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Emmanuelle Sophie Briolat, Mika Zagrobelny, Carl Erik Olsen, Jonathan D Blount, Martin Stevens
The distinctive black and red wing pattern of six-spot burnet moths (Zygaena filipendulae, L.) is a classic example of aposematism, advertising their potent cyanide-based defences. While such warning signals provide a qualitatively honest signal of unprofitability, the evidence for quantitative honesty, whereby variation in visual traits could provide accurate estimates of individual toxicity, is more equivocal. Combining measures of cyanogenic glucoside content and wing colour from the perspective of avian predators, we investigate the relationship between coloration and defences in Z...
May 16, 2018: Evolution; International Journal of Organic Evolution
Michael Forthman, Christiane Weirauch
The diversity of colour patterns and its importance in interactions with the environment make colouration in animals an intriguing research focus. Aposematic colouration is positively correlated with body size in certain groups of animals, suggesting that warning colours are more effective or that crypsis is harder to achieve in larger animals. Surprisingly, this relationship has not been recovered in studies investigating insects, which may have been confounded by a focus on aposematic taxa that are also gregarious...
May 9, 2018: Journal of Evolutionary Biology
Etelvino J H Bechara, Cassius V Stevani
Bioluminescence - visible and cold light emission by living organisms - is a worldwide phenomenon, reported in terrestrial and marine environments since ancient times. Light emission from microorganisms, fungi, plants and animals may have arisen as an evolutionary response against oxygen toxicity and was appropriated for sexual attraction, predation, aposematism, and camouflage. Light emission results from the oxidation of a substrate, luciferin, by molecular oxygen, catalyzed by a luciferase, producing oxyluciferin in the excited singlet state, which decays to the ground state by fluorescence emission...
2018: Anais da Academia Brasileira de Ciências
Emily Burdfield-Steel, Hannu Pakkanen, Bibiana Rojas, Juan A Galarza, Johanna Mappes
Many animals protect themselves from predation with chemicals, both self-made or sequestered from their diet. The potential drivers of the diversity of these chemicals have been long studied, but our knowledge of these chemicals and their acquisition mode is heavily based on specialist herbivores that sequester their defenses. The wood tiger moth (Arctia plantaginis, Linnaeus, 1758) is a well-studied aposematic species, but the nature of its chemical defenses has not been fully described . Here, we report the presence of two methoxypyrazines, 2-sec-butyl-3-methoxypyrazine and 2-isobutyl-3-methoxypyrazine, in the moths' defensive secretions...
March 1, 2018: Journal of Insect Science
Jan M Kaczmarek, Mikołaj Kaczmarski, Jan Mazurkiewicz, Janusz Kloskowski
In Batesian mimicry, a species lacking defences against predators benefits from mimicking the aposematic signal of a defended species, while the model may incur the costs of reduced defensive efficacy. Similar reciprocal indirect effects may emerge even when the signal is not mimicked; termed associational effects, such interactions are well known in plants sharing herbivores but have received little attention in animal studies. We investigated associational interactions in a system where unequally defended prey (chemically defended Bufo bufo and undefended Rana temporaria tadpoles), sharing general morphology but not an aposematic signal, were exposed to predation by the carp Cyprinus carpio along a gradient of relative prey abundance...
April 30, 2018: Oecologia
Thomas Carle, Rio Horiwaki, Anya Hurlbert, Yoshifumi Yamawaki
Animals learn to associate sensory cues with the palatability of food in order to avoid bitterness in food (a common sign of toxicity). Associations are important for active foraging predators to avoid unpalatable prey and to invest energy in searching for palatable prey only. However, it has been suggested that sit-and-wait predators might rely on the opportunity that palatable prey approach them by chance: the most efficient strategy could be to catch every available prey and then decide whether to ingest them or not...
2018: Journal of Insect Behavior
J P Lawrence, Michael Mahony, Brice P Noonan
Anti-predator signaling is highly variable with numerous examples of species employing cryptic coloration to avoid detection or conspicuous coloration (often coupled with a secondary defense) to ensure detection and recollection. While the ends of this spectrum are clear in their function, how species use intermediate signals is less clear. Australian Brood Frogs (Pseudophryne) display conspicuous coloration on both their dorsum and venter. Coupled with the alkaloid toxins these frogs possess, this coloration may be aposematic, providing a protective warning signal to predators...
2018: PloS One
Debora Wolff Bordignon, Valentina Zaffaroni Caorsi, Patrick Colombo, Michelle Abadie, Ismael Verrastro Brack, Bibiana Terra Dasoler, Márcio Borges-Martins
Aposematic signals as well as body behaviours may be important anti-predator defences. Species of the genus Melanophryniscus are characterised by having toxic lipophilic alkaloids in the skin and for presenting a red ventral colouration, which can be observed when they perform the behaviour called the unken reflex. Both the reflex behaviour and the colouration pattern are described as defence mechanisms. However, there are currently no studies testing their effectiveness against predators. This study aimed to test experimentally if both ventral conspicuous colouration and the unken reflex in Melanophryniscus cambaraensis function as aposematic signals against visually oriented predators (birds)...
2018: PloS One
J P Lawrence, Brice P Noonan
A few colors, such as red and yellow, are commonly found in aposematic (warning) signaling across taxa, independent of evolutionary relationships. These colors have unique traits (i.e., hue, brightness) that aid in their differentiation, and perhaps, their effectiveness in promoting avoidance learning. This repeated use calls into question the influence of selection on specific warning colors adopted by aposematic prey-predator systems. To disentangle the influence of color characteristics on this process, we trained week-old chickens (Gallus gallus domesticus) to learn to avoid distasteful food that was associated with one of three color signals (yellow, white, red) that varied in both hue and in brightness in order to assess which of these traits most influenced their ability to learn avoidance...
2018: PloS One
Michael L Yuan, Ian J Wang
Spatial heterogeneity in the strength or agents of selection can lead to geographic variation in ecologically important phenotypes. Many dendrobatid frogs sequester alkaloid toxins from their diets and often exhibit fixed mutations at NaV1.4, a voltage-gated sodium ion channel associated with alkaloid toxin resistance. Yet previous studies have noted an absence of resistance mutations in individuals from several species known to sequester alkaloid toxins, suggesting possible intraspecific variation for alkaloid resistance in these species...
2018: PloS One
Brian Folt, Maureen A Donnelly, Craig Guyer
The conspecific attraction hypothesis predicts that individuals are attracted to conspecifics because conspecifics may be cues to quality habitat and/or colonists may benefit from living in aggregations. Poison frogs (Dendrobatidae) are aposematic, territorial, and visually oriented-three characteristics which make dendrobatids an appropriate model to test for conspecific attraction. In this study, we tested this hypothesis using an extensive mark-recapture dataset of the strawberry poison frog ( Oophaga pumilio ) from La Selva Biological Station, Costa Rica...
March 2018: Ecology and Evolution
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...
March 2018: 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...
January 10, 2018: 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
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