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Thanh-Lan Gluckman, Nicholas I Mundy
Melanin pigmentation patterns are ubiquitous in animals and function in crypsis, physical protection, thermoregulation and signalling. In vertebrates, pigmentation patterns formed over large body regions as well as within appendages (hair/feathers) may be due to the differential distribution of pigment producing cells (melanocytes) and/or regulation of the melanin synthesis pathway. We took advantage of the pigmentation patterns of Japanese quail embryos (pale ventrum and patterned feathers dorsally) to explore the role of genes and their transcripts in regulating the function of the melanocortin-1-receptor (MC1R) via 1...
2017: PloS One
Harshad Vijay Mayekar, Ullasa Kodandaramaiah
Lepidopteran insects have provided excellent study systems for understanding adaptive phenotypic plasticity. Although there are a few well-studied examples of adult plasticity among tropical butterflies, our understanding of plasticity of larval and pupal stages is largely restricted to temperate butterflies. The environmental parameters inducing phenotypic plasticity and the selective pressures acting on phenotypes are likely to differ across tropical and temperate climate regimes. We tested the influence of relative humidity (RH), a prominent yet under-appreciated tropical climatic component, along with pupation substrate, larval development time, pupal sex and weight in determining pupal colour in the tropical satyrine butterfly Mycalesis mineus...
2017: PloS One
Julia Carolina Segami Marzal, Andreas Rudh, Björn Rogell, Anders Ödeen, Hanne Løvlie, Charlotte Rosher, Anna Qvarnström
Population divergence in sexual signals may lead to speciation through prezygotic isolation. Sexual signals can change solely due to variation in the level of natural selection acting against conspicuousness. However, directional mate choice (i.e., favoring conspicuousness) across different environments may lead to gene flow between populations, thereby delaying or even preventing the evolution of reproductive barriers and speciation. In this study, we test whether natural selection through predation upon mate-choosing females can favor corresponding changes in mate preferences...
January 2017: Ecology and Evolution
Laura E Bagge, Karen J Osborn, Sönke Johnsen
Transparent zooplankton and nekton are often nearly invisible when viewed under ambient light in the pelagic zone [1-3]. However, in this environment, where the light field is directional (and thus likely to cause reflections), and under the bioluminescent searchlights of potential predators, animals may be revealed by reflections from their body surface [4-7]. We investigated the cuticle surfaces of seven species of hyperiids (Crustacea; Amphipoda) using scanning electron microscopy and found two undocumented features that may reduce reflectance...
November 21, 2016: Current Biology: CB
Nuria Polo-Cavia, Ivan Gomez-Mestre
In heterogeneous environments, the capacity for colour change can be a valuable adaptation enhancing crypsis against predators. Alternatively, organisms might achieve concealment by evolving preferences for backgrounds that match their visual traits, thus avoiding the costs of plasticity. Here we examined the degree of plasticity in pigmentation of newt larvae (Lissotriton boscai) in relation to predation risk. Furthermore, we tested for associated metabolic costs and pigmentation-dependent background choice behaviour...
January 4, 2017: Scientific Reports
Linus Günther, Marlena D Lopez, Mirjam Knörnschild, Kyle Reid, Martina Nagy, Frieder Mayer
With their extraordinary species richness and diversity in ecological traits and social systems, bats are a promising taxon for testing socio-ecological hypotheses in order to get new insights into the evolution of animal social systems. Regarding its roosting habits, proboscis bats form an extreme by occupying sites which are usually completely exposed to daylight (e.g. tree trunks, vines or rocks). This is accompanied by morphological and behavioural adaptations to remain cryptic in exposed day roosts. With long-term behavioural observations and genetic parentage analyses of individually marked proboscis bats, we assessed its social dispersion and male mating strategy during day and night...
November 2016: Royal Society Open Science
Healy Hamilton, Norah Saarman, Graham Short, Anna B Sellas, Beth Moore, Tinya Hoang, Christopher L Grace, Martin Gomon, Karen Crow, W Brian Simison
The family Syngnathidae is a large and diverse clade of morphologically unique bony fishes, with 57 genera and 300 described species of seahorses, pipefishes, pipehorses, and seadragons. They primarily inhabit shallow coastal waters in temperate and tropical oceans, and are characterized by a fused jaw, male brooding, and extraordinary crypsis. Phylogenetic relationships within the Syngnathidae remain poorly resolved due to lack of generic taxon sampling, few diagnostic morphological characters, and limited molecular data...
October 29, 2016: Molecular Phylogenetics and Evolution
John Egan, Rebecca J Sharman, Kenneth C Scott-Brown, Paul George Lovell
Disruptive colouration is a visual camouflage composed of false edges and boundaries. Many disruptively camouflaged animals feature enhanced edges; light patches are surrounded by a lighter outline and/or a dark patches are surrounded by a darker outline. This camouflage is particularly common in amphibians, reptiles and lepidopterans. We explored the role that this pattern has in creating effective camouflage. In a visual search task utilising an ultra-large display area mimicking search tasks that might be found in nature, edge enhanced disruptive camouflage increases crypsis, even on substrates that do not provide an obvious visual match...
December 6, 2016: Scientific Reports
Martin Bulla, Mihai Valcu, Adriaan M Dokter, Alexei G Dondua, András Kosztolányi, Anne L Rutten, Barbara Helm, Brett K Sandercock, Bruce Casler, Bruno J Ens, Caleb S Spiegel, Chris J Hassell, Clemens Küpper, Clive Minton, Daniel Burgas, David B Lank, David C Payer, Egor Y Loktionov, Erica Nol, Eunbi Kwon, Fletcher Smith, H River Gates, Hana Vitnerová, Hanna Prüter, James A Johnson, James J H St Clair, Jean-François Lamarre, Jennie Rausch, Jeroen Reneerkens, Jesse R Conklin, Joanna Burger, Joe Liebezeit, Joël Bêty, Jonathan T Coleman, Jordi Figuerola, Jos C E W Hooijmeijer, José A Alves, Joseph A M Smith, Karel Weidinger, Kari Koivula, Ken Gosbell, Klaus-Michael Exo, Larry Niles, Laura Koloski, Laura McKinnon, Libor Praus, Marcel Klaassen, Marie-Andrée Giroux, Martin Sládeček, Megan L Boldenow, Michael I Goldstein, Miroslav Šálek, Nathan Senner, Nelli Rönkä, Nicolas Lecomte, Olivier Gilg, Orsolya Vincze, Oscar W Johnson, Paul A Smith, Paul F Woodard, Pavel S Tomkovich, Phil F Battley, Rebecca Bentzen, Richard B Lanctot, Ron Porter, Sarah T Saalfeld, Scott Freeman, Stephen C Brown, Stephen Yezerinac, Tamás Székely, Tomás Montalvo, Theunis Piersma, Vanessa Loverti, Veli-Matti Pakanen, Wim Tijsen, Bart Kempenaers
The behavioural rhythms of organisms are thought to be under strong selection, influenced by the rhythmicity of the environment. Such behavioural rhythms are well studied in isolated individuals under laboratory conditions, but free-living individuals have to temporally synchronize their activities with those of others, including potential mates, competitors, prey and predators. Individuals can temporally segregate their daily activities (for example, prey avoiding predators, subordinates avoiding dominants) or synchronize their activities (for example, group foraging, communal defence, pairs reproducing or caring for offspring)...
December 1, 2016: Nature
John W Rowe, David L Clark, Rebecca A Mortensen, Carolyn V Commissaris, Lawrence W Wittle, John K Tucker
Color and pigmentation patterns of the integument can facilitate crypsis, thermoregulation, and social signaling. According to the "thermal melanism hypothesis", cold environmental temperature should increase the quantity of melanin that is deposited in the integument thereby facilitating radiative warming. We studied the influences of water temperature (26°C or 31°C) and substrate color (black or white) on the degree of melanization in the red-eared slider, Trachemys scripta elegans, under laboratory conditions...
October 2016: Journal of Thermal Biology
C M Champ, M Vorobyev, N J Marshall
Coral reef fishes are among the most colourful animals in the world. Given the diversity of lifestyles and habitats on the reef, it is probable that in many instances coloration is a compromise between crypsis and communication. However, human observation of this coloration is biased by our primate visual system. Most animals have visual systems that are 'tuned' differently to humans; optimized for different parts of the visible spectrum. To understand reef fish colours, we need to reconstruct the appearance of colourful patterns and backgrounds as they are seen through the eyes of fish...
September 2016: Royal Society Open Science
R Alexander Pyron, Alejandro Arteaga, Lourdes Y Echevarría, Omar Torres-Carvajal
The genus Synophis contains a number of enigmatic species, distributed primarily in the Andean highlands of northern South America. Their extreme crypsis and rarity has precluded detailed study of most species. A recent flurry of collection activity resulted in the accession of many new specimens, and the description of 4 new species in 2015, doubling the number of described taxa. However, lingering questions remain regarding the assignment of many new and historical specimens, the morphological limits and geographical ranges of the species, and their phylogenetic relationships...
September 28, 2016: Zootaxa
W Clark, E Leclercq, H Migaud, J Nairn, A Davie
This study confirmed that observations of blue-green colouration in plasma fractions of the ballan wrasse Labrus bergylta were caused by the linear tetra-pyrrole biliverdin and that the molecule was of the physiologically relevant IXα isomer. Accumulation appears driven by chromogenic association with an unknown protein moiety which precludes enzymatic reduction and would suggest active management. It was demonstrated that the pigment did not fluctuate relative to ontogeny, or indeed binary gender in the species of interest, but mobilisation and depletion in the subset of individuals undergoing sex change at the time of study supports a potential association with gender inversion processes...
October 2016: Journal of Fish Biology
Fabio Cortesi, Zuzana Musilová, Sara M Stieb, Nathan S Hart, Ulrike E Siebeck, Karen L Cheney, Walter Salzburger, N Justin Marshall
Animals often change their habitat throughout ontogeny; yet, the triggers for habitat transitions and how these correlate with developmental changes - e.g. physiological, morphological and behavioural - remain largely unknown. Here, we investigated how ontogenetic changes in body coloration and of the visual system relate to habitat transitions in a coral reef fish. Adult dusky dottybacks, Pseudochromis fuscus, are aggressive mimics that change colour to imitate various fishes in their surroundings; however, little is known about the early life stages of this fish...
August 15, 2016: Journal of Experimental Biology
Chris B Wacker, Bronwyn M McAllan, Gerhard Körtner, Fritz Geiser
Mammalian fur often shows agouti banding with a proximal dark band near the skin and a lighter distal band. We examined the function of both bands in relation to camouflage, thermal properties of pelts, and thermal energetics of dunnarts (Sminthopsis crassicaudata), which are known to use torpor and basking. Although the distal band of dunnart fur darkened with increasing latitude, which is important for camouflage, it did not affect the thermal properties and the length of the dark band and total hair length were not correlated...
August 2016: Die Naturwissenschaften
Haruhiko Yasumuro, Yuzuru Ikeda
We examined effect of environmental enrichment on cuttlefish, the most neutrally advanced invertebrate, to compare species variation of genetic and environmental influences. Cuttlefish were reared from seven to 117 days in one of three environments, namely, "poor" (artificial bottom without objects), "standard" (sandy bottom), and "enriched" (sandy bottom with objects). In Experiment 1, we explored whether enrichment affects the exhibition of crypsis in the cuttlefish. The cuttlefish in the standard and enriched environments spent most of their time at the bottom, exhibiting the mottled or disruptive pattern starting at 27 days of age...
June 2016: Zoological Science
Nicola J Nadeau, Carolina Pardo-Diaz, Annabel Whibley, Megan A Supple, Suzanne V Saenko, Richard W R Wallbank, Grace C Wu, Luana Maroja, Laura Ferguson, Joseph J Hanly, Heather Hines, Camilo Salazar, Richard M Merrill, Andrea J Dowling, Richard H ffrench-Constant, Violaine Llaurens, Mathieu Joron, W Owen McMillan, Chris D Jiggins
The wing patterns of butterflies and moths (Lepidoptera) are diverse and striking examples of evolutionary diversification by natural selection. Lepidopteran wing colour patterns are a key innovation, consisting of arrays of coloured scales. We still lack a general understanding of how these patterns are controlled and whether this control shows any commonality across the 160,000 moth and 17,000 butterfly species. Here, we use fine-scale mapping with population genomics and gene expression analyses to identify a gene, cortex, that regulates pattern switches in multiple species across the mimetic radiation in Heliconius butterflies...
June 2, 2016: Nature
Theodore Stankowich, Lisa A Campbell
Mammals have independently evolved a wide variety of morphological adaptations for use in avoiding death by predation, including spines, quills, dermal plates, and noxious sprays. Although these traits appear to protect their bearer from predatory attack, it is less obvious why some species evolved them and others have not. We investigated the ecological correlates favoring the evolution of specialized defenses in mammals, focusing on conspicuousness to predators due to body size and openness of habitat. We scored species for the degree to which they are protected by spines, quills, dermal plating, and sprays and used phylogenetic comparative analyses to study the morphological and ecological factors that may favor their evolution...
July 2016: Evolution; International Journal of Organic Evolution
Eric F LoPresti, Richard Karban
Sand entrapment on plant surfaces, termed psammophory or sand armor, is a phylogenetically and geographically widespread trait. The functional significance of this phenomenon has been poorly investigated. Sand and soil are nonnutritive and difficult for herbivores to process, as well as visually identical to the background. We experimentally investigated whether this sand coating physically protected the plant from herbivores or increased crypsis (e.g., decreased apparency to herbivores). We tested the former hypothesis by removing entrapped sand from stems, petioles, and leaves of the sand verbena Abronia latifolia and by supplementing natural sand levels in the honeyscented pincushion plant Navarretia mellita...
April 2016: Ecology
Rafael Maia, Dustin R Rubenstein, Matthew D Shawkey
Colorful plumage plays a prominent role in the evolution of birds, influencing communication (sexual/social selection), and crypsis (natural selection). Comparative studies have focused primarily on these selective pressures, but the mechanisms underlying color production can also be important by constraining the color gamut upon which selection acts. Iridescence is particularly interesting to study the interaction between selection and color-producing mechanisms because a broad range of colors can be produced with a shared template, and innovations to this template further expand this by increasing the parameters interacting to produce colors...
May 2016: Evolution; International Journal of Organic Evolution
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