Sciences, University of Bristol, Bristol, U.K
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21
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Brien MN, Enciso-Romero J, Lloyd VJ, Curran EV, Parnell AJ, Morochz C, Salazar PA, Rastas P, Zinn T, Nadeau NJ. The genetic basis of structural colour variation in mimetic
Heliconius
butterflies. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200505. [PMID: 35634924 PMCID: PMC9149798 DOI: 10.1098/rstb.2020.0505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Structural colours, produced by the reflection of light from ultrastructures, have evolved multiple times in butterflies. Unlike pigmentary colours and patterns, little is known about the genetic basis of these colours. Reflective structures on wing-scale ridges are responsible for iridescent structural colour in many butterflies, including the Müllerian mimics Heliconius erato and Heliconius melpomene. Here, we quantify aspects of scale ultrastructure variation and colour in crosses between iridescent and non-iridescent subspecies of both of these species and perform quantitative trait locus (QTL) mapping. We show that iridescent structural colour has a complex genetic basis in both species, with offspring from crosses having a wide variation in blue colour (both hue and brightness) and scale structure measurements. We detect two different genomic regions in each species that explain modest amounts of this variation, with a sex-linked QTL in H. erato but not H. melpomene. We also find differences between species in the relationships between structure and colour, overall suggesting that these species have followed different evolutionary trajectories in their evolution of structural colour. We then identify genes within the QTL intervals that are differentially expressed between subspecies and/or wing regions, revealing likely candidates for genes controlling structural colour formation. This article is part of the theme issue ‘Genetic basis of adaptation and speciation: from loci to causative mutations’.
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Affiliation(s)
- Melanie N. Brien
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
| | - Juan Enciso-Romero
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
- Biology Program, Faculty of Natural Sciences, Universidad del Rosario, Bogotá, Colombia
| | - Victoria J. Lloyd
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
| | - Emma V. Curran
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
| | - Andrew J. Parnell
- Department of Physics and Astronomy, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH, UK
| | | | - Patricio A. Salazar
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
| | - Pasi Rastas
- Institute of Biotechnology, 00014 University of Helsinki, Finland
| | - Thomas Zinn
- ESRF - The European Synchrotron, 38043 Grenoble Cedex 9, France
| | - Nicola J. Nadeau
- Ecology and Evolutionary Biology, School of Biosciences, The University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
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22
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Hancock GRA, Troscianko J. CamoEvo: An open access toolbox for artificial camouflage evolution experiments. Evolution 2022; 76:870-882. [PMID: 35313008 PMCID: PMC9314924 DOI: 10.1111/evo.14476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 02/03/2022] [Indexed: 01/21/2023]
Abstract
Camouflage research has long shaped our understanding of evolution by natural selection, and elucidating the mechanisms by which camouflage operates remains a key question in visual ecology. However, the vast diversity of color patterns found in animals and their backgrounds, combined with the scope for complex interactions with receiver vision, presents a fundamental challenge for investigating optimal camouflage strategies. Genetic algorithms (GAs) have provided a potential method for accounting for these interactions, but with limited accessibility. Here, we present CamoEvo, an open-access toolbox for investigating camouflage pattern optimization by using tailored GAs, animal and egg maculation theory, and artificial predation experiments. This system allows for camouflage evolution within the span of just 10-30 generations (∼1-2 min per generation), producing patterns that are both significantly harder to detect and that are optimized to their background. CamoEvo was built in ImageJ to allow for integration with an array of existing open access camouflage analysis tools. We provide guides for editing and adjusting the predation experiment and GA as well as an example experiment. The speed and flexibility of this toolbox makes it adaptable for a wide range of computer-based phenotype optimization experiments.
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Affiliation(s)
- George R. A. Hancock
- Centre for Ecology and ConservationUniversity of ExeterPenrynTR10 9FEUnited Kingdom
| | - Jolyon Troscianko
- Centre for Ecology and ConservationUniversity of ExeterPenrynTR10 9FEUnited Kingdom
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23
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Sinnott‐Armstrong MA, Deanna R, Pretz C, Liu S, Harris JC, Dunbar‐Wallis A, Smith SD, Wheeler LC. How to approach the study of syndromes in macroevolution and ecology. Ecol Evol 2022; 12:e8583. [PMID: 35342598 PMCID: PMC8928880 DOI: 10.1002/ece3.8583] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/23/2021] [Accepted: 12/31/2021] [Indexed: 11/12/2022] Open
Abstract
Syndromes, wherein multiple traits evolve convergently in response to a shared selective driver, form a central concept in ecology and evolution. Recent work has questioned the existence of some classic syndromes, such as pollination and seed dispersal syndromes. Here, we discuss some of the major issues that have afflicted research into syndromes in macroevolution and ecology. First, correlated evolution of traits and hypothesized selective drivers is often relied on as the only evidence for adaptation of those traits to those hypothesized drivers, without supporting evidence. Second, the selective driver is often inferred from a combination of traits without explicit testing. Third, researchers often measure traits that are easy for humans to observe rather than measuring traits that are suited to testing the hypothesis of adaptation. Finally, species are often chosen for study because of their striking phenotypes, which leads to the illusion of syndromes and divergence. We argue that these issues can be avoided by combining studies of trait variation across entire clades or communities with explicit tests of adaptive hypotheses and that taking this approach will lead to a better understanding of syndrome‐like evolution and its drivers.
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Affiliation(s)
- Miranda A. Sinnott‐Armstrong
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
- Department of Chemistry University of Cambridge Cambridge UK
| | - Rocio Deanna
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
- Instituto Multidisciplinario de Biología Vegetal IMBIV (CONICET‐UNC) Córdoba Argentina
- Departamento de Ciencias Farmacéuticas Facultad de Ciencias Químicas (FCQ, UNC) Córdoba Argentina
| | - Chelsea Pretz
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
| | - Sukuan Liu
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
| | - Jesse C. Harris
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
| | - Amy Dunbar‐Wallis
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
| | - Stacey D. Smith
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
| | - Lucas C. Wheeler
- Department of Ecology and Evolutionary Biology University of Colorado‐Boulder Boulder Colorado USA
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24
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Stella D, Kleisner K. Visible beyond Violet: How Butterflies Manage Ultraviolet. INSECTS 2022; 13:insects13030242. [PMID: 35323542 PMCID: PMC8955501 DOI: 10.3390/insects13030242] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 02/12/2022] [Accepted: 02/23/2022] [Indexed: 12/04/2022]
Abstract
Ultraviolet (UV) means ‘beyond violet’ (from Latin ‘ultra’, meaning ‘beyond’), whereby violet is the colour with the highest frequencies in the ‘visible’ light spectrum. By ‘visible’ we mean human vision, but, in comparison to many other organisms, human visual perception is rather limited in terms of the wavelengths it can perceive. Still, this is why communication in the UV spectrum is often called hidden, although it most likely plays an important role in communicating various kinds of information among a wide variety of organisms. Since Silberglied’s revolutionary Communication in the Ultraviolet, comprehensive studies on UV signals in a wide list of genera are lacking. This review investigates the significance of UV reflectance (and UV absorption)—a feature often neglected in intra- and interspecific communication studies—mainly in Lepidoptera. Although the text focuses on various butterfly families, links and connections to other animal groups, such as birds, are also discussed in the context of ecology and the evolution of species. The basic mechanisms of UV colouration and factors shaping the characteristics of UV patterns are also discussed in a broad context of lepidopteran communication.
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Affiliation(s)
- David Stella
- Global Change Research Institute, The Czech Academy of Sciences, Bělidla 986/4a, 603 00 Brno, Czech Republic
- Department of Philosophy and History of Science, Faculty of Science, Charles University, 128 44 Prague, Czech Republic
| | - Karel Kleisner
- Department of Philosophy and History of Science, Faculty of Science, Charles University, 128 44 Prague, Czech Republic
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25
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Cezário RR, Gorb SN, Guillermo‐Ferreira R. Camouflage by counter‐brightness: the blue wings of Morpho dragonflies
Zenithoptera lanei
(Anisoptera: Libellulidae) match the water background. J Zool (1987) 2022. [DOI: 10.1111/jzo.12955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. R. Cezário
- Department of Biological Sciences Universidade Federal do Triângulo Mineiro Uberaba Brazil
- Graduate Program in Entomology University of São Paulo (USP) Ribeirão Preto Brazil
| | - S. N. Gorb
- Department of Functional Morphology and Biomechanics Zoological Institute Kiel University Kiel Germany
| | - R. Guillermo‐Ferreira
- Department of Biological Sciences Universidade Federal do Triângulo Mineiro Uberaba Brazil
- Graduate Program in Entomology University of São Paulo (USP) Ribeirão Preto Brazil
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26
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Robledo-Ospina LE, Rao D. Dangerous visions: a review of visual antipredator strategies in spiders. Evol Ecol 2022. [DOI: 10.1007/s10682-022-10156-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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27
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28
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Wuthrich KL, Nagel A, Swierk L. Rapid Body Color Change Provides Lizards with Facultative Crypsis in the Eyes of Their Avian Predators. Am Nat 2021; 199:277-290. [DOI: 10.1086/717678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Kelly Lin Wuthrich
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, New York 13902
| | - Amber Nagel
- Department of Chemical Engineering, University of Oklahoma, Norman, Oklahoma 73019
| | - Lindsey Swierk
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, New York 13902
- School of the Environment, Yale University, New Haven, Connecticut 06511; and Amazon Conservatory for Tropical Studies, Iquitos, Loreto 16001, Perú
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29
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Franklin AM, Rankin KJ, Ospina Rozo L, Medina I, Garcia JE, Ng L, Dong C, Wang L, Aulsebrook AE, Stuart‐Fox D. Cracks in the mirror hypothesis: High specularity does not reduce detection or predation risk. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Amanda M. Franklin
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Katrina J. Rankin
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Laura Ospina Rozo
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Iliana Medina
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Jair E. Garcia
- Bio‐Inspired Digital Sensing Lab RMIT University Melbourne Vic. Australia
| | - Leslie Ng
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Caroline Dong
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Lu‐Yi Wang
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Anne E. Aulsebrook
- School of BioSciences The University of Melbourne Parkville Vic. Australia
| | - Devi Stuart‐Fox
- School of BioSciences The University of Melbourne Parkville Vic. Australia
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30
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Barnett JB, Michalis C, Scott-Samuel NE, Cuthill IC. Colour pattern variation forms local background matching camouflage in a leaf-mimicking toad. J Evol Biol 2021; 34:1531-1540. [PMID: 34465010 DOI: 10.1111/jeb.13923] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/17/2021] [Accepted: 08/26/2021] [Indexed: 12/26/2022]
Abstract
Optimal camouflage can, in principle, be relatively easily achieved in simple, homogeneous, environments where backgrounds always have the same colour, brightness and patterning. Natural environments are, however, rarely homogenous, and species often find themselves viewed against varied backgrounds where the task of concealment is more challenging. One result of variable backgrounds is the evolution of intraspecific phenotypic variation which may either be generalized, with multiple similarly cryptic patterns, or specialized, with each discrete colour form maximizing concealment against a single component of the background. We investigated the role of phenotypic variation in a highly variable population of the Neotropical toad Rhinella margaritifera using visual modelling and a computer-based detection task. We found that phenotypic variation was not divided into discrete colour morphs, and all toads were well camouflaged against the forest floor. However, although the whole population may appear to consist of random samples from the background, the toads were a particularly close match to the leaf litter, suggesting that they masquerade as dead leaves, which are themselves variable. Furthermore, rather than each colour form being equally effective against a single background, each toad was specialized towards its own particular local surroundings, as suggested by a specialist strategy. Taken together, these data highlight the importance of background matching to a nominally masquerading species, as well as how habitat heterogeneity at multiple spatial scales may affect the evolution of camouflage and phenotypic variation.
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Affiliation(s)
- James B Barnett
- School of Biological Sciences, University of Bristol, Bristol, UK.,Redpath Museum, McGill University, Montreal, QC, Canada.,Department of Psychology, Neuroscience, & Behaviour, McMaster University, Hamilton, ON, Canada
| | | | | | - Innes C Cuthill
- School of Biological Sciences, University of Bristol, Bristol, UK
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31
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Briolat ES, Arenas LM, Hughes AE, Liggins E, Stevens M. Generalist camouflage can be more successful than microhabitat specialisation in natural environments. BMC Ecol Evol 2021; 21:151. [PMID: 34344323 PMCID: PMC8330473 DOI: 10.1186/s12862-021-01883-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 07/25/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Crypsis by background-matching is a critical form of anti-predator defence for animals exposed to visual predators, but achieving effective camouflage in patchy and variable natural environments is not straightforward. To cope with heterogeneous backgrounds, animals could either specialise on particular microhabitat patches, appearing cryptic in some areas but mismatching others, or adopt a compromise strategy, providing partial matching across different patch types. Existing studies have tested the effectiveness of compromise strategies in only a limited set of circumstances, primarily with small targets varying in pattern, and usually in screen-based tasks. Here, we measured the detection risk associated with different background-matching strategies for relatively large targets, with human observers searching for them in natural scenes, and focusing on colour. Model prey were designed to either 'specialise' on the colour of common microhabitat patches, or 'generalise' by matching the average colour of the whole visual scenes. RESULTS In both the field and an equivalent online computer-based search task, targets adopting the generalist strategy were more successful in evading detection than those matching microhabitat patches. This advantage occurred because, across all possible locations in these experiments, targets were typically viewed against a patchwork of different microhabitat areas; the putatively generalist targets were thus more similar on average to their various immediate surroundings than were the specialists. CONCLUSIONS Demonstrating close agreement between the results of field and online search experiments provides useful validation of online citizen science methods commonly used to test principles of camouflage, at least for human observers. In finding a survival benefit to matching the average colour of the visual scenes in our chosen environment, our results highlight the importance of relative scales in determining optimal camouflage strategies, and suggest how compromise coloration can succeed in nature.
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Affiliation(s)
| | - Lina María Arenas
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, TR10 9FE, Penryn, UK
| | - Anna E Hughes
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, TR10 9FE, Penryn, UK
- Department of Psychology, University of Essex, Wivenhoe House, CO4 3SQ, Colchester, UK
| | - Eric Liggins
- , QinetiQ, Cody Technology Park, Ively Road, Farnborough, GU14 0LX, Hampshire, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, TR10 9FE, Penryn, UK
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Cezário RR, Lopez VM, Gorb S, Guillermo-Ferreira R. Dynamic iridescent signals of male copperwing damselflies coupled with wing-clapping displays: the perspective of different receivers. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Dynamic signals are a widespread phenomenon in several taxa, usually associated with intraspecific communication. In contrast, dynamic iridescent signals are detectable only at specific angles of illumination; hence, the animal can hide the signal to avoid detection when necessary. This structural coloration is mostly dependent on the illumination, the contrast against the background and the vision of the receiver. Complex behavioural displays can be coupled with structural coloration to create dynamic visual signals that enhance these functions. Here, we address whether iridescence of the males of a damselfly that inhabits dark rainforests, Chalcopteryx scintillans, can be considered a dynamic visual signal. We analyse whether coloration is perceived by conspecifics, while reducing detectability to eavesdroppers against three types of backgrounds. Our results suggest that the visual background affects the detectability of male hindwings by different receivers, mostly predators and prey. We discuss whether these results and the angle dependence of colour could indicate a mechanism to avoid unwanted intraspecific interactions or even to lure both predators and prey. We conclude that the main functions of the dynamic iridescent signal are to communicate with conspecifics while hindering the signal for prey, adding evidence of the multifunctionality of structural coloration coupled with behavioural displays in animals.
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Affiliation(s)
- Rodrigo Roucourt Cezário
- Laboratory of Ecological Studies on Ethology and Evolution (LESTES Lab), Federal University of São Carlos, São Carlos, SP, Brazil
- Graduate program in Entomology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Vinicius Marques Lopez
- Laboratory of Ecological Studies on Ethology and Evolution (LESTES Lab), Federal University of São Carlos, São Carlos, SP, Brazil
- Graduate program in Entomology, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Stanislav Gorb
- Department of Functional Morphology and Biomechanics, Zoological Institute, Kiel University, Am Botanischen Garten 1–9, D-24098 Kiel, Germany
| | - Rhainer Guillermo-Ferreira
- Laboratory of Ecological Studies on Ethology and Evolution (LESTES Lab), Federal University of São Carlos, São Carlos, SP, Brazil
- Graduate program in Entomology, University of São Paulo, Ribeirão Preto, SP, Brazil
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Echeverri SA, Miller AE, Chen J, McQueen EW, Plakke M, Spicer M, Hoke KL, Stoddard MC, Morehouse NI. How signaling geometry shapes the efficacy and evolution of animal communication systems. Integr Comp Biol 2021; 61:787-813. [PMID: 34021338 DOI: 10.1093/icb/icab090] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Animal communication is inherently spatial. Both signal transmission and signal reception have spatial biases-involving direction, distance and position-that interact to determine signaling efficacy. Signals, be they visual, acoustic, or chemical, are often highly directional. Likewise, receivers may only be able to detect signals if they arrive from certain directions. Alignment between these directional biases is therefore critical for effective communication, with even slight misalignments disrupting perception of signaled information. In addition, signals often degrade as they travel from signaler to receiver, and environmental conditions that impact transmission can vary over even small spatiotemporal scales. Thus, how animals position themselves during communication is likely to be under strong selection. Despite this, our knowledge regarding the spatial arrangements of signalers and receivers during communication remains surprisingly coarse for most systems. We know even less about how signaler and receiver behaviors contribute to effective signaling alignment over time, or how signals themselves may have evolved to influence and/or respond to these aspects of animal communication. Here, we first describe why researchers should adopt a more explicitly geometric view of animal signaling, including issues of location, direction, and distance. We then describe how environmental and social influences introduce further complexities to the geometry of signaling. We discuss how multimodality offers new challenges and opportunities for signalers and receivers. We conclude with recommendations and future directions made visible by attention to the geometry of signaling.
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Affiliation(s)
| | - Audrey E Miller
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ
| | - Jason Chen
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, Emory University, Atlanta, GA
| | - Eden W McQueen
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Melissa Plakke
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS
| | - Michelle Spicer
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Biology Department, University of Puget Sound, Tacoma, WA
| | - Kim L Hoke
- Department of Biology, Colorado State University, Fort Collins, CO
| | | | - Nathan I Morehouse
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biological Sciences, University of Cincinnati, Cincinnati, OH
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34
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Barnett JB, Varela BJ, Jennings BJ, Lesbarrères D, Pruitt JN, Green DM. Habitat disturbance alters color contrast and the detectability of cryptic and aposematic frogs. Behav Ecol 2021. [DOI: 10.1093/beheco/arab032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Animals use color both to conceal and signal their presence, with patterns that match the background, disrupt shape recognition, or highlight features important for communication. The forms that these color patterns take are responses to the visual systems that observe them and the environments within which they are viewed. Increasingly, however, these environments are being affected by human activity. We studied how pattern characteristics and habitat change may affect the detectability of three frog color patterns from the Bocas del Toro archipelago in Panama: Beige-Striped Brown Allobates talamancae and two spotted morphs of Oophaga pumilio, Black-Spotted Green and Black-Spotted Red. To assess detectability, we used visual modeling of conspecifics and potential predators, along with a computer-based detection experiment with human participants. Although we found no evidence for disruptive camouflage, we did find clear evidence that A. talamancae stripes are inherently more cryptic than O. pumilio spots regardless of color. We found no evidence that color pattern polytypism in O. pumilio is related to differences in the forest floor between natural sites. We did, however, find strong evidence that human disturbance affects the visual environment and modifies absolute and rank order frog detectability. Human-induced environmental change reduces the effectiveness of camouflage in A. talamancae, reduces detectability of Black-Spotted Green O. pumilio, and increases chromatic contrast, but not detectability, in Black-Spotted Red O. pumilio. Insofar as predators may learn about prey defenses and make foraging decisions based on relative prey availability and suitability, such changes may have wider implications for predator–prey dynamics.
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Affiliation(s)
- James B Barnett
- Department of Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, ON, Canada
- Redpath Museum, McGill University, Montreal, QC, Canada
| | | | - Ben J Jennings
- The College of Health, Medicine and Life Sciences, Brunel University London, Kingston Lane, Uxbridge, UK
| | | | - Jonathan N Pruitt
- Department of Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, ON, Canada
| | - David M Green
- Redpath Museum, McGill University, Montreal, QC, Canada
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36
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Abstract
Amanda M. Franklin and Laura Ospina-Rozo introduce the biology and physics of gloss in nature.
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37
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The evolution of structural colour in butterflies. Curr Opin Genet Dev 2021; 69:28-34. [PMID: 33540167 DOI: 10.1016/j.gde.2021.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/21/2020] [Accepted: 01/01/2021] [Indexed: 01/23/2023]
Abstract
Butterflies display some of the most striking examples of structural colour in nature. These colours originate from cuticular scales that cover the wing surface, which have evolved a diverse suite of optical nanostructures capable of manipulating light. In this review we explore recent advances in the evolution of structural colour in butterflies. We discuss new insights into the underlying genetics and development of the structural colours in various nanostructure types. Improvements in -omic and imaging technologies have been paramount to these new advances and have permitted an increased appreciation of their development and evolution.
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38
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Araki Y, Sota T. Population genetic structure underlying the geographic variation in beetle structural colour with multiple transition zones. Mol Ecol 2020; 30:670-684. [PMID: 33253446 DOI: 10.1111/mec.15758] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/12/2020] [Accepted: 11/24/2020] [Indexed: 11/27/2022]
Abstract
We studied the population genetic structure underlying the geographic variation in the structural colour of the geotrupid dung beetle, Phelotrupes auratus, which exhibits metallic body colours of different reflectance wavelengths perceived as red, green and indigo. These forms occur parapatrically in an area of Japan. The colour variation was not related to variation in climatic factors. Using single nucleotide polymorphisms (SNPs) from restriction-site-associated DNA sequences, we discriminated five groups of populations (west/red, south/green, south/indigo, south/red and east/red) by a combination of genetic clusters (west, south and east) and three colour forms. There were three transition zones for the colour forms: two between the red and green forms were hybrid zones with steep genetic clines, which implies the existence of barriers to gene flow between regions with different colours. The remaining transition zone between the green and indigo forms lacked genetic differentiation, despite the evident colour changes, which implies regionally specific selection on the different colours. In a genomewide association study, we identified four SNPs that were associated with the red/green or indigo colour and were not linked with one another, which implies that the coloration was controlled by multiple loci, each affecting the expression of a different colour range. These loci may have controlled the transitions between different combinations of colours. Our study demonstrates that geographic colour variation within a species can be maintained by nonuniform interactions among barriers to gene flow, locally specific selection on different colours, and the effects of different colour loci.
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Affiliation(s)
- Yoshifumi Araki
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - Teiji Sota
- Department of Zoology, Graduate School of Science, Kyoto University, Kyoto, Japan
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39
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Stuart-Fox D, Ospina-Rozo L, Ng L, Franklin AM. The Paradox of Iridescent Signals. Trends Ecol Evol 2020; 36:187-195. [PMID: 33168152 DOI: 10.1016/j.tree.2020.10.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 10/05/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022]
Abstract
Signals reliably convey information to a receiver. To be reliable, differences between individuals in signal properties must be consistent and easily perceived and evaluated by receivers. Iridescent objects are often striking and vivid, but their appearance can change dramatically with viewing geometry and illumination. The changeable nature of iridescent surfaces creates a paradox: how can they be reliable signals? We contend that iridescent color patches can be reliable signals only if accompanied by specific adaptations to enhance reliability, such as structures and behaviors that limit perceived hue shift or enhance and control directionality. We highlight the challenges of studying iridescence and key considerations for the evaluation of its adaptive significance.
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Affiliation(s)
- Devi Stuart-Fox
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia.
| | - Laura Ospina-Rozo
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Leslie Ng
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Amanda M Franklin
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia
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40
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Bagge LE, Kenton AC, Lyons BA, Wehling MF, Goldstein DH. Mueller matrix characterizations of circularly polarized reflections from golden scarab beetles. APPLIED OPTICS 2020; 59:F85-F93. [PMID: 32749282 DOI: 10.1364/ao.398832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 06/16/2020] [Indexed: 06/11/2023]
Abstract
Circularly polarized light (CPL) reflections are rare in nature. Only a few animal groups-most notably certain stomatopod crustaceans and certain beetles in the family Scarabaeidae-are known to reflect CPL from incident unpolarized light. Here, we examine five species of metallic scarabs in the genus Chrysina that, to the naked human eye, look remarkably similar. Using a spectropolarimetric reflectometer to characterize the complete Mueller matrix elements of the beetles' elytral surfaces, we found that four of the five species were strongly left-handed circularly polarized (LHCP), and only one scarab species, Chrysina resplendens, had an overall lower degree of polarization and switched from LHCP to right-handed circularly polarized reflectance depending on wavelength.
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41
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Cai C, Tihelka E, Pan Y, Yin Z, Jiang R, Xia F, Huang D. Structural colours in diverse Mesozoic insects. Proc Biol Sci 2020; 287:20200301. [PMID: 32605519 DOI: 10.1098/rspb.2020.0301] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Structural colours, nature's most pure and intense colours, originate when light is scattered via nanoscale modulations of the refractive index. Original colours in fossils illuminate the ecological interactions among extinct organisms and functional evolution of colours. Here, we report multiple examples of vivid metallic colours in diverse insects from mid-Cretaceous amber. Scanning and transmission electron microscopy revealed a smooth outer surface and five alternating electron-dense and electron-lucent layers in the epicuticle of a fossil wasp, suggesting that multilayer reflectors, the most common biophotonic nanostructure in animals and even plants, are responsible for the exceptional preservation of colour in amber fossils. Based on theoretical modelling of the reflectance spectra, a reflective peak of wavelength of 514 nm was calculated, corresponding to the bluish-green colour observed under white light. The green to blue structural colours in fossil wasps, beetles and a fly most likely functioned as camouflage, although other functions such as thermoregulation cannot be ruled out. This discovery not only provides critical evidence of evolution of structural colours in arthropods, but also sheds light on the preservation potential of nanostructures of ancient animals through geological time.
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Affiliation(s)
- Chenyang Cai
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China
| | - Erik Tihelka
- Department of Animal Science, Hartpury College, Hartpury GL19 3BE, UK
| | - Yanhong Pan
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China.,School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, People's Republic of China
| | - Ziwei Yin
- Laboratory of Systematic Entomology, College of Life Sciences, Shanghai Normal University, Shanghai 200234, People's Republic of China
| | - Rixin Jiang
- Laboratory of Systematic Entomology, College of Life Sciences, Shanghai Normal University, Shanghai 200234, People's Republic of China
| | - Fangyuan Xia
- Lingpoge Amber Museum, Shanghai 201108, People's Republic of China
| | - Diying Huang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, People's Republic of China
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