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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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2
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Doherty CTM, Laidre ME. Doors to the Homes: Signal Potential of Red Coloration of Claws in Social Hermit Crabs. Integr Org Biol 2023; 5:obad018. [PMID: 37323238 PMCID: PMC10263385 DOI: 10.1093/iob/obad018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 05/09/2023] [Indexed: 06/17/2023] Open
Abstract
Red coloration on a signaler's body may be an informative signal in many animals. For species that inhabit architecture (e.g., burrows, nests, or other structures), certain parts of the body are more exposed than others, potentially serving as superior platforms for signaling via coloration. Yet whether animals differentially advertise red coloration on body parts that are more versus less exposed from their architecture remains to be tested. Here, we systematically quantified red coloration in social hermit crabs (Coenobita compressus). These crabs inhabit architecturally remodeled shells and have claws that visibly block the shell entrance, like doors to their homes. We hypothesized that red coloration of claws may be a signal of resource-holding potential (RHP). Consistent with this RHP signaling hypothesis, we found that within the same individuals' bodies, exposed claws showed significantly greater red coloration than unexposed carapaces. Furthermore, larger body size predicted greater red coloration of claws. Competing hypotheses (e.g., interspecific signaling, camouflage, and UV protection), while not explicitly tested, nevertheless appear unlikely based on natural history. Red claw coloration may therefore function as a signal to conspecifics, and experiments are now needed to test recipient responses. Broadly, relative to surrounding architecture, exposed body surfaces offer rich potential as signaling platforms for coloration.
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3
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Alfakih A, Watt PJ, Nadeau NJ. The physiological cost of colour change: evidence, implications and mitigations. J Exp Biol 2022; 225:275479. [PMID: 35593398 DOI: 10.1242/jeb.210401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Animals benefit from phenotypic plasticity in changing environments, but this can come at a cost. Colour change, used for camouflage, communication, thermoregulation and UV protection, represents one of the most common plastic traits in nature and is categorised as morphological or physiological depending on the mechanism and speed of the change. Colour change has been assumed to carry physiological costs, but current knowledge has not advanced beyond this basic assumption. The costs of changing colour will shape the evolution of colour change in animals, yet no coherent research has been conducted in this area, leaving a gap in our understanding. Therefore, in this Review, we examine the direct and indirect evidence of the physiological cost of colour change from the cellular to the population level, in animals that utilise chromatophores in colour change. Our Review concludes that the physiological costs result from either one or a combination of the processes of (i) production, (ii) translocation and (iii) maintenance of pigments within the colour-containing cells (chromatophores). In addition, both types of colour change (morphological and physiological) pose costs as they require energy for hormone production and neural signalling. Moreover, our Review upholds the hypothesis that, if repetitively used, rapid colour change (i.e. seconds-minutes) is more costly than slow colour change (days-weeks) given that rapidly colour-changing animals show mitigations, such as avoiding colour change when possible. We discuss the potential implications of this cost on colour change, behaviour and evolution of colour-changing animals, generating testable hypotheses and emphasising the need for future work to address this gap.
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Affiliation(s)
- Ateah Alfakih
- Department of Biology, Faculty of Science and Arts, Albaha University, Almakhwah 65553, Saudi Arabia.,Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
| | - Penelope J Watt
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
| | - Nicola J Nadeau
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK
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4
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Borisov RR, Nikonova IN, Parshin-Chudin AV, Kovacheva NP. Effect of Background Color on the Coloration of Juvenile Giant Freshwater Prawn Macrobrachium rosenbergii. RUSS J ECOL+ 2022. [DOI: 10.1134/s1067413622010039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Wuthrich KL, Nagel A, Swierk L. Rapid Body Color Change Provides Lizards with Facultative Crypsis in the Eyes of Their Avian Predators. Am Nat 2021; 199:277-290. [DOI: 10.1086/717678] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Kelly Lin Wuthrich
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, New York 13902
| | - Amber Nagel
- Department of Chemical Engineering, University of Oklahoma, Norman, Oklahoma 73019
| | - Lindsey Swierk
- Department of Biological Sciences, Binghamton University, State University of New York, Binghamton, New York 13902
- School of the Environment, Yale University, New Haven, Connecticut 06511; and Amazon Conservatory for Tropical Studies, Iquitos, Loreto 16001, Perú
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6
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Al-Soudy AS, Maselli V, Galdiero S, Kuba MJ, Polese G, Di Cosmo A. Identification and Characterization of a Rhodopsin Kinase Gene in the Suckers of Octopus vulgaris: Looking around Using Arms? BIOLOGY 2021; 10:biology10090936. [PMID: 34571813 PMCID: PMC8465341 DOI: 10.3390/biology10090936] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 09/08/2021] [Accepted: 09/16/2021] [Indexed: 11/16/2022]
Abstract
Simple Summary Octopus arms are a fascinating and evolutionarily unique sensory organ, with hundreds of motile suckers, each with thousands of sensory cells, lining eight highly flexible arms. Scientifically, there are many open questions regarding the sensory capabilities of the arms and specifically the highly innervated suckers. In our present work, we used a multidisciplinary approach to fully characterize the light-sensing molecule, Ov-GRK1, in the suckers, skin and retina of Octopus vulgaris. We sequenced the O. vulgaris GRK1 gene, defining a phylogenetic tree and performing a 3D structure model prediction. We found differences in the relative expression of mRNA in different sucker types at several locations along the arm, which might indicate a functional difference. Using labeling methods, we localized the expression to the highly sensitive sucker rim. Our findings indicate that octopus suckers, in specific areas of the arm, might have the ability for light sensing. We therefore suggest that suckers are tactile, chemical and light sensors. Abstract In their foraging behavior octopuses rely on arm search movements outside the visual field of the eyes. In these movements the environment is explored primarily by the suckers that line the entire length of the octopus arm. In this study, for the first time, we report the complete characterization of a light-sensing molecule, Ov-GRK1, in the suckers, skin and retina of Octopus vulgaris. We sequenced the O. vulgaris GRK1 gene, defining a phylogenetic tree and performing a 3D structure model prediction. Furthermore, we found differences in relative mRNA expression in different sucker types at several arm levels, and localized it through in situ hybridization. Our findings suggest that the suckers in octopus arms are much more multimodal than was previously shown, adding the potential for light sensing to the already known mechanical and chemical sensing abilities.
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Affiliation(s)
- Al-Sayed Al-Soudy
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy; (A.-S.A.-S.); (V.M.); (G.P.)
| | - Valeria Maselli
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy; (A.-S.A.-S.); (V.M.); (G.P.)
| | - Stefania Galdiero
- Department of Pharmacy, School of Medicine, University of Naples Federico II, Via Domenico Montesano 49, 80131 Naples, Italy;
| | - Michael J. Kuba
- Department of Neurobiology, Hebrew University of Jerusalem, P.O. Box 12271, Jerusalem 91120, Israel;
- Physics and Biology Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Okinawa 904-0945, Japan
| | - Gianluca Polese
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy; (A.-S.A.-S.); (V.M.); (G.P.)
| | - Anna Di Cosmo
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126 Naples, Italy; (A.-S.A.-S.); (V.M.); (G.P.)
- Correspondence:
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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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8
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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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9
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Dollion AY, Herrel A, Marquis O, Leroux-Coyau M, Meylan S. The colour of success: does female mate choice rely on male colour change in the chameleon Furcifer pardalis? J Exp Biol 2020; 223:jeb224550. [PMID: 32843362 DOI: 10.1242/jeb.224550] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 08/20/2020] [Indexed: 01/14/2023]
Abstract
Colour change is involved in various functions ranging from thermo- and hydroregulation to camouflage and communication. The role of colour change in communication has received increased attention over the past few decades, yet has been studied predominantly in the context of intrasexual competition. Here, we investigate the role of colour change in mate choice in an animal that can change its colour, the panther chameleon (Furcifer pardalis). We conducted behavioural experiments and colour analysis to investigate whether colour changes, including in the UV range, are involved in mate choice. This study presents evidence of female mate choice for specific aspects of colour change in courting males, both in the visible (i.e. human visible range: 400-700 nm) and the UV range. Females chose males exhibiting more saturation changes regardless of the body region and spectral range. In addition, females chose males showing fewer brightness changes at the level of the lateral line and males showing lower hue changes at the level of the bands and the interbands, in the visible range. At UV wavelengths, selected males showed more brightness changes and higher maximum brightness. These results suggest that male colour change is important in female mate choice in the panther chameleon.
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Affiliation(s)
- Alexis Y Dollion
- Université de Paris, 75006 Paris, France
- Sorbonne Université, CNRS, IRD, INRA, Institut d'Ecologie et des Sciences de l'Environnement-Paris, iEES-Paris, 75252 Paris, France
- Département Adaptations du vivant, UMR 7179 C.N.R.S/M.N.H.N, 75005 Paris, France
| | - Anthony Herrel
- Département Adaptations du vivant, UMR 7179 C.N.R.S/M.N.H.N, 75005 Paris, France
| | - Olivier Marquis
- Muséum national d'Histoire naturelle, Parc Zoologique de Paris, 75012 Paris, France
| | - Mathieu Leroux-Coyau
- Sorbonne Université, CNRS, IRD, INRA, Institut d'Ecologie et des Sciences de l'Environnement-Paris, iEES-Paris, 75252 Paris, France
| | - Sandrine Meylan
- Sorbonne Université, CNRS, IRD, INRA, Institut d'Ecologie et des Sciences de l'Environnement-Paris, iEES-Paris, 75252 Paris, France
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10
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Sacchi R, Cancian S, Ghia D, Fea G, Coladonato A. Color variation in signal crayfish Pacifastacus leniusculus. Curr Zool 2020; 67:35-43. [PMID: 33654488 PMCID: PMC7901764 DOI: 10.1093/cz/zoaa031] [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: 04/29/2020] [Accepted: 06/09/2020] [Indexed: 11/18/2022] Open
Abstract
External coloration in animals depends on the interaction of several different factors including the genetics and epigenetics processes that underlie the color expression, the mechanisms of color perception, and the general mechanisms controlling color evolution and function. Among all, camouflages from predators and conspicuousness are of particular interest because pose animal to choose between opposite adjustment in coloration. The external coloration of crustaceans is mainly due to the accumulation of carotenoids in the exoskeleton and the epidermal layer, and the trade-off between camouflage and communication had led to a variety of responses, involving signal partitioning, spectral sensibility, changing coloration, or signaling behavior. Here, we used digital images to explore intrapopulation variability of the external coloration of Pacifastacus leniusculus among body regions within an individual and between sexes. We found that 1) ventral coloration of claws are more saturated and brilliant than upper parts, 2) males express a more saturated and brightness coloration than females, especially on the lower portion of claws, 3) color intensity and brightness increases with size differently in different body regions, and 4) brightness is more variable in males than in females. All the above patterns support the hypothesis that color in this species could be the result of a compromise between camouflage from predators and conspicuousness for communication. The results of this study suggest that carotenoid might have something to do with intraspecific communication and perform more complex functions than that of a simple pigment.
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Affiliation(s)
- Roberto Sacchi
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Viale Taramelli 24, Pavia, I-27100, Italy
| | - Stefania Cancian
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Viale Taramelli 24, Pavia, I-27100, Italy
| | - Daniela Ghia
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Viale Taramelli 24, Pavia, I-27100, Italy
| | - Gianluca Fea
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Viale Taramelli 24, Pavia, I-27100, Italy
| | - Alan Coladonato
- Dipartimento di Scienze della Terra e dell'Ambiente, Università degli Studi di Pavia, Viale Taramelli 24, Pavia, I-27100, Italy
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Prakash S, Kumar A. Varying colour pattern, yet genetically similar: Pebble Crab Seulocia vittata (Stimpson, 1858) (Brachyura: Leucosiidae) from the southeastern coast of India. JOURNAL OF THREATENED TAXA 2020. [DOI: 10.11609/jott.5801.12.5.15612-15618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Five adult specimens of leucosiid crab Seulocia vittata (Stimpson, 1858) were recently collected off the coast of Palk Bay, southern India. Typical morphological examination revealed the presence of two colour patterns: grey and red. Interestingly, molecular analysis based on the barcoding gene cytochrome oxidase sub unit I (COI) revealed that both grey and red colour patterns in S. vittata showed 0% sequence divergence between the specimens. This indicates a situation of reverse cryptic behavior in this crab. Surprisingly, the evolutionary and ecological processes leading to the absence of genetic divergence and variation in morphology (colour pattern) in S. vittata complex remain to be addressed.
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12
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Cho K, Ryu CS, Jeong S, Kim Y. Potential adverse effect of tyrosinase inhibitors on teleosts:A review. Comp Biochem Physiol C Toxicol Pharmacol 2020; 228:108655. [PMID: 31678677 DOI: 10.1016/j.cbpc.2019.108655] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 01/19/2023]
Abstract
Coloration plays a crucial role in the social communication and survival of organisms. Multidisciplinary studies have been conducted to elucidate the correlation between coloration and melanin biosynthesis (referred as melanogenesis). The multi-copper enzyme tyrosinase catalyzes the first two steps of melanogenesis for coloration in teleosts. Due to the increasing demand of tyrosinase inhibitors for the production of skin whitening cosmetics, hypopigmentation pharmaceuticals, and anti-browning agents, a large number of natural and synthetic inhibitors have been developed over the past few decades. Although a number of previous studies have focused on human use and toxicity, such as the increased cytotoxic effects of ROS-generating compounds, their ecotoxicological impacts on aquatic organisms are still poorly understood. Hence, the focus of the present review is to describe the role of coloration in teleosts as well as potential ecotoxicological effects elicited by exposure to tyrosinase inhibitors. Furthermore, this review introduces our recently registered adverse outcome pathway (AOP) related to tyrosinase inhibition and population decline in teleosts.
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Affiliation(s)
- Kichul Cho
- Department of Genetic Resources Research, National Marine Biodiversity Institute of Korea, Seocheon-gun, Republic of Korea; Environmental Safety Group, Korea Institute of Science and Technology (KIST) Europe, Campus E 7.1, 66123 Saarbrücken, Germany
| | - Chang Seon Ryu
- Environmental Safety Group, Korea Institute of Science and Technology (KIST) Europe, Campus E 7.1, 66123 Saarbrücken, Germany
| | - Seongho Jeong
- Environmental Safety Group, Korea Institute of Science and Technology (KIST) Europe, Campus E 7.1, 66123 Saarbrücken, Germany
| | - Youngjun Kim
- Environmental Safety Group, Korea Institute of Science and Technology (KIST) Europe, Campus E 7.1, 66123 Saarbrücken, Germany.
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13
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Chabenat A, Bellanger C, Jozet-Alves C, Knigge T. Hidden in the sand: Alteration of burying behaviour in shore crabs and cuttlefish by antidepressant exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 186:109738. [PMID: 31610357 DOI: 10.1016/j.ecoenv.2019.109738] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 09/24/2019] [Accepted: 09/25/2019] [Indexed: 06/10/2023]
Abstract
Pharmaceuticals such as antidepressants are constantly released into the aquatic environment. Consequently, fluoxetine (FLX) and venlafaxine (VEN), the active molecules of Prozac© and Effexor©, are detected up to several µg.L-1 in freshwater and marine coastal waters. Both compounds act on the serotoninergic system, which may result in behavioural impairment, especially in juvenile animals presumed to be more susceptible to low concentrations than adults. The objective of this study was to determine whether environmental concentrations of FLX alone or combined with VEN modulate innate burying behaviour in two juvenile marine invertebrates, i.e. Sepia officinalis and Carcinus maenas. Juvenile cuttlefish were exposed from hatching to 30 days post-hatching to either FLX alone (i.e. 5 ng.L-1) or in mixture with VEN (i.e. either 2.5 ng.L-1 or 5 ng.L-1 of each antidepressant). Juvenile crabs (<2 cm carapace width) were exposed for a period of 22 days to 5 ng.L-1 of FLX and a mixture of 5 ng.L-1 of FLX and VEN each. Several parameters of sand-digging behaviour were analysed weekly in both species. The occurrence of sand-digging behaviour decreased in cuttlefish exposed to a mixture of FLX and VEN at the lowest concentration (2.5 ng.L-1 each). Because sand-digging behaviour improved in controls, this decrease was likely to be related to a modification of maturation and/or learning processes. At the mixture of 5 ng.L-1 VEN and FLX each, a better body covering was observed in juvenile crabs. In both species, innate behaviour was modified under exposure to mixtures of FLX and VEN at environmentally realistic concentrations. These alterations were observed at an early developmental stage, when animals are particularly prone to predation. Hence, modified maturation of behavioural traits and, putatively, learning processes by exposure to pseudo-persistent antidepressants may affect the survival of these two species in 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, 14000, Caen, 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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14
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Green SD, Duarte RC, Kellett E, Alagaratnam N, Stevens M. Colour change and behavioural choice facilitate chameleon prawn camouflage against different seaweed backgrounds. Commun Biol 2019; 2:230. [PMID: 31263774 PMCID: PMC6588621 DOI: 10.1038/s42003-019-0465-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 05/20/2019] [Indexed: 12/17/2022] Open
Abstract
Camouflage is driven by matching the visual environment, yet natural habitats are rarely uniform and comprise many backgrounds. Therefore, species often exhibit adaptive traits to maintain crypsis, including colour change and behavioural choice of substrates. However, previous work largely considered these solutions in isolation, whereas many species may use a combination of behaviour and appearance to facilitate concealment. Here we show that green and red chameleon prawns (Hippolyte varians) closely resemble their associated seaweed substrates to the vision of predatory fish, and that they can change colour to effectively match new backgrounds. Prawns also select colour-matching substrates when offered a choice. However, colour change occurs over weeks, consistent with seasonal changes in algal cover, whereas behavioural choice of matching substrates occurs in the short-term, facilitating matches within heterogeneous environments. We demonstrate how colour change and behaviour combine to facilitate camouflage against different substrates in environments varying spatially and temporally.
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Affiliation(s)
- Samuel D. Green
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall, TR10 9FE UK
| | - Rafael C. Duarte
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, 11612-109 Brazil
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), São Bernardo do Campo, 09606-045 Brazil
| | - Emily Kellett
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall, TR10 9FE UK
| | - Natasha Alagaratnam
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall, TR10 9FE UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter (Penryn Campus), Cornwall, TR10 9FE UK
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15
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Price N, Green S, Troscianko J, Tregenza T, Stevens M. Background matching and disruptive coloration as habitat-specific strategies for camouflage. Sci Rep 2019; 9:7840. [PMID: 31127182 PMCID: PMC6534618 DOI: 10.1038/s41598-019-44349-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/15/2019] [Indexed: 12/31/2022] Open
Abstract
Camouflage is a key defence across taxa and frequently critical to survival. A common strategy is background matching, resembling the colour and pattern of the environment. This approach, however, may be ineffective in complex habitats where matching one patch may lead to increased visibility in other patches. In contrast, disruptive coloration, which disguises body outlines, may be effective against complex backgrounds. These ideas have rarely been tested and previous work focuses on artificial systems. Here, we test the camouflage strategies of the shore crab (Carcinus maenas) in two habitats, being a species that is highly variable, capable of plastic changes in appearance, and lives in multiple environments. Using predator (bird and fish) vision modelling and image analysis, we quantified background matching and disruption in crabs from rock pools and mudflats, predicting that disruption would dominate in visually complex rock pools but background matching in more uniform mudflats. As expected, rock pool individuals had significantly higher edge disruption than mudflat crabs, whereas mudflat crabs more closely matched the substrate than rock pool crabs for colour, luminance, and pattern. Our study demonstrates facultative expression of camouflage strategies dependent on the visual environment, with implications for the evolution and interrelatedness of defensive strategies.
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Affiliation(s)
- Natasha Price
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Samuel Green
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Jolyon Troscianko
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Tom Tregenza
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK.
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16
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Nokelainen O, Maynes R, Mynott S, Price N, Stevens M. Improved camouflage through ontogenetic colour change confers reduced detection risk in shore crabs. Funct Ecol 2019; 33:654-669. [PMID: 31217655 PMCID: PMC6559319 DOI: 10.1111/1365-2435.13280] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 11/29/2018] [Indexed: 11/30/2022]
Abstract
Animals from many taxa, from snakes and crabs to caterpillars and lobsters, change appearance with age, but the reasons why this occurs are rarely tested.We show the importance that ontogenetic changes in coloration have on the camouflage of the green shore crabs (Carcinus maenas), known for their remarkable phenotypic variation and plasticity in colour and pattern.In controlled conditions, we reared juvenile crabs of two shades, pale or dark, on two background types simulating different habitats for 10 weeks.In contrast to expectations for reversible colour change, crabs did not tune their background match to specific microhabitats, but instead, and regardless of treatment, all developed a uniform dark green phenotype. This parallels changes in shore crab appearance with age observed in the field.Next, we undertook a citizen science experiment at the Natural History Museum London, where human subjects ("predators") searched for crabs representing natural colour variation from different habitats, simulating predator vision.In concert, crabs were not hardest to find against their original habitat, but instead, the dark green phenotype was hardest to detect against all backgrounds.The evolution of camouflage can be better understood by acknowledging that the optimal phenotype to hide from predators may change over the life history of many animals, including the utilization of a generalist camouflage strategy. A plain language summary is available for this article.
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Affiliation(s)
- Ossi Nokelainen
- Centre for Ecology and Conservation, College of Life and Environmental ScienceUniversity of ExeterPenrynUK
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Ruth Maynes
- Centre for Ecology and Conservation, College of Life and Environmental ScienceUniversity of ExeterPenrynUK
| | - Sara Mynott
- Centre for Ecology and Conservation, College of Life and Environmental ScienceUniversity of ExeterPenrynUK
| | - Natasha Price
- Centre for Ecology and Conservation, College of Life and Environmental ScienceUniversity of ExeterPenrynUK
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental ScienceUniversity of ExeterPenrynUK
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17
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Weller HI, Westneat MW. Quantitative color profiling of digital images with earth mover's distance using the R package colordistance. PeerJ 2019; 7:e6398. [PMID: 30775177 PMCID: PMC6371918 DOI: 10.7717/peerj.6398] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 01/03/2019] [Indexed: 11/20/2022] Open
Abstract
Biological color may be adaptive or incidental, seasonal or permanent, species- or population-specific, or modified for breeding, defense or camouflage. Although color is a hugely informative aspect of biology, quantitative color comparisons are notoriously difficult. Color comparison is limited by categorization methods, with available tools requiring either subjective classifications, or expensive equipment, software, and expertise. We present an R package for processing images of organisms (or other objects) in order to quantify color profiles, gather color trait data, and compare color palettes on the basis of color similarity and amount. The package treats image pixels as 3D coordinates in a "color space," producing a multidimensional color histogram for each image. Pairwise distances between histograms are computed using earth mover's distance, a technique borrowed from computer vision, that compares histograms using transportation costs. Users choose a color space, parameters for generating color histograms, and a pairwise comparison method to produce a color distance matrix for a set of images. The package is intended as a more rigorous alternative to subjective, manual digital image analyses, not as a replacement for more advanced techniques that rely on detailed spectrophotometry methods unavailable to many users. Here, we outline the basic functions of colordistance, provide guidelines for the available color spaces and quantification methods, and compare this toolkit with other available methods. The tools presented for quantitative color analysis may be applied to a broad range of questions in biology and other disciplines.
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Affiliation(s)
- Hannah I. Weller
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA
| | - Mark W. Westneat
- Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL, USA
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18
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Duarte RC, Stevens M, Flores AAV. The adaptive value of camouflage and colour change in a polymorphic prawn. Sci Rep 2018; 8:16028. [PMID: 30375480 PMCID: PMC6207773 DOI: 10.1038/s41598-018-34470-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/17/2018] [Indexed: 11/11/2022] Open
Abstract
Camouflage has been a textbook example of natural selection and adaptation since the time of the earliest evolutionists. However, aside from correlational evidence and studies using artificial dummy prey, experiments directly showing that better camouflaged prey to predator vision are at reduced risk of attack are lacking. Here, we show that the level of camouflage achieved through colour adjustments towards the appearance of seaweed habitats is adaptive in reducing predation pressure in the prawn Hippolyte obliquimanus. Digital image analysis and visual modelling of a fish predator (seahorse) predicted that brown prawns would be imperfectly concealed against both brown and red seaweed respectively, whereas pink prawns should be well camouflaged only in red weed. Predation trials with captive seahorses (Hippocampus reidi), coupled with high-speed video analyses, closely matched model predictions: predation rates were similar for brown prawns between seaweed types, but pink individuals were attacked significantly less on red than brown weed. Our work provides some of the clearest direct evidence to date that colour polymorphism and colour change provides a clear adaptive advantage for camouflage, and also highlights how this can be asymmetric across morphs and habitats (i.e. dependent on the specific background-morph combination).
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Affiliation(s)
- Rafael Campos Duarte
- Centro de Biologia Marinha, Universidade de São Paulo, Rod. Manoel Hypólito do Rego, km 131.5, São Sebastião, SP, 11612-109, Brazil.
- Programa de Pós-Graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Augusto Alberto Valero Flores
- Centro de Biologia Marinha, Universidade de São Paulo, Rod. Manoel Hypólito do Rego, km 131.5, São Sebastião, SP, 11612-109, Brazil
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19
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Dell'Aglio DD, Troscianko J, McMillan WO, Stevens M, Jiggins CD. The appearance of mimetic Heliconius butterflies to predators and conspecifics. Evolution 2018; 72:2156-2166. [PMID: 30129174 PMCID: PMC6221148 DOI: 10.1111/evo.13583] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 08/01/2018] [Accepted: 08/10/2018] [Indexed: 02/05/2023]
Abstract
Adaptive coloration is under conflicting selection pressures: choosing potential mates and warning signaling against visually guided predators. Different elements of the color signal may therefore be tuned by evolution for different functions. We investigated how mimicry in four pairs of Heliconius comimics is potentially seen both from the perspective of butterflies and birds. Visual sensitivities of eight candidate avian predators were predicted through genetic analysis of their opsin genes. Using digital image color analysis, combined with bird and butterfly visual system models, we explored how predators and conspecifics may visualize mimetic patterns. Ultraviolet vision (UVS) birds are able to discriminate between the yellow and white colors of comimics better than violet vision (VS) birds. For Heliconius vision, males and females differ in their ability to discriminate comimics. Female vision and red filtering pigments have a significant effect on the perception of the yellow forewing band and the red ventral forewing pattern. A behavioral experiment showed that UV cues are used in mating behavior; removal of such cues was associated with an increased tendency to approach comimics as compared to conspecifics. We have therefore shown that visual signals can act to both reduce the cost of confusion in courtship and maintain the advantages of mimicry.
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Affiliation(s)
- Denise Dalbosco Dell'Aglio
- Butterfly Genetics Group, Department of Zoology, University of Cambridge, United Kingdom.,Smithsonian Tropical Research Institute, Panama City, Panama
| | - Jolyon Troscianko
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom
| | - W Owen McMillan
- Smithsonian Tropical Research Institute, Panama City, Panama
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn, United Kingdom
| | - Chris D Jiggins
- Butterfly Genetics Group, Department of Zoology, University of Cambridge, United Kingdom.,Smithsonian Tropical Research Institute, Panama City, Panama
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20
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Correlates of color polymorphism in coconut crabs Birgus latro. ZOOLOGY 2018; 129:1-8. [DOI: 10.1016/j.zool.2018.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 06/02/2018] [Accepted: 06/04/2018] [Indexed: 11/23/2022]
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21
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Briolat ES, Zagrobelny M, Olsen CE, Blount JD, Stevens M. Sex differences but no evidence of quantitative honesty in the warning signals of six-spot burnet moths (Zygaena filipendulae L.). Evolution 2018; 72:1460-1474. [PMID: 29767461 PMCID: PMC6099377 DOI: 10.1111/evo.13505] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/22/2018] [Accepted: 05/05/2018] [Indexed: 11/29/2022]
Abstract
The distinctive black and red wing pattern of six-spot burnet moths (Zygaena filipendulae, L.) is a classic example of aposematism, advertising their potent cyanide-based defences. While such warning signals provide a qualitatively honest signal of unprofitability, the evidence for quantitative honesty, whereby variation in visual traits could provide accurate estimates of individual toxicity, is more equivocal. Combining measures of cyanogenic glucoside content and wing color from the perspective of avian predators, we investigate the relationship between coloration and defences in Z. filipendulae, to test signal honesty both within and across populations. There were no significant relationships between mean cyanogenic glucoside concentration and metrics of wing coloration across populations in males, yet in females higher cyanogenic glucoside levels were associated with smaller and lighter red forewing markings. Trends within populations were similarly inconsistent with quantitative honesty, and persistent differences between the sexes were apparent: larger females, carrying a greater total cyanogenic glucoside load, displayed larger but less conspicuous markings than smaller males, according to several color metrics. The overall high aversiveness of cyanogenic glucosides and fluctuations in color and toxin levels during an individual's lifetime may contribute to these results, highlighting generally important reasons why signal honesty should not always be expected in aposematic species.
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Affiliation(s)
- Emmanuelle Sophie Briolat
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterPenrynCornwall TR10 9FEUnited Kingdom
| | - Mika Zagrobelny
- Plant Biochemistry Laboratory and Copenhagen Plant Science CentreDepartment of Plant and Environmental SciencesUniversity of Copenhagen40 Thorvaldsensvej, DK‐1871 Frederiksberg CCopenhagenDenmark
| | - Carl Erik Olsen
- Plant Biochemistry Laboratory and Copenhagen Plant Science CentreDepartment of Plant and Environmental SciencesUniversity of Copenhagen40 Thorvaldsensvej, DK‐1871 Frederiksberg CCopenhagenDenmark
| | - Jonathan D. Blount
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterPenrynCornwall TR10 9FEUnited Kingdom
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of ExeterPenrynCornwall TR10 9FEUnited Kingdom
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22
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Affiliation(s)
- Tim Caro
- Department of Wildlife, Fish and Conservation Biology, University of California, Davis, CA, USA
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23
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Del Valle JC, Gallardo-López A, Buide ML, Whittall JB, Narbona E. Digital photography provides a fast, reliable, and noninvasive method to estimate anthocyanin pigment concentration in reproductive and vegetative plant tissues. Ecol Evol 2018; 8:3064-3076. [PMID: 29607006 PMCID: PMC5869271 DOI: 10.1002/ece3.3804] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/31/2017] [Accepted: 12/06/2017] [Indexed: 02/03/2023] Open
Abstract
Anthocyanin pigments have become a model trait for evolutionary ecology as they often provide adaptive benefits for plants. Anthocyanins have been traditionally quantified biochemically or more recently using spectral reflectance. However, both methods require destructive sampling and can be labor intensive and challenging with small samples. Recent advances in digital photography and image processing make it the method of choice for measuring color in the wild. Here, we use digital images as a quick, noninvasive method to estimate relative anthocyanin concentrations in species exhibiting color variation. Using a consumer‐level digital camera and a free image processing toolbox, we extracted RGB values from digital images to generate color indices. We tested petals, stems, pedicels, and calyces of six species, which contain different types of anthocyanin pigments and exhibit different pigmentation patterns. Color indices were assessed by their correlation to biochemically determined anthocyanin concentrations. For comparison, we also calculated color indices from spectral reflectance and tested the correlation with anthocyanin concentration. Indices perform differently depending on the nature of the color variation. For both digital images and spectral reflectance, the most accurate estimates of anthocyanin concentration emerge from anthocyanin content‐chroma ratio, anthocyanin content‐chroma basic, and strength of green indices. Color indices derived from both digital images and spectral reflectance strongly correlate with biochemically determined anthocyanin concentration; however, the estimates from digital images performed better than spectral reflectance in terms of r2 and normalized root‐mean‐square error. This was particularly noticeable in a species with striped petals, but in the case of striped calyces, both methods showed a comparable relationship with anthocyanin concentration. Using digital images brings new opportunities to accurately quantify the anthocyanin concentrations in both floral and vegetative tissues. This method is efficient, completely noninvasive, applicable to both uniform and patterned color, and works with samples of any size.
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Affiliation(s)
- José C Del Valle
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
| | - Antonio Gallardo-López
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
| | - Mª Luisa Buide
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
| | | | - Eduardo Narbona
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
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Badás EP, Martínez J, Rivero-de Aguilar J, Ponce C, Stevens M, Merino S. Colour change in a structural ornament is related to individual quality, parasites and mating patterns in the blue tit. Naturwissenschaften 2018; 105:17. [PMID: 29404701 DOI: 10.1007/s00114-018-1539-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/27/2017] [Accepted: 01/11/2018] [Indexed: 10/18/2022]
Abstract
Carry-over effects refer to processes that occur in one season and influence fitness in the following. In birds, two costly activities, namely reproduction and moult, are restricted to a small time window, and sometimes overlap. Thus, colour in newly moulted feathers is likely to be affected by the costs of reproduction. Using models of bird vision we investigated male colour change in a free-living population of blue tits (Cyanistes caeruleus) in three sampling occasions: spring 1, winter and spring 2. We related crown, tail, breast and cheek feather colouration after the moult (winter) to the intensity of infections by blood parasites during reproduction (spring 1). In the following spring (spring 2), we explored mating patterns with respect to changes in feather colour (springs 1 vs. 2). Males that were less intensely infected by the malaria parasite Plasmodium while breeding showed purer white cheek feathers in winter, which may indicate higher feather quality. Increased brightness in the white cheek was associated with better body condition during reproduction. In the following season, males with brighter cheeks paired with females that had noticeably brighter cheek patches compared to the male's previous mate. These results suggest that the conditions experienced during reproduction are likely to affect moult and thus feather colouration, at least in the white patch. High quality individuals may allocate resources efficiently during reproduction increasing future reproductive success through variation in mating patterns. Carry-over effects from reproduction might extend not only to the non-breeding phase, but also to the following breeding season.
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Affiliation(s)
- E P Badás
- Department of Evolutionary Ecology, National Museum of Natural Sciences, Jose Gutierrez Abascal 2, 28006, Madrid, Spain.
| | - J Martínez
- Department of Biomedicine and Biotechnology, University of Alcalá de Henares, Ctra. Madrid-Barcelona km 33600, 28871 Alcalá de Henares, Madrid, Spain
| | - J Rivero-de Aguilar
- Department of Biomedicine and Biotechnology, University of Alcalá de Henares, Ctra. Madrid-Barcelona km 33600, 28871 Alcalá de Henares, Madrid, Spain
| | - C Ponce
- Department of Evolutionary Ecology, National Museum of Natural Sciences, Jose Gutierrez Abascal 2, 28006, Madrid, Spain
| | - M Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - S Merino
- Department of Evolutionary Ecology, National Museum of Natural Sciences, Jose Gutierrez Abascal 2, 28006, Madrid, Spain
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Eacock A, Rowland HM, Edmonds N, Saccheri IJ. Colour change of twig-mimicking peppered moth larvae is a continuous reaction norm that increases camouflage against avian predators. PeerJ 2017; 5:e3999. [PMID: 29158965 PMCID: PMC5691783 DOI: 10.7717/peerj.3999] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/17/2017] [Indexed: 01/15/2023] Open
Abstract
Camouflage, and in particular background-matching, is one of the most common anti-predator strategies observed in nature. Animals can improve their match to the colour/pattern of their surroundings through background selection, and/or by plastic colour change. Colour change can occur rapidly (a few seconds), or it may be slow, taking hours to days. Many studies have explored the cues and mechanisms behind rapid colour change, but there is a considerable lack of information about slow colour change in the context of predation: the cues that initiate it, and the range of phenotypes that are produced. Here we show that peppered moth (Biston betularia) larvae respond to colour and luminance of the twigs they rest on, and exhibit a continuous reaction norm of phenotypes. When presented with a heterogeneous environment of mixed twig colours, individual larvae specialise crypsis towards one colour rather than developing an intermediate colour. Flexible colour change in this species has likely evolved in association with wind dispersal and polyphagy, which result in caterpillars settling and feeding in a diverse range of visual environments. This is the first example of visually induced slow colour change in Lepidoptera that has been objectively quantified and measured from the visual perspective of natural predators.
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Affiliation(s)
- Amy Eacock
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Hannah M. Rowland
- Predators and Prey Research Group, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Nicola Edmonds
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Ilik J. Saccheri
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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26
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27
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Stevens M, Troscianko J, Wilson-Aggarwal JK, Spottiswoode CN. Improvement of individual camouflage through background choice in ground-nesting birds. Nat Ecol Evol 2017; 1:1325-1333. [PMID: 28890937 PMCID: PMC5584661 DOI: 10.1038/s41559-017-0256-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 06/26/2017] [Indexed: 12/29/2022]
Abstract
Animal camouflage is a longstanding example of adaptation. Much research has tested how camouflage prevents detection and recognition, largely focusing on changes to an animal's own appearance over evolution. However, animals could also substantially alter their camouflage by behaviourally choosing appropriate substrates. Recent studies suggest that individuals from several animal taxa could select backgrounds or positions to improve concealment. Here, we test whether individual wild animals choose backgrounds in complex environments, and whether this improves camouflage against predator vision. We studied nest site selection by nine species of ground-nesting birds (nightjars, plovers and coursers) in Zambia, and used image analysis and vision modeling to quantify egg and plumage camouflage to predator vision. Individual birds chose backgrounds that enhanced their camouflage, being better matched to their chosen backgrounds than to other potential backgrounds with respect to multiple aspects of camouflage. This occurred at all three spatial scales tested (a few cm and five meters from the nest, and compared to other sites chosen by conspecifics), and was the case for the eggs of all bird groups studied, and for adult nightjar plumage. Thus, individual wild animals improve their camouflage through active background choice, with choices highly refined across multiple spatial scales.
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Affiliation(s)
- Martin Stevens
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
| | - Jolyon Troscianko
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Jared K Wilson-Aggarwal
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Claire N Spottiswoode
- Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, 7701, South Africa
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28
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Duarte RC, Flores AAV, Stevens M. Camouflage through colour change: mechanisms, adaptive value and ecological significance. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160342. [PMID: 28533459 PMCID: PMC5444063 DOI: 10.1098/rstb.2016.0342] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2016] [Indexed: 12/05/2022] Open
Abstract
Animals from a wide range of taxonomic groups are capable of colour change, of which camouflage is one of the main functions. A considerable amount of past work on this subject has investigated species capable of extremely rapid colour change (in seconds). However, relatively slow colour change (over hours, days, weeks and months), as well as changes arising via developmental plasticity are probably more common than rapid changes, yet less studied. We discuss three key areas of colour change and camouflage. First, we review the mechanisms underpinning colour change and developmental plasticity for camouflage, including cellular processes, visual feedback, hormonal control and dietary factors. Second, we discuss the adaptive value of colour change for camouflage, including the use of different camouflage types. Third, we discuss the evolutionary-ecological implications of colour change for concealment, including what it can tell us about intraspecific colour diversity, morph-specific strategies, and matching to different environments and microhabitats. Throughout, we discuss key unresolved questions and present directions for future work, and highlight how colour change facilitates camouflage among habitats and arises when animals are faced with environmental changes occurring over a range of spatial and temporal scales.This article is part of the themed issue 'Animal coloration: production, perception, function and application'.
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Affiliation(s)
- Rafael C Duarte
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, Brazil
- Programa de Pós-Graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Augusto A V Flores
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, Brazil
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
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Insect herbivory may cause changes in the visual properties of leaves and affect the camouflage of herbivores to avian predators. Behav Ecol Sociobiol 2017. [DOI: 10.1007/s00265-017-2326-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Uy FMK, Ravichandran S, Patel KS, Aresty J, Aresty PP, Audett RM, Chen K, Epple L, Jeffries SF, Serein GN, Tullis-Joyce P, Uy JAC. Active background choice facilitates crypsis in a tropical crab. Biotropica 2017. [DOI: 10.1111/btp.12429] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Floria M. K. Uy
- Department of Biology; University of Miami; Coral Gables FL 33146 USA
| | | | - Krisha S. Patel
- Department of Biology; University of Miami; Coral Gables FL 33146 USA
| | | | | | - Raymond M. Audett
- Department of Biology; University of Miami; Coral Gables FL 33146 USA
| | - Kelvin Chen
- Department of Biology; Amherst College; Amherst MA 01002 USA
| | - Lauren Epple
- Department of Biology; University of Miami; Coral Gables FL 33146 USA
| | | | - Gilbert N. Serein
- Department of Biology; University of Miami; Coral Gables FL 33146 USA
| | | | - J. Albert C. Uy
- Department of Biology; University of Miami; Coral Gables FL 33146 USA
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Cadena V, Smith KR, Endler JA, Stuart-Fox D. Geographic divergence and colour change in response to visual backgrounds and illumination intensity in bearded dragons. J Exp Biol 2017; 220:1048-1055. [DOI: 10.1242/jeb.148544] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 12/19/2016] [Indexed: 01/01/2023]
Abstract
ABSTRACT
Animals may improve camouflage by both dynamic colour change and local evolutionary adaptation of colour but we have little understanding of their relative importance in colour-changing species. We tested for differences in colour change in response to background colour and light intensity in two populations of central bearded dragon lizards (Pogona vitticeps) representing the extremes in body coloration and geographical range. We found that bearded dragons change colour in response to various backgrounds and that colour change is affected by illumination intensity. Within-individual colour change was similar in magnitude in the two populations but varied between backgrounds. However, at the endpoints of colour change, each population showed greater similarity to backgrounds that were representative of the local habitat compared with the other population, indicating local adaptation to visual backgrounds. Our results suggest that even in species that change colour, both phenotypic plasticity and geographic divergence of coloration may contribute to improved camouflage.
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Affiliation(s)
- Viviana Cadena
- School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
| | - Kathleen R. Smith
- School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
| | - John A. Endler
- School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC, Australia
| | - Devi Stuart-Fox
- School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
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Smithers SP, Wilson A, Stevens M. Rock pool gobies change their body pattern in response to background features. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blw022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Tapia-McClung H, Ajuria Ibarra H, Rao D. Quantifying Human Visible Color Variation from High Definition Digital Images of Orb Web Spiders. PLoS One 2016; 11:e0166371. [PMID: 27902724 PMCID: PMC5130188 DOI: 10.1371/journal.pone.0166371] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 10/27/2016] [Indexed: 12/04/2022] Open
Abstract
Digital processing and analysis of high resolution images of 30 individuals of the orb web spider Verrucosa arenata were performed to extract and quantify human visible colors present on the dorsal abdomen of this species. Color extraction was performed with minimal user intervention using an unsupervised algorithm to determine groups of colors on each individual spider, which was then analyzed in order to quantify and classify the colors obtained, both spatially and using energy and entropy measures of the digital images. Analysis shows that the colors cover a small region of the visible spectrum, are not spatially homogeneously distributed over the patterns and from an entropic point of view, colors that cover a smaller region on the whole pattern carry more information than colors covering a larger region. This study demonstrates the use of processing tools to create automatic systems to extract valuable information from digital images that are precise, efficient and helpful for the understanding of the underlying biology.
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Affiliation(s)
- Horacio Tapia-McClung
- Laboratorio Nacional de Informática Avanzada, A.C., Xalapa, Veracruz, México
- * E-mail:
| | | | - Dinesh Rao
- INBIOTECA, Universidad Veracruzana, Xalapa, Veracruz, México
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Abstract
Camouflage is one of the most widespread forms of anti-predator defence and prevents prey individuals from being detected or correctly recognized by would-be predators. Over the past decade, there has been a resurgence of interest in both the evolution of prey camouflage patterns, and in understanding animal cognition in a more ecological context. However, these fields rarely collide, and the role of cognition in the evolution of camouflage is poorly understood. Here, we review what we currently know about the role of both predator and prey cognition in the evolution of prey camouflage, outline why cognition may be an important selective pressure driving the evolution of camouflage and consider how studying the cognitive processes of animals may prove to be a useful tool to study the evolution of camouflage, and vice versa. In doing so, we highlight that we still have a lot to learn about the role of cognition in the evolution of camouflage and identify a number of avenues for future research.
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Affiliation(s)
- John Skelhorn
- Centre for Behaviour & Evolution, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
| | - Candy Rowe
- Centre for Behaviour & Evolution, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK
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Duarte RC, Stevens M, Flores AAV. Shape, colour plasticity, and habitat use indicate morph-specific camouflage strategies in a marine shrimp. BMC Evol Biol 2016; 16:218. [PMID: 27756220 PMCID: PMC5070350 DOI: 10.1186/s12862-016-0796-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 10/10/2016] [Indexed: 11/28/2022] Open
Abstract
Background Colour and shape polymorphisms are important features of many species and may allow individuals to exploit a wider array of habitats, including through behavioural differences among morphs. In addition, differences among individuals in behaviour and morphology may reflect different strategies, for example utilising different approaches to camouflage. Hippolyte obliquimanus is a small shrimp species inhabiting different shallow-water vegetated habitats. Populations comprise two main morphs: homogeneous shrimp of variable colour (H) and transparent individuals with coloured stripes (ST). These morphs follow different distribution patterns between their main algal habitats; the brown weed Sargassum furcatum and the pink-red weed Galaxaura marginata. In this study, we first investigated morph-specific colour change and habitat selection, as mechanisms underlying camouflage and spatial distribution patterns in nature. Then, we examined habitat fidelity, mobility, and morphological traits, further indicating patterns of habitat use. Results H shrimp are capable of changing colour in just a few days towards their algal background, achieving better concealment in the more marginal, and less preferred, red weed habitat. Furthermore, laboratory trials showed that habitat fidelity is higher for H shrimp, whereas swimming activity is higher for the ST morph, aligned to morphological evidence indicating these two morphs comprise a more benthic (H) and a more pelagic (ST) life-style, respectively. Conclusions Results suggest that H shrimp utilise a camouflage strategy specialised to a limited number of backgrounds at any one time, whereas ST individuals comprise a phenotype with more generalist camouflage (transparency) linked to a more generalist background utilisation. The coexistence within a population of distinct morphotypes with apparently alternative strategies of habitat use and camouflage may reflect differential responses to substantial seasonal changes in macroalgal cover. Our findings also demonstrate how colour change, behaviour, morphology, and background use all interact in achieving camouflage. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0796-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rafael C Duarte
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, Brazil. .,Programa de Pós-Graduação em Biologia Comparada, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil.
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Augusto A V Flores
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, Brazil
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Kelley JL, Davies WIL. The Biological Mechanisms and Behavioral Functions of Opsin-Based Light Detection by the Skin. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00106] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Stevens M, Broderick AC, Godley BJ, Lown AE, Troscianko J, Weber N, Weber SB. Phenotype-environment matching in sand fleas. Biol Lett 2016; 11:rsbl.2015.0494. [PMID: 26268993 PMCID: PMC4571681 DOI: 10.1098/rsbl.2015.0494] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Camouflage is perhaps the most widespread anti-predator strategy in nature, found in numerous animal groups. A long-standing prediction is that individuals should have camouflage tuned to the visual backgrounds where they live. However, while several studies have demonstrated phenotype–environment associations, few have directly shown that this confers an improvement in camouflage, particularly with respect to predator vision. Here, we show that an intertidal crustacean, the sand flea (Hippa testudinaria), has coloration tuned to the different substrates on which it occurs when viewed by potential avian predators. Individual sand fleas from a small, oceanic island (Ascension) matched the colour and luminance of their own beaches more closely than neighbouring beaches to a model of avian vision. Based on past work, this phenotype–environment matching is likely to be driven through ontogenetic changes rather than genetic adaptation. Our work provides some of the first direct evidence that animal coloration is tuned to provide camouflage to prospective predators against a range of visual backgrounds, in a population of animals occurring over a small geographical range.
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Affiliation(s)
- Martin Stevens
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Annette C Broderick
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Brendan J Godley
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Alice E Lown
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Jolyon Troscianko
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK
| | - Nicola Weber
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK Conservation Office, Ascension Island Government, Georgetown, Ascension Island, ASCN 1ZZ, South Atlantic Ocean
| | - Sam B Weber
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK Conservation Office, Ascension Island Government, Georgetown, Ascension Island, ASCN 1ZZ, South Atlantic Ocean
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Kang C, Kim YE, Jang Y. Colour and pattern change against visually heterogeneous backgrounds in the tree frog Hyla japonica. Sci Rep 2016; 6:22601. [PMID: 26932675 PMCID: PMC4773871 DOI: 10.1038/srep22601] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/17/2016] [Indexed: 11/28/2022] Open
Abstract
Colour change in animals can be adaptive phenotypic plasticity in heterogeneous environments. Camouflage through background colour matching has been considered a primary force that drives the evolution of colour changing ability. However, the mechanism to which animals change their colour and patterns under visually heterogeneous backgrounds (i.e. consisting of more than one colour) has only been identified in limited taxa. Here, we investigated the colour change process of the Japanese tree frog (Hyla japonica) against patterned backgrounds and elucidated how the expression of dorsal patterns changes against various achromatic/chromatic backgrounds with/without patterns. Our main findings are i) frogs primarily responded to the achromatic differences in background, ii) their contrasting dorsal patterns were conditionally expressed dependent on the brightness of backgrounds, iii) against mixed coloured background, frogs adopted intermediate forms between two colours. Using predator (avian and snake) vision models, we determined that colour differences against different backgrounds yielded perceptible changes in dorsal colours. We also found substantial individual variation in colour changing ability and the levels of dorsal pattern expression between individuals. We discuss the possibility of correlational selection on colour changing ability and resting behaviour that maintains the high variation in colour changing ability within population.
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Affiliation(s)
- Changku Kang
- Department of Biology, Carleton University, Ottawa, ON, K1S 5B6, Canada.,Division of EcoScience, Ewha Womans University, Seoul, 120-570, Republic of Korea
| | - Ye Eun Kim
- Division of EcoScience, Ewha Womans University, Seoul, 120-570, Republic of Korea
| | - Yikweon Jang
- Division of EcoScience, Ewha Womans University, Seoul, 120-570, Republic of Korea
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Troscianko J, Stevens M. Image calibration and analysis toolbox - a free software suite for objectively measuring reflectance, colour and pattern. Methods Ecol Evol 2015; 6:1320-1331. [PMID: 27076902 PMCID: PMC4791150 DOI: 10.1111/2041-210x.12439] [Citation(s) in RCA: 237] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/27/2015] [Indexed: 12/01/2022]
Abstract
Quantitative measurements of colour, pattern and morphology are vital to a growing range of disciplines. Digital cameras are readily available and already widely used for making these measurements, having numerous advantages over other techniques, such as spectrometry. However, off-the-shelf consumer cameras are designed to produce images for human viewing, meaning that their uncalibrated photographs cannot be used for making reliable, quantitative measurements. Many studies still fail to appreciate this, and of those scientists who are aware of such issues, many are hindered by a lack of usable tools for making objective measurements from photographs.We have developed an image processing toolbox that generates images that are linear with respect to radiance from the RAW files of numerous camera brands and can combine image channels from multispectral cameras, including additional ultraviolet photographs. Images are then normalised using one or more grey standards to control for lighting conditions. This enables objective measures of reflectance and colour using a wide range of consumer cameras. Furthermore, if the camera's spectral sensitivities are known, the software can convert images to correspond to the visual system (cone-catch values) of a wide range of animals, enabling human and non-human visual systems to be modelled. The toolbox also provides image analysis tools that can extract luminance (lightness), colour and pattern information. Furthermore, all processing is performed on 32-bit floating point images rather than commonly used 8-bit images. This increases precision and reduces the likelihood of data loss through rounding error or saturation of pixels, while also facilitating the measurement of objects with shiny or fluorescent properties.All cameras tested using this software were found to demonstrate a linear response within each image and across a range of exposure times. Cone-catch mapping functions were highly robust, converting images to several animal visual systems and yielding data that agreed closely with spectrometer-based estimates.Our imaging toolbox is freely available as an addition to the open source ImageJ software. We believe that it will considerably enhance the appropriate use of digital cameras across multiple areas of biology, in particular researchers aiming to quantify animal and plant visual signals.
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Affiliation(s)
- Jolyon Troscianko
- Centre for Ecology & Conservation College of Life & Environmental Sciences University of Exeter Penryn Campus Penryn TR10 9FE UK
| | - Martin Stevens
- Centre for Ecology & Conservation College of Life & Environmental Sciences University of Exeter Penryn Campus Penryn TR10 9FE UK
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Renoult JP, Kelber A, Schaefer HM. Colour spaces in ecology and evolutionary biology. Biol Rev Camb Philos Soc 2015; 92:292-315. [DOI: 10.1111/brv.12230] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 09/14/2015] [Accepted: 09/17/2015] [Indexed: 12/19/2022]
Affiliation(s)
- Julien P. Renoult
- Institute of Arts Creations Theories & Aesthetics, CNRS-University Paris 1 Panthéon-Sorbonne; 47 r. des bergers 75015 Paris France
| | - Almut Kelber
- Lund Vision Group, Department of Biology; Lund University; Helgonavägen 3 22362 Lund Sweden
| | - H. Martin Schaefer
- Department of Evolutionary Biology and Animal Ecology; Faculty of Biology, University of Freiburg; Hauptstrasse 1 79104 Freiburg Germany
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Marshall KLA, Philpot KE, Damas-Moreira I, Stevens M. Intraspecific Colour Variation among Lizards in Distinct Island Environments Enhances Local Camouflage. PLoS One 2015; 10:e0135241. [PMID: 26372454 PMCID: PMC4570707 DOI: 10.1371/journal.pone.0135241] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 07/20/2015] [Indexed: 11/19/2022] Open
Abstract
Within-species colour variation is widespread among animals. Understanding how this arises can elucidate evolutionary mechanisms, such as those underlying reproductive isolation and speciation. Here, we investigated whether five island populations of Aegean wall lizards (Podarcis erhardii) have more effective camouflage against their own (local) island substrates than against other (non-local) island substrates to avian predators, and whether this was linked to island differences in substrate appearance. We also investigated whether degree of local substrate matching varied among island populations and between sexes. In most populations, both sexes were better matched against local backgrounds than against non-local backgrounds, particularly in terms of luminance (perceived lightness), which usually occurred when local and non-local backgrounds were different in appearance. This was found even between island populations that historically had a land connection and in populations that have been isolated relatively recently, suggesting that isolation in these distinct island environments has been sufficient to cause enhanced local background matching, sometimes on a rapid evolutionary time-scale. However, heightened local matching was poorer in populations inhabiting more variable and unstable environments with a prolonged history of volcanic activity. Overall, these results show that lizard coloration is tuned to provide camouflage in local environments, either due to genetic adaptation or changes during development. Yet, the occurrence and extent of selection for local matching may depend on specific conditions associated with local ecology and biogeographic history. These results emphasize how anti-predator adaptations to different environments can drive divergence within a species, which may contribute to reproductive isolation among populations and lead to ecological speciation.
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Affiliation(s)
- Kate L. A. Marshall
- Behavioural Ecology Group, Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Kate E. Philpot
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Isabel Damas-Moreira
- CIBIO Research Centre in Biodiversity and Genetic Resources, InBIO, Universidade do Porto, Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão, Vila do Conde, Portugal
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
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Russell BJ, Dierssen HM. Use of Hyperspectral Imagery to Assess Cryptic Color Matching in Sargassum Associated Crabs. PLoS One 2015; 10:e0136260. [PMID: 26352667 PMCID: PMC4564216 DOI: 10.1371/journal.pone.0136260] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 08/03/2015] [Indexed: 01/01/2023] Open
Abstract
Mats of the pelagic macroalgae Sargassum represent a complex environment for the study of marine camouflage at the air-sea interface. Endemic organisms have convergently evolved similar colors and patterns, but quantitative assessments of camouflage strategies are lacking. Here, spectral camouflage of two crab species (Portunus sayi and Planes minutus) was assessed using hyperspectral imagery (HSI). Crabs matched Sargassum reflectance across blue and green wavelengths (400-550 nm) and diverged at longer wavelengths. Maximum discrepancy was observed in the far-red (i.e., 675 nm) where Chlorophyll a absorption occurred in Sargassum and not the crabs. In a quantum catch color model, both crabs showed effective color matching against blue/green sensitive dichromat fish, but were still discernible to tetrachromat bird predators that have visual sensitivity to far red wavelengths. The two species showed opposing trends in background matching with relation to body size. Variation in model parameters revealed that discrimination of crab and background was impacted by distance from the predator, and the ratio of cone cell types for bird predators. This is one of the first studies to detail background color matching in this unique, challenging ecosystem at the air-sea interface.
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Affiliation(s)
- Brandon J. Russell
- Department of Marine Science, University of Connecticut, Groton, CT, 06340, United States of America
| | - Heidi M. Dierssen
- Department of Marine Science, University of Connecticut, Groton, CT, 06340, United States of America
- Department of Geography, University of Connecticut, Storrs, CT, 06268, United States of America
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María Arenas L, Walter D, Stevens M. Signal honesty and predation risk among a closely related group of aposematic species. Sci Rep 2015; 5:11021. [PMID: 26046332 PMCID: PMC4457162 DOI: 10.1038/srep11021] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 05/12/2015] [Indexed: 11/13/2022] Open
Abstract
Many animals have bright colours to warn predators that they have defences and are not worth attacking. However, it remains unclear whether the strength of warning colours reliably indicate levels of defence. Few studies have unambiguously established if warning signals are honest, and have rarely considered predator vision or conspicuousness against the background. Importantly, little data exists either on how differences in signal strength translate into survival advantages. Ladybirds exhibit impressive variation in coloration both among and within species. Here we demonstrate that different levels of toxicity exist among and within ladybird species, and that signal contrast against the background is a good predictor of toxicity, showing that the colours are honest signals. Furthermore, field experiments with ladybird models created with regards to predator vision show that models with lower conspicuousness were attacked more frequently. This provides one of the most comprehensive studies on signal honesty in warning coloration to date.
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Affiliation(s)
- Lina María Arenas
- 1] Department of Zoology, University of Cambridge, Downing Street, CB2 3EJ, UK [2] Centre for Ecology &Conservation, College of Life &Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Dominic Walter
- Centre for Ecology &Conservation, College of Life &Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Martin Stevens
- Centre for Ecology &Conservation, College of Life &Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK
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Stevens M, Lown AE, Wood LE. Camouflage and individual variation in shore crabs (Carcinus maenas) from different habitats. PLoS One 2014; 9:e115586. [PMID: 25551233 PMCID: PMC4281232 DOI: 10.1371/journal.pone.0115586] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 11/29/2014] [Indexed: 12/01/2022] Open
Abstract
Camouflage is widespread throughout the natural world and conceals animals from predators in a vast range of habitats. Because successful camouflage usually involves matching aspects of the background environment, species and populations should evolve appearances tuned to their local habitat, termed phenotype-environment associations. However, although this has been studied in various species, little work has objectively quantified the appearances of camouflaged animals from different habitats, or related this to factors such as ontogeny and individual variation. Here, we tested for phenotype-environment associations in the common shore crab (Carcinus maenas), a species highly variable in appearance and found in a wide range of habitats. We used field surveys and digital image analysis of the colors and patterns of crabs found in four locations around Cornwall in the UK to quantify how individuals vary with habitat (predominantly rockpool, mussel bed, and mudflat). We find that individuals from sites comprising different backgrounds show substantial differences in several aspects of color and pattern, and that this is also dependent on life stage (adult or juvenile). Furthermore, the level of individual variation is dependent on site and life stage, with juvenile crabs often more variable than adults, and individuals from more homogenous habitats less diverse. Ours is the most comprehensive study to date exploring phenotype-environment associations for camouflage and individual variation in a species, and we discuss the implications of our results in terms of the mechanisms and selection pressures that may drive this.
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Affiliation(s)
- Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Alice E Lown
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
| | - Louisa E Wood
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, United Kingdom
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Abstract
Camouflage is found in a wide range of species living in numerous habitat types, offering protection from visually guided predators. This includes many species from the intertidal zone, which must cope with background types diverse in appearance and with multiple predator groups foraging at high and low tide. Many animals are capable of either relatively slow (hours, days, weeks) or rapid (seconds and minutes) colour change in order to better resemble the background against which they are found, but most work has been restricted to a few species or taxa. It is often suggested that many small intertidal fish are capable of colour change for camouflage, yet little experimental work has addressed this. Here, we test rock gobies (Gobius paganellus) for colour change abilities, and whether they can tune their appearance to match the background. In two experiments, we place gobies on backgrounds of different brightness (black or white), and of different colours (red and blue) and use digital image analysis and modelling of predator (avian) vision to quantify colour and luminance (perceived lightness) changes and camouflage. We find that gobies are capable of rapid colour change (occurring within one minute), and that they can change their luminance on lighter or darker backgrounds. When presented on backgrounds of different colours, gobies also change their colour (hue and saturation) while keeping luminance the same. These changes lead to predicted improvements in camouflage match to the background. Our study shows that small rockpool fish are capable of rapid visual change for concealment, and that this may be an important mechanism in many species to avoid predation, especially in complex heterogeneous environments.
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Kang C, Stevens M, Moon JY, Lee SI, Jablonski PG. Camouflage through behavior in moths: the role of background matching and disruptive coloration. Behav Ecol 2014. [DOI: 10.1093/beheco/aru150] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Arenas LM, Troscianko J, Stevens M. Color contrast and stability as key elements for effective warning signals. Front Ecol Evol 2014. [DOI: 10.3389/fevo.2014.00025] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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