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Stark G, Ma L, Zeng ZG, Du WG, Levy O. State-dependent movement choices of desert lizards: The role of behavioural thermoregulation during summer and winter. J Therm Biol 2024; 121:103841. [PMID: 38552446 DOI: 10.1016/j.jtherbio.2024.103841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/01/2024] [Accepted: 03/06/2024] [Indexed: 05/26/2024]
Abstract
Environmental temperatures are increasing worldwide, threatening desert ectotherms already living at their thermal limits. Organisms with flexible thermoregulatory behaviours may be able to mitigate the effects of extreme temperatures by moving among microhabitats, yet little work has tracked movement patterns of desert ectotherms in the wild over diurnal scales or compared behaviour among seasons. Here, we used camera traps to track the thermoregulatory behaviour and microhabitat choices of 30 desert lizards (Messalina bahaldini) in custom, outdoor arenas that provided access to open, rock, and bush microhabitats. We found that in the summer, lizards preferred to move to the shaded microhabitats and remain there under warmer conditions. During winter, however, lizards' activity was not related to temperature, and lizards mostly chose to remain in the open habitat. Interestingly, in both seasons, lizards tended to remain in their current microhabitat and moved infrequently between certain combinations of microhabitats. Our study shows that thermoregulation (shade-seeking behaviour) is a major factor during summer, helping lizards to avoid extreme temperatures, but not during winter, and shows a novel effect of current microhabitat on movement, suggesting that other biotic or abiotic factors may also drive microhabitat choice. Understanding the complex factors at play in microhabitat choice is critical for developing conservation programs that effectively mitigate the negative impacts of climate change on desert animals.
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Affiliation(s)
- Gavin Stark
- Tel Aviv University, Faculty of Life Sciences, School of Zoology, Israel.
| | - Liang Ma
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China; School of Ecology, Shenzhen Campus of Sun Yat-sen University, Shenzhen 518107, People's Republic of China.
| | - Zhi-Gao Zeng
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
| | - Wei-Guo Du
- Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China.
| | - Ofir Levy
- Tel Aviv University, Faculty of Life Sciences, School of Zoology, Israel.
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2
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de Alcantara Viana JV, Campos Duarte R, Vieira C, Augusto Poleto Antiqueira P, Bach A, de Mello G, Silva L, Rabelo Oliveira Leal C, Quevedo Romero G. Crypsis by background matching and disruptive coloration as drivers of substrate occupation in sympatric Amazonian bark praying mantises. Sci Rep 2023; 13:19985. [PMID: 37968331 PMCID: PMC10652001 DOI: 10.1038/s41598-023-46204-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 10/29/2023] [Indexed: 11/17/2023] Open
Abstract
Background matching and disruptive coloration are common camouflage strategies in nature, but few studies have accurately measured their protective value in living organisms. Amazon's Bark praying mantises exhibit colour patterns matching whitish and greenish-brown tree trunks. We tested the functional significance of background matching and disruptive coloration of different praying mantis morphospecies (white, grey and green) detected by DNA barcoding. Through image analysis, avian visual models and field experiments using humans as potential predators, we explored whether the background occupation of mantises provides camouflage against predation. Data were obtained for individuals against their occupied tree trunks (whitish or greenish-brown) and microhabitats (lichen or bryophyte patches), compared to non-occupied trunks. White and grey mantises showed lower colour contrasts against occupied trunks at the scale of tree trunk, with no differences in luminance contrasts. Conversely, green mantises showed lower colour and luminance contrasts against microhabitats and also exhibited high edge disruption against greenish-brown trunks. The camouflage of white and green mantis models against colour-matching trunks increased search time and reduced encounter distance of human predators. We highlight the importance of camouflage strategies at different spatial scales to enhance individual survival against predators. Specifically, we present a stunning study system to investigate the relationship of phylogenetically related species that use camouflage in sympatry.
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Affiliation(s)
- João Vitor de Alcantara Viana
- Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil.
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil.
| | - Rafael Campos Duarte
- Universidade Federal Do ABC, São Bernardo Do Campo, São Paulo, CEP 09606-045, Brazil
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
| | - Camila Vieira
- Departamento de Ciências Básicas, Universidade de São Paulo (USP), Campus de Pirassununga, Pirassununga, São Paulo, CEP 13635-900, Brazil
| | - Pablo Augusto Poleto Antiqueira
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil
| | - Andressa Bach
- Programa de Pós-Graduação Em Ecologia E Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Costa, N° 2367, Boa Esperança, Cuiabá, 78060900, Brazil
| | - Gabriel de Mello
- Programa de Pós-Graduação Em Ecologia E Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Costa, N° 2367, Boa Esperança, Cuiabá, 78060900, Brazil
| | - Lorhaine Silva
- Programa de Pós-Graduação Em Ecologia E Conservação da Biodiversidade, Instituto de Biociências, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Costa, N° 2367, Boa Esperança, Cuiabá, 78060900, Brazil
| | - Camila Rabelo Oliveira Leal
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil
| | - Gustavo Quevedo Romero
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, Campinas, São Paulo, CEP 13083-970, Brazil
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3
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Recknagel H, Harvey WT, Layton M, Elmer KR. Common lizard microhabitat selection varies by sex, parity mode, and colouration. BMC Ecol Evol 2023; 23:47. [PMID: 37667183 PMCID: PMC10478496 DOI: 10.1186/s12862-023-02158-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 08/22/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Animals select and interact with their environment in various ways, including to ensure their physiology is at its optimal capacity, access to prey is possible, and predators can be avoided. Often conflicting, the balance of choices made may vary depending on an individual's life-history and condition. The common lizard (Zootoca vivipara) has egg-laying and live-bearing lineages and displays a variety of dorsal patterns and colouration. How colouration and reproductive mode affect habitat selection decisions on the landscape is not known. In this study, we first tested if co-occurring male and female viviparous and oviparous common lizards differ in their microhabitat selection. Second, we tested if the dorsal colouration of an individual lizard matched its basking site choice within the microhabitat where it was encountered, which could be related to camouflage and crypsis. RESULTS We found that site use differed from the habitat otherwise available, suggesting lizards actively choose the composition and structure of their microhabitat. Females were found in areas with more wood and less bare ground compared to males; we speculate that this may be for better camouflage and reducing predation risk during pregnancy, when females are less mobile. Microhabitat use also differed by parity mode: viviparous lizards were found in areas with more density of flowering plants, while oviparous lizards were found in areas that were wetter and had more moss. This may relate to differing habitat preferences of viviparous vs. oviparous for clutch lay sites. We found that an individual's dorsal colouration matched that of the substrate of its basking site. This could indicate that individuals may choose their basking site to optimise camouflage within microhabitat. Further, all individuals were found basking in areas close to cover, which we expect could be used to escape predation. CONCLUSIONS Our study suggests that common lizards may actively choose their microhabitat and basking site, balancing physiological requirements, escape response and camouflage as a tactic for predator avoidance. This varies for parity modes, sexes, and dorsal colourations, suggesting that individual optimisation strategies are influenced by inter-individual variation within populations as well as determined by evolutionary differences associated with life history.
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Affiliation(s)
- Hans Recknagel
- School of Biodiversity, One Health & Veterinary Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
- Biotechnical Faculty, Department of Biology, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - William T Harvey
- School of Biodiversity, One Health & Veterinary Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
- Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Megan Layton
- School of Biodiversity, One Health & Veterinary Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Kathryn R Elmer
- School of Biodiversity, One Health & Veterinary Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK.
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4
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Hughes AE, Briolat ES, Arenas LM, Liggins E, Stevens M. Varying benefits of generalist and specialist camouflage in two versus four background environments. Behav Ecol 2023; 34:426-436. [PMID: 37192921 PMCID: PMC10183209 DOI: 10.1093/beheco/arac114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 11/08/2022] [Accepted: 11/24/2022] [Indexed: 05/18/2023] Open
Abstract
Background-matching camouflage is a well-established strategy to reduce detection, but implementing this on heterogeneous backgrounds is challenging. For prey with fixed color patterns, solutions include specializing on a particular visual microhabitat, or adopting a compromise or generalist appearance, matching multiple backgrounds less well. Existing studies suggest both approaches can succeed, but most consider relatively simple scenarios, where artificial prey appear against two backgrounds differing in a single visual characteristic. Here, we used computer-based search tasks with human participants to test the relative benefits of specializing and generalizing for complex targets, displayed on either two or four types of naturalistic backgrounds. Across two background types, specialization was beneficial on average. However, the success of this strategy varied with search duration, such that generalist targets could outperform specialists over short search durations due to the presence of poorly matched specialists. Over longer searches, the remaining well-matched specialists had greater success than generalists, leading to an overall benefit of specialization at longer search durations. Against four different backgrounds, the initial cost to specialization was greater, so specialists and generalists ultimately experienced similar survival. Generalists performed better when their patterning was a compromise between backgrounds that were more similar to each other than when backgrounds were more different, with similarity in luminance more relevant than pattern differences. Time dependence in the relative success of these strategies suggests that predator search behavior may affect optimal camouflage in real-world situations.
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Affiliation(s)
- Anna E Hughes
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
- Department of Psychology, University of Essex, Wivenhoe House, Colchester CO4 3SQ, UK
| | - Emmanuelle S Briolat
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Lina María Arenas
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Eric Liggins
- QinetiQ, Cody Technology Park, Ively Road, Farnborough, Hampshire GU14 0LX, UK
| | - Martin Stevens
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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5
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Abstract
Abstract
Variation in color morph behavior is an important factor in the maintenance of color polymorphism. Alternative anti-predator behaviors are often associated with morphological traits such as coloration, possibly because predator-mediated viability selection favors certain combinations of anti-predator behavior and color. The Aegean wall lizard, Podarcis erhardii, is color polymorphic and populations can have up to three monochromatic morphs: orange, yellow, and white. We investigated whether escape behaviors differ among coexisting color morphs, and if morph behaviors are repeatable across different populations with the same predator species. Specifically, we assessed color morph flight initiation distance (FID), distance to the nearest refuge (DNR), and distance to chosen refuge (DR) in two populations of Aegean wall lizards from Naxos island. We also analyzed the type of refugia color morphs selected and their re-emergence behavior following a standardized approach. We found that orange morphs have different escape behaviors from white and yellow morphs, and these differences are consistent in both populations we sampled. Orange morphs have shorter FIDs, DNRs, and DRs; select different refuge types; and re-emerge less often after being approached compared to white and yellow morphs. Observed differences in color morph escape behaviors support the idea that morphs have evolved alternative behavioral strategies that may play a role in population-level morph maintenance and loss.
Significance statement
Color polymorphic species often differ in behaviors related to reproduction, but differences in other behaviors are relatively underexplored. In this study, we use an experimental approach in two natural populations of color populations of color polymorphic lizards to determine that color morphs have diverged in their escape behaviors. By conducting our experiments in two different populations with similar predator regimes, we show for the first time that behavioral differences among intra-specific color morphs are repeatable across populations, suggesting that alternative behavioral strategies have evolved in this species. Using this experimental approach, we demonstrate that the brightest orange morph stays closer to refuge than other morphs, uses a different refuge type (vegetation) more often than other morphs (wall crevices), and take much longer to emerge from refuge after a simulated predation event than other morphs. Thus, selective pressures from visual predators may differ between morphs and play a role in the evolution and maintenance of color polymorphisms in these types of systems. Our study species, Podarcis erhardii, belongs to a highly color polymorphic genus (19/23 spp. are color polymorphic) that contains the same three color morphs, thus we believe our results may be relevant to more than just P. erhardii.
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6
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Bradley HS, Craig MD, Cross AT, Tomlinson S, Bamford MJ, Bateman PW. Revealing microhabitat requirements of an endangered specialist lizard with LiDAR. Sci Rep 2022; 12:5193. [PMID: 35338156 PMCID: PMC8956745 DOI: 10.1038/s41598-022-08524-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 02/17/2022] [Indexed: 11/29/2022] Open
Abstract
A central principle of threatened species management is the requirement for detailed understanding of species habitat requirements. Difficult terrain or cryptic behaviour can, however, make the study of habitat or microhabitat requirements difficult, calling for innovative data collection techniques. We used high-resolution terrestrial LiDAR imaging to develop three-dimensional models of log piles, quantifying the structural characteristics linked with occupancy of an endangered cryptic reptile, the western spiny-tailed skink (Egernia stokesii badia). Inhabited log piles were generally taller with smaller entrance hollows and a wider main log, had more high-hanging branches, fewer low-hanging branches, more mid- and understorey cover, and lower maximum canopy height. Significant characteristics linked with occupancy were longer log piles, an average of three logs, less canopy cover, and the presence of overhanging vegetation, likely relating to colony segregation, thermoregulatory requirements, and foraging opportunities. In addition to optimising translocation site selection, understanding microhabitat specificity of E. s. badia will help inform a range of management objectives, such as targeted monitoring and invasive predator control. There are also diverse opportunities for the application of this technology to a wide variety of future ecological studies and wildlife management initiatives pertaining to a range of cryptic, understudied taxa.
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Affiliation(s)
- Holly S Bradley
- ARC Centre for Mine Site Restoration, School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, Perth, WA, 6102, Australia.
| | - Michael D Craig
- School of Biological Sciences, University of Western Australia, Crawley, WA, 6009, Australia.,School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, 6150, Australia
| | - Adam T Cross
- ARC Centre for Mine Site Restoration, School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, Perth, WA, 6102, Australia.,EcoHealth Network (http://ecohealthglobal.org), 1330 Beacon St, Suite 355a, Brookline, MA, 02446, USA
| | - Sean Tomlinson
- School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, Perth, WA, 6102, Australia.,Kings Park Science, Department of Biodiversity, Conservation and Attractions, Kattij Close, Kings Park, WA, 6005, Australia.,School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, SA, 5000, Australia
| | - Michael J Bamford
- Bamford Consulting Ecologists, Plover Way, Kingsley, WA, 6026, Australia
| | - Philip W Bateman
- Behavioural Ecology Laboratory, School of Molecular and Life Sciences, Curtin University, Kent Street, Bentley, Perth, WA, 6102, Australia
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7
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Wan L, Liu Z, Wang T, Yang M, Li J, Sun H, Niu C, Zhao W, Jin Y. Camouflage versus running performance as strategies against predation in a lizard inhabiting different habitats. Ecol Evol 2021; 11:17409-17416. [PMID: 34938517 PMCID: PMC8668757 DOI: 10.1002/ece3.8374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 10/30/2021] [Accepted: 11/02/2021] [Indexed: 11/13/2022] Open
Abstract
Running speed and camouflage are associated with the foraging and anti-predator abilities of animals. The toad-headed lizard, Phrynocephalus versicolor, has evolved a darker dorsal color in melanistic habitats and maintained a lighter color in adjacent, non-melanistic habitats. We test the hypothesis that lizards have weaker running speed on well-matching backgrounds than on less matching backgrounds. We used lizard models to compare the predation pressure, while the running speed of dark and light lizards were compared in field tunnels using a video recording method. Our results indicated that both the dark lizards in melanistic Heishankou (HSK) and the light lizards in non-melanistic Guazhou (GZ) face lower predation pressure than potential color-background unmatched lizards. The light lizards have a potentially higher running speed than darker lizards in melanistic habitats, which implies that substrate color matching populations with benefits of camouflage might have lower anti-predation pressure, and the costs of investment in melanin production may reduce running capacity.
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Affiliation(s)
- Lixia Wan
- College of Life SciencesNorthwest Normal UniversityLanzhouChina
| | - Zhenxia Liu
- College of Life SciencesNorthwest Normal UniversityLanzhouChina
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Tao Wang
- College of life sciences and medicineZhejiang Sci‐Tech UniversityHangzhouChina
| | - Minglu Yang
- College of Life SciencesNorthwest Normal UniversityLanzhouChina
| | - Jiasheng Li
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Hui Sun
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Chenkai Niu
- College of Life SciencesLanzhou UniversityLanzhouChina
| | - Wei Zhao
- College of Life SciencesLanzhou UniversityLanzhouChina
| | - Yuanting Jin
- College of Life SciencesChina Jiliang UniversityHangzhouChina
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8
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González-Miguéns R, Soler-Zamora C, Villar-Depablo M, Todorov M, Lara E. Multiple convergences in the evolutionary history of the testate amoeba family Arcellidae (Amoebozoa: Arcellinida: Sphaerothecina): when the ecology rules the morphology. Zool J Linn Soc 2021. [DOI: 10.1093/zoolinnean/zlab074] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Protists are probably the most species-rich eukaryotes, yet their systematics are inaccurate, leading to an underestimation of their actual diversity. Arcellinida (= lobose testate amoebae) are amoebozoans that build a test (a hard shell) whose shape and composition are taxonomically informative. One of the most successful groups is Arcellidae, a family found worldwide in many freshwater and terrestrial environments where they are indicators of environmental quality. However, the systematics of the family is based on works published nearly a century ago. We re-evaluated the systematics based on single-cell barcoding, morphological and ecological data. Overall, test shape appears to be more related to environmental characteristics than to the species’ phylogenetic position. We show several convergences in organisms with similar ecology, some traditionally described species being paraphyletic. Based on conservative traits, we review the synapomorphies of the infraorder Sphaerothecina, compile a list of synonyms and describe a new genus Galeripora, with five new combinations. Seven new species: Arcella guadarramensis sp. nov., Galeripora balari sp. nov., Galeripora bufonipellita sp. nov., Galeripora galeriformis sp. nov., Galeripora naiadis sp. nov., Galeripora sitiens sp. nov. andGaleripora succelli sp. nov. are also described here.
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Affiliation(s)
| | | | - Mar Villar-Depablo
- Real Jardín Botánico (RJB-CSIC), Plaza Murillo 2, Madrid, Spain
- Museo Nacional de Ciencias Naturales (MNCN-CSIC), Serrano 115 bis, Madrid, Spain
| | - Milcho Todorov
- Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Science, Sofia, Bulgaria
| | - Enrique Lara
- Real Jardín Botánico (RJB-CSIC), Plaza Murillo 2, Madrid, Spain
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9
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Bertolesi GE, Debnath N, Atkinson-Leadbeater K, Niedzwiecka A, McFarlane S. Distinct type II opsins in the eye decode light properties for background adaptation and behavioural background preference. Mol Ecol 2021; 30:6659-6676. [PMID: 34592025 DOI: 10.1111/mec.16203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/02/2021] [Accepted: 09/10/2021] [Indexed: 12/17/2022]
Abstract
Crypsis increases survival by reducing predator detection. Xenopus laevis tadpoles decode light properties from the substrate to induce two responses: a cryptic coloration response where dorsal skin pigmentation is adjusted to the colour of the substrate (background adaptation) and a behavioural crypsis where organisms move to align with a specific colour surface (background preference). Both processes require organisms to detect reflected light from the substrate. We explored the relationship between background adaptation and preference and the light properties able to trigger both responses. We also analysed which retinal photosensor (type II opsin) is involved. Our results showed that these two processes are segregated mechanistically, as there is no correlation between the preference for a specific background with the level of skin pigmentation, and different dorsal retina-localized type II opsins appear to underlie the two crypsis modes. Indeed, inhibition of melanopsin affects background adaptation but not background preference. Instead, we propose pinopsin is the photosensor involved in background preference. pinopsin mRNA is co-expressed with mRNA for the sws1 cone photopigment in dorsally located photoreceptors. Importantly, the developmental onset of pinopsin expression aligns with the emergence of the preference for a white background, but after the background adaptation phenotype appears. Furthermore, white background preference of tadpoles is associated with increased pinopsin expression, a feature that is lost in premetamorphic froglets along with a preference for a white background. Thus, our data show a mechanistic dissociation between background adaptation and background preference, and we suggest melanopsin and pinopsin, respectively, initiate the two responses.
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Affiliation(s)
- Gabriel E Bertolesi
- Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.,Department of Cell Biology and Anatomy, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | - Nilakshi Debnath
- Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.,Department of Cell Biology and Anatomy, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
| | | | - Anna Niedzwiecka
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada
| | - Sarah McFarlane
- Hotchkiss Brain Institute, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada.,Department of Cell Biology and Anatomy, Alberta Children's Hospital Research Institute, Calgary, Alberta, Canada
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10
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Information content of ultraviolet-reflecting colour patches and visual perception of body coloration in the Tyrrhenian wall lizard Podarcis tiliguerta. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03023-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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11
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Garner AM, Pamfilie AM, Dhinojwala A, Niewiarowski PH. Tokay geckos (Gekkonidae: Gekko gecko) preferentially use substrates that elicit maximal adhesive performance. J Exp Biol 2021; 224:jeb.241240. [PMID: 33504587 DOI: 10.1242/jeb.241240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/13/2021] [Indexed: 01/22/2023]
Abstract
Gecko substrate use is likely influenced by adhesive performance, yet few studies have demonstrated this empirically. Herein, we examined the substrate use, adhesive performance and vertical clinging behaviour of Gekko gecko in captivity to investigate whether adhesive performance influences patterns of substrate use. We found that geckos were observed significantly more often on the substrate (glass) that elicited maximal adhesive performance relative to its availability within our experimental enclosures, indicating that geckos preferentially use substrates on which their adhesive performance is maximal. Our work here provides additional, yet crucial data establishing connections between adhesive performance and patterns of substrate use in captivity, suggesting the hypothesis that substrate preferences of free-ranging geckos should be correlated with adhesive performance. Clearly, further experimental and field research is necessary to test this hypothesis and identify other parameters that individually and/or collectively influence the habitat use of free-ranging geckos.
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Affiliation(s)
- Austin M Garner
- Gecko Adhesion Research Group, The University of Akron, Akron, OH 44325-3908, USA .,Integrated Bioscience Program, The University of Akron, Akron, OH 44325-3908, USA.,Department of Biology, The University of Akron, Akron, OH 44325-3908, USA
| | - Alexandra M Pamfilie
- Gecko Adhesion Research Group, The University of Akron, Akron, OH 44325-3908, USA.,Department of Biology, The University of Akron, Akron, OH 44325-3908, USA
| | - Ali Dhinojwala
- Gecko Adhesion Research Group, The University of Akron, Akron, OH 44325-3908, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH 44325-3908, USA.,School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325-3909, USA
| | - Peter H Niewiarowski
- Gecko Adhesion Research Group, The University of Akron, Akron, OH 44325-3908, USA.,Integrated Bioscience Program, The University of Akron, Akron, OH 44325-3908, USA.,Department of Biology, The University of Akron, Akron, OH 44325-3908, USA
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12
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van den Berg CP, Hollenkamp M, Mitchell LJ, Watson EJ, Green NF, Marshall NJ, Cheney KL. More than noise: context-dependent luminance contrast discrimination in a coral reef fish ( Rhinecanthus aculeatus). J Exp Biol 2020; 223:jeb232090. [PMID: 32967998 DOI: 10.1242/jeb.232090] [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: 06/26/2020] [Accepted: 09/11/2020] [Indexed: 01/19/2023]
Abstract
Achromatic (luminance) vision is used by animals to perceive motion, pattern, space and texture. Luminance contrast sensitivity thresholds are often poorly characterised for individual species and are applied across a diverse range of perceptual contexts using over-simplified assumptions of an animal's visual system. Such thresholds are often estimated using the receptor noise limited model (RNL). However, the suitability of the RNL model to describe luminance contrast perception remains poorly tested. Here, we investigated context-dependent luminance discrimination using triggerfish (Rhinecanthus aculeatus) presented with large achromatic stimuli (spots) against uniform achromatic backgrounds of varying absolute and relative contrasts. 'Dark' and 'bright' spots were presented against relatively dark and bright backgrounds. We found significant differences in luminance discrimination thresholds across treatments. When measured using Michelson contrast, thresholds for bright spots on a bright background were significantly higher than for other scenarios, and the lowest threshold was found when dark spots were presented on dark backgrounds. Thresholds expressed in Weber contrast revealed lower thresholds for spots darker than their backgrounds, which is consistent with the literature. The RNL model was unable to estimate threshold scaling across scenarios as predicted by the Weber-Fechner law, highlighting limitations in the current use of the RNL model to quantify luminance contrast perception. Our study confirms that luminance contrast discrimination thresholds are context dependent and should therefore be interpreted with caution.
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Affiliation(s)
- Cedric P van den Berg
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Michelle Hollenkamp
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Laurie J Mitchell
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Erin J Watson
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Naomi F Green
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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13
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Nokelainen O, Brito JC, Scott-Samuel NE, Valkonen JK, Boratyński Z. Camouflage accuracy in Sahara-Sahel desert rodents. J Anim Ecol 2020; 89:1658-1669. [PMID: 32227336 DOI: 10.1111/1365-2656.13225] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 01/31/2020] [Indexed: 01/21/2023]
Abstract
Camouflage helps animals to hide from predators and is therefore key to survival. Although widespread convergence of animal phenotypes to their natural environment is well-established, there is a lack of knowledge about how species compromise camouflage accuracy across different background types in their habitat. Here we tested how background matching has responded to top-down selection by avian and mammalian predators using Sahara-Sahel desert rodents in North Africa. We show that the fur colouration of several species has become an accurate match to different types of desert habitats. This is supported by a correlation analysis of colour and pattern metrics, investigation of animal-to-background similarities at different spatial scales and is confirmed by modelling of two predator vision systems. The background match was closest across large (or global) spatial scales, suggesting a generalist camouflage tactic for many background types. Some species, may have a better match to the background over small (or focal) spatial scales, which could be the result of habitat choices or differential predation. Nevertheless, predicted discrimination distances of fur colouration were virtually indistinguishable for mammalian and low for avian vision model, which implies effective camouflage. Our study provides one of the best documented cases of multilevel camouflage accuracy in geographically widespread taxa. We conclude that background matching has become an effective and common adaptation against predatory threat in Sahara-Sahelian desert rodents.
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Affiliation(s)
- Ossi Nokelainen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - José Carlos Brito
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Porto, Portugal
| | | | - Janne K Valkonen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Zbyszek Boratyński
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Porto, Portugal
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14
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Allen WL, Moreno N, Gamble T, Chiari Y. Ecological, behavioral, and phylogenetic influences on the evolution of dorsal color pattern in geckos. Evolution 2020; 74:1033-1047. [PMID: 31886521 DOI: 10.1111/evo.13915] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 12/04/2019] [Accepted: 12/15/2019] [Indexed: 12/13/2022]
Abstract
The dorsal surfaces of many taxonomic groups often feature repetitive pattern elements consisting of stripes, spots, or bands. Here, we investigate how distinct categories of camouflage pattern work by relating them to ecological and behavioral traits in 439 species of gecko. We use phylogenetic comparative methods to test outstanding hypotheses based on camouflage theory and research in other taxa. We found that bands are associated with nocturnal activity, suggesting bands provide effective camouflage for motionless geckos resting in refugia during the day. A predicted association between stripes and diurnal activity was not supported, suggesting that stripes do not work via dazzle camouflage mechanisms in geckos. This, along with a lack of support for our prediction that plain patterning should be associated with open habitats, suggests that similar camouflage patterns do not work in consistent ways across taxa. We also found that plain and striped lineages frequently switched between using open or closed habitats, whereas spotted lineages rarely transitioned. This suggests that pattern categories differ in how specialized or generalized their camouflage is. This result has ramifications for theory on how camouflage compromises to background heterogeneity and how camouflage pattern might influence evolutionary trajectories.
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Affiliation(s)
- William L Allen
- Department of Biosciences, Swansea University, Swansea, UK, SA2 8PP
| | - Nickolas Moreno
- Department of Biology, University of South Alabama, Mobile, Alabama, 36688
| | - Tony Gamble
- Department of Biological Sciences, Marquette University, Milwaukee, Wisconsin, 53233.,Bell Museum of Natural History, University of Minnesota, Saint Paul, Minnesota, 55113.,Milwaukee Public Museum, Milwaukee, Wisconsin, 53233
| | - Ylenia Chiari
- Department of Biology, University of South Alabama, Mobile, Alabama, 36688.,Department of Biology, George Mason University, Manassas, Virginia, 20110
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15
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Edelaar P, Baños-Villalba A, Quevedo DP, Escudero G, Bolnick DI, Jordán-Andrade A. Biased movement drives local cryptic coloration on distinct urban pavements. Proc Biol Sci 2019; 286:20191343. [PMID: 31575366 DOI: 10.1098/rspb.2019.1343] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Explanations of how organisms might adapt to urban environments have mostly focused on divergent natural selection and adaptive plasticity. However, differential habitat choice has been suggested as an alternative. Here, we test for habitat choice in enhancing crypsis in ground-perching grasshoppers colonizing an urbanized environment, composed of a mosaic of four distinctly coloured substrates (asphalt roads and adjacent pavements). Additionally, we determine its relative importance compared to present-day natural selection and phenotypic plasticity. We found that grasshoppers are very mobile, but nevertheless approximately match the colour of their local substrate. By manipulating grasshopper colour, we confirm that grasshoppers increase the usage of those urban substrates that resemble their own colours. This selective movement actively improves crypsis. Colour divergence between grasshoppers on different substrates is not or hardly owing to present-day natural selection, because observed mortality rates are too low to counteract random substrate use. Additional experiments also show negligible contributions from plasticity in colour. Our results confirm that matching habitat choice can be an important driver of adaptation to urban environments. In general, studies should more fully incorporate that individuals are not only selective targets (i.e. selected on by the environment), but also selective agents (i.e. selecting their own environments).
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Affiliation(s)
- Pim Edelaar
- Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, Carretera Utrera km.1, 41013 Seville, Spain
| | - Adrian Baños-Villalba
- Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, Carretera Utrera km.1, 41013 Seville, Spain
| | - David P Quevedo
- Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, Carretera Utrera km.1, 41013 Seville, Spain.,Department of Ethology and Biodiversity Conservation, Doñana Biological Station-Spanish Research Council (EBD-CSIC), Avenida Americo Vespucio 26, 41092 Seville, Spain
| | - Graciela Escudero
- Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, Carretera Utrera km.1, 41013 Seville, Spain
| | - Daniel I Bolnick
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75N. Eagleville Road, Storrs, CT 06269-3043, USA.,Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Aída Jordán-Andrade
- Department of Molecular Biology and Biochemical Engineering, University Pablo de Olavide, Carretera Utrera km.1, 41013 Seville, Spain
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16
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Where to do number two: Lizards prefer to defecate on the largest rock in the territory. Behav Processes 2019; 167:103937. [DOI: 10.1016/j.beproc.2019.103937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/01/2019] [Accepted: 08/06/2019] [Indexed: 11/20/2022]
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17
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Dong CM, McLean CA, Moussalli A, Stuart‐Fox D. Conserved visual sensitivities across divergent lizard lineages that differ in an ultraviolet sexual signal. Ecol Evol 2019; 9:11824-11832. [PMID: 31695890 PMCID: PMC6822044 DOI: 10.1002/ece3.5686] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/02/2019] [Accepted: 09/05/2019] [Indexed: 01/04/2023] Open
Abstract
The sensory drive hypothesis predicts the correlated evolution of signaling traits and sensory perception in differing environments. For visual signals, adaptive divergence in both color signals and visual sensitivities between populations may contribute to reproductive isolation and promote speciation, but this has rarely been tested or shown in terrestrial species. We tested whether opsin protein expression differs between divergent lineages of the tawny dragon (Ctenophorus decresii) that differ in the presence/absence of an ultraviolet sexual signal. We measured the expression of four retinal cone opsin genes (SWS1, SWS2, RH2, and LWS) using droplet digital PCR. We show that gene expression between lineages does not differ significantly, including the UV wavelength sensitive SWS1. We discuss these results in the context of mounting evidence that visual sensitivities are highly conserved in terrestrial systems. Multiple competing requirements may constrain divergence of visual sensitivities in response to sexual signals. Instead, signal contrast could be increased via alternative mechanisms, such as background selection. Our results contribute to a growing understanding of the roles of visual ecology, phylogeny, and behavior on visual system evolution in reptiles.
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Affiliation(s)
- Caroline M. Dong
- School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
- Sciences DepartmentMuseums VictoriaCarltonVictoriaAustralia
| | - Claire A. McLean
- School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
- Sciences DepartmentMuseums VictoriaCarltonVictoriaAustralia
| | | | - Devi Stuart‐Fox
- School of BioSciencesThe University of MelbourneParkvilleVictoriaAustralia
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18
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Tong H, Li J, Wo Y, Shao G, Zhao W, Aguilar‐Gómez D, Jin Y. Effects of substrate color on intraspecific body color variation in the toad-headed lizard, Phrynocephalus versicolor. Ecol Evol 2019; 9:10253-10262. [PMID: 31624549 PMCID: PMC6787858 DOI: 10.1002/ece3.5545] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 12/19/2022] Open
Abstract
Diversity in animal coloration is generally associated with adaptation to their living habitats, ranging from territorial display and sexual selection to predation or predation avoidance, and thermoregulation. However, the mechanism underlying color variation in toad-headed Phrynocephalus lizards remains poorly understood. In this study, we investigated the population color variation of Phrynocephalus versicolor. We found that lizards distributed in dark substrate have darker dorsal coloration (melanic lizards) than populations living in light substrates. This characteristic may improve their camouflage effectiveness. A reciprocal substrate translocation experiment was conducted to clarify the potential role of morphological adaptation and physiological plasticity of this variation. Spectrometry technology and digital photography were used to quantify the color variation of the above-mentioned melanic and nonmelanic P. versicolor populations and their native substrate. Additionally, substrate color preference in both populations was investigated with choice experiments. Our results indicate that the melanic and nonmelanic populations with remarkable habitat color difference were significantly different on measured reflectance, luminance, and RGB values. Twenty-four hours, 30 days, and 60 days of substrate translocation treatment had little effects on dorsal color change. We also found that melanic lizards choose to live in dark substrate, while nonmelanic lizards have no preference for substrate color. In conclusion, our results support that the dorsal coloration of P. versicolor, associated with substrate color, is likely a morphological adaptation rather than phenotypic plasticity.
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Affiliation(s)
- Haojie Tong
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Jiasheng Li
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Yubin Wo
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Gang Shao
- College of Life SciencesChina Jiliang UniversityHangzhouChina
| | - Wei Zhao
- School of Life SciencesLanzhou UniversityLanzhouChina
| | | | - Yuanting Jin
- College of Life SciencesChina Jiliang UniversityHangzhouChina
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19
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Salisbury JW, Peters RA. Non-random perch selection by cryptic lizards, Amphibolurus muricatus. Behav Ecol Sociobiol 2019. [DOI: 10.1007/s00265-019-2730-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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20
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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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21
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Zduniak M, Pillay N, Schradin C. Basking African striped mice choose warmer locations to heat up: evidence from a field study. J Zool (1987) 2019. [DOI: 10.1111/jzo.12687] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Zduniak
- Department of Systematic Zoology Adam Mickiewicz University Poznań Poland
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
| | - N. Pillay
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
| | - C. Schradin
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
- IPHC, UNISTRA, CNRS Strasbourg France
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22
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Affiliation(s)
- I. C. Cuthill
- School of Biological Sciences University of Bristol Bristol UK
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23
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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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24
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Stevens M, Ruxton GD. The key role of behaviour in animal camouflage. Biol Rev Camb Philos Soc 2019; 94:116-134. [PMID: 29927061 PMCID: PMC6378595 DOI: 10.1111/brv.12438] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 05/25/2018] [Accepted: 05/31/2018] [Indexed: 01/24/2023]
Abstract
Animal camouflage represents one of the most important ways of preventing (or facilitating) predation. It attracted the attention of the earliest evolutionary biologists, and today remains a focus of investigation in areas ranging from evolutionary ecology, animal decision-making, optimal strategies, visual psychology, computer science, to materials science. Most work focuses on the role of animal morphology per se, and its interactions with the background in affecting detection and recognition. However, the behaviour of organisms is likely to be crucial in affecting camouflage too, through background choice, body orientation and positioning; and strategies of camouflage that require movement. A wealth of potential mechanisms may affect such behaviours, from imprinting and self-assessment to genetics, and operate at several levels (species, morph, and individual). Over many years there have been numerous studies investigating the role of behaviour in camouflage, but to date, no effort to synthesise these studies and ideas into a coherent framework. Here, we review key work on behaviour and camouflage, highlight the mechanisms involved and implications of behaviour, discuss the importance of this in a changing world, and offer suggestions for addressing the many important gaps in our understanding of this subject.
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Affiliation(s)
- Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental SciencesUniversity of Exeter, Penryn CampusPenryn, TR10 9FEU.K.
| | - Graeme D. Ruxton
- School of BiologyUniversity of St AndrewsSt Andrews, KY16 9THU.K.
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25
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Resolving tradeoffs among crypsis, escape behavior, and microhabitat use in sexually dichromatic species. Oecologia 2018; 189:91-104. [PMID: 30430233 DOI: 10.1007/s00442-018-4301-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 11/08/2018] [Indexed: 10/27/2022]
Abstract
Variation in color pattern between populations of cryptic animals is common and typically attributed to selection pressures from visual predators combined with variation in substrate composition. However, little is known about how cryptic color pattern relates to varied rates of predation, and few studies simultaneously analyze patterns of escape behavior and microhabitat use along with variation in color pattern, even though these traits evolve in tandem. Here, we use a combination of calibrated photographs and spectrometry to examine the influence of spatial heterogeneity in rates of predation on dorsal brightness in the Florida scrub lizard (Sceloporus woodi), a cryptic and sexually dimorphic species. Simultaneously, we analyze patterns of escape behavior and microhabitat use measured in the field. The results of this study indicate that populations inhabiting environments of increased predation have less color variation and more closely match the color of local substrate than populations sampled in environments of relaxed predation. Populations exposed to increased predation also show more pronounced escape behavior and are more selective in their use of microhabitat. Interestingly, geographic variation of dorsal brightness, escape behavior, and microhabitat use were greater for females than for males. Our results not only provide empirical evidence for theories of adaptive coloration, but suggest that sexual dichromatism can be maintained by selection pressures related to predation.
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26
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27
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Matthews G, Goulet CT, Delhey K, Atkins ZS, While GM, Gardner MG, Chapple DG. Avian predation intensity as a driver of clinal variation in colour morph frequency. J Anim Ecol 2018; 87:1667-1684. [PMID: 30098209 DOI: 10.1111/1365-2656.12894] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 07/28/2018] [Indexed: 12/23/2022]
Abstract
Phenotypic variation provides the framework for natural selection to work upon, enabling adaptive evolution. One of the most discernible manifestations of phenotypic variability is colour variation. When this variation is discrete, genetically based colour pattern morphs occur simultaneously within a population. Why and how colour polymorphisms are maintained is an evolutionary puzzle. Several evolutionary drivers have been hypothesized as influencing clinal patterns of morph frequency, with spatial variation in climate and predation being considered especially important. Despite this, no study has examined both of their roles simultaneously. The aims of this study were to: (a) examine the covariation of physiology, environmental variables and colouration at a local scale; and (b) determine if these factors and their interplay explain broad clinal variation in morph frequency. We used the lizard Liopholis whitii as a model system, as this species displays a discrete, heritable polymorphism for colour pattern (plain-backed, patterned morphs) whose morph frequency varies latitudinally. We measured reflectance, field activity temperatures and microhabitat structure to test for differences in crypsis, thermal biology and microhabitat selection of patterned and plain-backed morphs within a single population where colour morphs occur sympatrically. We then used data from the literature to perform a broad-scale analysis to identify whether these factors also explained the latitudinal variation of morph frequency in this species. At the local scale, plain-backed morphs were found to be less cryptic than patterned morphs while no other differences were detected in terms of thermal biology, dorsal reflectance and microhabitat use. At a broader scale, predation was the most influential factor mediating morph frequency across latitudes. However, the observed pattern of morph frequency is opposite to what the modelling results suggest in that the incidence of the least cryptic morph is highest where predation pressure is most severe. Clinal variation in the level of background matching between morphs or the potential reproductive advantage by the plain-backed morph may, instead, be driving the observed morph frequency. Together, these results provide key insights into the evolution of local adaptation as well as the ecological forces involved in driving the dynamics of colour polymorphism.
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Affiliation(s)
- Genevieve Matthews
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Celine T Goulet
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Kaspar Delhey
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Zak S Atkins
- Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Victoria, Australia
| | - Geoffrey M While
- School of Biological Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Michael G Gardner
- School of Biological Sciences, Flinders University of South Australia, Adelaide, South Australia, Australia.,The Evolutionary Biology Unit, South Australian Museum, Adelaide, South Australia, Australia
| | - David G Chapple
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
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28
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Walton OC, Stevens M. Avian vision models and field experiments determine the survival value of peppered moth camouflage. Commun Biol 2018; 1:118. [PMID: 30271998 PMCID: PMC6123793 DOI: 10.1038/s42003-018-0126-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/25/2018] [Indexed: 11/14/2022] Open
Abstract
Animal defensive coloration has long provided many important examples of evolution and adaptation. Of these, industrial melanism in the peppered moth is the classic textbook example of evolution in action, whereby dark and pale morphs suffer differential predation in polluted and unpolluted woodland based on their camouflage. Despite extensive work, a striking gap remains in that no study has ever objectively quantified their camouflage or related this directly to predation risk. Here we use image analysis and avian vision models to show that pale individuals more closely match lichen backgrounds than dark morphs. Artificial predation experiments in unpolluted woodland show 21% higher survival rates of pale than melanic individuals. Overall, we provide the strongest direct evidence to date that peppered moth morph frequencies stem from differential camouflage and avian predation, providing key support for this iconic example of natural selection.
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Affiliation(s)
- Olivia C Walton
- 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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Individual egg camouflage is influenced by microhabitat selection and use of nest materials in ground-nesting birds. Behav Ecol Sociobiol 2018. [DOI: 10.1007/s00265-018-2558-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Wilby D, Riches S, Daly IM, Bird A, Wheelwright M, Foster JJ. Hermit crabs (Pagurus bernhardus) use visual contrast in self-assessment of camouflage. J Exp Biol 2018; 221:221/13/jeb173831. [DOI: 10.1242/jeb.173831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 05/15/2018] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Animals can make use of camouflage to reduce the likelihood of visual detection or recognition and thus improve their chances of survival. Background matching, where body colouration is closely matched to the surrounding substrate, is one form of camouflage. Hermit crabs have the opportunity to choose their camouflage independently of body colouration as they inhabit empty gastropod shells, making them ideal to study their choice of camouflage. We used 3D-printed artificial shells of varying contrasts against a grey substrate to test whether hermit crabs prefer shells that they perceive as less conspicuous. Contrast-minimising shells were chosen for Weber contrasts stronger than −0.5. However, in looming experiments, animals responded to contrasts as weak as −0.2, indicating that while they can detect differences between shells and the background, they are only motivated to move into those shells when the alternatives contrast strongly. This suggests a trade-off between camouflage and vulnerability introduced by switching shells.
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Affiliation(s)
- David Wilby
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Samuel Riches
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Ilse M. Daly
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Andrew Bird
- School of Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
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Tan EJ, Reid CAM, Symonds MRE, Jurado-Rivera JA, Elgar MA. The Role of Life-History and Ecology in the Evolution of Color Patterns in Australian Chrysomeline Beetles. Front Ecol Evol 2017. [DOI: 10.3389/fevo.2017.00140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Olsson P, Lind O, Kelber A. Chromatic and achromatic vision: parameter choice and limitations for reliable model predictions. Behav Ecol 2017. [DOI: 10.1093/beheco/arx133] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Peter Olsson
- Department of Biology, Lund University, Lund, Sweden
| | - Olle Lind
- Department of Philosophy, Lund University, Lund, Sweden
| | - Almut Kelber
- Department of Biology, Lund University, Lund, Sweden
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Niu Y, Chen Z, Stevens M, Sun H. Divergence in cryptic leaf colour provides local camouflage in an alpine plant. Proc Biol Sci 2017; 284:20171654. [PMID: 28978734 PMCID: PMC5647307 DOI: 10.1098/rspb.2017.1654] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 08/31/2017] [Indexed: 11/12/2022] Open
Abstract
The efficacy of camouflage through background matching is highly environment-dependent, often resulting in intraspecific colour divergence in animals to optimize crypsis in different visual environments. This phenomenon is largely unexplored in plants, although several lines of evidence suggest they do use crypsis to avoid damage by herbivores. Using Corydalis hemidicentra, an alpine plant with cryptic leaf colour, we quantified background matching between leaves and surrounding rocks in five populations based on an approximate model of their butterfly enemy's colour perception. We also investigated the pigment basis of leaf colour variation and the association between feeding risk and camouflage efficacy. We show that plants exhibit remarkable colour divergence between populations, consistent with differences in rock appearances. Leaf colour varies because of a different quantitative combination of two basic pigments-chlorophyll and anthocyanin-plus different air spaces. As expected, leaf colours are better matched against their native backgrounds than against foreign ones in the eyes of the butterfly. Furthermore, improved crypsis tends to be associated with a higher level of feeding risk. These results suggest that divergent cryptic leaf colour may have evolved to optimize local camouflage in various visual environments, extending our understanding of colour evolution and intraspecific phenotype diversity in plants.
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Affiliation(s)
- Yang Niu
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
| | - Zhe Chen
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Hang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
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Nokelainen O, Hubbard N, Lown AE, Wood LE, Stevens M. Through predators’ eyes: phenotype–environment associations in shore crab coloration at different spatial scales. Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blx101] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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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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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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Klomp DA, Stuart-Fox D, Das I, Ord TJ. Gliding lizards use the position of the sun to enhance social display. Biol Lett 2017; 13:20160979. [PMID: 28179410 PMCID: PMC5326517 DOI: 10.1098/rsbl.2016.0979] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 01/14/2017] [Indexed: 11/12/2022] Open
Abstract
Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare example of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.
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Affiliation(s)
- Danielle A Klomp
- Evolution and Ecology Research Centre, and the School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
| | - Devi Stuart-Fox
- School of BioSciences, University of Melbourne, Melbourne, Australia
| | - Indraneil Das
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan, Sarawak, Malaysia
| | - Terry J Ord
- Evolution and Ecology Research Centre, and the School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, 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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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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Troscianko J, Wilson-Aggarwal J, Spottiswoode CN, Stevens M. Nest covering in plovers: How modifying the visual environment influences egg camouflage. Ecol Evol 2016; 6:7536-7545. [PMID: 27895898 PMCID: PMC5114662 DOI: 10.1002/ece3.2494] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/25/2016] [Accepted: 08/30/2016] [Indexed: 11/06/2022] Open
Abstract
Camouflage is one of the most widespread antipredator defences, and its mechanistic basis has attracted considerable interest in recent years. The effectiveness of camouflage depends on the interaction between an animal's appearance and its background. Concealment can therefore be improved by changes to an animal's own appearance, by behaviorally selecting an optimal background, or by modifying the background to better match the animal's own appearance. Research to date has largely focussed on the first of these mechanisms, whereas there has been little work on the second and almost none on the third. Even though a number of animal species may potentially modify their environment to improve individual-specific camouflage, this has rarely if ever been quantitatively investigated, or its adaptive value tested. Kittlitz's plovers (Charadrius pecuarius) use material (stones and vegetation) to cover their nests when predators approach, providing concealment that is independent of the inflexible appearance of the adult or eggs, and that can be adjusted to suit the local surrounding background. We used digital imaging and predator vision modeling to investigate the camouflage properties of covered nests, and whether their camouflage affected their survival. The plovers' nest-covering materials were consistent with a trade-off between selecting materials that matched the color of the eggs, while resulting in poorer nest pattern and contrast matching to the nest surroundings. Alternatively, the systematic use of materials with high-contrast and small-pattern grain sizes could reflect a deliberate disruptive coloration strategy, whereby high-contrast material breaks up the telltale outline of the clutch. No camouflage variables predicted nest survival. Our study highlights the potential for camouflage to be enhanced by background modification. This provides a flexible system for modifying an animal's conspicuousness, to which the main limitation may be the available materials rather than the animal's appearance.
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Affiliation(s)
| | | | - Claire N Spottiswoode
- Department of Zoology University of Cambridge Cambridge UK; DST-NRF Centre of Excellence at the FitzPatrick Institute University of Cape Town Cape Town South Africa
| | - Martin Stevens
- Centre for Ecology and Conservation University of Exeter Penryn UK
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