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van den Berg CP, Santon M, Endler JA, Drummond L, Dawson BR, Santiago C, Weber N, Cheney KL. Chemical defences indicate bold colour patterns with reduced variability in aposematic nudibranchs. Proc Biol Sci 2024; 291:20240953. [PMID: 39013421 PMCID: PMC11251778 DOI: 10.1098/rspb.2024.0953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 05/31/2024] [Accepted: 05/31/2024] [Indexed: 07/18/2024] Open
Abstract
The selective factors that shape phenotypic diversity in prey communities with aposematic animals are diverse and coincide with similar diversity in the strength of underlying secondary defences. However, quantitative assessments of colour pattern variation and the strength of chemical defences in assemblages of aposematic species are lacking. We quantified colour pattern diversity using quantitative colour pattern analysis (QCPA) in 13 dorid nudibranch species (Infraorder: Doridoidei) that varied in the strength of their chemical defences. We accounted for the physiological properties of a potential predator's visual system (a triggerfish, Rhinecanthus aculeatus) and modelled the appearance of nudibranchs from multiple viewing distances (2 and 10 cm). We identified distinct colour pattern properties associated with the presence and strength of chemical defences. Specifically, increases in chemical defences indicated increases in colour pattern boldness (i.e. visual contrast elicited via either or potentially coinciding chromatic, achromatic and/or spatial contrast). Colour patterns were also less variable among species with chemical defences when compared to undefended species. Our results indicate correlations between secondary defences and diverse, bold colouration while showing that chemical defences coincide with decreased colour pattern variability among species. Our study suggests that complex spatiochromatic properties of colour patterns perceived by potential predators can be used to make inferences on the presence and strength of chemical defences.
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Affiliation(s)
- Cedric P. van den Berg
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
- Ecology of Vision Laboratory, School of Biological Sciences, University of Bristol, BristolBS8 1TQ, UK
| | - Matteo Santon
- Ecology of Vision Laboratory, School of Biological Sciences, University of Bristol, BristolBS8 1TQ, UK
| | - John A. Endler
- Zoology and Ecology, Tropical Environments Sciences, College of Science & Engineering, James Cook University, Cairns, QLD4878, Australia
| | - Leon Drummond
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
| | - Bethany R. Dawson
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
| | - Carl Santiago
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
| | - Nathalie Weber
- Faculty of Biology and Medicine, School of Biological Sciences, The University of Lausanne, Lausanne1015, Switzerland
| | - Karen L. Cheney
- Marine Sensory Ecology Group, School of the Environment, The University of Queensland, Brisbane4072, Australia
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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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García‐Campa J, Müller W, Morales J. Offspring plumage coloration as a condition-dependent signal in the blue tit. Ecol Evol 2023; 13:e9787. [PMID: 36744078 PMCID: PMC9889846 DOI: 10.1002/ece3.9787] [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: 09/28/2022] [Revised: 01/10/2023] [Accepted: 01/13/2023] [Indexed: 02/04/2023] Open
Abstract
In many species, offspring display conspicuous coloration already early in life, even though they might be very vulnerable to predation at this stage. However, most attention has been drawn to the conspicuous plumage displayed by adult individuals in a sexual context, while other signaling functions have been explored much less. Here, we investigated whether the yellow breast plumage of blue tit (Cyanistes caeruleus) nestlings shows patterns of condition dependence and hence signals individual quality, as has been described for adult birds. During three consecutive breeding seasons, we, therefore, explored the association between nestling body mass and three color components of the yellow breast plumage (i.e., UV chroma, carotenoid chroma, and total brightness), considering both within and among nest effects. Variation in carotenoid chroma was not related to body mass. However, UV chroma and total brightness varied with body mass on an among-nest level, suggesting that they might signal aspects of genetic quality or parental rearing capacity. Interestingly, we also found a within-nest effect of body mass on total brightness, suggesting that this is a good candidate for a condition-dependent signal within the family. Thus, other family members could rely on brightness to adjust their behavioral strategies, such as feeding behavior in parents. Our study thus reveals that certain color components of the yellow breast plumage might signal different aspects of offspring quality, and they might have a correlated signaling value across life-history stages.
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Affiliation(s)
- Jorge García‐Campa
- Department of Evolutionary EcologyNational Museum of Natural Sciences – Spanish National Research Council (CSIC)MadridSpain
| | - Wendt Müller
- Department of Biology, Behavioural Ecology and Ecophysiology GroupUniversity of AntwerpAntwerpBelgium
| | - Judith Morales
- Department of Evolutionary EcologyNational Museum of Natural Sciences – Spanish National Research Council (CSIC)MadridSpain
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Westphal GH, Stewart Merrill TE. Partitioning variance in immune traits in a zooplankton host-Fungal parasite system. Ecol Evol 2022; 12:e9640. [PMID: 36545366 PMCID: PMC9763022 DOI: 10.1002/ece3.9640] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 11/21/2022] [Accepted: 11/29/2022] [Indexed: 12/24/2022] Open
Abstract
Host immune traits arise from both genetic and environmental sources of variation. When immune traits have a strong genetic basis, the presence and severity of disease in a population may influence the distribution of those traits. Our study addressed how two immune-related traits (gut penetrability and the hemocyte response) are shaped by genetic and environmental sources of variation, and how the presence of a virulent disease altered the relative frequency of these traits in natural populations. Daphnia dentifera hosts were sampled from five Indiana lakes between June and December 2017 before and during epidemics of their fungal pathogen, Metschnikowia bicuspidata. Collected Daphnia were experimentally exposed to Metschnikowia and assayed for their gut penetrability, hemocyte response, and multi-locus genotype. Mixed-effects models were constructed to partition variance in immune traits between genetic and environmental sources. We then isolated the genetic sources to produce genotype-specific estimates of immune traits for each multi-locus genotype. Finally, we assessed the relative frequency and dynamics of genotypes during epidemics and asked whether genotypes with more robust immune responses increased in frequency during epidemics. Although genotype was an important source of variation for both gut penetrability and the hemocyte response, environmental factors (e.g., resource availability, Metschnikowia prevalence, and co-infection) still explained a large portion of observed variation, suggesting a high degree of flexibility in Daphnia immune traits. Additionally, no significant associations were detected between a genotype's immune traits and its frequency in a population. Our study highlights the power of variance partitioning in understanding the factors driving variation in Daphnia traits and motivates further research on immunological flexibility and the ecological drivers of immune variation.
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Affiliation(s)
- Grace H. Westphal
- School of Integrative BiologyUniversity of Illinois Urbana‐ChampaignChampaignIllinoisUSA,Department of Biological ScienceFlorida State UniversityTallahasseeFloridaUSA
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Barnett JB, Yeager J, McEwen BL, Kinley I, Anderson HM, Guevara J. Size-dependent colouration balances conspicuous aposematism and camouflage. J Evol Biol 2022. [PMID: 36514842 DOI: 10.1111/jeb.14143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 11/09/2022] [Indexed: 12/15/2022]
Abstract
Colour is an important component of many different defensive strategies, but signal efficacy and detectability will also depend on the size of the coloured structures, and how pattern size interacts with the background. Consequently, size-dependent changes in colouration are common among many different species as juveniles and adults frequently use colour for different purposes in different environmental contexts. A widespread strategy in many species is switching from crypsis to conspicuous aposematic signalling as increasing body size can reduce the efficacy of camouflage, while other antipredator defences may strengthen. Curiously, despite being chemically defended, the gold-striped frog (Lithodytes lineatus, Leptodactylidae) appears to do the opposite, with bright yellow stripes found in smaller individuals, whereas larger frogs exhibit dull brown stripes. Here, we investigated whether size-dependent differences in colour support distinct defensive strategies. We first used visual modelling of potential predators to assess how colour contrast varied among frogs of different sizes. We found that contrast peaked in mid-sized individuals while the largest individuals had the least contrasting patterns. We then used two detection experiments with human participants to evaluate how colour and body size affected overall detectability. These experiments revealed that larger body sizes were easier to detect, but that the colours of smaller frogs were more detectable than those of larger frogs. Taken together our data support the hypothesis that the primary defensive strategy changes from conspicuous aposematism to camouflage with increasing size, implying size-dependent differences in the efficacy of defensive colouration. We discuss our data in relation to theories of size-dependent aposematism and evaluate the evidence for and against a possible size-dependent mimicry complex with sympatric poison frogs (Dendrobatidae).
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Affiliation(s)
- James B Barnett
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Ontario, Hamilton, Canada
| | - Justin Yeager
- Biodiversidad Medio Ambiente y Salud (BIOMAS), Direccion General de Investigacion, Universidad de las Américas, Quito, Ecuador
| | - Brendan L McEwen
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Ontario, Hamilton, Canada
| | - Isaac Kinley
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Ontario, Hamilton, Canada
| | - Hannah M Anderson
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Ontario, Hamilton, Canada
| | - Jennifer Guevara
- Department of Psychology, Neuroscience & Behaviour, McMaster University, Ontario, Hamilton, Canada.,Grupo de Investigación Ecosistemas Tropicales y Cambio Global, Facultad Ciencias de la Vida, Universidad Regional Amazónica Ikiam, Tena, Ecuador
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Pereira Martins AR, Martins LP, Ho W, McMillan WO, Ready JS, Barrett R. Scale-dependent environmental effects on phenotypic distributions in Heliconius butterflies. Ecol Evol 2022; 12:e9286. [PMID: 36177141 PMCID: PMC9471044 DOI: 10.1002/ece3.9286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/08/2022] [Accepted: 08/17/2022] [Indexed: 01/26/2023] Open
Abstract
Identifying the relative importance of different mechanisms responsible for the emergence and maintenance of phenotypic diversity can be challenging, as multiple selective pressures and stochastic events are involved in these processes. Therefore, testing how environmental conditions shape the distribution of phenotypes can offer important insights on local adaptation, divergence, and speciation. The red-yellow Müllerian mimicry ring of Heliconius butterflies exhibits a wide diversity of color patterns across the Neotropics and is involved in multiple hybrid zones, making it a powerful system to investigate environmental drivers of phenotypic distributions. Using the distantly related Heliconius erato and Heliconius melpomene co-mimics and a multiscale distribution approach, we investigated whether distinct phenotypes of these species are associated with different environmental conditions. We show that Heliconius red-yellow phenotypic distribution is strongly driven by environmental gradients (especially thermal and precipitation variables), but that phenotype and environment associations vary with spatial scale. While co-mimics are usually predicted to occur in similar environments at large spatial scales, patterns at local scales are not always consistent (i.e., different variables are best predictors of phenotypic occurrence in different locations) or congruent (i.e., co-mimics show distinct associations with environment). We suggest that large-scale analyses are important for identifying how environmental factors shape broad mimetic phenotypic distributions, but that local studies are essential to understand the context-dependent biotic, abiotic, and historical mechanisms driving finer-scale phenotypic transitions.
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Affiliation(s)
- Ananda R. Pereira Martins
- Redpath MuseumMcGill UniversityMontrealQuebecCanada,Smithsonian Tropical Research InstitutePanama CityPanama
| | - Lucas P. Martins
- School of Biological SciencesUniversity of CanterburyChristchurchNew Zealand
| | | | | | - Jonathan S. Ready
- Instituto de Ciências BiológicasUniversidade Federal do ParáBelémBrazil
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Kemp DJ. Multiple views on animal coloration: a comment on Postema et al. Behav Ecol 2022. [DOI: 10.1093/beheco/arac083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Darrell J Kemp
- School of Natural Sciences, Macquarie University , North Ryde, New South Wales, 2109 , Australia
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Stuart-Fox D. Defensive coloration as a multivariate optimum: a comment on Postema et al. Behav Ecol 2022. [DOI: 10.1093/beheco/arac065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Devi Stuart-Fox
- School of BioSciences, The University of Melbourne , Royal Parade, Parkville, VIC 3010 , Australia
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