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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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da Rocha SM, Magnusson WE, Rojas D, Lima AP. Colour, location and movement: what do models tell us about predation on colour morphs of a poison frog from eastern Amazonia? BEHAVIOUR 2022. [DOI: 10.1163/1568539x-bja10168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Abstract
Many dendrobatid frogs are known to be aposematic: brightly coloured and unpalatable to predators. To deceive predators, frog models used to test for predatory colour bias must be similar in size, colour, shape, and movement to frogs. We carried out an experiment with moving models of the species Adelphobates galactonotus, in two localities. A. galactonotus is a polytypic frog and each population of the species has a distinct colour. Birds and mammals were the vertebrates responsible for the marks on the models, but there was no difference in frequency of attacks on local-, non-local- and cryptic-colour models. Only invertebrates avoided cryptic models. Different populations of the species seem to be under different predation pressure, but colour differentiation in this species is probably related to other mechanisms, such as sexual selection.
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Affiliation(s)
- Sulamita M.C. da Rocha
- Instituto Nacional de Pesquisas da Amazônia, Programa de Pós-Graduação em Ecologia, Av. André, Araújo 2936, 69011-970 Manaus, AM, Brazil
| | - William E. Magnusson
- Instituto Nacional de Pesquisas da Amazônia, Programa de Pós-Graduação em Ecologia, Av. André, Araújo 2936, 69011-970 Manaus, AM, Brazil
- Instituto Nacional de Pesquisas da Amazônia, Coordenação de Pesquisas em Biodiversidade, Av. André Araújo, 2936, 69011-970, Manaus, AM, Brazil
| | - Diana Rojas
- Ecopescado, P.O. Box 37, 69640-000 Tabatinga, AM, Brazil
| | - Albertina P. Lima
- Instituto Nacional de Pesquisas da Amazônia, Programa de Pós-Graduação em Ecologia, Av. André, Araújo 2936, 69011-970 Manaus, AM, Brazil
- Instituto Nacional de Pesquisas da Amazônia, Coordenação de Pesquisas em Biodiversidade, Av. André Araújo, 2936, 69011-970, Manaus, AM, Brazil
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Oyen KJ, Croucher L, Benoit JB. Tonic Immobility Is Influenced by Starvation, Life Stage, and Body Mass in Ixodid Ticks. JOURNAL OF MEDICAL ENTOMOLOGY 2021; 58:1030-1040. [PMID: 33590870 PMCID: PMC8122239 DOI: 10.1093/jme/tjab003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Indexed: 05/09/2023]
Abstract
The ability to escape predation modulates predator-prey interactions and represents a crucial aspect of organismal life history, influencing feeding, mating success, and survival. Thanatosis, also known as death feigning or tonic immobility (TI), is taxonomically widespread, but understudied in blood-feeding vectors. Hematophagous arthropods, such as ticks, are unique among animals as their predators (birds, mice, lizards, frogs, and other invertebrates) may also be their source of food. Therefore, the trade-off between predator avoidance and host-seeking may shift as the time since the last bloodmeal increases. Because ticks are slow-moving and unable to fly, or otherwise escape, we predicted that they may use TI to avoid predation, but that TI would be influenced by time since the last bloodmeal (starvation). We therefore aimed to quantify this relationship, examining the effect of starvation, body mass, and ontogeny on TI for two tick species: Dermacentor variabilis (Say) (Acari: Ixodidae) and Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae). As we predicted, the duration and use of TI decreased with time since feeding and emergence across species and life stages. Therefore, ticks may become more aggressive in their search for a bloodmeal as they continue to starve, opting to treat potential predators as hosts, rather than avoiding predation by feigning death. Antipredator behaviors such as TI may influence the intensity and amount of time ticks spend searching for hosts, driving patterns of tick-borne pathogen transmission. This identification and quantification of a novel antipredation strategy add a new component to our understanding of tick life history.
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Affiliation(s)
- Kennan J Oyen
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
- Corresponding author, e-mail:
| | - Lillian Croucher
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH, USA
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Medina I, Vega-Trejo R, Wallenius T, Esquerré D, León C, Perez DM, Head ML. No link between nymph and adult coloration in shield bugs: weak selection by predators. Proc Biol Sci 2020; 287:20201011. [PMID: 32576112 PMCID: PMC7329039 DOI: 10.1098/rspb.2020.1011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/04/2020] [Indexed: 11/12/2022] Open
Abstract
Many organisms use different antipredator strategies throughout their life, but little is known about the reasons or implications of such changes. For years, it has been suggested that selection by predators should favour uniformity in local warning signals. If this is the case, we would expect high resemblance in colour across life stages in aposematic animals where young and adults share similar morphology and habitat. In this study, we used shield bugs (Hemiptera: Pentatomoidea) to test whether colour and colour diversity evolve similarly at different life stages. Since many of these bugs are considered to be aposematic, we also combined multi-species analyses with predation experiments on the cotton harlequin bug to test whether there is evidence of selection for uniformity in colour across life stages. Overall, we show that the diversity of colours used by both life stages is comparable, but adults are more cryptic than nymphs. We also demonstrate that nymphs and adults of the same species do not tend to look alike. Experiments on our model system suggest that predators can generalise among life stages that look different, and exhibit strong neophobia. Altogether, our results show no evidence of selection favouring colour similarity between adults and nymphs in this speciose clade.
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Affiliation(s)
- Iliana Medina
- School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | - Thomas Wallenius
- Division of Ecology and Evolution, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Damien Esquerré
- Division of Ecology and Evolution, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Constanza León
- Division of Ecology and Evolution, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Daniela M. Perez
- Division of Ecology and Evolution, Australian National University, Canberra, Australian Capital Territory 0200, Australia
| | - Megan L. Head
- Division of Ecology and Evolution, Australian National University, Canberra, Australian Capital Territory 0200, Australia
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Myette AL, Hossie TJ, Murray DL. Defensive posture in a terrestrial salamander deflects predatory strikes irrespective of body size. Behav Ecol 2019. [DOI: 10.1093/beheco/arz137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
A wide variety of prey use defensive postures as a means of protection from predators. Many salamanders engage in broadly similar defensive postures, which may function as a warning signal and reduce the probability of attack, or may deflect predator attacks away from vital body parts. The extent to which these strategies (i.e., aposematism and deflection) act exclusively or synergistically, however, remains unknown. We deployed clay salamanders in the field, manipulating size (small, large) and posture (resting, defensive), and documented attack rates across three predator types. Competing risks analysis revealed that attack rates were affected by model size, deployment period, and leaf litter depth at the site of deployment, whereas model posture had no significant effect. Model size and posture did not interact, indicating that defensive posture was ineffective in deterring attack irrespective of prey size. Model prey in the defensive posture received significantly more attacks on the tail irrespective of size, and the defensive posture was more effective at deflecting avian attacks compared to mammal predation. We conclude that defensive posture increases tail conspicuousness without increasing predation risk, and primarily functions to deflect attacks away from vital body parts. The efficacy of defection may be further increased by tail undulation, however our use of static models means that we cannot exclude aposematic or deimatic functions for such movements. Our results provide important support for the deflection hypothesis in explaining antipredator behavior, and thereby set the stage for additional research targeting the functionality of attack deflection in natural predator–prey encounters.
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Affiliation(s)
- Alexander L Myette
- Department of Environmental and Life Sciences, Trent University, Peterborough, ON, Canada
| | - Thomas J Hossie
- Department of Biology, Trent University, Peterborough, Ontario, Canada
| | - Dennis L Murray
- Department of Biology, Trent University, Peterborough, Ontario, Canada
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Behm JE, Waite BR, Hsieh ST, Helmus MR. Benefits and limitations of three-dimensional printing technology for ecological research. BMC Ecol 2018; 18:32. [PMID: 30200934 PMCID: PMC6131837 DOI: 10.1186/s12898-018-0190-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 09/03/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ecological research often involves sampling and manipulating non-model organisms that reside in heterogeneous environments. As such, ecologists often adapt techniques and ideas from industry and other scientific fields to design and build equipment, tools, and experimental contraptions custom-made for the ecological systems under study. Three-dimensional (3D) printing provides a way to rapidly produce identical and novel objects that could be used in ecological studies, yet ecologists have been slow to adopt this new technology. Here, we provide ecologists with an introduction to 3D printing. RESULTS First, we give an overview of the ecological research areas in which 3D printing is predicted to be the most impactful and review current studies that have already used 3D printed objects. We then outline a methodological workflow for integrating 3D printing into an ecological research program and give a detailed example of a successful implementation of our 3D printing workflow for 3D printed models of the brown anole, Anolis sagrei, for a field predation study. After testing two print media in the field, we show that the models printed from the less expensive and more sustainable material (blend of 70% plastic and 30% recycled wood fiber) were just as durable and had equal predator attack rates as the more expensive material (100% virgin plastic). CONCLUSIONS Overall, 3D printing can provide time and cost savings to ecologists, and with recent advances in less toxic, biodegradable, and recyclable print materials, ecologists can choose to minimize social and environmental impacts associated with 3D printing. The main hurdles for implementing 3D printing-availability of resources like printers, scanners, and software, as well as reaching proficiency in using 3D image software-may be easier to overcome at institutions with digital imaging centers run by knowledgeable staff. As with any new technology, the benefits of 3D printing are specific to a particular project, and ecologists must consider the investments of developing usable 3D materials for research versus other methods of generating those materials.
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Affiliation(s)
- Jocelyn E Behm
- Integrative Ecology Lab, Center for Biodiversity, Department of Biology, Temple University, Philadelphia, PA, USA. .,Department of Ecological Science-Animal Ecology, VU University Amsterdam, Amsterdam, The Netherlands.
| | - Brenna R Waite
- Integrative Ecology Lab, Center for Biodiversity, Department of Biology, Temple University, Philadelphia, PA, USA.,School of Biological Sciences, University of Western Australia, Perth, WA, Australia
| | - S Tonia Hsieh
- Department of Biology, Temple University, Philadelphia, PA, USA
| | - Matthew R Helmus
- Integrative Ecology Lab, Center for Biodiversity, Department of Biology, Temple University, Philadelphia, PA, USA
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An Empirical Test Indicates Only Qualitatively Honest Aposematic Signaling Within a Population of Vertebrates. J HERPETOL 2018. [DOI: 10.1670/17-047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kelleher SR, Silla AJ, Dingemanse NJ, Byrne PG. Body size predicts between-individual differences in exploration behaviour in the southern corroboree frog. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.05.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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9
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Flores EE, Stevens M, Moore AJ, Rowland HM, Blount JD. Body size but not warning signal luminance influences predation risk in recently metamorphosed poison frogs. Ecol Evol 2015; 5:4603-16. [PMID: 26668726 PMCID: PMC4670055 DOI: 10.1002/ece3.1731] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 08/19/2015] [Accepted: 08/22/2015] [Indexed: 01/05/2023] Open
Abstract
During early development, many aposematic species have bright and conspicuous warning appearance, but have yet to acquire chemical defenses, a phenotypic state which presumably makes them vulnerable to predation. Body size and signal luminance in particular are known to be sensitive to variation in early nutrition. However, the relative importance of these traits as determinants of predation risk in juveniles is not known. To address this question, we utilized computer‐assisted design (CAD) and information on putative predator visual sensitivities to produce artificial models of postmetamorphic froglets that varied in terms of body size and signal luminance. We then deployed the artificial models in the field and measured rates of attack by birds and unknown predators. Our results indicate that body size was a significant predictor of artificial prey survival. Rates of attack by bird predators were significantly higher on smaller models. However, predation by birds did not differ between artificial models of varying signal luminance. This suggests that at the completion of metamorphosis, smaller froglets may be at a selective disadvantage, potentially because predators can discern they have relatively low levels of chemical defense compared to larger froglets. There is likely to be a premium on efficient foraging, giving rise to rapid growth and the acquisition of toxins from dietary sources in juvenile poison frogs.
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Affiliation(s)
- Eric E Flores
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK ; Sistema Nacional de Investigacion de Panama (SNI) Panama
| | - Martin Stevens
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK
| | - Allen J Moore
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK ; Department of Genetics University of Georgia 30602 Athens Georgia
| | | | - Jonathan D Blount
- Centre for Ecology and Conservation College of Life & Environmental Sciences University of Exeter Penryn UK
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