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Tan M, Zhang S, Stevens M, Li D, Tan EJ. Antipredator defences in motion: animals reduce predation risks by concealing or misleading motion signals. Biol Rev Camb Philos Soc 2024; 99:778-796. [PMID: 38174819 DOI: 10.1111/brv.13044] [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: 12/06/2022] [Revised: 12/13/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024]
Abstract
Motion is a crucial part of the natural world, yet our understanding of how animals avoid predation whilst moving remains rather limited. Although several theories have been proposed for how antipredator defence may be facilitated during motion, there is often a lack of supporting empirical evidence, or conflicting findings. Furthermore, many studies have shown that motion often 'breaks' camouflage, as sudden movement can be detected even before an individual is recognised. Whilst some static camouflage strategies may conceal moving animals to a certain extent, more emphasis should be given to other modes of camouflage and related defences in the context of motion (e.g. flicker fusion camouflage, active motion camouflage, motion dazzle, and protean motion). Furthermore, when motion is involved, defence strategies are not necessarily limited to concealment. An animal can also rely on motion to mislead predators with regards to its trajectory, location, size, colour pattern, or even identity. In this review, we discuss the various underlying antipredator strategies and the mechanisms through which they may be linked to motion, conceptualising existing empirical and theoretical studies from two perspectives - concealing and misleading effects. We also highlight gaps in our understanding of these antipredator strategies, and suggest possible methodologies for experimental designs/test subjects (i.e. prey and/or predators) and future research directions.
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Affiliation(s)
- Min Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
| | - Shichang Zhang
- Centre for Behavioural Ecology & Evolution, State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, Hubei, China
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Daiqin Li
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
- Centre for Behavioural Ecology & Evolution, State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, Hubei, China
| | - Eunice J Tan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore, 117543, Singapore
- Division of Science, Yale-NUS College, 16 College Avenue West, Singapore, 138527, Singapore
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2
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Otte PJ, Cromsigt JPGM, Smit C, Hofmeester TR. Snow cover-related camouflage mismatch increases detection by predators. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:327-337. [PMID: 38247310 DOI: 10.1002/jez.2784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/04/2024] [Accepted: 01/08/2024] [Indexed: 01/23/2024]
Abstract
Camouflage expressed by animals is an adaptation to local environments that certain animals express to maximize survival and fitness. Animals at higher latitudes change their coat color according to a seasonally changing environment, expressing a white coat in winter and a darker coat in summer. The timing of molting is tightly linked to the appearance and disappearance of snow and is mainly regulated by photoperiod. However, due to climate change, an increasing mismatch is observed between the coat color of these species and their environment. Here, we conducted an experiment in northern Sweden, with white and brown decoys to study how camouflage (mis)-match influenced (1) predator attraction to decoys, and (2) predation events. Using camera trap data, we showed that mismatching decoys attracted more predators and experienced a higher likelihood of predation events in comparison to matching decoys, suggesting that camouflage mismatched animals experience increased detection by predators. These results provide insight into the function of a seasonal color coat and the need for this adaptation to maximize fitness in an environment that is exposed to high seasonality. Thus, our results suggest that, with increasing climate change and reduced snow cover, animals expressing a seasonal color coat will experience a decrease in survival.
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Affiliation(s)
- Pieter J Otte
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Joris P G M Cromsigt
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden
- Department of Zoology, Centre for African Conservation Ecology, Nelson Mandela University, Gqeberha, South Africa
| | - Christian Smit
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Tim R Hofmeester
- Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden
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Ike CS, Muhammad N, Bibi N, Alhazmi S, Eoghan F. Discriminative context-aware network for camouflaged object detection. Front Artif Intell 2024; 7:1347898. [PMID: 38601112 PMCID: PMC11004367 DOI: 10.3389/frai.2024.1347898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 03/12/2024] [Indexed: 04/12/2024] Open
Abstract
Introduction Animals use camouflage (background matching, disruptive coloration, etc.) for protection, confusing predators and making detection difficult. Camouflage Object Detection (COD) tackles this challenge by identifying objects seamlessly blended into their surroundings. Existing COD techniques struggle with hidden objects due to noisy inferences inherent in natural environments. To address this, we propose the Discriminative Context-aware Network (DiCANet) for improved COD performance. Methods DiCANet addresses camouflage challenges through a two-stage approach. First, an adaptive restoration block intelligently learns feature weights, prioritizing informative channels and pixels. This enhances convolutional neural networks' ability to represent diverse data and handle complex camouflage. Second, a cascaded detection module with an enlarged receptive field refines the object prediction map, achieving clear boundaries without post-processing. Results Without post-processing, DiCANet achieves state-of-the-art performance on challenging COD datasets (CAMO, CHAMELEON, COD10K) by generating accurate saliency maps with rich contextual details and precise boundaries. Discussion DiCANet tackles the challenge of identifying camouflaged objects in noisy environments with its two-stage restoration and cascaded detection approach. This innovative architecture surpasses existing methods in COD tasks, as proven by benchmark dataset experiments.
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Affiliation(s)
| | - Nazeer Muhammad
- School of Computing, Pak-Austria Fachhochschule Institute of Applied Sciences and Technology, Haripur, Pakistan
| | - Nargis Bibi
- Department of Computer Science, Fatima Jinnah Women University, Rawalpindi, Pakistan
| | - Samah Alhazmi
- Computer Science Department, College of Computing and Informatics, Saudi Electronic University, Riyadh, Saudi Arabia
| | - Furey Eoghan
- Department of Computing, Atlantic Technological University, Letterkenny, Ireland
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Nokelainen O, Silvasti SA, Strauss SY, Wahlberg N, Mappes J. Predator selection on phenotypic variability of cryptic and aposematic moths. Nat Commun 2024; 15:1678. [PMID: 38395999 PMCID: PMC10891176 DOI: 10.1038/s41467-024-45329-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 01/17/2024] [Indexed: 02/25/2024] Open
Abstract
Natural selection generally favours phenotypic variability in camouflaged organisms, whereas aposematic organisms are expected to evolve a more uniform warning coloration. However, no comprehensive analysis of the phenotypic consequences of predator selection in aposematic and cryptic species exists. Using state-of-the-art image analysis, we examine 2800 wing images of 82 moth species accessed via three online museum databases. We test whether anti-predator strategy (i.e., camouflage or aposematism) explains intraspecific variation in wing colour and pattern across northern hemisphere moths. In addition, we test two mutually non-exclusive, ecological hypotheses to explain variation in colour pattern: diel-activity or dietary-niche. In this work, taking into account phylogenetic relationships, moth phenotypic variability is best explained by anti-predator strategy with camouflaged moths being more variable in wing patterning than aposematic species.
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Affiliation(s)
- Ossi Nokelainen
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikki Biocenter 3, P.O. Box 65, 40014, Helsinki, Finland.
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland.
- Open Science Centre, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland.
| | - Sanni A Silvasti
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, FI-40014, Jyväskylä, Finland
- School of Natural Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Sharon Y Strauss
- Department of Evolution and Ecology, University of California at Davis, 2320 Storer Hall, One Shields Avenue, Davis, CA, 95616, USA
- Wissenschaftskolleg zu Berlin, Wallotstrasse 19, Berlin, 14193, Germany
| | - Niklas Wahlberg
- Department of Biology, Lund University, Sölvegatan 37, SE-223 62, Lund, Sweden
| | - Johanna Mappes
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Viikki Biocenter 3, P.O. Box 65, 40014, Helsinki, Finland.
- Wissenschaftskolleg zu Berlin, Wallotstrasse 19, Berlin, 14193, Germany.
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Newman BA, D’Angelo GJ. A Review of Cervidae Visual Ecology. Animals (Basel) 2024; 14:420. [PMID: 38338063 PMCID: PMC10854973 DOI: 10.3390/ani14030420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/21/2024] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
This review examines the visual systems of cervids in relation to their ability to meet their ecological needs and how their visual systems are specialized for particular tasks. Cervidae encompasses a diverse group of mammals that serve as important ecological drivers within their ecosystems. Despite evidence of highly specialized visual systems, a large portion of cervid research ignores or fails to consider the realities of cervid vision as it relates to their ecology. Failure to account for an animal's visual ecology during research can lead to unintentional biases and uninformed conclusions regarding the decision making and behaviors for a species or population. Our review addresses core behaviors and their interrelationship with cervid visual characteristics. Historically, the study of cervid visual characteristics has been restricted to specific areas of inquiry such as color vision and contains limited integration into broader ecological and behavioral research. The purpose of our review is to bridge these gaps by offering a comprehensive review of cervid visual ecology that emphasizes the interplay between the visual adaptations of cervids and their interactions with habitats and other species. Ultimately, a better understanding of cervid visual ecology allows researchers to gain deeper insights into their behavior and ecology, providing critical information for conservation and management efforts.
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Affiliation(s)
- Blaise A. Newman
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
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Zhang Z, Wang T, Wang J, Sun Y. Features Split and Aggregation Network for Camouflaged Object Detection. J Imaging 2024; 10:24. [PMID: 38249009 PMCID: PMC11154448 DOI: 10.3390/jimaging10010024] [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: 12/10/2023] [Revised: 01/08/2024] [Accepted: 01/15/2024] [Indexed: 01/23/2024] Open
Abstract
Higher standards have been proposed for detection systems since camouflaged objects are not distinct enough, making it possible to ignore the difference between their background and foreground. In this paper, we present a new framework for Camouflaged Object Detection (COD) named FSANet, which consists mainly of three operations: spatial detail mining (SDM), cross-scale feature combination (CFC), and hierarchical feature aggregation decoder (HFAD). The framework simulates the three-stage detection process of the human visual mechanism when observing a camouflaged scene. Specifically, we have extracted five feature layers using the backbone and divided them into two parts with the second layer as the boundary. The SDM module simulates the human cursory inspection of the camouflaged objects to gather spatial details (such as edge, texture, etc.) and fuses the features to create a cursory impression. The CFC module is used to observe high-level features from various viewing angles and extracts the same features by thoroughly filtering features of various levels. We also design side-join multiplication in the CFC module to avoid detail distortion and use feature element-wise multiplication to filter out noise. Finally, we construct an HFAD module to deeply mine effective features from these two stages, direct the fusion of low-level features using high-level semantic knowledge, and improve the camouflage map using hierarchical cascade technology. Compared to the nineteen deep-learning-based methods in terms of seven widely used metrics, our proposed framework has clear advantages on four public COD datasets, demonstrating the effectiveness and superiority of our model.
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Affiliation(s)
- Zejin Zhang
- HDU-ITMO Joint Institute, Hangzhou Dianzi University, Hangzhou 310018, China; (Z.Z.); (T.W.); (Y.S.)
| | - Tao Wang
- HDU-ITMO Joint Institute, Hangzhou Dianzi University, Hangzhou 310018, China; (Z.Z.); (T.W.); (Y.S.)
| | - Jian Wang
- HDU-ITMO Joint Institute, Hangzhou Dianzi University, Hangzhou 310018, China; (Z.Z.); (T.W.); (Y.S.)
- School of Automation, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Yao Sun
- HDU-ITMO Joint Institute, Hangzhou Dianzi University, Hangzhou 310018, China; (Z.Z.); (T.W.); (Y.S.)
- School of Automation, Hangzhou Dianzi University, Hangzhou 310018, China
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Roulin A, Dubey S, Ito S, Wakamatsu K. Melanin-based plumage coloration and melanin content in organs in the barn owl. JOURNAL OF ORNITHOLOGY 2023; 165:429-438. [PMID: 38496038 PMCID: PMC10940376 DOI: 10.1007/s10336-023-02137-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 11/22/2023] [Accepted: 11/28/2023] [Indexed: 03/19/2024]
Abstract
Although the evolutionary ecology of melanin pigments and melanin-based coloration has been studied in great details, particularly in birds, little is known about the function of melanin stored inside the body. In the barn owl Tyto alba, in which individuals vary in the degree of reddish pheomelanin-based coloration and in the size of black eumelanic feather spots, we measured the concentration in melanin pigments in seven organs. The eyes had by far the most melanin then the skin, pectoral muscle, heart, liver, trachea, and uropygial gland. The concentration in eumelanin was not necessarily correlated with the concentration in pheomelanin suggesting that their production can be regulated independently from each other. Redder barn owls had more pheomelanin in the skin and uropygial gland than white owls, while owls displaying larger black feather spots had more eumelanin in the skin than small-spotted owls. More data are required to evaluate whether melanin-based traits can evolve as an indirect response to selection exerted on melanin deposition in organs.
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Affiliation(s)
- Alexandre Roulin
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
| | - Sylvain Dubey
- Department of Ecology and Evolution, University of Lausanne, Biophore Building, CH-1015 Lausanne, Switzerland
- HW Romandie SA, Avenue Des Alpes 25, CH-1820 Montreux, Switzerland
| | - Shosuke Ito
- Institute for Melanin Chemistry, Fujita Health University, Toyoake, Aichi 470-1192 Japan
| | - Kazumasa Wakamatsu
- Institute for Melanin Chemistry, Fujita Health University, Toyoake, Aichi 470-1192 Japan
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Zhang Y, Cai X, Hou Y, Chen W, Zhang J. Triphenyltin Influenced Carotenoid-Based Coloration in Coral Reef Fish, Amphiprion ocellaris, by Disrupting Carotenoid Metabolism. TOXICS 2023; 12:13. [PMID: 38250969 PMCID: PMC10820653 DOI: 10.3390/toxics12010013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/07/2023] [Accepted: 12/13/2023] [Indexed: 01/23/2024]
Abstract
Triphenyltin (TPT), a kind of persistent pollutant, is prevalent in the aquatic environment and could pose a threat to coral reef fish. However, little is known about the toxicity of TPT on coral reef fish, especially regarding the representative characteristics of body coloration. Therefore, this study chose the clownfish (Amphiprion ocellaris) in order to investigate the effects of TPT exposure on its carotenoid-based body coloration under the environmentally relevant concentrations (0, 1, 10 and 100 ng/L). After TPT exposure for 60 d, the carotenoid contents were decreased and histological damage in the liver was found, shown as nuclear pyknosis and shift, lipid deposition and fibrotic tissue hyperplasia. Liver transcriptomic analysis showed that TPT exposure interfered with oxidative phosphorylation and fatty acid metabolism pathways, which related to carotenoids uptake and metabolism. Furthermore, TPT exposure led to oxidative damage in the liver, which is responsible for the changes in the antioxidant capacity of enzymes, including GSH, MDA, POD, CAT and T-SOD. TPT exposure also affected the genes (Scarb1, CD36, Stard3 and Stard5) related to carotenoid absorption and transport, as well as the genes (GstP1 and Bco2) related to carotenoid deposition and decomposition. Taken together, our results demonstrate that TPT influenced carotenoid-based coloration in coral reef fish by disrupting carotenoid metabolism, which complements the ecotoxicological effects and toxic mechanisms of TPT and provides data for the body color biology of coral reef fishes.
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Affiliation(s)
- Yan Zhang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China; (Y.Z.); (Y.H.); (W.C.)
| | - Xingwei Cai
- Hainan Academy of Ocean and Fisheries Sciences, Haikou 570206, China;
| | - Yu Hou
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China; (Y.Z.); (Y.H.); (W.C.)
| | - Wenming Chen
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China; (Y.Z.); (Y.H.); (W.C.)
| | - Jiliang Zhang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, Key Laboratory of Tropical Animal and Plant Ecology of Hainan Province, College of Life Sciences, Hainan Normal University, Haikou 571158, China; (Y.Z.); (Y.H.); (W.C.)
- Hainan Provincial Key Laboratory of Ecological Civilization and Integrated Land-Sea Development, Haikou 571158, China
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9
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de Alcantara Viana JV, Campos Duarte R, Vieira C, Augusto Poleto Antiqueira P, Bach A, de Mello G, Silva L, Rabelo Oliveira Leal C, Quevedo Romero G. Crypsis by background matching and disruptive coloration as drivers of substrate occupation in sympatric Amazonian bark praying mantises. Sci Rep 2023; 13:19985. [PMID: 37968331 PMCID: PMC10652001 DOI: 10.1038/s41598-023-46204-x] [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: 08/02/2023] [Accepted: 10/29/2023] [Indexed: 11/17/2023] Open
Abstract
Background matching and disruptive coloration are common camouflage strategies in nature, but few studies have accurately measured their protective value in living organisms. Amazon's Bark praying mantises exhibit colour patterns matching whitish and greenish-brown tree trunks. We tested the functional significance of background matching and disruptive coloration of different praying mantis morphospecies (white, grey and green) detected by DNA barcoding. Through image analysis, avian visual models and field experiments using humans as potential predators, we explored whether the background occupation of mantises provides camouflage against predation. Data were obtained for individuals against their occupied tree trunks (whitish or greenish-brown) and microhabitats (lichen or bryophyte patches), compared to non-occupied trunks. White and grey mantises showed lower colour contrasts against occupied trunks at the scale of tree trunk, with no differences in luminance contrasts. Conversely, green mantises showed lower colour and luminance contrasts against microhabitats and also exhibited high edge disruption against greenish-brown trunks. The camouflage of white and green mantis models against colour-matching trunks increased search time and reduced encounter distance of human predators. We highlight the importance of camouflage strategies at different spatial scales to enhance individual survival against predators. Specifically, we present a stunning study system to investigate the relationship of phylogenetically related species that use camouflage in sympatry.
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Affiliation(s)
- João Vitor de Alcantara Viana
- Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil.
| | - Rafael Campos Duarte
- Universidade Federal Do ABC, São Bernardo Do Campo, São Paulo, CEP 09606-045, Brazil
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Camila Vieira
- Departamento de Ciências Básicas, Universidade de São Paulo (USP), Campus de Pirassununga, Pirassununga, São Paulo, CEP 13635-900, Brazil
| | - Pablo Augusto Poleto Antiqueira
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil
| | - Andressa Bach
- Programa de Pós-Graduação Em Ecologia E Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Costa, N° 2367, Boa Esperança, Cuiabá, 78060900, Brazil
| | - Gabriel de Mello
- Programa de Pós-Graduação Em Ecologia E Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Costa, N° 2367, Boa Esperança, Cuiabá, 78060900, Brazil
| | - Lorhaine Silva
- Programa de Pós-Graduação Em Ecologia E Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Costa, N° 2367, Boa Esperança, Cuiabá, 78060900, Brazil
| | - Camila Rabelo Oliveira Leal
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil
| | - Gustavo Quevedo Romero
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil
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10
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Banfi F, Meiri S, Shine R, Van Damme R, Baeckens S. Foraging mode constrains the evolution of cephalic horns in lizards and snakes. Biol Lett 2023; 19:20230395. [PMID: 37990563 PMCID: PMC10663784 DOI: 10.1098/rsbl.2023.0395] [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: 08/31/2023] [Accepted: 10/31/2023] [Indexed: 11/23/2023] Open
Abstract
A phylogenetically diverse minority of snake and lizard species exhibit rostral and ocular appendages that substantially modify the shape of their heads. These cephalic horns have evolved multiple times in diverse squamate lineages, enabling comparative tests of hypotheses on the benefits and costs of these distinctive traits. Here, we demonstrate correlated evolution between the occurrence of horns and foraging mode. We argue that although horns may be beneficial for various functions (e.g. camouflage, defence) in animals that move infrequently, they make active foragers more conspicuous to prey and predators, and hence are maladaptive. We therefore expected horns to be more common in species that ambush prey (entailing low movement rates) rather than in actively searching (frequently moving) species. Consistent with that hypothesis, our phylogenetic comparative analysis of published data on 1939 species reveals that cephalic horns occur almost exclusively in sit-and-wait predators. This finding underlines how foraging mode constrains the morphology of squamates and provides a compelling starting point for similar studies in other animal groups.
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Affiliation(s)
- Federico Banfi
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Shai Meiri
- School of Zoology & the Steinhardt Museum of Natural History, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Richard Shine
- School of Natural Sciences, Macquarie University, Balaclava Rd, Macquarie Park New South Wales 2109, Australia
| | - Raoul Van Damme
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
| | - Simon Baeckens
- Laboratory of Functional Morphology, Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
- Evolution and Optics of Nanostructures Group, Department of Biology, Ghent University, Ledeganckstraat 35, 9000 Ghent, Belgium
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11
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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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12
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King J, Hemmi JM, Kelley JL. Camouflage using three-dimensional surface disruption. Biol Lett 2023; 19:20220596. [PMID: 37528728 PMCID: PMC10394419 DOI: 10.1098/rsbl.2022.0596] [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: 12/15/2022] [Accepted: 07/17/2023] [Indexed: 08/03/2023] Open
Abstract
Disruptive markings are common in animal patterns and can provide camouflage benefits by concealing the body's true edges and/or by breaking the surface of the body into multiple depth planes. Disruptive patterns that are accentuated by high contrast borders are most likely to provide false depth cues to enhance camouflage, but studies to date have used visual detection models or humans as predators. We presented three-dimensional-printed moth-like targets to wild bird predators to determine whether: (1) three-dimensional prey with disrupted body surfaces have higher survival than three-dimensional prey with continuous surfaces, (2) two-dimensional prey with disruptive patterns or enhanced edge markings have higher survival than non-patterned two-dimensional prey. We found a survival benefit for three-dimensional prey with disrupted surfaces, and a significant effect of mean wing luminance. There was no evidence that false depth cues provided the same protective benefits as physical surface disruption in three-dimensional prey, perhaps because our treatments did not mimic the complexity of patterns found in natural animal markings. Our findings indicate that disruption of surface continuity is an important strategy for concealing a three-dimensional body shape.
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Affiliation(s)
- Jemma King
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Perth, Australia
| | - Jan M. Hemmi
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Perth, Australia
- UWA Oceans Institute, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Perth, Australia
| | - Jennifer L. Kelley
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Perth, Australia
- UWA Oceans Institute, The University of Western Australia, 35 Stirling Highway, Crawley 6009, Perth, Australia
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13
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Liedtke HC, Lopez-Hervas K, Galván I, Polo-Cavia N, Gomez-Mestre I. Background matching through fast and reversible melanin-based pigmentation plasticity in tadpoles comes with morphological and antioxidant changes. Sci Rep 2023; 13:12064. [PMID: 37495600 PMCID: PMC10371988 DOI: 10.1038/s41598-023-39107-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Accepted: 07/20/2023] [Indexed: 07/28/2023] Open
Abstract
Facultative colour change is widespread in the animal kingdom, and has been documented in many distantly related amphibians. However, experimental data testing the extent of facultative colour change, and associated physiological and morphological implications are comparatively scarce. Background matching in the face of spatial and temporal environmental variation is thought to be an important proximate function of colour change in aquatic amphibian larvae. This is particularly relevant for species with long larval periods such as the western spadefoot toad, Pelobates cultripes, whose tadpoles spend up to six months developing in temporary waterbodies with temporally variable vegetation. By rearing tadpoles on different coloured backgrounds, we show that P. cultripes larvae can regulate pigmentation to track fine-grained differences in background brightness, but not hue or saturation. We found that colour change is rapid, reversible, and primarily achieved through changes in the quantity of eumelanin in the skin. We show that this increased eumelanin production and/or maintenance is also correlated with changes in morphology and oxidative stress, with more pigmented tadpoles growing larger tail fins and having an improved redox status.
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Affiliation(s)
- H Christoph Liedtke
- Ecology Evolution and Development Group. Biological Station of Doñana - CSIC, 41092, Seville, Spain.
| | - Karem Lopez-Hervas
- Max Planck Institute for Evolutionary Biology, August-Thienemann Str. 2, 24306, Plön, Germany
| | - Ismael Galván
- Department of Evolutionary Ecology, National Museum of Natural Sciences, CSIC, 28006, Madrid, Spain
| | - Nuria Polo-Cavia
- Department of Biology, Universidad Autónoma de Madrid, Ciudad Universitaria de Cantoblanco, 28049, Madrid, Spain
| | - Ivan Gomez-Mestre
- Ecology Evolution and Development Group. Biological Station of Doñana - CSIC, 41092, Seville, Spain
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14
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Barrone J, Vidal MC, Stevenson R. Sphingid caterpillars conspicuous patches do not function as distractive marks or warning against predators. Ecol Evol 2023; 13:e10334. [PMID: 37492454 PMCID: PMC10363802 DOI: 10.1002/ece3.10334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 07/01/2023] [Accepted: 07/05/2023] [Indexed: 07/27/2023] Open
Abstract
To avoid predation by visual predators, caterpillars can be cryptic to decrease detectability or aposematic to warn predators of potential unpalatability. However, for some species, it is not clear if conspicuous patches are selected to avoid predation. For example, Pandora sphinx (Eumorpha pandorus, Lepidoptera: Sphingidae) caterpillars are assumed to be palatable and have both cryptic (green, brown) and conspicuous (orange, red) color morphs. Five lateral, off-white to yellow patches on either side may serve as a warning for predators or to draw attention away from the caterpillar's form to function as distractive marks. We conducted a field study in three temperate fragmented forests in Massachusetts to investigate the potential utility of E. pandorus coloration and conspicuous patches. Using four plasticine caterpillar prey model treatments, green and red with and without lateral conspicuous patches, we tested the effects of color, patch patterning, and seasonality on attack rates by a variety of taxa. We found that 43% of the prey models (n = 964) had bite marks by an array of predators including arthropods (67.5%), birds (18.2%), rodents (11.5%), and large mammals (2.8%). Arthropods as dominant predators align with conclusions from previous studies of prey models placed near ground level. Attack rates peaked for arthropods in late August and early September but were more constant across trials for vertebrates. Arthropods, a heterogeneous group, as indicated by the variety of bite marks, showed significantly higher attack rates on green colored prey models and a tendency of higher attack on solid (non-patch patterned) prey models. Vertebrates, more visually oriented predators, had significantly higher attack rates on red colored prey models and patch patterned prey models. Thus, our results did not suggest that conspicuous patch patterning reduced predation and therefore, we did not find support for the distractive mark hypothesis or warning hypothesis. Further, our study shows clear contrasting interpretations by different predators regarding visual defensive strategies.
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Affiliation(s)
- Julia Barrone
- Department of BiologyUniversity of Massachusetts BostonBostonMassachusettsUSA
| | - Mayra C. Vidal
- Department of BiologyUniversity of Massachusetts BostonBostonMassachusettsUSA
| | - Robert Stevenson
- Department of BiologyUniversity of Massachusetts BostonBostonMassachusettsUSA
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15
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Rubin JJ, Kawahara AY. A framework for understanding post-detection deception in predator-prey interactions. PeerJ 2023; 11:e15389. [PMID: 37377786 PMCID: PMC10292197 DOI: 10.7717/peerj.15389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 04/19/2023] [Indexed: 06/29/2023] Open
Abstract
Predators and prey exist in persistent conflict that often hinges on deception-the transmission of misleading or manipulative signals-as a means for survival. Deceptive traits are widespread across taxa and sensory systems, representing an evolutionarily successful and common strategy. Moreover, the highly conserved nature of the major sensory systems often extends these traits past single species predator-prey interactions toward a broader set of perceivers. As such, deceptive traits can provide a unique window into the capabilities, constraints and commonalities across divergent and phylogenetically-related perceivers. Researchers have studied deceptive traits for centuries, but a unified framework for categorizing different types of post-detection deception in predator-prey conflict still holds potential to inform future research. We suggest that deceptive traits can be distinguished by their effect on object formation processes. Perceptual objects are composed of physical attributes (what) and spatial (where) information. Deceptive traits that operate after object formation can therefore influence the perception and processing of either or both of these axes. We build upon previous work using a perceiver perspective approach to delineate deceptive traits by whether they closely match the sensory information of another object or create a discrepancy between perception and reality by exploiting the sensory shortcuts and perceptual biases of their perceiver. We then further divide this second category, sensory illusions, into traits that distort object characteristics along either the what or where axes, and those that create the perception of whole novel objects, integrating the what/where axes. Using predator-prey examples, we detail each step in this framework and propose future avenues for research. We suggest that this framework will help organize the many forms of deceptive traits and help generate predictions about selective forces that have driven animal form and behavior across evolutionary time.
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Affiliation(s)
- Juliette J. Rubin
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Akito Y. Kawahara
- McGuire Center for Lepidoptera and Biodiversity, Florida Museum of Natural History, University of Florida, Gainesville, FL, USA
- Department of Biology, University of Florida, Gainesville, FL, USA
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16
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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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17
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Moise RI, Eccles GR, Mettke-Hofmann C. Enclosure Background Preferences Differ between Sexes and Color Morphs in the Gouldian Finch. Animals (Basel) 2023; 13:ani13081353. [PMID: 37106916 PMCID: PMC10135138 DOI: 10.3390/ani13081353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/28/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Most wild animals camouflage well into their environment, providing protection from predators, whereas captive animals often contrast with their background. This can cause stress for the animal, which may perceive it as being exposed. Theory suggests that prey is more difficult to detect in front of complex backgrounds; hence, animals should prefer complex over simple backgrounds. We tested this in the polymorphic Gouldian finch by providing a complex background pattern in one half of the flight cage and a simple background pattern in the other half for 10 days (phase 1). Patterns were then swapped and presented for another week (phase 2). Groups of four birds consisting of either pure black-headed or red-headed or mixed head color (two black-headed and two red-headed) pairings were tested. Gouldian finches spent significantly more time in front of the simple background in phase 1 but not in phase 2. Specifically, females preferred the simple background in phase 1 significantly more than males. Moreover, red-headed birds consistently perched in front of the simple background, whereas black-headed birds used both backgrounds, particularly in phase 2. Results indicate that background preferences differ between sexes and morphs, which should be considered when designing backgrounds. Moreover, natural habitat preferences need consideration.
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Affiliation(s)
- Robert I Moise
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Georgina R Eccles
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
- Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, Kingsville, TX 78363, USA
| | - Claudia Mettke-Hofmann
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
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18
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Ontogenetic change in the effectiveness of camouflage: growth versus pattern matching in Fowler's toad. Anim Behav 2023. [DOI: 10.1016/j.anbehav.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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19
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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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20
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Mark CJ, O'Hanlon JC, Holwell GI. Camouflage in lichen moths: Field predation experiments and avian vision modelling demonstrate the importance of wing pattern elements and background for survival. J Anim Ecol 2022; 91:2358-2369. [PMID: 36169598 PMCID: PMC10092008 DOI: 10.1111/1365-2656.13817] [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: 02/02/2022] [Accepted: 09/15/2022] [Indexed: 12/15/2022]
Abstract
Background matching is perhaps the most ubiquitous form of defensive camouflage in the animal kingdom, an adaptive strategy that relies on the visual resemblance between a prey organism and its background to promote concealment from predators. The importance of background matching has been acknowledged for over a century, yet despite its renown and apparent pervasiveness, few studies exist that have objectively quantified its occurrence and tested the functional significance of background matching in a specific animal study system. The North Island lichen moth Declana atronivea presents a fascinating system to investigate such anti-predator coloration. This species possesses high contrast black and white forewings that appear to resemble lichen. Here we assessed the contribution of background matching to the antipredator defence of D. atronivea using field predation experiments with realistic models. We found that D. atronivea coloration confers a significant survival advantage against native avian predators when on lichen backgrounds compared to bark backgrounds, with an intermediate level of predation occurring when models were near, but not on lichen. This suggests that D. atronivea wing patterns are an adaptation for background matching. We subsequently used calibrated digital photography, avian vision modelling and image analysis techniques to objectively quantify the degree of background matching exhibited by D. atronivea and assessed the contribution of different visual elements (colour, luminance and pattern) to camouflage in this species. Only the pattern elements of D. atronivea presented a close match to that of the lichen backgrounds, with both chromatic and achromatic cues found to be poor predictors of background matching in this species. This study is one of the first to integrate vision modelling, quantitative image analysis and field predation experiments using realistic models to objectively quantify the level and functional significance of background matching in a real species, and presents an ideal system for further investigating the interrelation between multiple mechanisms of camouflage.
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Affiliation(s)
- Cassandra J Mark
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - James C O'Hanlon
- School of Science and Technology, University of New England, Armidale, New South Wales, Australia
| | - Gregory I Holwell
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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21
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Dark wing pigmentation as a mechanism for improved flight efficiency in the Larinae. Commun Biol 2022; 5:1205. [DOI: 10.1038/s42003-022-04144-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 10/20/2022] [Indexed: 11/23/2022] Open
Abstract
AbstractThere are many hypotheses explaining the diversity of colours and patterns found in nature, but they are often difficult to examine empirically. Recent studies show the dark upperside of gliding birds’ wings could reduce drag by decreasing the density of surrounding air. It may therefore be expected that species with darker wings have less efficient morphology than their paler counterparts. I conducted an analysis of the Larinae (gulls), which exhibit extreme variation in wing (mantle and wingtip) melanization, to test whether wing loading is a predictor of wing darkness. I found that, for each standard deviation increase in wing loading, mantle darkness is predicted to increase by 1.2 shades on the Kodak grey scale. Wing loading is also positively related to the proportion of black on wingtips. Furthermore, heavier species have lower aspect ratio wings, suggesting that dark wings have evolved to improve the trade-off between maneuverability and long distance flight.
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22
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Spatial differentiation of background matching strategies along a Late Pleistocene range expansion route. Evol Ecol 2022. [DOI: 10.1007/s10682-022-10216-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Court M, Paula JR, Macau M, Otjacques E, Repolho T, Rosa R, Lopes VM. Camouflage and Exploratory Avoidance of Newborn Cuttlefish under Warming and Acidification. BIOLOGY 2022; 11:1394. [PMID: 36290300 PMCID: PMC9598447 DOI: 10.3390/biology11101394] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/19/2022] [Accepted: 09/20/2022] [Indexed: 06/16/2023]
Abstract
Ocean warming and acidification have been shown to elicit deleterious effects on cephalopod mollusks, especially during early ontogeny, albeit effects on behavior remain largely unexplored. This study aimed to evaluate, for the first time, the effect of end-of-the-century projected levels of ocean warming (W; + 3 °C) and acidification (A; 980 µatm pCO2) on Sepia officinalis hatchlings' exploratory behavior and ability to camouflage in different substrate complexities (sand and black and white gravel). Cuttlefish were recorded in open field tests, from which mobility and exploratory avoidance behavior data were obtained. Latency to camouflage was registered remotely, and pixel intensity of body planes and background gravel were extracted from photographs. Hatching success was lowered under A and W combined (AW; 72.7%) compared to control conditions (C; 98.8%). Motion-related behaviors were not affected by the treatments. AW delayed camouflage response in the gravel substrate compared to W alone. Moreover, cuttlefish exhibited a higher contrast and consequently a stronger disruptive pattern under W, with no changes in background matching. These findings suggest that, although climate change may elicit relevant physiological challenges to cuttlefish, camouflage and mobility of these mollusks are not undermined under the ocean of tomorrow.
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Affiliation(s)
- Mélanie Court
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
| | - José Ricardo Paula
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Marta Macau
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
| | - Eve Otjacques
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
- Carnegie Institution for Science, Division of Biosphere Sciences and Engineering, Church Laboratory, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA 91125, USA
| | - Tiago Repolho
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Rui Rosa
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
- Departamento de Biologia Animal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Vanessa Madeira Lopes
- MARE—Marine and Environmental Sciences Centre & ARNET—Aquatic Research Network, Laboratório Marítimo da Guia, Faculdade de Ciências, Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
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24
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Macedo T, Carlos Campos J, Nokelainen O, Scott-Samuel NE, Boratyński Z. The effect of spatial and temporal scale on camouflage in North African rodents. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Background matching, a common form of camouflage, is a widespread anti-predator adaptation that hinders detection or recognition by increasing the resemblance of prey to its environment. However, the natural environment is complex and both spatially and temporally variable, which constrains effective background matching as an anti-predator strategy. Here, using remote sensing data (publicly available satellite imagery), we investigated how variation of habitat parameters predicts background matching in 16 Sahara–Sahel rodent species across spatial and temporal scales. All fur colour parameters (hue, saturation and brightness) strongly matched the respective habitats of the different species. Background matching in terms of hue was best at the microscale, whereas results for saturation and brightness showed more variation across spatial scales among species. Camouflage across the temporal scale (from 1 to 3 years before capture) was variable among species for all colour parameters. These complex interactions suggest that, in desert rodents, colour parameters are differentially sensitive to the respective scale of the habitat, plausibly reflecting the behaviour and life history of the species and the ecological properties determining their activity patterns. Consequently, the division between habitat (camouflage) generalists and specialists might become blurred in temporally changing and spatially variable environments.
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Affiliation(s)
- Tiago Macedo
- Department of Biology, Faculty of Science, University of Porto , 4099-002 Porto , Portugal
| | - João Carlos Campos
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto; BIOPOLIS Program in Genomics, Biodiversity and Land Planning , Campus Vairão, 4485-661 Vairão , Portugal
| | - Ossi Nokelainen
- Department of Biological and Environmental Science, University of Jyväskylä , PO Box 35, 40014, Jyväskylä , Finland
| | | | - Zbyszek Boratyński
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto; BIOPOLIS Program in Genomics, Biodiversity and Land Planning , Campus Vairão, 4485-661 Vairão , Portugal
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25
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de Alcantara Viana JV, Vieira C, Duarte RC, Romero GQ. Predator responses to prey camouflage strategies: a meta-analysis. Proc Biol Sci 2022; 289:20220980. [PMID: 36100020 PMCID: PMC9470275 DOI: 10.1098/rspb.2022.0980] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/15/2022] [Indexed: 11/12/2022] Open
Abstract
Although numerous studies about camouflage have been conducted in the last few decades, there is still a significant gap in our knowledge about the magnitude of protective value of different camouflage strategies in prey detection and survival. Furthermore, the functional significance of several camouflage strategies remains controversial. Here we carried out a comprehensive meta-analysis including comparisons of different camouflage strategies as well as predator and prey types, considering two response variables: mean predator search time (ST) (63 studies) and predator attack rate (AR) of camouflaged prey (28 studies). Overall, camouflage increased the predator ST by 62.56% and decreased the AR of prey by 27.34%. Masquerade was the camouflage strategy that most increased predator ST (295.43%). Background matching and disruptive coloration did not differ from each other. Motion camouflage did not increase ST but decreases AR on prey. We found no evidence that eyespot increases ST and decreases AR by predators. The different types of predators did not differ from each other, but caterpillars were the type of prey that most influenced the magnitude of camouflage's effect. We highlight the potential evolutionary mechanisms that led camouflage to be a highly effective anti-predatory adaptation, as well as potential discrepancies or redundancies among strategies, predator and prey types.
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Affiliation(s)
- João Vitor de Alcantara Viana
- Programa de Pós-graduação em Ecologia, Universidade Estadual de Campinas (UNICAMP), Instituto de Biologia, Laboratório de Interações Multitróficas e Biodiversidade, Campinas, São Paulo, Brazil
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, CEP 13083-970 Campinas, São Paulo, Brazil
| | - Camila Vieira
- Departamento de Ciências Básicas, Universidade de São Paulo (USP), campus de Pirassununga, CEP 13635-900 Pirassununga, São Paulo, Brazil
| | - Rafael Campos Duarte
- Universidade Federal do ABC, CEP 09606-045 São Bernardo do Campo, São Paulo, Brazil
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Gustavo Quevedo Romero
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, CEP 13083-970 Campinas, São Paulo, Brazil
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Mohammadi S, Yang L, Bulbert M, Rowland HM. Defence mitigation by predators of chemically defended prey integrated over the predation sequence and across biological levels with a focus on cardiotonic steroids. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220363. [PMID: 36133149 PMCID: PMC9449480 DOI: 10.1098/rsos.220363] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/17/2022] [Indexed: 05/10/2023]
Abstract
Predator-prey interactions have long served as models for the investigation of adaptation and fitness in natural environments. Anti-predator defences such as mimicry and camouflage provide some of the best examples of evolution. Predators, in turn, have evolved sensory systems, cognitive abilities and physiological resistance to prey defences. In contrast to prey defences which have been reviewed extensively, the evolution of predator counter-strategies has received less attention. To gain a comprehensive view of how prey defences can influence the evolution of predator counter-strategies, it is essential to investigate how and when selection can operate. In this review we evaluate how predators overcome prey defences during (i) encounter, (ii) detection, (iii) identification, (iv) approach, (v) subjugation, and (vi) consumption. We focus on prey that are protected by cardiotonic steroids (CTS)-defensive compounds that are found in a wide range of taxa, and that have a specific physiological target. In this system, coevolution is well characterized between specialist insect herbivores and their host plants but evidence for coevolution between CTS-defended prey and their predators has received less attention. Using the predation sequence framework, we organize 574 studies reporting predators overcoming CTS defences, integrate these counter-strategies across biological levels of organization, and discuss the costs and benefits of attacking CTS-defended prey. We show that distinct lineages of predators have evolved dissecting behaviour, changes in perception of risk and of taste perception, and target-site insensitivity. We draw attention to biochemical, hormonal and microbiological strategies that have yet to be investigated as predator counter-adaptations to CTS defences. We show that the predation sequence framework will be useful for organizing future studies of chemically mediated systems and coevolution.
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Affiliation(s)
- Shabnam Mohammadi
- School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
- Institut für Zell- und Systembiologie der Tiere, Universität Hamburg, Hamburg, Germany
- Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Lu Yang
- Wellcome Sanger Institute, Cambridge, UK
| | - Matthew Bulbert
- Department of Biological Sciences, Macquarie University North Ryde, New South Wales, Australia
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, University of Oxford Brookes, Oxford, UK
- Max Planck Institute for Chemical Ecology, Jena, Germany
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27
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Mohammadi S, Yang L, Bulbert M, Rowland HM. Defence mitigation by predators of chemically defended prey integrated over the predation sequence and across biological levels with a focus on cardiotonic steroids. ROYAL SOCIETY OPEN SCIENCE 2022; 9:220363. [PMID: 36133149 DOI: 10.6084/m9.figshare.c.6168216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/17/2022] [Indexed: 05/25/2023]
Abstract
Predator-prey interactions have long served as models for the investigation of adaptation and fitness in natural environments. Anti-predator defences such as mimicry and camouflage provide some of the best examples of evolution. Predators, in turn, have evolved sensory systems, cognitive abilities and physiological resistance to prey defences. In contrast to prey defences which have been reviewed extensively, the evolution of predator counter-strategies has received less attention. To gain a comprehensive view of how prey defences can influence the evolution of predator counter-strategies, it is essential to investigate how and when selection can operate. In this review we evaluate how predators overcome prey defences during (i) encounter, (ii) detection, (iii) identification, (iv) approach, (v) subjugation, and (vi) consumption. We focus on prey that are protected by cardiotonic steroids (CTS)-defensive compounds that are found in a wide range of taxa, and that have a specific physiological target. In this system, coevolution is well characterized between specialist insect herbivores and their host plants but evidence for coevolution between CTS-defended prey and their predators has received less attention. Using the predation sequence framework, we organize 574 studies reporting predators overcoming CTS defences, integrate these counter-strategies across biological levels of organization, and discuss the costs and benefits of attacking CTS-defended prey. We show that distinct lineages of predators have evolved dissecting behaviour, changes in perception of risk and of taste perception, and target-site insensitivity. We draw attention to biochemical, hormonal and microbiological strategies that have yet to be investigated as predator counter-adaptations to CTS defences. We show that the predation sequence framework will be useful for organizing future studies of chemically mediated systems and coevolution.
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Affiliation(s)
- Shabnam Mohammadi
- School of Biological Sciences, University of Nebraska, Lincoln, NE, USA
- Institut für Zell- und Systembiologie der Tiere, Universität Hamburg, Hamburg, Germany
- Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Lu Yang
- Wellcome Sanger Institute, Cambridge, UK
| | - Matthew Bulbert
- Department of Biological Sciences, Macquarie University North Ryde, New South Wales, Australia
- Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, University of Oxford Brookes, Oxford, UK
- Max Planck Institute for Chemical Ecology, Jena, Germany
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de Alcantara Viana JV, Lourenço Garcia de Brito V, de Melo C. Colour matching by arthropods in burned and unburned backgrounds in a Neotropical savanna. AUSTRAL ECOL 2022. [DOI: 10.1111/aec.13225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- João Vitor de Alcantara Viana
- Programa de Pós‐Graduação em Ecologia e Conservação de Recursos Naturais, Laboratório de Ornitologia e Bioacústica Universidade Federal de Uberlândia (UFU) Uberlândia Brazil
- Programa de Pós‐Graduação em Ecologia, Laboratório de Interações Multitróficas e Biodiversidade, Instituto de Biologia Universidade Estadual de Campinas (UNICAMP) Campinas
- Laboratório de Interações Multitróficas e Biodiversidade Departamento de Biologia Animal, Instituto de Biologia Universidade Estadual de Campinas CP 6109, CEP 13083-970 Campinas São Paulo Brazil
| | | | - Celine de Melo
- Instituto de Biologia Universidade Federal de Uberlândia Uberlândia Brazil
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29
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Kelley JL, Allen WL. Multiple opportunities arise from multiple color defense strategies: a comment on Postema et al. Behav Ecol 2022. [DOI: 10.1093/beheco/arac070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jennifer L Kelley
- School of Biological Sciences and UWA Oceans Institute, The University of Western Australia , Crawley 6009, Perth, WA , Australia
| | - William L Allen
- Department of Biosciences, Swansea University , Singleton Park, Swansea SA2 8PP , UK
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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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Pohl S, Bungum HZ, Lee KEM, Sani MAB, Poh YH, Wahab RBHA, Norma-Rashid Y, Tan EJ. Age and Appearance Shape Behavioral Responses of Phasmids in a Dynamic Environment. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2021.767940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Although morphological adaptations leading to crypsis or mimicry have been studied extensively, their interaction with particular behaviors to avoid detection or recognition is understudied. Yet animal behaviors interact with morphology to reduce detection risk, and the level of protection conferred likely changes according to the surrounding environment. Apart from providing a locational cue for predators, prey motion can also serve as concealing behavior in a dynamic environment to prevent detection by potential predators or prey. Phasmids are conventionally known to rely on their adaptive resemblance to plant parts for protection, and this resemblance may vary across life stages and species. However, little is known about how their behaviors interact with their appearance and their environment. We investigated two species of phasmids with varying morphology and color patterns at different ontogenetic stages and examined their behavioral responses to a wind stimulus as a proxy for a dynamic environment. While adult behaviors were mostly species-specific, behavioral responses of nymphs varied with appearance and environmental condition. Display of different behaviors classified as revealing was positively correlated, while the display of concealing behaviors, except for swaying, was mostly negatively correlated with other behaviors. Exhibition of specific behaviors varied with appearance and environmental condition, suggesting that these behavioral responses could help reduce detection or recognition cues. We discuss the differences in behavioral responses in the context of how the behaviors could reveal or conceal the phasmids from potential predators. Our results provide a novel investigation into adaptive resemblance strategies of phasmids through the interaction of behavior and morphology, and highlight the importance of considering the effects of dynamic environments on sending and receiving cues.
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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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Abstract
In the last decade, increasing literature focused on camouflaging as a strategy adopted to cope with social environment by patients with autism spectrum disorder (ASD). A better understanding of this phenomenon may shed more light on cognitive mechanisms and coping strategies of patients in the autism continuum, eventually leading to reconsider some previous "dogmas" in this field, such as the gender discrepancy in ASD diagnosis. Moreover, shared features can be observed in the camouflaging strategies adopted among the general population, among patients of the autism spectrum, and among patients with different kinds of psychiatric disorders, further challenging our perspectives. Camouflaging behaviors might be considered as a transdiagnostic element, closely associated with the continuous distribution of the autism spectrum among the general and the clinical population.
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35
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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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36
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Reimchen TE, Hunter D, Eggenberger JH. Black bear colour polymorphism through a fragmented Snell’s window. Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blab073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
The white colour morph of the black bear (Ursus americanus kermodei) occurring on islands on the coast of British Columbia, western Canada, captures more salmon (Oncorhynchus spp.) than does the black morph and is hypothesized to have reduced contrast against the sky from the visual perspective of the salmon. We tested this hypothesis in a natural salmon stream by recording the number and proximity of chum salmon (Oncorhynchus keta) approaches (N = 1617 fish, 91 trials) towards life-size bear models differing in body and leg coloration under a mixed forest-sky canopy. Although salmon approached the white models at a much higher rate than black models, consistent with camouflage, we found greater abrupt evasions to the black models, largely independent of their contrast against the above-surface or below-surface backgrounds. Upward-facing sub-surface video-imaging through the rippled water-air interface indicated major visual fragmentation of the model’s integrity. We suggest that increased evasiveness to black models reflects an evolutionary response due to 3+ million years of trophic interaction between salmon and bears, and that the major differences between calm vs. rippled conditions through the optical cone (Snell’s window) at the water-air interface remains a largely unexplored theme in assessing foraging preferences and adaptive coloration within and among species using the water-air interface.
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Affiliation(s)
- Thomas E Reimchen
- Department of Biology, University of Victoria, Victoria, B.C., Canada
| | - Danial Hunter
- Department of Biology, University of Victoria, Victoria, B.C., Canada
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Tan EJ, Elgar MA. Motion: enhancing signals and concealing cues. Biol Open 2021; 10:271863. [PMID: 34414408 PMCID: PMC8411570 DOI: 10.1242/bio.058762] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/02/2021] [Indexed: 01/15/2023] Open
Abstract
Animal colour patterns remain a lively focus of evolutionary and behavioural ecology, despite the considerable conceptual and technical developments over the last four decades. Nevertheless, our current understanding of the function and efficacy of animal colour patterns remains largely shaped by a focus on stationary animals, typically in a static background. Yet, this rarely reflects the natural world: most animals are mobile in their search for food and mates, and their surrounding environment is usually dynamic. Thus, visual signalling involves not only animal colour patterns, but also the patterns of animal motion and behaviour, often in the context of a potentially dynamic background. While motion can reveal information about the signaller by attracting attention or revealing signaller attributes, motion can also be a means of concealing cues, by reducing the likelihood of detection (motion camouflage, motion masquerade and flicker-fusion effect) or the likelihood of capture following detection (motion dazzle and confusion effect). The interaction between the colour patterns of the animal and its local environment is further affected by the behaviour of the individual. Our review details how motion is intricately linked to signalling and suggests some avenues for future research. This Review has an associated Future Leader to Watch interview with the first author. Summary: While motion can reveal information about the signaller, motion can also be a means of concealing cues by reducing the likelihood of detection or the likelihood of capture following detection.
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Affiliation(s)
- Eunice J Tan
- Division of Science, Yale-NUS College, Singapore 138527, Singapore
| | - Mark A Elgar
- School of BioSciences, University of Melbourne, Melbourne, Victoria 3010, Australia
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Huang K, Li C, Zhang J, Wang B. Cascade and Fusion: A Deep Learning Approach for Camouflaged Object Sensing. SENSORS 2021; 21:s21165455. [PMID: 34450897 PMCID: PMC8400738 DOI: 10.3390/s21165455] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 07/29/2021] [Accepted: 08/08/2021] [Indexed: 11/16/2022]
Abstract
The demand for the sensor-based detection of camouflage objects widely exists in biological research, remote sensing, and military applications. However, the performance of traditional object detection algorithms is limited, as they are incapable of extracting informative parts from low signal-to-noise ratio features. To address this problem, we propose Camouflaged Object Detection with Cascade and Feedback Fusion (CODCEF), a deep learning framework based on an RGB optical sensor that leverages a cascaded structure with Feedback Partial Decoders (FPD) instead of a traditional encoder–decoder structure. Through a selective fusion strategy and feedback loop, FPD reduces the loss of information and the interference of noises in the process of feature interweaving. Furthermore, we introduce Pixel Perception Fusion (PPF) loss, which aims to pay more attention to local pixels that might become the edges of an object. Experimental results on an edge device show that CODCEF achieved competitive results compared with 10 state-of-the-art methods.
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Affiliation(s)
- Kaihong Huang
- Department of Computer Science and Engineering, Southeast University, Nanjing 211189, China;
| | - Chunshu Li
- Department of Artificial Intelligence, Southeast University, Nanjing 211189, China;
| | - Jiaqi Zhang
- Department of Computer Science, Brown University, Providence, RI 02860, USA;
| | - Beilun Wang
- Department of Artificial Intelligence, Southeast University, Nanjing 211189, China;
- Correspondence: or
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39
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Dynamic visual noise promotes social attraction, but does not affect group size preference, in a shoaling fish. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.04.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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40
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Almeida DA, Mappes J, Gordon S. Predator-Induced Plasticity on Warning Signal and Larval Life-History Traits of the Aposematic Wood Tiger Moth, Arctia plantaginis. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.658177] [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] Open
Abstract
Predator-induced plasticity in life-history and antipredator traits during the larval period has been extensively studied in organisms with complex life-histories. However, it is unclear whether different levels of predation could induce warning signals in aposematic organisms. Here, we investigated whether predator-simulated handling affects warning coloration and life-history traits in the aposematic wood tiger moth larva, Arctia plantaginis. As juveniles, a larger orange patch on an otherwise black body signifies a more efficient warning signal against predators but this comes at the costs of conspicuousness and thermoregulation. Given this, one would expect that an increase in predation risk would induce flexible expression of the orange patch. Prior research in this system points to plastic effects being important as a response to environmental changes for life history traits, but we had yet to assess whether this was the case for predation risk, a key driver of this species evolution. Using a full-sib rearing design, in which individuals were reared in the presence and absence of a non-lethal simulated bird attack, we evaluated flexible responses of warning signal size (number of orange segments), growth, molting events, and development time in wood tiger moths. All measured traits except development time showed a significant response to predation. Larvae from the predation treatment developed a more melanized warning signal (smaller orange patch), reached a smaller body size, and molted more often. Our results suggest plasticity is indeed important in aposematic organisms, but in this case may be complicated by the trade-off between costly pigmentation and other life-history traits.
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41
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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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Chabenat A, Bellanger C, Knigge T. Effects of environmental antidepressants on colour change and locomotor behaviour in juvenile shore crabs, Carcinus maenas. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 234:105808. [PMID: 33774504 DOI: 10.1016/j.aquatox.2021.105808] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 02/24/2021] [Accepted: 03/06/2021] [Indexed: 06/12/2023]
Abstract
Juvenile crabs of Carcinus maenas thrive in coastal waters reputed to be the receptacle of continental pollution. Amongst the many pollutants encountered, antidepressants, such as fluoxetine (FLX) and venlafaxine (VEN), often detected at the ng•L-1 range, are particularly worrying because of their action on the levels of monoamines, such as serotonin, noradrenaline and dopamine. In crustaceans, those monoamines are involved in colour change through their action on neuropeptide hormones. In addition, they are known to have a role in different behaviours, such as locomotion. Both colour change and locomotion are strategies used by juvenile crabs to hide and escape from predators. To investigate if the presence of antidepressants may alter behaviours of ecological importance, juvenile crabs were exposed to environmentally realistic concentrations of either 5 ng•L-1 of FLX alone or in combination with VEN at 5 ng•L-1. The ability to change colour depending on the environment and the locomotor activity of juvenile crabs were monitored weekly over 25 days. Animals exposed to antidepressants displayed a different pattern of colour change than the controls, especially those exposed to the combination of FLX and VEN at 5 ng•L-1 each, and were less efficient to adapt to their environment, i.e., they were not as pale and not as dark as controls or crabs exposed to FLX at 5 ng•L-1. Moreover, juvenile crabs exposed to the combination of antidepressants exhibited an enhanced locomotor activity throughout the exposure period with a higher velocity and distance moved as well as more time spend moving. The alteration of cryptic behaviours, such as colour change and locomotion by antidepressants persistently present in marine environment at low concentrations may have an impact on the survival of juvenile of C. maenas on the long term.
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Affiliation(s)
- Apolline Chabenat
- NORMANDIE UNIV, UNILEHAVRE, FR CNRS 3730 SCALE, UMR-I02, Environmental Stress and Biomonitoring of Aquatic Environments (SEBIO), 76600 LE HAVRE, France; NORMANDIE UNIV, UNICAEN, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-14000 CAEN, France; UNIV RENNES, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000 RENNES, France
| | - Cécile Bellanger
- NORMANDIE UNIV, UNICAEN, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-14000 CAEN, France; UNIV RENNES, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000 RENNES, France
| | - Thomas Knigge
- NORMANDIE UNIV, UNILEHAVRE, FR CNRS 3730 SCALE, UMR-I02, Environmental Stress and Biomonitoring of Aquatic Environments (SEBIO), 76600 LE HAVRE, France.
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Cueva Del Castillo R, González-Zertuche M, Ramírez-Delgado VH. Interpopulation variation in sexual dichromatism in the Neotropical grasshopper Sphenarium purpurascens (Orthoptera: Pyrgomorphidae). Biol J Linn Soc Lond 2021. [DOI: 10.1093/biolinnean/blaa227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Cryptic coloration is an adaptative defensive mechanism against predators. Colour patterns appear cryptic through general background coloration matching or disruptive coloration. Disruptive coloration might evolve in visually heterogeneous microhabitats, whereas background matching could be favoured in chromatically homogeneous microhabitats. In this study, we used digital photography to explore the potential use of disruptive coloration and background matching in males and females of the Neotropical grasshopper Sphenarium purpurascens in different habitats. We found chromatic differences in three habitats and sexual dichromatism that might be explained by local adaptation. Although females and males were sexually dichromatic, interpopulation differences were found in the magnitude of the sexual dichromatism. In a highly contrasting environment, both males and females seemed to follow a disruptive strategy, whereas in a heterogeneous environments males and females followed different colour cryptic strategies, in which males were more disruptive than females, and females exhibited high background matching with fewer disruptive elements. Selective predation in different microhabitats and differences in mobility between the sexes might explain the colour pattern divergence between females and males.
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Affiliation(s)
- Raúl Cueva Del Castillo
- UBIPRO, Laboratorio de Ecología, FES Iztacala, Universidad Nacional Autónoma de México, A.P. 314, Tlalnepantla, Estatado de México, CP, Mexico
| | - Miguel González-Zertuche
- UBIPRO, Laboratorio de Ecología, FES Iztacala, Universidad Nacional Autónoma de México, A.P. 314, Tlalnepantla, Estatado de México, CP, Mexico
| | - Víctor Hugo Ramírez-Delgado
- UBIPRO, Laboratorio de Ecología, FES Iztacala, Universidad Nacional Autónoma de México, A.P. 314, Tlalnepantla, Estatado de México, CP, Mexico
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Troscianko J, Nokelainen O, Skelhorn J, Stevens M. Variable crab camouflage patterns defeat search image formation. Commun Biol 2021; 4:287. [PMID: 33674781 PMCID: PMC7935895 DOI: 10.1038/s42003-021-01817-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 02/04/2021] [Indexed: 11/09/2022] Open
Abstract
Understanding what maintains the broad spectrum of variation in animal phenotypes and how this influences survival is a key question in biology. Frequency dependent selection - where predators temporarily focus on one morph at the expense of others by forming a "search image" - can help explain this phenomenon. However, past work has never tested real prey colour patterns, and rarely considered the role of different types of camouflage. Using a novel citizen science computer experiment that presented crab "prey" to humans against natural backgrounds in specific sequences, we were able to test a range of key hypotheses concerning the interactions between predator learning, camouflage and morph. As predicted, switching between morphs did hinder detection, and this effect was most pronounced when crabs had "disruptive" markings that were more effective at destroying the body outline. To our knowledge, this is the first evidence for variability in natural colour patterns hindering search image formation in predators, and as such presents a mechanism that facilitates phenotypic diversity in nature.
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Affiliation(s)
- Jolyon Troscianko
- Centre for Ecology and Conservation, College of Life and Environmental Science, University of Exeter, TR10 9FE, Penryn, UK.
| | - Ossi Nokelainen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - John Skelhorn
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, NE2 4HH, Newcastle upon Tyne, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Science, University of Exeter, TR10 9FE, Penryn, UK
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Etheredge RI, Schartl M, Jordan A. Decontextualized learning for interpretable hierarchical representations of visual patterns. PATTERNS (NEW YORK, N.Y.) 2021; 2:100193. [PMID: 33659910 PMCID: PMC7892362 DOI: 10.1016/j.patter.2020.100193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 11/08/2020] [Accepted: 12/17/2020] [Indexed: 11/30/2022]
Abstract
Apart from discriminative modeling, the application of deep convolutional neural networks to basic research utilizing natural imaging data faces unique hurdles. Here, we present decontextualized hierarchical representation learning (DHRL), designed specifically to overcome these limitations. DHRL enables the broader use of small datasets, which are typical in most studies. It also captures spatial relationships between features, provides novel tools for investigating latent variables, and achieves state-of-the-art disentanglement scores on small datasets. DHRL is enabled by a novel preprocessing technique inspired by generative model chaining and an improved ladder network architecture and regularization scheme. More than an analytical tool, DHRL enables novel capabilities for virtual experiments performed directly on a latent representation, which may transform the way we perform investigations of natural image features, directly integrating analytical, empirical, and theoretical approaches.
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Affiliation(s)
- Robert Ian Etheredge
- Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany
- Center for the Advanced Study of Collective Behavior, University of Konstanz, Konstanz, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Manfred Schartl
- Centro de Investigaciones Científicas de las Huastecas Aguazarca, A.C., Calnali, Hidalgo, Mexico
- Developmental Biochemistry, Biocenter, University of Würzburg, Würzburg, Bavaria, Germany
- Hagler Institute for Advanced Study, Texas A&M University, College Station, TX, USA
- Xiphophorus Genetic Stock Center, Texas State University San Marcos, San Marcos, TX, USA
| | - Alex Jordan
- Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany
- Center for the Advanced Study of Collective Behavior, University of Konstanz, Konstanz, Germany
- Department of Biology, University of Konstanz, Konstanz, Germany
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Abstract
A new study finds that human collecting may have driven the evolution of background-matching camouflage in an alpine medicinal plant.
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Affiliation(s)
- Adrian G Dyer
- Bio-Inspired Digital Sensing Lab (BIDS), School of Media and Communication, RMIT University, Melbourne, Australia.
| | - Jair E Garcia
- Bio-Inspired Digital Sensing Lab (BIDS), School of Media and Communication, RMIT University, Melbourne, Australia
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Yeager J, Barnett JB. Ultraviolet components offer minimal contrast enhancement to an aposematic signal. Ecol Evol 2020; 10:13576-13582. [PMID: 33391663 PMCID: PMC7771128 DOI: 10.1002/ece3.6969] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/23/2020] [Accepted: 09/28/2020] [Indexed: 12/03/2022] Open
Abstract
Aposematic and sexual signals are often characterized by bright, highly contrasting colors. Many species can see colors beyond the human visible spectrum, and ultraviolet (UV) reflection has been found to play an important role in communication and sexual selection. However, the role of UV in aposematic signals is poorly explored. Poison frogs frequently produce high-contrast signals that have been linked to both aposematism and intraspecific communication. Yet despite considerable efforts studying interspecific and intraspecific diversity in color, poison frogs are not known to perceive UV, and UV reflection of the integument has not been described. We report UV-reflective spots in a population of Oophaga sylvatica and quantify the effect of UV on visual contrast with models of avian vision. We found that the frogs are highly contrasting, but UV had a minimal effect on signal saliency. These data highlight the importance of considering UV reflectance within aposematic signals, but that UV should not necessarily be regarded as an independent signal.
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Affiliation(s)
- Justin Yeager
- Biodiversidad Medio Ambiente y SaludUniversidad de Las AméricasQuitoEcuador
| | - James B. Barnett
- Department of Psychology, Neuroscience & BehaviourMcMaster UniversityHamiltonONCanada
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Goedert D, Clement D, Calsbeek R. Evolutionary trade‐offs may interact with physiological constraints to maintain color variation. ECOL MONOGR 2020. [DOI: 10.1002/ecm.1430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Debora Goedert
- Department of Biological Sciences Dartmouth College Hanover03755 New Hampshire USA
- Ministry of Education of Brazil CAPES Foundation Brasília DF95616Brazil
| | - Dale Clement
- Department of Biological Sciences Dartmouth College Hanover03755 New Hampshire USA
| | - Ryan Calsbeek
- Department of Biological Sciences Dartmouth College Hanover03755 New Hampshire USA
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Nokelainen O, Sreelatha LB, Brito JC, Campos JC, Scott-Samuel NE, Valkonen JK, Boratyński Z. Camouflage in arid environments: the case of Sahara-Sahel desert rodents. JOURNAL OF VERTEBRATE BIOLOGY 2020. [DOI: 10.25225/jvb.20007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Ossi Nokelainen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland; e-mail:
| | - Lekshmi B. Sreelatha
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail:
| | - José Carlos Brito
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail:
| | - João C. Campos
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail:
| | | | - Janne K. Valkonen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland; e-mail:
| | - Zbyszek Boratyński
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal; e-mail:
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