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James B Barnett, Innes C Cuthill, Nicholas E Scott-Samuel
Defended prey often use distinctive, conspicuous, colours to advertise their unprofitability to potential predators (aposematism). These warning signals are frequently made up of salient, high contrast, stripes which have been hypothesized to increase the speed and accuracy of predator avoidance learning. Limitations in predator visual acuity, however, mean that these patterns cannot be resolved when viewed from a distance, and adjacent patches of colour will blend together (pattern blending). We investigated how saliency changes at different viewing distances in the toxic and brightly coloured cinnabar moth caterpillar ( Tyria jacobaeae )...
February 2018: Royal Society Open Science
Petr Veselý, Barbora Ernestová, Oldřich Nedvěd, Roman Fuchs
Growing evidence exists that aposematic and toxic prey may be included in a predator's diet when the predator experiences physiological stress. The tree sparrow Passer montanus is known to have a significant portion of aposematic and toxic ladybirds in its natural diet. Here, we present experiments testing the attack and eating rate of the tree sparrow toward the invasive aposematic harlequin ladybird Harmonia axyridis . We wondered whether the sparrow's ability to prey on native ladybirds predisposes them to also prey on harlequin ladybirds...
June 2017: Current Zoology
Michal Motyka, Lucie Kampova, Ladislav Bocak
Multiple patterns and intraspecific polymorphism should not persist in mutualistic Müllerian systems due to purifying and frequency-dependent selection, but they are commonly identified in nature. We analysed molecular phylogeny and reconstructed dispersal history of 58 species of Dilophotes (Coleoptera: Lycidae) in Asia. Dilophotes colonized the Great Sundas and Malay Peninsula where they joined extensive mimetic communities of net-winged beetles. We identified the brightly bi-coloured males and females which adverged on five occasions to different autochthonous models...
February 27, 2018: Scientific Reports
Andressa Paladini, Daniela M Takiya, Julie M Urban, Jason R Cryan
The spittlebug family Cercopidae (Hemiptera: Auchenorrhyncha: Cicadomorpha: Cercopoidea) is distributed worldwide, with highest species diversity in the tropics. Several included species are economically important pests of major agricultural crops and cultivated pasture grasses. Taxonomically, Cercopidae is divided into two subfamilies: the paraphyletic Old World Cercopinae and the monophyletic New World Ischnorhininae. Results are here presented from an investigation of phylogenetic relationships within Ischnorhininae based on DNA sequences from seven loci (18S rDNA, 28S rDNA, Histone 2A, Histone 3, Wingless, Cytochrome Oxidase I, and Cytochrome Oxidase II) generated from exemplars of 119 spittlebug species...
December 20, 2017: Molecular Phylogenetics and Evolution
Alexandre B Roland, Juan C Santos, Bella C Carriker, Stephanie N Caty, Elicio E Tapia, Luis A Coloma, Lauren A O'Connell
Some South American poison frogs (Dendrobatidae) are chemically defended and use bright aposematic colors to warn potential predators of their unpalatability. Aposematic signals are often frequency-dependent where individuals deviating from a local model are at a higher risk of predation. However, extreme diversity in the aposematic signal has been documented in poison frogs, especially in Oophaga . Here, we explore the phylogeographic pattern among color-divergent populations of the Little Devil poison frog Oophaga sylvatica by analyzing population structure and genetic differentiation to evaluate which processes could account for color diversity within and among populations...
November 2017: Ecology and Evolution
Lu-Yi Wang, Wen-San Huang, Hsin-Chieh Tang, Lung-Chun Huang, Chung-Ping Lin
Anti-predator strategies are significant components of adaptation in prey species. Aposematic prey are expected to possess effective defences that have evolved simultaneously with their warning colours. This study tested the hypothesis of the defensive function and ecological significance of the hard body in aposematic Pachyrhynchus weevils pioneered by Alfred Russel Wallace nearly 150 years ago. We used predation trials with Japalura tree lizards to assess the survivorship of 'hard' (mature) versus 'soft' (teneral) and 'clawed' (intact) versus 'clawless' (surgically removed) weevils...
January 25, 2018: Journal of Experimental Biology
Bodo D Wilts, Aidan J M Vey, Adriana D Briscoe, Doekele G Stavenga
BACKGROUND: Longwing butterflies, Heliconius sp., also called heliconians, are striking examples of diversity and mimicry in butterflies. Heliconians feature strongly colored patterns on their wings, arising from wing scales colored by pigments and/or nanostructures, which serve as an aposematic signal. RESULTS: Here, we investigate the coloration mechanisms among several species of Heliconius by applying scanning electron microscopy, (micro)spectrophotometry, and imaging scatterometry...
November 21, 2017: BMC Evolutionary Biology
Sandra R Schachat, Richard G Robbins, Jerome Goddard
Among the hard ticks (Acari: Ixodidae), many species in the section Metastriata have intricate ornamentation on the scutum that is often used as a taxonomic character. However, the biological function(s) of this ornamentation remains unknown. Here, we summarize the main functions of color patterns recognized in the animal kingdom-thermoregulation, aposematism, camouflage, aggregation, mate recognition, and sexual signaling-and evaluate the potential of each of these to explain ornamentation in hard ticks. We also note the challenges and uncertainties involved in interpreting ornamentation in ticks as well as potential approaches for future research...
October 17, 2017: Journal of Medical Entomology
Bibiana Rojas, Emily Burdfield-Steel, Hannu Pakkanen, Kaisa Suisto, Michael Maczka, Stefan Schulz, Johanna Mappes
Animals have evolved different defensive strategies to survive predation, among which chemical defences are particularly widespread and diverse. Here we investigate the function of chemical defence diversity, hypothesizing that such diversity has evolved as a response to multiple enemies. The aposematic wood tiger moth (Arctia plantaginis) displays conspicuous hindwing coloration and secretes distinct defensive fluids from its thoracic glands and abdomen. We presented the two defensive fluids from laboratory-reared moths to two biologically relevant predators, birds and ants, and measured their reaction in controlled bioassays (no information on colour was provided)...
September 27, 2017: Proceedings. Biological Sciences
S Tharanga Aluthwattha, Rhett D Harrison, Kithsiri B Ranawana, Cheng Xu, Ren Lai, Jin Chen
It is widely believed that aposematic signals should be conspicuous, but in nature, they vary from highly conspicuous to near cryptic. Current theory, including the honest signal or trade-off hypotheses of the toxicity-conspicuousness relationship, cannot explain why adequately toxic species vary substantially in their conspicuousness. Through a study of similarly toxic Danainae (Nymphalidae) butterflies and their mimics that vary remarkably in their conspicuousness, we show that the benefits of conspicuousness vary along a gradient of predation pressure...
September 2017: Ecology and Evolution
Andrés Posso-Terranova, José Á Andrés
Aposematic signals represent one of the classical systems to study evolution and, as such, they have received considerable empirical and theoretical investigation. Despite the extensive literature on aposematic coloration, much uncertainty remains about genetic changes responsible for the repeated evolution of similar signals in multiple lineages. Here, we study the diversification and convergence of coloration among lineages of aposematic harlequin poison frogs (Oophaga histrionica complex). Our results suggest that different background phenotypes, showing different color and/or luminance contrast, have evolved independently at least twice in this group...
November 2017: Evolution; International Journal of Organic Evolution
Anne E Winters, Naomi F Green, Nerida G Wilson, Martin J How, Mary J Garson, N Justin Marshall, Karen L Cheney
Warning signal variation is ubiquitous but paradoxical: low variability should aid recognition and learning by predators. However, spatial variability in the direction and strength of selection for individual elements of the warning signal may allow phenotypic variation for some components, but not others. Variation in selection may occur if predators only learn particular colour pattern components rather than the entire signal. Here, we used a nudibranch mollusc, Goniobranchus splendidus, which exhibits a conspicuous red spot/white body/yellow rim colour pattern, to test this hypothesis...
August 30, 2017: Proceedings. Biological Sciences
Heather M Hines, Paige Witkowski, Joseph S Wilson, Kazumasa Wakamatsu
The stinging hymenopteran velvet ants (Mutillidae) and bumble bees (Apidae: Bombus spp.) have both undergone extensive diversification in aposematic color patterns, including yellow-red hues and contrasting dark-light body coloration, as a result of Müllerian mimicry. Understanding the genetic and developmental mechanisms underlying shifts in these mimetic colors requires characterization of their pigmentation. In this study, a combination of solubility, spectrophotometry, and melanin degradation analysis are applied to several color forms and species of these lineages to determine that orange-red colors in both lineages are comprised of primarily dopamine-derived pheomelanins...
2017: PloS One
Rute B Clemente-Carvalho, Marcos Vaira, Laura E King, Daria Koscinski, Maria I Bonansea, Stephen C Lougheed
The Yungas Redbelly Toad, Melanophryniscus rubriventris, is patchily distributed in Argentina, confined to the upland portion (1000-2000m above sea level) of the montane forests of northern and central regions of Salta, and in central-eastern and south-eastern Jujuy. This species is known for its striking aposematic color variation across its geographic distribution, and was once treated as a complex of three subspecies based on distinctive color patterns. Here we assess the geographical genetic variation within M...
November 2017: Molecular Phylogenetics and Evolution
Yûsuke KonDo, Shinichi Yoda, Takayuki Mizoguchi, Toshiya Ando, Junichi Yamaguchi, Kimiko Yamamoto, Yutaka Banno, Haruhiko Fujiwara
A stripe pattern is an aposematic or camouflage coloration often observed among various caterpillars. However, how this ecologically important pattern is formed is largely unknown. The silkworm dominant mutant Zebra (Ze) has a black stripe in the anterior margin of each dorsal segment. Here, fine linkage mapping of 3,135 larvae revealed a 63-kbp region responsible for the Ze locus, which contained three candidate genes, including the Toll ligand gene spätzle3 (spz-3). Both electroporation-mediated ectopic expression and RNAi analyses showed that, among candidate genes, only processed spz-3 induced melanin pigmentation and that Toll-8 was the candidate receptor gene of spz-3 This Toll ligand/receptor set is also involved in melanization of other mutant Striped (p(S) ), which has broader stripes...
August 1, 2017: Proceedings of the National Academy of Sciences of the United States of America
Ariel Rodríguez, James D Burgon, Mariana Lyra, Iker Irisarri, Denis Baurain, Leon Blaustein, Bayram Göçmen, Sven Künzel, Barbara K Mable, Arne W Nolte, Michael Veith, Sebastian Steinfartz, Kathryn R Elmer, Hervé Philippe, Miguel Vences
The rise of high-throughput sequencing techniques provides the unprecedented opportunity to analyse controversial phylogenetic relationships in great depth, but also introduces a risk of being misinterpreted by high node support values influenced by unevenly distributed missing data or unrealistic model assumptions. Here, we use three largely independent phylogenomic data sets to reconstruct the controversial phylogeny of true salamanders of the genus Salamandra, a group of amphibians providing an intriguing model to study the evolution of aposematism and viviparity...
October 2017: Molecular Phylogenetics and Evolution
Josef Beneš, Petr Veselý
Birds are usually considered the main predators shaping the evolution of aposematic signals and mimicry. Nevertheless, some lizards also represent predominately visually oriented predators, so they may also play an important role in the evolution of aposematism. Despite this fact, experimental evidence regarding the responses of lizards to aposematic prey is very poor compared to such evidence in birds. Lizards possess very similar sensory and cognitive abilities to those of birds and their response to aposematic prey may thus be affected by very similar processes...
August 2017: Zoology: Analysis of Complex Systems, ZACS
James B Barnett, Innes C Cuthill, Nicholas E Scott-Samuel
The effect of viewing distance on the perception of visual texture is well known: spatial frequencies higher than the resolution limit of an observer's visual system will be summed and perceived as a single combined colour. In animal defensive colour patterns, distance-dependent pattern blending may allow aposematic patterns, salient at close range, to match the background to distant observers. Indeed, recent research has indicated that reducing the distance from which a salient signal can be detected can increase survival over camouflage or conspicuous aposematism alone...
July 12, 2017: Proceedings. Biological Sciences
Tammy M Duong, Ann B Gomez, Thomas N Sherratt
Aposematism is an evolved, cross-species association between a preys' unprofitability and the presence of conspicuous signals. Avian predators have been widely employed to understand the evolution of these warning signals However, insect predators are abundant, diverse, and highly visual foragers that have been shown to be capable of learned aversion. Therefore, it is likely that their behaviour also shapes the nature of anti-predator traits. In this study, we evaluated the rates of attack of a community (13 species) of mature adult dragonflies (Odonata) on artificial prey of varying size (2...
2017: PloS One
Eva Landová, Kateřina Hotová Svádová, Roman Fuchs, Pavel Štys, Alice Exnerová
Social learning plays an important role in acquiring new foraging skills and food preferences in many bird species but its potential role in learning to avoid aposematic prey has never been studied. We tested the effect of social learning on the acquisition of avoidance of aposematic insect prey (firebug Pyrrhocoris apterus; Heteroptera) in juvenile, hand-reared great tits (Parus major). Behaviour towards aposematic prey was compared between two groups of birds: (1) the observers that were, prior to encounter with firebugs, allowed to watch the experienced conspecific demonstrator repeatedly refuse to attack the prey, and (2) the control birds that lacked this opportunity...
September 2017: Animal Cognition
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