1
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Wang S, Vasas V, Freeland L, Osorio D, Versace E. Spontaneous biases enhance generalization in the neonate brain. iScience 2024; 27:110195. [PMID: 38989452 PMCID: PMC11233965 DOI: 10.1016/j.isci.2024.110195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 03/25/2024] [Accepted: 06/03/2024] [Indexed: 07/12/2024] Open
Abstract
Inductive generalization is adaptive in novel contexts for both biological and artificial intelligence. Spontaneous generalization in inexperienced animals raises questions on whether predispositions (evolutionarily acquired biases, or priors) enable generalization from sparse data, without reinforcement. We exposed neonate chicks to an artificial social partner of a specific color, and then looked at generalization on the red-yellow or blue-green ranges. Generalization was inconsistent with an unbiased model. Biases included asymmetrical generalization gradients, some preferences for unfamiliar stimuli, different speed of learning, faster learning for colors infrequent in the natural spectrum. Generalization was consistent with a Bayesian model that incorporates predispositions as initial preferences and treats the learning process as an update of predispositions. Newborn chicks are evolutionarily prepared for generalization, via biases independent from experience, reinforcement, or supervision. To solve the problem of induction, biological and artificial intelligence can use biases tuned to infrequent stimuli, such as the red and blue colors.
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Affiliation(s)
- Shuge Wang
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Vera Vasas
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Laura Freeland
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Daniel Osorio
- School of Life Sciences, University of Sussex, Brighton, UK
| | - Elisabetta Versace
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
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2
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Gawel L, Powell EC, Brock M, Taylor LA. Conspicuous stripes on prey capture attention and reduce attacks by foraging jumping spiders. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230907. [PMID: 38026030 PMCID: PMC10663800 DOI: 10.1098/rsos.230907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/30/2023] [Indexed: 12/01/2023]
Abstract
Many animals avoid predation using aposematic displays that pair toxic/dangerous defences with conspicuous achromatic warning patterns, such as high-contrast stripes. To understand how these prey defences work, we need to understand the decision-making of visual predators. Here we gave two species of jumping spiders (Phidippus regius and Habronattus trimaculatus) choice tests using live termites that had their back patterns manipulated using paper capes (solid white, solid black, striped). For P. regius, black and striped termites were quicker to capture attention. Yet despite this increased attention, striped termites were attacked at lower rates than either white or black. This suggests that the termite's contrast with the background elicits attention, but the internal striped body patterning reduces attacks. Results from tests with H. trimaculatus were qualitatively similar but did not meet the threshold for statistical significance. Additional exploratory analyses suggest that attention to and aversion to stripes is at least partially innate and provide further insight into how decision-making played out during trials. Because of their rich diversity (over 6500 species) that includes variation in natural history, toxin susceptibility and degree of colour vision, jumping spiders are well suited to test broad generalizations about how and why aposematic displays work.
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Affiliation(s)
- Lauren Gawel
- Entomology and Nematology Department, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
| | - Erin C. Powell
- Entomology and Nematology Department, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
- Florida State Collection of Arthropods, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, 1911 SW 34th St, Gainesville, FL 32608, USA
| | - Michelle Brock
- Entomology and Nematology Department, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
| | - Lisa A. Taylor
- Entomology and Nematology Department, University of Florida, 1881 Natural Area Drive, Gainesville, FL 32611, USA
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3
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Rucker F, Taylor C, Kaser-Eichberger A, Schroedl F. Parasympathetic and sympathetic control of emmetropization in chick. Exp Eye Res 2023; 232:109508. [PMID: 37230289 PMCID: PMC10452042 DOI: 10.1016/j.exer.2023.109508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/04/2023] [Accepted: 05/15/2023] [Indexed: 05/27/2023]
Abstract
Emmetropization can be altered by temporal visual stimulation and the spectral properties of the visual environment. The goal of the current experiment is to test the hypothesis that there is an interaction between these properties and autonomic innervation. For that purpose, selective lesions of the autonomic nervous system were performed in chickens followed by temporal stimulation. Parasympathetic lesioning involved transection of both the ciliary ganglion and the pterygopalatine ganglion (PPG_CGX; n = 38), while sympathetic lesioning involved transection of the superior cervical ganglion (SCGX; n = 49). After one week of recovery, chicks were then exposed to temporally modulated light (3 days, 2 Hz, Mean: 680 lux) that was either achromatic (with blue [RGB], or without blue [RG]), or chromatic (with blue [B/Y] or without blue [R/G]). Control birds with lesions, or unlesioned, were exposed to white [RGB] or yellow [RG] light. Ocular biometry and refraction (Lenstar and a Hartinger refractometer) was measured before and after exposure to light stimulation. Measurements were statistically analyzed for the effects of a lack of autonomic input and the type of temporal stimulation. In PPG_CGX lesioned eyes, there was no effect of the lesions one-week post-surgery. However, after exposure to achromatic modulation, the lens thickened (with blue) and the choroid thickened (without blue) but there was no effect on axial growth. Chromatic modulation thinned the choroid with R/G. In the SGX lesioned eye, there was no effect of the lesion 1-week post-surgery. However, after exposure to achromatic modulation (without blue), the lens thickened and there was a reduction in vitreous chamber depth and axial length. Chromatic modulation caused a small increase in vitreous chamber depth with R/G. Both autonomic lesion and visual stimulation were necessary to affect the growth of ocular components. The bidirectional responses observed in axial growth and in choroidal changes suggest that autonomic innervation combined with spectral cues from longitudinal chromatic aberration may provide a mechanism for homeostatic control of emmetropization.
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Affiliation(s)
- Frances Rucker
- New England College of Optometry, 424 Beacon St., Boston, MA, 02115, USA.
| | - Chris Taylor
- New England College of Optometry, 424 Beacon St., Boston, MA, 02115, USA
| | - Alexandra Kaser-Eichberger
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology - Salzburg Paracelsus Medical University, Salzburg, Austria
| | - Falk Schroedl
- Center for Anatomy and Cell Biology, Institute of Anatomy and Cell Biology - Salzburg Paracelsus Medical University, Salzburg, Austria
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4
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McLellan CF, Cuthill IC, Montgomery SH. Pattern variation is linked to anti-predator coloration in butterfly larvae. Proc Biol Sci 2023; 290:20230811. [PMID: 37357867 PMCID: PMC10291709 DOI: 10.1098/rspb.2023.0811] [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: 04/05/2023] [Accepted: 06/07/2023] [Indexed: 06/27/2023] Open
Abstract
Prey animals typically try to avoid being detected and/or advertise to would-be predators that they should be avoided. Both anti-predator strategies primarily rely on colour to succeed, but the specific patterning used is also important. While the role of patterning in camouflage is relatively clear, the design features of aposematic patterns are less well understood. Here, we use a comparative approach to investigate how pattern use varies across a phylogeny of 268 species of cryptic and aposematic butterfly larvae, which also vary in social behaviour. We find that longitudinal stripes are used more frequently by cryptic larvae, and that patterns putatively linked to crypsis are more likely to be used by solitary larvae. By contrast, aposematic larvae are more likely to use horizontal bands and spots, but we find no differences in the use of individual pattern elements between solitary and gregarious aposematic species. However, solitary aposematic larvae are more likely to display multiple pattern elements, whereas those with no pattern are more likely to be gregarious. Our study advances our understanding of how pattern variation, coloration and social behaviour covary across lepidopteran larvae, and highlights new questions about how patterning affects larval detectability and predator responses to aposematic prey.
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Affiliation(s)
- Callum F. McLellan
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Innes C. Cuthill
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Stephen H. Montgomery
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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5
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de Alcantara Viana JV, Vieira C, Duarte RC, Romero GQ. Predator responses to prey camouflage strategies: a meta-analysis. Proc Biol Sci 2022; 289:20220980. [PMID: 36100020 PMCID: PMC9470275 DOI: 10.1098/rspb.2022.0980] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/15/2022] [Indexed: 11/12/2022] Open
Abstract
Although numerous studies about camouflage have been conducted in the last few decades, there is still a significant gap in our knowledge about the magnitude of protective value of different camouflage strategies in prey detection and survival. Furthermore, the functional significance of several camouflage strategies remains controversial. Here we carried out a comprehensive meta-analysis including comparisons of different camouflage strategies as well as predator and prey types, considering two response variables: mean predator search time (ST) (63 studies) and predator attack rate (AR) of camouflaged prey (28 studies). Overall, camouflage increased the predator ST by 62.56% and decreased the AR of prey by 27.34%. Masquerade was the camouflage strategy that most increased predator ST (295.43%). Background matching and disruptive coloration did not differ from each other. Motion camouflage did not increase ST but decreases AR on prey. We found no evidence that eyespot increases ST and decreases AR by predators. The different types of predators did not differ from each other, but caterpillars were the type of prey that most influenced the magnitude of camouflage's effect. We highlight the potential evolutionary mechanisms that led camouflage to be a highly effective anti-predatory adaptation, as well as potential discrepancies or redundancies among strategies, predator and prey types.
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Affiliation(s)
- João Vitor de Alcantara Viana
- Programa de Pós-graduação em Ecologia, Universidade Estadual de Campinas (UNICAMP), Instituto de Biologia, Laboratório de Interações Multitróficas e Biodiversidade, Campinas, São Paulo, Brazil
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, CEP 13083-970 Campinas, São Paulo, Brazil
| | - Camila Vieira
- Departamento de Ciências Básicas, Universidade de São Paulo (USP), campus de Pirassununga, CEP 13635-900 Pirassununga, São Paulo, Brazil
| | - Rafael Campos Duarte
- Universidade Federal do ABC, CEP 09606-045 São Bernardo do Campo, São Paulo, Brazil
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Gustavo Quevedo Romero
- Laboratório de Interações Multitróficas e Biodiversidade, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), CP 6109, CEP 13083-970 Campinas, São Paulo, Brazil
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6
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de Alcantara Viana JV, Lourenço Garcia de Brito V, de Melo C. Colour matching by arthropods in burned and unburned backgrounds in a Neotropical savanna. AUSTRAL ECOL 2022. [DOI: 10.1111/aec.13225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- João Vitor de Alcantara Viana
- Programa de Pós‐Graduação em Ecologia e Conservação de Recursos Naturais, Laboratório de Ornitologia e Bioacústica Universidade Federal de Uberlândia (UFU) Uberlândia Brazil
- Programa de Pós‐Graduação em Ecologia, Laboratório de Interações Multitróficas e Biodiversidade, Instituto de Biologia Universidade Estadual de Campinas (UNICAMP) Campinas
- Laboratório de Interações Multitróficas e Biodiversidade Departamento de Biologia Animal, Instituto de Biologia Universidade Estadual de Campinas CP 6109, CEP 13083-970 Campinas São Paulo Brazil
| | | | - Celine de Melo
- Instituto de Biologia Universidade Federal de Uberlândia Uberlândia Brazil
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7
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Gulizia JP, Downs KM. The Effects of Feed Color on Broiler Performance between Day 1 and 21. Animals (Basel) 2021; 11:1511. [PMID: 34071014 PMCID: PMC8224657 DOI: 10.3390/ani11061511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/12/2021] [Accepted: 05/20/2021] [Indexed: 11/16/2022] Open
Abstract
Two trials were conducted to determine feed color effects on broiler performance. A completely randomized design was used. Trial 1 included four treatments: control (complete broiler starter diet), red, green, and blue; and Trial 2 included four treatments: control, orange, yellow, and purple. Each trial had 4 treatments with 4 replicates (60 birds/treatment) fed to 240 male Cobb 500 broilers during a 21 d grow out. Data were analyzed using the GLM procedure. In Trial 1, there were no treatment effects on average body weight, body weight gain, and feed consumption (p > 0.05). Adjusted feed conversion for control (1.23) was less than red (1.27; p = 0.001) and green (1.26; p = 0.009), with blue (1.25; p = 0.056) tending to be different during the experimental period. In Trial 2, there were no treatment effects on average body weight, feed consumption, and adjusted feed conversion during this study (p > 0.05). Body weight gain between d 1 to 14 for purple (490.78 g/bird) was more than orange (467 g/bird; p = 0.013) and yellow (461 g/bird; p= 0.004), with control (474 g/bird; p = 0.052) tending to be different. Results indicate that these feed colors had some, albeit limited, influence on broiler performance parameters.
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Affiliation(s)
| | - Kevin M. Downs
- School of Agriculture, Middle Tennessee State University, Murfreesboro, TN 37132, USA;
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8
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White TE, Umbers KDL. Meta-analytic evidence for quantitative honesty in aposematic signals. Proc Biol Sci 2021; 288:20210679. [PMID: 33906408 PMCID: PMC8080005 DOI: 10.1098/rspb.2021.0679] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 04/08/2021] [Indexed: 12/30/2022] Open
Abstract
The combined use of noxious chemical defences and conspicuous warning colours is a ubiquitous anti-predator strategy. That such signals advertise the presence of defences is inherent to their function, but their predicted potential for quantitative honesty-the positive scaling of signal salience with the strength of protection-is the subject of enduring debate. Here, we systematically synthesized the available evidence to test this prediction using meta-analysis. We found evidence for a positive correlation between warning colour expression and the extent of chemical defences across taxa. Notably, this relationship held at all scales; among individuals, populations and species, though substantial between-study heterogeneity remains unexplained. Consideration of the design of signals revealed that all visual features, from colour to contrast, were equally informative of the extent of prey defence. Our results affirm a central prediction of honesty-based models of signal function and narrow the scope of possible mechanisms shaping the evolution of aposematism. They suggest diverse pathways to the encoding and exchange of information, while highlighting the need for deeper knowledge of the ecology of chemical defences to enrich our understanding of this widespread anti-predator adaptation.
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Affiliation(s)
- Thomas E. White
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales 2106, Australia
| | - Kate D. L. Umbers
- School of Science, Western Sydney University, Penrith, New South Wales 2751, Australia
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales 2751, Australia
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9
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Variation in carotenoid-containing retinal oil droplets correlates with variation in perception of carotenoid coloration. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02874-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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10
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Pattern contrast influences wariness in naïve predators towards aposematic patterns. Sci Rep 2020; 10:9246. [PMID: 32514003 PMCID: PMC7280217 DOI: 10.1038/s41598-020-65754-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 04/27/2020] [Indexed: 11/08/2022] Open
Abstract
An apparent and common feature of aposematic patterns is that they contain a high level of achromatic (luminance) contrast, for example, many warning signals combine black spots and stripes with a lighter colour such as yellow. However, the potential importance of achromatic contrast, as distinct from colour contrast, in reducing predation has been largely overlooked. Here, using domestic chicks as a model predator, we manipulated the degree of achromatic contrast in warning patterns to test if high luminance contrast in aposematic signals is important for deterring naïve predators. We found that the chicks were less likely to approach and eat prey with high contrast compared to low contrast patterns. These findings suggest that aposematic prey patterns with a high luminance contrast can benefit from increased survival through eliciting unlearned biases in naïve avian predators. Our work also highlights the importance of considering luminance contrast in future work investigating why aposematic patterns take the particular forms that they do.
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11
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Zidar J, Balogh ACV, Leimar O, Løvlie H. Generalization of learned preferences covaries with behavioral flexibility in red junglefowl chicks. Behav Ecol 2019; 30:1375-1381. [PMID: 31579147 PMCID: PMC6765379 DOI: 10.1093/beheco/arz088] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 04/19/2019] [Accepted: 07/08/2019] [Indexed: 11/18/2022] Open
Abstract
The relationship between animal cognition and consistent among-individual behavioral differences (i.e., behavioral types, animal personality, or coping styles), has recently received increased research attention. Focus has mainly been on linking different behavioral types to performance in learning tasks. It has been suggested that behavioral differences could influence also how individuals use previously learnt information to generalize about new stimuli with similar properties. Nonetheless, this has rarely been empirically tested. Here, we therefore explore the possibility that individual variation in generalization is related to variation in behavioral types in red junglefowl chicks (Gallus gallus). We show that more behaviorally flexible chicks have a stronger preference for a novel stimulus that is intermediate between 2 learnt positive stimuli compared to more inflexible chicks. Thus, more flexible and inflexible chicks differ in how they generalize. Further, behavioral flexibility correlates with fearfulness, suggesting a coping style, supporting that variation in generalization is related to variation in behavioral types. How individuals generalize affects decision making and responses to novel situations or objects, and can thus have a broad influence on the life of an individual. Our results add to the growing body of evidence linking cognition to consistent behavioral differences.
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Affiliation(s)
- Josefina Zidar
- Department of Physics, Chemistry and Biology, IFM Biology, Linköping University, Campus Valla, inköping, Sweden
| | - Alexandra C V Balogh
- Department of Physics, Chemistry and Biology, IFM Biology, Linköping University, Campus Valla, inköping, Sweden
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Olof Leimar
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Hanne Løvlie
- Department of Physics, Chemistry and Biology, IFM Biology, Linköping University, Campus Valla, inköping, Sweden
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12
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Thoreson WB, Dacey DM. Diverse Cell Types, Circuits, and Mechanisms for Color Vision in the Vertebrate Retina. Physiol Rev 2019; 99:1527-1573. [PMID: 31140374 PMCID: PMC6689740 DOI: 10.1152/physrev.00027.2018] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 01/13/2023] Open
Abstract
Synaptic interactions to extract information about wavelength, and thus color, begin in the vertebrate retina with three classes of light-sensitive cells: rod photoreceptors at low light levels, multiple types of cone photoreceptors that vary in spectral sensitivity, and intrinsically photosensitive ganglion cells that contain the photopigment melanopsin. When isolated from its neighbors, a photoreceptor confounds photon flux with wavelength and so by itself provides no information about color. The retina has evolved elaborate color opponent circuitry for extracting wavelength information by comparing the activities of different photoreceptor types broadly tuned to different parts of the visible spectrum. We review studies concerning the circuit mechanisms mediating opponent interactions in a range of species, from tetrachromatic fish with diverse color opponent cell types to common dichromatic mammals where cone opponency is restricted to a subset of specialized circuits. Distinct among mammals, primates have reinvented trichromatic color vision using novel strategies to incorporate evolution of an additional photopigment gene into the foveal structure and circuitry that supports high-resolution vision. Color vision is absent at scotopic light levels when only rods are active, but rods interact with cone signals to influence color perception at mesopic light levels. Recent evidence suggests melanopsin-mediated signals, which have been identified as a substrate for setting circadian rhythms, may also influence color perception. We consider circuits that may mediate these interactions. While cone opponency is a relatively simple neural computation, it has been implemented in vertebrates by diverse neural mechanisms that are not yet fully understood.
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Affiliation(s)
- Wallace B Thoreson
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center , Omaha, Nebraska ; and Department of Biological Structure, Washington National Primate Research Center, University of Washington , Seattle, Washington
| | - Dennis M Dacey
- Department of Ophthalmology and Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical Center , Omaha, Nebraska ; and Department of Biological Structure, Washington National Primate Research Center, University of Washington , Seattle, Washington
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13
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Zipple MN, Caves EM, Green PA, Peters S, Johnsen S, Nowicki S. Categorical colour perception occurs in both signalling and non-signalling colour ranges in a songbird. Proc Biol Sci 2019; 286:20190524. [PMID: 31138066 DOI: 10.1098/rspb.2019.0524] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although perception begins when a stimulus is transduced by a sensory neuron, numerous perceptual mechanisms can modify sensory information as it is processed by an animal's nervous system. One such mechanism is categorical perception, in which (1) continuously varying stimuli are labelled as belonging to a discrete number of categories and (2) there is enhanced discrimination between stimuli from different categories as compared with equally different stimuli from within the same category. We have shown previously that female zebra finches ( Taeniopygia guttata) categorically perceive colours along an orange-red continuum that aligns with the carotenoid-based coloration of male beaks, a trait that serves as an assessment signal in female mate choice. Here, we demonstrate that categorical perception occurs along a blue-green continuum as well, suggesting that categorical colour perception may be a general feature of zebra finch vision. Although we identified two categories in both the blue-green and the orange-red ranges, we also found that individuals could better differentiate colours from within the same category in the blue-green as compared with the orange-red range, indicative of less clear categorization in the blue-green range. We discuss reasons why categorical perception may vary across the visible spectrum, including the possibility that such differences are linked to the behavioural or ecological function of different colour ranges.
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Affiliation(s)
| | | | | | - Susan Peters
- Biology Department, Duke University , Durham NC , USA
| | - Sönke Johnsen
- Biology Department, Duke University , Durham NC , USA
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14
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Galván I. Correlated Evolution of White Spots on Ears and Closed Habitat Preferences in Felids. J MAMM EVOL 2019. [DOI: 10.1007/s10914-019-09464-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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15
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Briolat ES, Zagrobelny M, Olsen CE, Blount JD, Stevens M. No evidence of quantitative signal honesty across species of aposematic burnet moths (Lepidoptera: Zygaenidae). J Evol Biol 2018; 32:31-48. [PMID: 30317689 PMCID: PMC6378400 DOI: 10.1111/jeb.13389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 10/03/2018] [Accepted: 10/09/2018] [Indexed: 11/30/2022]
Abstract
Many defended species use conspicuous visual warning signals to deter potential predators from attacking. Traditional theory holds that these signals should converge on similar forms, yet variation in visual traits and the levels of defensive chemicals is common, both within and between species. It is currently unclear how the strength of signals and potency of defences might be related: conflicting theories suggest that aposematic signals should be quantitatively honest, or, in contrast, that investment in one component should be prioritized over the other, while empirical tests have yielded contrasting results. Here, we advance this debate by examining the relationship between defensive chemicals and signal properties in a family of aposematic Lepidoptera, accounting for phylogenetic relationships and quantifying coloration from the perspective of relevant predators. We test for correlations between toxin levels and measures of wing colour across 14 species of day‐flying burnet and forester moths (Lepidoptera: Zygaenidae), protected by highly aversive cyanogenic glucosides, and find no clear evidence of quantitative signal honesty. Significant relationships between toxin levels and coloration vary between sexes and sampling years, and several trends run contrary to expectations for signal honesty. Although toxin concentration is positively correlated with increasing luminance contrast in forewing pattern in 1 year, higher toxin levels are also associated with paler and less chromatically salient markings, at least in females, in another year. Our study also serves to highlight important factors, including sex‐specific trends and seasonal variation, that should be accounted for in future work on signal honesty in aposematic species.
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Affiliation(s)
- Emmanuelle S Briolat
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, UK
| | - Mika Zagrobelny
- Plant Biochemistry Laboratory and Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Carl E Olsen
- Plant Biochemistry Laboratory and Copenhagen Plant Science Centre, Department of Plant and Environmental Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonathan D Blount
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, UK
| | - Martin Stevens
- Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn, UK
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16
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Green NF, Urquhart HH, van den Berg CP, Marshall NJ, Cheney KL. Pattern edges improve predator learning of aposematic signals. Behav Ecol 2018. [DOI: 10.1093/beheco/ary089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Naomi F Green
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Holly H Urquhart
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Cedric P van den Berg
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
- Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
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17
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Xavier GM, Brito VLG, Gonzaga MO. Colour matching in an orb‐web spider: a twig‐masquerading species as seen by potential predators. J Zool (1987) 2018. [DOI: 10.1111/jzo.12568] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. M. Xavier
- Pós‐Graduação em Ecologia e Conservação de Recursos Naturais Universidade Federal de Uberlândia Uberlândia Brazil
| | - V. L. G. Brito
- Instituto de Biologia Universidade Federal de Uberlândia Uberlândia Brazil
| | - M. O. Gonzaga
- Instituto de Biologia Universidade Federal de Uberlândia Uberlândia Brazil
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18
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Mitkus M, Olsson P, Toomey MB, Corbo JC, Kelber A. Specialized photoreceptor composition in the raptor fovea. J Comp Neurol 2017; 525:2152-2163. [PMID: 28199005 PMCID: PMC6235456 DOI: 10.1002/cne.24190] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 01/13/2017] [Accepted: 02/07/2017] [Indexed: 11/08/2022]
Abstract
The retinae of many bird species contain a depression with high photoreceptor density known as the fovea. Many species of raptors have two foveae, a deep central fovea and a shallower temporal fovea. Birds have six types of photoreceptors: rods, active in dim light, double cones that are thought to mediate achromatic discrimination, and four types of single cones mediating color vision. To maximize visual acuity, the fovea should only contain photoreceptors contributing to high-resolution vision. Interestingly, it has been suggested that raptors might lack double cones in the fovea. We used transmission electron microscopy and immunohistochemistry to evaluate this claim in five raptor species: the common buzzard (Buteo buteo), the honey buzzard (Pernis apivorus), the Eurasian sparrowhawk (Accipiter nisus), the red kite (Milvus milvus), and the peregrine falcon (Falco peregrinus). We found that all species, except the Eurasian sparrowhawk, lack double cones in the center of the central fovea. The size of the double cone-free zone differed between species. Only the common buzzard had a double cone-free zone in the temporal fovea. In three species, we examined opsin expression in the central fovea and found evidence that rod opsin positive cells were absent and violet-sensitive cone and green-sensitive cone opsin positive cells were present. We conclude that not only double cones, but also single cones may contribute to high-resolution vision in birds, and that raptors may in fact possess high-resolution tetrachromatic vision in the central fovea.
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Affiliation(s)
- Mindaugas Mitkus
- Lund Vision Group, Department of Biology, Lund University, Sölvegatan 35, 22364, Lund, Sweden
| | - Peter Olsson
- Lund Vision Group, Department of Biology, Lund University, Sölvegatan 35, 22364, Lund, Sweden
| | - Matthew B. Toomey
- Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Joseph C. Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
| | - Almut Kelber
- Lund Vision Group, Department of Biology, Lund University, Sölvegatan 35, 22364, Lund, Sweden
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19
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DELL'AGLIO DENISED, STEVENS MARTIN, JIGGINS CHRISD. Avoidance of an aposematically coloured butterfly by wild birds in a tropical forest. ECOLOGICAL ENTOMOLOGY 2016; 41:627-632. [PMID: 27708481 PMCID: PMC5026159 DOI: 10.1111/een.12335] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 04/14/2016] [Accepted: 05/18/2016] [Indexed: 06/06/2023]
Abstract
1. Birds are considered to be the primary selective agents for warning colouration in butterflies, and select for aposematic mimicry by learning to avoid brightly coloured prey after unpleasant experiences. It has long been thought that bright colouration plays an important role in promoting the avoidance of distasteful prey by birds. 2. The hypothesis that warning colouration facilitates memorability and promotes predator avoidance was tested by means of a field experiment using distasteful model butterflies. Artificial butterflies with a Heliconius colour pattern unknown to local birds were generated using bird vision models, either coloured or achromatic, and hung in tree branches in a tropical forest. Two sequential trials were conducted at each site to test avoidance by naïve and experienced predators. 3. There was a significant reduction in predation in the second trial. Also, coloured models were attacked less than achromatic models. Specifically, coloured butterflies were attacked significantly less in the second trial, but there was no significant decrease in predation on achromatic models. 4. The present results imply an important role for colour in enhancing aversion of aposematic butterflies. It has also been demonstrated that previous experience of distasteful prey can lead to enhanced avoidance in subsequent trials, supporting mimicry theory.
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Affiliation(s)
- DENISE D. DELL'AGLIO
- Butterfly Genetics Group, Department of ZoologyUniversity of CambridgeCambridgeU.K.
- Smithsonian Tropical Research InstitutePanama CityPanama
| | - MARTIN STEVENS
- Centre for Ecology & Conservation, College of Life & Environmental SciencesUniversity of ExeterPenrynU.K.
| | - CHRIS D. JIGGINS
- Butterfly Genetics Group, Department of ZoologyUniversity of CambridgeCambridgeU.K.
- Smithsonian Tropical Research InstitutePanama CityPanama
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20
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Effects of directionality, signal intensity, and short-wavelength components on iridescent warning signal efficacy. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2141-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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21
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Rothman GR, Blackiston DJ, Levin M. Color and intensity discrimination in Xenopus laevis tadpoles. Anim Cogn 2016; 19:911-9. [PMID: 27146661 DOI: 10.1007/s10071-016-0990-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 04/19/2016] [Accepted: 04/25/2016] [Indexed: 12/12/2022]
Abstract
Investigations into the physiology of Xenopus laevis have the potential to greatly accelerate biomedical research, especially concerning neural plasticity and sensory systems, but are limited by the lack of available information on behavioral learning in this species. Here, we attempt to lay the foundations for a behavioral assay in Xenopus that can be used in conjunction with biological manipulations. We tested cohorts of Xenopus tadpoles across four light-mediated active-avoidance experiments, using either wavelength or intensity as the salient discriminative cue. In the wavelength task, we determine a baseline learning rate and characterize retention of learning, identifying active extinction effects as far more potent than the passage of time in the loss of behavior. In the intensity task, we examine the effects of varying differences between the discriminative stimuli on acquisition and extinction and identify a critical range of intensity differences where learning changes. The results of our experiments demonstrate that Xenopus is a tractable model organism for cognitive research and can learn a variety of associative tasks in the laboratory settings. These data reveal new aspects of the Xenopus larval visual processing system and facilitate future research between cognitive methods and biological/chemical manipulations to study mechanisms of brain structure and function.
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Affiliation(s)
- Gabriel R Rothman
- Department of Biology, Center for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA, 02155, USA
| | - Douglas J Blackiston
- Department of Biology, Center for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA, 02155, USA
| | - Michael Levin
- Department of Biology, Center for Regenerative and Developmental Biology, Tufts University, 200 Boston Avenue, Suite 4600, Medford, MA, 02155, USA.
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22
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Kang C, Cho HJ, Lee SI, Jablonski PG. Post-attack Aposematic Display in Prey Facilitates Predator Avoidance Learning. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00035] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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23
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24
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Willink B, García-Rodríguez A, Bolaños F, Pröhl H. The interplay between multiple predators and prey colour divergence. Biol J Linn Soc Lond 2014. [DOI: 10.1111/bij.12355] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Beatriz Willink
- Escuela de Biología; Universidad de Costa Rica; Ciudad Universitaria Rodrigo Facio 2060 San José Costa Rica
- Department of Biology; Lund University; SE-223 62 Lund Sweden
| | - Adrián García-Rodríguez
- Museo de Zoología; Universidad de Costa Rica; Ciudad Universitaria Rodrigo Facio 2060 San José Costa Rica
- Departamento de Botanica, Ecologia e Zoologia; Universidade Federal do Rio Grande do Norte; Natal Rio Grande do Norte Brazil
| | - Federico Bolaños
- Escuela de Biología; Universidad de Costa Rica; Ciudad Universitaria Rodrigo Facio 2060 San José Costa Rica
| | - Heike Pröhl
- Institute of Zoology; University of Veterinary Medicine of Hannover; Bünteweg 17 30559 Hannover Germany
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25
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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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26
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Ferreira WC, Marcon D. Revisiting the 1879 model for Evolutionary Mimicry by Fritz Müller: New mathematical approaches. ECOLOGICAL COMPLEXITY 2014. [DOI: 10.1016/j.ecocom.2013.07.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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27
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28
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Fabricant SA, Exnerová A, Ježová D, Štys P. Scared by shiny? The value of iridescence in aposematic signalling of the hibiscus harlequin bug. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.01.021] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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29
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Cheney KL, Cortesi F, How MJ, Wilson NG, Blomberg SP, Winters AE, Umanzör S, Marshall NJ. Conspicuous visual signals do not coevolve with increased body size in marine sea slugs. J Evol Biol 2014; 27:676-87. [PMID: 24588922 DOI: 10.1111/jeb.12348] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 01/13/2014] [Accepted: 01/23/2014] [Indexed: 11/29/2022]
Abstract
Many taxa use conspicuous colouration to attract mates, signal chemical defences (aposematism) or for thermoregulation. Conspicuousness is a key feature of aposematic signals, and experimental evidence suggests that predators avoid conspicuous prey more readily when they exhibit larger body size and/or pattern elements. Aposematic prey species may therefore evolve a larger body size due to predatory selection pressures, or alternatively, larger prey species may be more likely to evolve aposematic colouration. Therefore, a positive correlation between conspicuousness and body size should exist. Here, we investigated whether there was a phylogenetic correlation between the conspicuousness of animal patterns and body size using an intriguing, understudied model system to examine questions on the evolution of animal signals, namely nudibranchs (opisthobranch molluscs). We also used new ways to compare animal patterns quantitatively with their background habitat in terms of intensity variance and spatial frequency power spectra. In studies of aposematism, conspicuousness is usually quantified using the spectral contrast of animal colour patches against its background; however, other components of visual signals, such as pattern, luminance and spectral sensitivities of potential observers, are largely ignored. Contrary to our prediction, we found that the conspicuousness of body patterns in over 70 nudibranch species decreased as body size increased, indicating that crypsis was not limited to a smaller body size. Therefore, alternative selective pressures on body size and development of colour patterns, other than those inflicted by visual hunting predators, may act more strongly on the evolution of aposematism in nudibranch molluscs.
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Affiliation(s)
- K L Cheney
- School of Biological Sciences, The University of Queensland, St Lucia, Qld, Australia
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30
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Willink B, Brenes-Mora E, Bolaños F, Pröhl H. Not everything is black and white: color and behavioral variation reveal a continuum between cryptic and aposematic strategies in a polymorphic poison frog. Evolution 2013; 67:2783-94. [PMID: 24094333 DOI: 10.1111/evo.12153] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 04/15/2013] [Indexed: 11/28/2022]
Abstract
Aposematism and crypsis are often viewed as two extremes of a continuum of visual conspicuousness to predators. Theory predicts that behavioral and coloration conspicuousness should vary in tandem along the conspicuousness spectrum for antipredator strategies to be effective. Here we used visual modeling of contrast and behavioral observations to examine the conspicuousness of four populations of the granular poison frog, Oophaga granulifera, which exhibits almost continuous variation in dorsal color. The patterns of geographic variation in color, visual contrast, and behavior support a gradient of overall conspicuousness along the distribution of O. granulifera. Red and green populations, at the extremes of the color distribution, differ in all elements of color, contrast, and behavior, strongly reflecting aposematic and cryptic strategies. However, there is no smooth cline in any elements of behavior or coloration between the two extremes. Instead populations of intermediate colors attain intermediate conspicuousness by displaying different combinations of aposematic and cryptic traits. We argue that coloration divergence among populations may be linked to the evolution of a gradient of strategies to balance the costs of detection by predators and the benefits of learned aversion.
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Affiliation(s)
- Beatriz Willink
- Sistema de Estudios de Posgrado, Universidad de Costa Rica, Ciudad Universitaria, San José, 2060, Costa Rica.
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31
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Cheney K, Newport C, McClure E, Marshall J. Colour vision and response bias in a coral reef fish. J Exp Biol 2013; 216:2967-73. [DOI: 10.1242/jeb.087932] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Animals use coloured signals for a variety of communication purposes, including to attract potential mates, recognize individuals, defend territories and warn predators of secondary defences (aposematism). To understand the mechanisms that drive the evolution and design of such visual signals, it is important to understand the visual systems and potential response biases of signal receivers. Here, we provide raw data on the spectral capabilities of a coral reef fish, Picasso triggerfish Rhinecanthus aculeatus, which are potentially trichromatic with three cone sensitivities of 413 nm (single cone), 480 nm (double cone, medium sensitivity), 528 nm (double cone, long sensitivity) and a rod sensitivity of 498 nm. The ocular media have a 50% transmission cut off at 405 nm. Behavioural experiments confirmed colour vision over their spectral range; triggerfish were significantly more likely to choose coloured stimuli over grey distractors, irrespective of luminance. We then examined whether response biases existed towards coloured and patterned stimuli to provide insights into how visual signals - in particular, aposematic colouration - may evolve. Triggerfish showed a preferential foraging response bias to red and green stimuli, in contrast to blue and yellow, irrespective of pattern. There was no response bias to patterned over monochromatic non-patterned stimuli. A foraging response bias towards red in fish differs to that of avian predators, who often avoid red food items. Red is frequently associated with warning colouration in terrestrial environments (ladybirds, snakes, frogs), whilst blue is used in aquatic environments (blue-ringed octopus, nudibranchs); whether the design of warning (aposematic) displays is a cause or consequence of response biases is unclear.
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32
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Zylinski S, Osorio D. Visual contrast and color in rapid learning of novel patterns by chicks. J Exp Biol 2013; 216:4184-9. [DOI: 10.1242/jeb.085001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Biological communication signals often combine bright and dark colors, such as yellow and black, but it is unclear why such patterns are effective. The literature on aposematism suggests that high contrast patterns may be easily learnt or innately avoided, whereas studies of sexual signaling refer to their attractiveness or to their cost. Here in experiments with poultry chicks trained to find food in patterned containers, we confirm that elevated contrast dramatically increases the rate of initial attack on novel stimuli, but this response is labile. The chicks peck once at a novel unrewarded stimulus and then ignore it for at least 24 hours. Such single trial learning has not previously been reported for birds without a positively aversive unconditioned stimulus. We then test and reject two hypotheses about the function of high contrast patterns: first that the preferential responses are due to novelty, and second that elevated contrast enhances learning about a novel color. More generally, the observations are consistent with the idea that elevated contrast attracts attention, thereby enhancing both initial responses - whether positive or negative - and the rate of learning.
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33
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Aronsson M, Gamberale-Stille G. Evidence of signaling benefits to contrasting internal color boundaries in warning coloration. Behav Ecol 2012. [DOI: 10.1093/beheco/ars170] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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34
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Colour and pattern similarity in mimicry: evidence for a hierarchical discriminative learning of different components. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2012.07.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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IHALAINEN EIRA, LINDSTEDT CARITA. Do avian predators select for seasonal polyphenism in the European map butterfly Araschnia levana (Lepidoptera: Nymphalidae)? Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01922.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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36
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Stevens M, Ruxton GD. Linking the evolution and form of warning coloration in nature. Proc Biol Sci 2011; 279:417-26. [PMID: 22113031 DOI: 10.1098/rspb.2011.1932] [Citation(s) in RCA: 164] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many animals are toxic or unpalatable and signal this to predators with warning signals (aposematism). Aposematic appearance has long been a classical system to study predator-prey interactions, communication and signalling, and animal behaviour and learning. The area has received considerable empirical and theoretical investigation. However, most research has centred on understanding the initial evolution of aposematism, despite the fact that these studies often tell us little about the form and diversity of real warning signals in nature. In contrast, less attention has been given to the mechanistic basis of aposematic markings; that is, 'what makes an effective warning signal?', and the efficacy of warning signals has been neglected. Furthermore, unlike other areas of adaptive coloration research (such as camouflage and mate choice), studies of warning coloration have often been slow to address predator vision and psychology. Here, we review the current understanding of warning signal form, with an aim to comprehend the diversity of warning signals in nature. We present hypotheses and suggestions for future work regarding our current understanding of several inter-related questions covering the form of warning signals and their relationship with predator vision, learning, and links to broader issues in evolutionary ecology such as mate choice and speciation.
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Affiliation(s)
- Martin Stevens
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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37
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Lecuelle S, Leterrier C, Chagneau AM, Laviron F, Lescoat P, Bastianelli D, Bertin A, Bouvarel I. Experience with a variety of feed colours reduces feed neophobia in the turkey. Appl Anim Behav Sci 2011. [DOI: 10.1016/j.applanim.2011.08.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Blackiston D, Briscoe AD, Weiss MR. Color vision and learning in the monarch butterfly, Danaus plexippus (Nymphalidae). ACTA ACUST UNITED AC 2011; 214:509-20. [PMID: 21228210 DOI: 10.1242/jeb.048728] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The monarch butterfly, Danaus plexippus, is well known for its intimate association with milkweed plants and its incredible multi-generational trans-continental migrations. However, little is known about monarch butterflies' color perception or learning ability, despite the importance of visual information to butterfly behavior in the contexts of nectar foraging, host-plant location and mate recognition. We used both theoretical and experimental approaches to address basic questions about monarch color vision and learning ability. Color space modeling based on the three known spectral classes of photoreceptors present in the eye suggests that monarchs should not be able to discriminate between long wavelength colors without making use of a dark orange lateral filtering pigment distributed heterogeneously in the eye. In the context of nectar foraging, monarchs show strong innate preferences, rapidly learn to associate colors with sugar rewards and learn non-innately preferred colors as quickly and proficiently as they do innately preferred colors. Butterflies also demonstrate asymmetric confusion between specific pairs of colors, which is likely a function of stimulus brightness. Monarchs readily learn to associate a second color with reward, and in general, learning parameters do not vary with temporal sequence of training. In addition, monarchs have true color vision; that is, they can discriminate colors on the basis of wavelength, independent of intensity. Finally, behavioral trials confirm that monarchs do make use of lateral filtering pigments to enhance long-wavelength discrimination. Our results demonstrate that monarchs are proficient and flexible color learners; these capabilities should allow them to respond rapidly to changing nectar availabilities as they travel over migratory routes, across both space and time.
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Affiliation(s)
- Douglas Blackiston
- Department of Biology, 406 Reiss Bldg., Georgetown University, 37th & O Sts. NW, Washington, DC 20057 USA
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39
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Lindstedt C, Eager H, Ihalainen E, Kahilainen A, Stevens M, Mappes J. Direction and strength of selection by predators for the color of the aposematic wood tiger moth. Behav Ecol 2011. [DOI: 10.1093/beheco/arr017] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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40
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Lecuelle S, Bouvarel I, Chagneau A, Laviron F, Lescoat P, Leterrier C. Early visual experience of food does not appear to reduce subsequent feed neophobia in turkeys. Poult Sci 2011; 90:1-9. [DOI: 10.3382/ps.2010-00882] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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41
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Abstract
Aposematism is defined as the use of conspicuous colouration to warn predators that an individual is chemically or otherwise defended. Mechanisms that drive the evolution of aposematism are complex. Theoretical and empirical studies show that conspicuousness can be either positively or negatively correlated with toxicity as once aposematism is established, species can allocate resources into becoming more conspicuous and/or increase secondary defences. Here, we investigated the evolution of conspicuousness and toxicity in marine opisthobranchs. Conspicuousness of colour signals was assessed using spectral reflectance measurements and theoretical vision models from the perspective of two reef fish signal receivers. The relative toxicity of chemicals extracted from each opisthobranch species was then determined using toxicity assays. Using a phylogenetic comparative analysis, we found a significant correlation between conspicuousness and toxicity, indicating that conspicuousness acts as an honest signal when signifying level of defence and provides evidence for aposematism in opisthobranchs.
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Affiliation(s)
- F Cortesi
- School of Biological Sciences, The University of Queensland, QLD, Australia
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42
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Visual modeling shows that avian host parents use multiple visual cues in rejecting parasitic eggs. Proc Natl Acad Sci U S A 2010; 107:8672-6. [PMID: 20421497 DOI: 10.1073/pnas.0910486107] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
One of the most striking outcomes of coevolution between species is egg mimicry by brood parasitic birds, resulting from rejection behavior by discriminating host parents. Yet, how exactly does a host detect a parasitic egg? Brood parasitism and egg rejection behavior provide a model system for exploring the relative importance of different visual cues used in a behavioral task. Although hosts are discriminating, we do not know exactly what cues they use, and to answer this it is crucial to account for the receiver's visual perception. Color, luminance ("perceived lightness") and pattern information have never been simultaneously quantified and experimentally tested through a bird's eye. The cuckoo finch Anomalospiza imberbis and its hosts show spectacular polymorphisms in egg appearance, providing a good opportunity for investigating visual discrimination owing to the large range of patterns and colors involved. Here we combine field experiments in Africa with modeling of avian color vision and pattern discrimination to identify the specific visual cues used by hosts in making rejection decisions. We found that disparity between host and foreign eggs in both color and several aspects of pattern (dispersion, principal marking size, and variability in marking size) were important predictors of rejection, especially color. These cues correspond exactly to the principal differences between host and parasitic eggs, showing that hosts use the most reliable available cues in making rejection decisions, and select for parasitic eggs that are increasingly mimetic in a range of visual attributes.
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Balogh ACV, Gamberale-Stille G, Tullberg BS, Leimar O. FEATURE THEORY AND THE TWO-STEP HYPOTHESIS OF MÜLLERIAN MIMICRY EVOLUTION. Evolution 2010; 64:810-22. [DOI: 10.1111/j.1558-5646.2009.00852.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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44
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Why do orb-weaving spiders (Cyclosa ginnaga) decorate their webs with silk spirals and plant detritus? Anim Behav 2010. [DOI: 10.1016/j.anbehav.2009.10.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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45
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Aronsson M, Gamberale-Stille G. Importance of internal pattern contrast and contrast against the background in aposematic signals. Behav Ecol 2009. [DOI: 10.1093/beheco/arp141] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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46
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Tan EJ, Li D. Detritus decorations of an orb-weaving spider, Cyclosa mulmeinensis (Thorell): for food or camouflage? ACTA ACUST UNITED AC 2009; 212:1832-9. [PMID: 19483001 DOI: 10.1242/jeb.030502] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Many species of the orb-web spider genus Cyclosa often adorn their webs with decorations of prey remains, egg sacs and/or plant detritus, termed ;detritus decorations'. These detritus decorations have been hypothesised to camouflage the spider from predators or prey and thus reduce predation risk or increase foraging success. In the present study, we tested these two alternative hypotheses simultaneously using two types of detritus decorations (prey remain and egg sac) built by Cyclosa mulmeinensis (Thorell). By monitoring the possible responses of predators to spiders on their webs with and without decorations in the field, we tested whether web decorations would reduce the mortality of spiders. Wasp predators were observed to fly in the vicinity of webs with decorations slightly more often than in the vicinity of webs without decorations but there were very few attacks on spiders by wasps. By comparing the insect interception rates of webs with and without decorations in the field, we tested whether web decorations would increase the foraging success. Webs decorated with prey remains or egg sacs intercepted more insects than those without in the field. By calculating colour contrasts of both prey-remain and egg-sac decorations against spiders viewed by bird (blue tits) and hymenopteran (e.g. wasps) predators as well as hymenopteran (bees) prey, we showed that C. mulmeinensis spiders on webs with egg-sac decorations were invisible to both hymenopteran prey and predators and bird predators over short and long distances. While spiders on webs with prey-remain decorations were invisible to both hymenopterans and birds over short distances, spiders on webs with prey-remain decorations were visible to both predators and prey over long distances. Our results thus suggest that decorating webs with prey remains and egg sacs in C. mulmeinensis may primarily function as camouflage to conceal the spider from insects rather than as prey attractants, possibly contributing to the interception of more insect prey. However, the detritus decorations exhibit varying success as camouflage against predators, depending on whether predators are jumping spiders, wasps or birds, as well as on the decoration type.
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Affiliation(s)
- Eunice J Tan
- Department of Biological Sciences, National University of Singapore, Singapore 117543
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Gamberale-Stille G, Johansen AI, Tullberg BS. Change in protective coloration in the striated shieldbug Graphosoma lineatum (Heteroptera: Pentatomidae): predator avoidance and generalization among different life stages. Evol Ecol 2009. [DOI: 10.1007/s10682-009-9315-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Baddeley RJ, Osorio D, Jones CD. Generalization of color by chickens: experimental observations and a Bayesian model. Am Nat 2009; 169 Suppl 1:S27-41. [PMID: 19426091 DOI: 10.1086/510142] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sensory generalization influences animals' responses to novel stimuli. Because color forms a perceptual continuum, it is a good subject for studying generalization. Moreover, because different causes of variation in spectral signals, such as pigmentation, gloss, and illumination, have differing behavioral significance, it may be beneficial to have adaptable generalization. We report on generalization by poultry chicks following differential training to rewarded (T(+)) and unrewarded (T(-)) colors, in particular on the phenomenon of peak shift, which leads to subjects preferring stimuli displaced away from T(-). The first three experiments test effects of learning either a fine or a coarse discrimination. In experiments 1 and 2, peak shift occurs, but contrary to some predictions, the shift is smaller after the animal learned a fine discrimination than after it learned a coarse discrimination. Experiment 3 finds a similar effect for generalization on a color axis orthogonal to that separating T(+) from T(-). Experiment 4 shows that generalization is rapidly modified by experience. These results imply that the scale of a "perceptual ruler" is set by experience. We show that the observations are consistent with generalization following principles of Bayesian inference, which forms a powerful framework for understanding this type of behavior.
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Affiliation(s)
- R J Baddeley
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom
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Osorio D, Ham AD, Gonda Z, Andrew RJ. Sensory generalization and learning about novel colours by poultry chicks. Q J Exp Psychol (Hove) 2009; 62:1249-56. [PMID: 19235098 DOI: 10.1080/17470210802671305] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
In nature animals constantly encounter novel stimuli and need to generalize from known stimuli. The animal may then learn about the novel stimulus. Hull (1947) suggested that as they learn animals distinguish knowledge based on direct experience from inference by generalization and in support of this view suggested that if a subject is directly trained to a stimulus subsequent extinction of responses is slower than when the response is based on generalization. Such an effect is also predicted by Bayesian models that relate the rate of learning to uncertainty in the estimate of stimulus value. We find support for this prediction when chicks learn about a novel colour (orange) if the initial evaluation is based on similarity to known colours (red, yellow). Specifically, if an expected food reward is absent the rate of extinction of the response to the novel stimulus exceeds that for the familiar colours. Interestingly, the change in relative preference for novel and familiar stimuli occurs after a delay of an hour. This type of delay has not, to our knowledge, been reported in previous studies of single-trial learning, but given its importance of generalization in natural behaviour this type of learning may have wide relevance.
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Affiliation(s)
- Daniel Osorio
- School of Life Sciences, University of Sussex, Brighton, UK.
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Svádová K, Exnerová A, Štys P, Landová E, Valenta J, Fučíková A, Socha R. Role of different colours of aposematic insects in learning, memory and generalization of naïve bird predators. Anim Behav 2009. [DOI: 10.1016/j.anbehav.2008.09.034] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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