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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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2
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Winters AE, Chan W, White AM, van den Berg CP, Garson MJ, Cheney KL. Weapons or deterrents? Nudibranch molluscs use distinct ecological modes of chemical defence against predators. J Anim Ecol 2021; 91:831-844. [PMID: 34839542 DOI: 10.1111/1365-2656.13643] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/15/2021] [Indexed: 11/28/2022]
Abstract
Defensive chemicals are used by plants and animals to reduce the risk of predation through different mechanisms, including toxins that cause injury and harm (weapons) and unpalatable or odiferous compounds that prevent attacks (deterrents). However, whether effective defences are both toxins and deterrents, or work in just one modality is often unclear. In this study, our primary aim was to determine whether defensive compounds stored by nudibranch molluscs acted as weapons (in terms of being toxic), deterrents (in terms of being distasteful) or both. Our secondary aim was to investigate the response of different taxa to these defensive compounds. To do this, we identified secondary metabolites in 30 species of nudibranch molluscs and investigated their deterrent properties using antifeedant assays with three taxa: rock pool shrimp, Palaemon serenus, and two fish species: triggerfish Rhinecanthus aculeatus and toadfish Tetractenos hamiltoni. We compared these results to toxicity assays using brine shrimp Artemia sp. and previously published toxicity data with a damselfish Chromis viridis. Overall, we found no clear relationship between palatability and toxicity, but instead classified defensive compounds into the following categories: Class I & II-highly unpalatable and highly toxic; Class I-weakly unpalatable and highly toxic; Class II-highly unpalatable but weakly toxic; WR (weak response)-weakly unpalatable and weakly toxic. We also found eight extracts from six species that did not display activity in any assays indicating they may have very limited chemical defensive mechanisms (NR, no response). We found that the different classes of secondary metabolites were similarly unpalatable to fish and shrimp, except extracts from Phyllidiidae nudibranchs (isonitriles) that were highly unpalatable to shrimp but weakly unpalatable to fish. Our results pave the way towards better understanding how animal chemical defences work against a variety of predators. We highlight the need to disentangle weapons and deterrents in future work on anti-predator defences to better understand the foraging decisions faced by predators, the resultant selection pressures imposed on prey and the evolution of different anti-predator strategies.
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Affiliation(s)
- Anne E Winters
- School of Biological Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - Weili Chan
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld, Australia
| | - Andrew M White
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld, Australia
| | - Cedric P van den Berg
- School of Biological Sciences, The University of Queensland, Brisbane, Qld, Australia
| | - Mary J Garson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld, Australia
| | - Karen L Cheney
- School of Biological Sciences, The University of Queensland, Brisbane, Qld, Australia
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3
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Variation in size and shape of toxin glands among cane toads from native-range and invasive populations. Sci Rep 2021; 11:936. [PMID: 33441802 PMCID: PMC7806831 DOI: 10.1038/s41598-020-80191-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 12/14/2020] [Indexed: 12/19/2022] Open
Abstract
If optimal investment in anti-predator defences depends on predation risk, invading new regions (and thus, encountering different predators) may favour shifts in that investment. Cane toads offer an ideal system to test this prediction: expensive anti-predator toxins are stored mainly in parotoid glands whose dimensions are easy to measure, and toad invasions have changed the suites of predators they encounter. Although plasticity may influence parotoid morphology, comparisons between parents and progeny revealed that gland dimensions were highly heritable. That heritability supports the plausibility of an evolved basis to variation in gland dimensions. Measurements of 3779 adult toads show that females have larger glands than males, invasive populations have larger glands than in the native-range, and that parotoid sexual size dimorphism varies strongly among invaded areas. Geographic variation in parotoid morphology may be driven by predation risk to both adult toads and offspring (provisioned with toxins by their mother), with toxins allocated to eggs exacerbating the risk of cannibalism but reducing the risk of interspecific predation. Investment into chemical defences has evolved rapidly during the cane toad’s international diaspora, consistent with the hypothesis that organisms flexibly adjust resource allocation to anti-predator tactics in response to novel challenges.
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4
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DE Meester G, Šunje E, Prinsen E, Verbruggen E, VAN Damme R. Toxin variation among salamander populations: discussing potential causes and future directions. Integr Zool 2020; 16:336-353. [PMID: 32965720 DOI: 10.1111/1749-4877.12492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Amphibians produce defensive chemicals which provide protection against both predators and infections. Within species, populations can differ considerably in the composition and amount of these chemical defenses. Studying intraspecific variation in toxins and linking it to environmental variables may help us to identify the selective drivers of toxin evolution, such as predation pressure and infection risk. Recently, there has been a renewed interest in the unique toxins produced by salamanders from the genus Salamandra: the samandarines. Despite this attention, intraspecific variation has largely been ignored within Salamandra-species. The aim of this study was to investigate whether geographic variation in profiles of samandarines exists, by sampling 4 populations of Salamandra atra over its range in the Dinaric Alps. In addition, we preliminary explored whether potential variation could be explained by predation (counting the number of snake species) and infection risk (cultivation and genomic analyses of collected soil samples). Salamanders from the 4 populations differed in toxin composition and in the size of their poison glands, although not in overall toxin quantity. Nor predation nor infection risk could explain this variation, as populations barely differed in these variables. Sampling over a much broader geographic range, using better estimators for predation and infection risk, will contribute to an improved understanding of how environment may shape variation in chemical defenses. Nevertheless, as the 4 populations of S. atra did differ in their toxin profiles, we propose that this species provides an interesting opportunity for further ecological and evolutionary studies on amphibian toxins.
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Affiliation(s)
- Gilles DE Meester
- Department of Biology, Functional Morphology Group, University of Antwerp, Wilrijk, Belgium
| | - Emina Šunje
- Department of Biology, Functional Morphology Group, University of Antwerp, Wilrijk, Belgium.,Department of Biology, Faculty of Natural Sciences, University of Sarajevo, Sarajevo, Bosnia-Hercegovina.,Herpetological Association in Bosnia and Herzegovina: BHHU: ATRA, Sarajevo, Bosnia-Hercegovina
| | - Els Prinsen
- Department of Biology, Impress, University of Antwerp, Wilrijk, Belgium
| | - Erik Verbruggen
- Department of Biology, Plant and Ecosystems, University of Antwerp, Wilrijk, Belgium
| | - Raoul VAN Damme
- Department of Biology, Functional Morphology Group, University of Antwerp, Wilrijk, Belgium
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5
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Toxicity and Alkaloid Profiling of the Skin of the Golfo Dulcean Poison Frog Phyllobates vittatus (Dendrobatidae). J Chem Ecol 2019; 45:914-925. [PMID: 31802386 DOI: 10.1007/s10886-019-01116-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/30/2019] [Accepted: 10/10/2019] [Indexed: 01/01/2023]
Abstract
Frogs in the genus Phyllobates are known for the presence of batrachotoxin, a highly toxic alkaloid, in their skin. Nevertheless, Phyllobates frogs from Costa Rica and Panama (P. lugubris and P. vittatus) are considered non-toxic, as they have been reported to harbor low concentrations of this alkaloid. However, the potential toxicity of Central American Phyllobates has not been assessed experimentally. Our goal was to determine the toxicity of the whole skin of P. vittatus, an endemic species from the Southeastern Pacific region of Costa Rica. We performed median lethal dose (LD50) tests in mice to determine general toxicity, and an irritant assay based on the behavioral responses of mice to subcutaneous injection, to determine differences in irritability, as a measure of toxicity, among three study localities. Using UPLC-ESI-QTOF, we obtained chemical profiles of the methanolic extract of frog skins. Due to the absence of mortality at the studied doses, we were unable to estimate LD50. However, we recorded a list of toxicity symptoms in mice that are consistent with cardiotoxic effects, and found that mice presented more symptoms at higher concentrations of skin extracts during the first hour of the LD50 assays, recovering completely at all doses by the end of the assay. On the other hand, we did not detect differences in irritability among studied localities. Additionally, we putatively identified three toxic alkaloids (Batrachotoxinin A, DHQ 251A and Lehm 275A). This study provides the first experimental data on the toxicity and associated symptoms in mice, as well as the chemical profile of the skin of P. vittatus. We suggest that the skin alkaloids of P. vitattus may confer a chemical defense towards predators.
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Hämäläinen L, Mappes J, Thorogood R, Valkonen JK, Karttunen K, Salmi T, Rowland HM. Predators’ consumption of unpalatable prey does not vary as a function of bitter taste perception. Behav Ecol 2019. [DOI: 10.1093/beheco/arz199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Many prey species contain defensive chemicals that are described as tasting bitter. Bitter taste perception is, therefore, assumed to be important when predators are learning about prey defenses. However, it is not known how individuals differ in their response to bitter taste, and how this influences their foraging decisions. We conducted taste perception assays in which wild-caught great tits (Parus major) were given water with increasing concentrations of bitter-tasting chloroquine diphosphate until they showed an aversive response to bitter taste. This response threshold was found to vary considerably among individuals, ranging from chloroquine concentrations of 0.01 mmol/L to 8 mmol/L. We next investigated whether the response threshold influenced the consumption of defended prey during avoidance learning by presenting birds with novel palatable and defended prey in a random sequence until they refused to attack defended prey. We predicted that individuals with taste response thresholds at lower concentrations would consume fewer defended prey before rejecting them, but found that the response threshold had no effect on the birds’ foraging choices. Instead, willingness to consume defended prey was influenced by the birds’ body condition. This effect was age- and sex-dependent, with adult males attacking more of the defended prey when their body condition was poor, whereas body condition did not have an effect on the foraging choices of juveniles and females. Together, our results suggest that even though taste perception might be important for recognizing prey toxicity, other factors, such as predators’ energetic state, drive the decisions to consume chemically defended prey.
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Affiliation(s)
- Liisa Hämäläinen
- Department of Zoology, University of Cambridge, Cambridge, UK
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Johanna Mappes
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Rose Thorogood
- Department of Zoology, University of Cambridge, Cambridge, UK
- HiLIFE Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
- Research Programme in Organismal & Evolutionary Biology, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Janne K Valkonen
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Kaijamari Karttunen
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Tuuli Salmi
- Department of Biological and Environmental Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - Hannah M Rowland
- Department of Zoology, University of Cambridge, Cambridge, UK
- Institute of Zoology, Zoological Society of London, Regent’s Park, London, UK
- Max Planck Institute for Chemical Ecology, Jena, Germany
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Wei J, Shao W, Cao M, Ge J, Yang P, Chen L, Wang X, Kang L. Phenylacetonitrile in locusts facilitates an antipredator defense by acting as an olfactory aposematic signal and cyanide precursor. SCIENCE ADVANCES 2019; 5:eaav5495. [PMID: 30746481 PMCID: PMC6357733 DOI: 10.1126/sciadv.aav5495] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/11/2018] [Indexed: 05/22/2023]
Abstract
Many aggregating animals use aposematic signals to advertise their toxicity to predators. However, the coordination between aposematic signals and toxins is poorly understood. Here, we reveal that phenylacetonitrile (PAN) acts as an olfactory aposematic signal and precursor of hypertoxic hydrogen cyanide (HCN) to protect gregarious locusts from predation. We found that PAN biosynthesis from phenylalanine is catalyzed by CYP305M2, a novel gene encoding a cytochrome P450 enzyme in gregarious locusts. The RNA interference (RNAi) knockdown of CYP305M2 increases the vulnerability of gregarious locusts to bird predation. By contrast, the elevation of PAN levels through supplementation with synthetic PAN increases the resistance of solitary locusts to predation. When locusts are attacked by birds, PAN is converted to HCN, which causes food poisoning in birds. Our results indicate that locusts develop a defense mechanism wherein an aposematic compound is converted to hypertoxic cyanide in resistance to predation by natural enemies.
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Affiliation(s)
- Jianing Wei
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Wenbo Shao
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Minmin Cao
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Jin Ge
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Pengcheng Yang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, P. R. China
| | - Li Chen
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- Corresponding author. (L.K.); (X.W.)
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, P. R. China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing 100101, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
- Corresponding author. (L.K.); (X.W.)
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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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9
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Thorogood R, Kokko H, Mappes J. Social transmission of avoidance among predators facilitates the spread of novel prey. Nat Ecol Evol 2017; 2:254-261. [DOI: 10.1038/s41559-017-0418-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 11/03/2017] [Indexed: 11/09/2022]
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10
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Ujszegi J, Móricz ÁM, Krüzselyi D, Hettyey A. Skin toxin production of toads changes during early ontogeny but is not adjusted to the microbiota of the aquatic environment. Evol Ecol 2017. [DOI: 10.1007/s10682-017-9920-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Üveges B, Fera G, Móricz ÁM, Krüzselyi D, Bókony V, Hettyey A. Age- and environment-dependent changes in chemical defences of larval and post-metamorphic toads. BMC Evol Biol 2017; 17:137. [PMID: 28610604 PMCID: PMC5470210 DOI: 10.1186/s12862-017-0956-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 04/25/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Chemical defences are widespread in animals, but how their production is adjusted to ecological conditions is poorly known. Optimal defence theory predicts that inducible defences are favoured over constitutive defences when toxin production is costly and the need for it varies across environments. However, if some environmental changes occur predictably (e.g. coupled to transitions during ontogeny), whereas others are unpredictable (e.g. predation, food availability), changes in defences may have constitutive as well as plastic elements. To investigate this phenomenon, we raised common toad (Bufo bufo) tadpoles with ad libitum or limited food and in the presence or absence of chemical cues on predation risk, and measured their toxin content on 5 occasions during early ontogeny. RESULTS The number of compounds showed limited variation with age in tadpoles and was unaffected by food limitation and predator cues. The total amount of bufadienolides first increased and later decreased during development, and it was elevated in young and mid-aged tadpoles with limited food availability compared to their ad libitum fed conspecifics, whereas it did not change in response to cues on predation risk. We provide the first evidence for the active synthesis of defensive toxin compounds this early during ontogeny in amphibians. Furthermore, the observation of increased quantities of bufadienolides in food-restricted tadpoles is the first experimental demonstration of resource-dependent induction of elevated de novo toxin production, suggesting a role for bufadienolides in allelopathy. CONCLUSIONS Our study shows that the evolution of phenotypic plasticity in chemical defences may depend on the ecological context (i.e. predation vs. competition). Our results furthermore suggest that the age-dependent changes in the diversity of toxin compounds in developing toads may be fixed (i.e., constitutive), timed for the developmental stages in which they are most reliant on their chemical arsenal, whereas inducible plasticity may prevail in the amount of synthesized compounds.
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Affiliation(s)
- Bálint Üveges
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Gábor Fera
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Ágnes M. Móricz
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Dániel Krüzselyi
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Veronika Bókony
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó út 15, Budapest, 1022 Hungary
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12
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Hämäläinen L, Rowland HM, Mappes J, Thorogood R. Can video playback provide social information for foraging blue tits? PeerJ 2017; 5:e3062. [PMID: 28344901 PMCID: PMC5363260 DOI: 10.7717/peerj.3062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 02/03/2017] [Indexed: 11/20/2022] Open
Abstract
Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators encountering. Here we present blue tits (Cyanistes caeruleus) videos of demonstrators discovering palatable or aversive prey (injected with bitter-tasting Bitrex) from coloured feeding cups. First we quantify variation in demonstrators' responses to the prey items: aversive prey provoked high rates of beak wiping and head shaking. We then show that focal blue tits respond differently to the presence of a demonstrator on a video screen, depending on whether demonstrators discover palatable or aversive prey. Focal birds faced the video screen more during aversive prey presentations, and made more head turns. Regardless of prey type, focal birds also hopped more frequently during the presence of a demonstrator (compared to a control video of a different coloured feeding cup in an empty cage). Finally, we tested if demonstrators' behaviour affected focal birds' food preferences by giving individuals a choice to forage from the same cup as a demonstrator, or from the cup in the control video. We found that only half of the individuals made their choice in accordance to social information in the videos, i.e., their foraging choices were not different from random. Individuals that chose in accordance with a demonstrator, however, made their choice faster than individuals that chose an alternative cup. Together, our results suggest that video playback can provide social cues to blue tits, but individuals vary greatly in how they use this information in their foraging decisions.
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Affiliation(s)
- Liisa Hämäläinen
- Department of Zoology, University of Cambridge , Cambridge , United Kingdom
| | - Hannah M Rowland
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom; Institute of Zoology, Zoological Society of London, London, United Kindgom
| | - Johanna Mappes
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä , Jyväskylä , Finland
| | - Rose Thorogood
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom; Department of Biosciences, University of Helsinki, Helsinki, Finland
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13
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Westermann FL, McPherson IS, Jones TH, Milicich L, Lester PJ. Toxicity and utilization of chemical weapons: does toxicity and venom utilization contribute to the formation of species communities? Ecol Evol 2015; 5:3103-13. [PMID: 26357539 PMCID: PMC4559053 DOI: 10.1002/ece3.1595] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 06/09/2015] [Accepted: 06/14/2015] [Indexed: 11/06/2022] Open
Abstract
Toxicity and the utilization of venom are essential features in the ecology of many animal species and have been hypothesized to be important factors contributing to the assembly of communities through competitive interactions. Ants of the genus Monomorium utilize a variety of venom compositions, which have been reported to give them a competitive advantage. Here, we investigate two pairs of Monomorium species, which differ in the structural compositions of their venom and their co-occurrence patterns with the invasive Argentine ant. We looked at the effects of Monomorium venom toxicity, venom utilization, and aggressive physical interactions on Monomorium and Argentine ant survival rates during arena trials. The venom toxicity of the two species co-occurring with the invasive Argentine ants was found to be significantly higher than the toxicity of the two species which do not. There was no correlation between venom toxicity and Monomorium survival; however, three of the four Monomorium species displayed significant variability in their venom usage which was associated with the number of Argentine ant workers encountered during trials. Average Monomorium mortality varied significantly between species, and in Monomorium smithii and Monomorium antipodum, aggressive interactions with Argentine ants had a significant negative effect on their mortality. Our study demonstrates that different factors and strategies can contribute to the ability of a species to withstand the pressure of a dominant invader at high abundance, and venom chemistry appears to be only one of several strategies utilized.
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Affiliation(s)
- Fabian L Westermann
- Centre for Biodiversity and Restoration Ecology, Victoria University of Wellington PO Box 600, Wellington, New Zealand
| | - Iain S McPherson
- Department of Chemistry, Virginia Military Institute Lexington, Virginia, 24401
| | - Tappey H Jones
- Department of Chemistry, Virginia Military Institute Lexington, Virginia, 24401
| | - Lesley Milicich
- Centre for Biodiversity and Restoration Ecology, Victoria University of Wellington PO Box 600, Wellington, New Zealand
| | - Philip J Lester
- Centre for Biodiversity and Restoration Ecology, Victoria University of Wellington PO Box 600, Wellington, New Zealand
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Summers K, Speed MP, Blount JD, Stuckert AMM. Are aposematic signals honest? A review. J Evol Biol 2015; 28:1583-99. [DOI: 10.1111/jeb.12676] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 06/08/2015] [Accepted: 06/11/2015] [Indexed: 01/22/2023]
Affiliation(s)
- K. Summers
- Department of Biology; East Carolina University; Greenville NC USA
| | - M. P. Speed
- Department of Evolution, Ecology, and Behaviour; University of Liverpool; Liverpool UK
| | - J. D. Blount
- Centre for Ecology and Conservation, Biosciences; University of Exeter; Penryn UK
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15
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Ecological pharmacodynamics: prey toxin evolution depends on the physiological characteristics of predators. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2014.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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16
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Polčák D, Gvoždík L. Should I stay or should I go? The influence of temperature and sex on predator-induced responses in newts. Anim Behav 2014. [DOI: 10.1016/j.anbehav.2013.12.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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17
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Nokelainen O, Lindstedt C, Mappes J. Environment-mediated morph-linked immune and life-history responses in the aposematic wood tiger moth. J Anim Ecol 2013; 82:653-62. [PMID: 23356667 DOI: 10.1111/1365-2656.12037] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 11/20/2012] [Indexed: 12/01/2022]
Abstract
1. Warning signals are expected to evolve towards conspicuousness and monomorphism, and thereby hamper the evolution of multiple colour morphs. Here, we test fitness responses to different rearing densities to explain colour polymorphism in aposematic wood tiger moth (Parasemia plantaginis) males. 2. We used larval lines sired by white or yellow adult males selected for small or large melanization patterns of coloration. We reared these selected lines either solitarily (favourable conditions) or in aggregations (challenged conditions), and followed their performance to adult stage. We tested whether differences in larval density affected life-history traits, adult melanin expression, adult morph (white or yellow) survival and immunological responses. 3. We found that the aggregated environment increased mortality of larvae, but decreased larval developmental time and pupa weight. Adult wing melanin pigmentation was dependent on larval melanin expression but not rearing density. We also confirmed that adult wing coloration had a genetic basis (h(2) = 0.42) and was not influenced by larval growth density. Adult yellow males survived better from aggregations in comparison with white males, which may be related to differences in immune defence. White males had better encapsulation ability, whereas yellow males had increased lytic activity of haemolymph in the aggregations. 4. Our main results highlight, that morph-linked immune responses mediated by differential growth density may facilitate the maintenance of colour polymorphism in aposematic species. In nature, risk of diseases and parasites vary spatially and temporally. Therefore, both yellow and white adult morphs can be maintained due to their differential investment in immune defence in heterogeneous environments.
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Affiliation(s)
- Ossi Nokelainen
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, P.O. Box 35, 40014, Finland
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18
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Disengtangling the evolution of weak warning signals: high detection risk and low production costs of chemical defences in gregarious pine sawfly larvae. Evol Ecol 2011. [DOI: 10.1007/s10682-010-9456-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Mochida K. Temperature-Dependent Aposematic Behavior in the NewtCynops pyrrhogaster. Zoolog Sci 2010; 27:555-8. [DOI: 10.2108/zsj.27.555] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Greenlees MJ, Phillips BL, Shine R. Adjusting to a toxic invader: native Australian frogs learn not to prey on cane toads. Behav Ecol 2010. [DOI: 10.1093/beheco/arq095] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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21
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Cane toad toxicity: an assessment of extracts from early developmental stages and adult tissues using MDCK cell culture. Toxicon 2009; 53:385-91. [PMID: 18948131 DOI: 10.1016/j.toxicon.2008.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 09/19/2008] [Accepted: 10/07/2008] [Indexed: 11/21/2022]
Abstract
Extracts of the cane toad (Bufo [Chaunus] marinus) adversely affected the growth of Mardin-Darby canine kidney (MDCK) cells during culture. In a similar manner to ouabain treatment, application of toad extracts over a 24 h period resulted in high levels of cytotoxicity, as indicated by cell detachment, increased membrane permeability and loss of mitochondrial function. Cell viability and growth were unchanged for controls (PBS) and increased with the application of Limnodynastes peronii tadpole and adult frog extracts. We investigated the general cytotoxicity of cane toad developmental stages (e.g., eggs, embryonic hatchlings, tadpoles and post-metamorphic toadlets) as well as selected adult tissues (e.g. skin, gut, liver). Our results showed that pre-metamorphic cane toad aqueous extracts used at 1 mg/ml on MDCK cells generated cytotoxicity levels comparable to ouabain treatment (3 microM). After normalisation, extracts from 2-3-month-old toadlets appeared less toxic than pre- and early metamorphic stages. Adult tissues revealed a gradient of cytotoxicity levels ranging from non-toxic brain to highly toxic dorsal skin extracts.
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22
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Lindstedt C, Talsma JHR, Ihalainen E, Lindström L, Mappes J. Diet quality affects warning coloration indirectly: excretion costs in a generalist herbivore. Evolution 2009; 64:68-78. [PMID: 19659593 DOI: 10.1111/j.1558-5646.2009.00796.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Aposematic herbivores are under selection pressure from their host plants and predators. Although many aposematic herbivores exploit plant toxins in their own secondary defense, dealing with these harmful compounds might underlay costs. We studied whether the allocation of energy to detoxification and/or sequestration of host plant defense chemicals trades off with warning signal expression. We used a generalist aposematic herbivore Parasemia plantaginis (Arctiidae), whose adults and larvae show extensive phenotypic and genetic variation in coloration. We reared larvae from selection lines for small and large larval warning signals on Plantago lanceolata with either low or high concentration of iridoid glycosides (IGs). Larvae disposed of IGs effectively; their body IG content was low irrespective of their diet. Detoxification was costly as individuals reared on the high IG diet produced fewer offspring. The IG concentration of the diet did not affect larval coloration (no trade-off) but the wings of females were lighter orange (vs. dark red) when reared on the high IG diet. Thus, the difference in plant secondary chemicals did not induce variation in the chemical defense efficacy of aposematic individuals but caused variation in reproductive output and warning signals of females.
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Affiliation(s)
- Carita Lindstedt
- Department of Biological and Environmental Sciences, Centre of Excellence in Evolutionary Research, University of Jyväskylä, Jyväskylä, Finland.
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23
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Higginson AD, Ruxton GD. Dynamic models allowing for flexibility in complex life histories accurately predict timing of metamorphosis and antipredator strategies of prey. Funct Ecol 2009. [DOI: 10.1111/j.1365-2435.2009.01598.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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24
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FILIN I. A diffusion-based approach to stochastic individual growth and energy budget, with consequences to life-history optimization and population dynamics. J Evol Biol 2009; 22:1252-67. [DOI: 10.1111/j.1420-9101.2009.01741.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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25
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Hamilton R, Siva-Jothy M, Boots M. Two arms are better than one: parasite variation leads to combined inducible and constitutive innate immune responses. Proc Biol Sci 2008; 275:937-45. [PMID: 18230594 DOI: 10.1098/rspb.2007.1574] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Parasites represent a major threat to all organisms which has led to the evolution of an array of complex and effective defence mechanisms. Common to both vertebrates and invertebrates are innate immune mechanisms that can be either constitutively expressed or induced on exposure to infection. In nature, we find that a combination of both induced and constitutive responses are employed by vertebrates, invertebrates and, to an extent, plants when they are exposed to a parasite. Here we use a simple within-host model motivated by the insect immune system, consisting of both constitutive and induced responses, to address the question of why both types of response are maintained so ubiquitously. Generally, induced responses are thought to be advantageous because they are only used when required but are too costly to maintain constantly, while constitutive responses are advantageous because they are always ready to act. However, using a simple cost function but with no a priori assumptions about relative costs, we show that variability in parasite growth rates selects for a strategy that combines both constitutive and induced defences. Differential costs are therefore not necessary to explain the adoption of both forms of defence. Clearly, hosts are likely to be challenged by variable parasites in nature and this is sufficient to explain why it is optimal to deploy both arms of the innate immune system.
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Affiliation(s)
- Ruth Hamilton
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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26
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Skelhorn J, Ruxton GD. Ecological factors influencing the evolution of insects' chemical defenses. Behav Ecol 2007. [DOI: 10.1093/beheco/arm115] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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27
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OJALA K, LINDSTRÖM L, MAPPES J. Life-history constraints and warning signal expression in an arctiid moth. Funct Ecol 2007. [DOI: 10.1111/j.1365-2435.2007.01322.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Abstract
The conspicuous displays that warn predators of defenses carried by potential prey have been of interest to evolutionary biologists from the time of Wallace and Darwin to the present day. Although most studies implicitly assume that these "aposematic" warning signals simply indicate the presence of some repellent defense such as a toxin, it has been speculated that the intensity of the signal might reliably indicate the strength of defense so that, for example, the nastiest prey might "shout loudest" about their unprofitability. Recent phylogenetic and empirical studies of Dendrobatid frogs provide contradictory views, in one instance showing a positive correlation between toxin levels and conspicuousness, in another showing a breakdown of this relationship. In this paper we present an optimization model, which can potentially account for these divergent results. Our model locates the optimal values of defensive traits that are influenced by a range of costs and benefits. We show that optimal aposematic conspicuousness can be positively correlated with optimal prey toxicity, especially where population sizes and season lengths vary between species. In other cases, optimal aposematic conspicuousness may be negatively correlated with toxicity; this is especially the case when the marginal costs of aposematic displays vary between members of different populations. Finally, when displays incur no allocation costs there may be no single optimum value for aposematic conspicuousness, rather a large array of alternative forms of a display may have equal fitness.
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Affiliation(s)
- Michael P Speed
- School of Biological Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
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