Ultraviolet reflectance in a melanin-based plumage trait is heritable

Question: Is ultraviolet (UV) reflectance of melanin-based plumage ornaments heritable? Data studied: We considered the barn owl (Two alba), a species that varies continuously from white to reddish-brown, a pheomelanin-based trait. Methods: To perform a partial cross-fostering experiment. we exchanged one to three hatchlings between 16 pairs of nests with a similar hatching date. This experiment allocated hatchlings randomly among rearing environments. Forty-nine days later, we collected three feathers per individual to measure UV reflectance. Conclusions: The cross-fostering experiment showed that. independently of human-visible coloration, variation in UV reflectance is significantly sensitive to origin-related factors.

Préparatifs de Noël en Angleterre [le plumage des canards ou des oies en groupe] : [photographie de presse] / [Agence Rol]

Référence bibliographique : Rol, 57316

Covariation between plumage colour polymorphism and diet in the Barn Owl Tyto alba

Several hypotheses might explain the evolution and maintenance of colour morphs within animal populations. The 'alternative foraging strategy' hypothesis states that alternative colour morphs exploit different ecological niches. This hypothesis predicts that morphs differ in diet, either because foraging success on alternative prey species is morph-dependent or because differently coloured individuals exploit alternative habitats. I examined this prediction in the Barn Owl Tyto alba, a bird that varies in plumage coloration continuously from dark reddish-brown to white. On the European continent, Owls are light-coloured (subspecies T. a. alba) in the south and reddish-brown (T. a. guttata) in the north; in central Europe the two subspecies interbreed, generating many colour variants. If plumage coloration indicates alternative foraging strategies, in sympatry dark- and light-coloured owls should consume prey species that are typical of the diets of T. a. guttata and T. a. alba in allopatry, respectively. In line with this prediction, both in allopatry and in sympatry in Switzerland T. a. guttata fed primarily upon Common Voles Microtus arvalis and T. a. alba upon Wood Mice Apodemus spp. Statistical analyses suggest that morph-dependent diet did not arise from a non-random habitat distribution of owls with respect to plumage coloration. This suggests that foraging success upon alternative prey is morph-dependent.

Els Colors : estratègia i imatge empresarial

L’estudi presentat en aquest informe correspon a la investigació al voltant del paper del color al màrqueting empresarial. La seva influència, ja sigui com a eina comunicativa o identificadora d’un producte o empresa, es torna molt superior a la qualse li podria atribuir en un primer moment (fins al punt de convertir-se en un aspecte clau) quan s’observa la reacció dels consumidors davant les seves variacions i l’aplicació que en fan les companyies.La primera idea a confirmar pel treball és el caràcter inconscient de les reaccions generades per la percepció visual i les motivacions existents per explotarles.Un estudi sobre els precursors i les teories actuals de la psicologia del color condueix a una comparació entre allò que reflecteixen els estudis amb la realitat empresarial actual, mostrant una correlació evident entre valors de les organitzacions iles seves expressions pictòriques i exemplificant situacions de coincidència entre canvi de color i canvi d’estratègia corporativa. Aquest procés dóna lloc a la hipòtesi principal: el color és un element indispensable del procés de comercialització.Per tal de contrastar-la, inicialment s’acudirà a l’evidència recaptada mitjançant un qüestionari d’elaboració pròpia. A partir dels seus resultats, observarem com els consumidors no creuen estar tan influenciats per l’estètica i el color dels productes que compren com efectivament ho estan, i podrem seguir reafirmant la teoria exposada a la primera part amb paral·lelismes respecte les opinions mostrades.A continuació, es reflexionarà sobre quatre funcions del color aplicades a l’empresa de les quals aquestes es poden beneficiar: segmentador de mercats, indicador de canvi de tendència, identificador nacional i element associatiu immediat.Les determinacions preses a cada apartat a partir de reflexions teòriques i exemples formaran un entramat de conclusions que posarà fi al projecte en un apartat en el quals’ordenen les bases per a la correcta aplicació del color al món empresarial, en funció del rol de la companyia dins del seu mercat, els valors a transmetre, el tipus de producte a comerciar, etc.Finalment, els nombrosos fonaments que se li poden atribuir a favor fan que lahipòtesi inicial quedi ratificada com a certa, ja que es demostrarà una permanent voluntat per part de les empreses d’influir sobre el comportament dels destinataris del seu procés publicitari mitjançant aquest recurs, ja sigui de manera directa o indirecta.

Experimental support for the make-up hypothesis in nestling tawny owls (Strix aluco)

Body condition can affect coloration of traits used in sexual selection and parent-offspring communication by inducing rapid internal changes in pigment concentration or aggregation, thickness of collagen arrays, or blood flux. The recent "makeup hypothesis" proposes an alternative honesty-reinforcing mechanism, with behaviorally mediated deposition of substances on body surfaces ("cosmetics") generating covariation between body condition and coloration. In birds, the uropygial gland wax is actively spread on feathers using the bill and changes in its deposition rate may cause rapid changes in bill and plumage coloration. Using tawny owl nestlings, we tested 3 predictions of the makeup hypothesis, namely that 1) quantity of preen wax deposited accounts for variation in bill coloration, 2) an immune stimulation (induced by injection of a lipopolysaccharide [LPS]) impairs uropygial gland wax production, and 3) different intensities of immune stimulations (strong vs. weak stimulations induced by injections of either LPS or phytohemagglutinin [PHA], respectively) and high versus low food availabilities result in different bill colorations. We found that 1) preen wax reduced bill brightness, 2) a challenge with LPS impaired uropygial gland development, and 3) nestlings challenged with LPS had a brighter bill than PHA-injected nestlings, whereas diet manipulation had no significant effect. Altogether, these results suggest that a strong immune challenge may decrease preen wax deposition rate on the bill of nestling birds, at least by impairing gland wax production, which causes a change in bill coloration. Our study therefore highlights that cosmetic colors might signal short-term variation in immunological status.

Use of artificial substrates of different colors for oviposition by the brown stink bug Euschistus heros (Hemiptera, Pentatomidae)

Aiming to contribute to a rearing methodology for the brown stink bug, Euschistus heros, in the laboratory, we evaluated oviposition on artificial substrates of different colors. During six days, oviposition was evaluated daily, by counting the total number of eggs, number of clutches, and eggs/clutch. Females laid 12,463 eggs, in 1,677 clutches, resulting in an average of 7.28 ± 0.44 eggs/clutch. Black, brown, and green felt had the most eggs and clutches. The results demonstrated that many colors are suitable as oviposition substrate for E. heros, providing information for the mass rearing of this insect.

Fall colors of Iowa: Created by Amanda Carstens,1997.

This brochure includes colorful pictures of fall colors in Iowa. Also has information on why trees change colors and how to identify the species of tree through its leaves. Informs you on where and when to find the best viewing sites of fall foliage in Iowa.

Plumage ornaments, bacterial colonisation and signalling in european starling, "Sturnus vulgaris"

Abstract Animal behaviours or structures are used by senders as signals to try to increase their fitness by altering the behaviour of receivers. A large fraction of studies on sexual selection have focussed on male ornaments and have demonstrated that these ornaments signal the quality of their owner and are used by female for mate choice. Although females can also exhibit conspicuous traits, studies on female ornaments are markedly lacking. In chapter 1, we show that female starlings are showier on chest whiteness than males and that females' whiteness may potentially indicate female condition at the start of breeding and provide fitness advantages to breeding birds. Furthermore we point out that feather density and abrasion are important factors shaping the expression of chest whiteness. This suggests that further understanding of the evolution of chest whiteness in Starlings requires to examine the environmental and physiological factors that shape feather condition. Plumage may suffer from damage through abrasion and bacterial activity. In chapter 2, we focus on factors that influence feather-degrading bacterial communities. Within the hypothesis that parental care can be trade-off against the demands of self-maintenance, we show that a brood size manipulation modifies the structure of feather-degrading bacterial communities and the density of free- living bacteria. Thus we have pointed out a potentially poorly known cost of reproduction. In the same context of a trade-off between reproductive activities and individual self-maintenance, chapter 3 shows that at a proximate level in females but not in males, the individual variation in time and/or energy allocated in reproductive activities is associated with prolactin hormone levels. Our study provides evidence for the existence of a sex related difference in the relationship between brood size and prolactin levels. Birds have evolved sanitation behaviours and preen gland secretions to preserve the condition of their plumage. In chapter 4, we describe a method that allows to measure preen gland in situ. Then we use this method to characterize a number of phenotypic and ecological factors that explain variation in preen gland size in free-living individuals. In parent-offspring interactions, parents use offspring signals to provision their brood. In chapter 5, we demonstrate that nestling flanges and body skin reflect in the ultra-violet (UV) wavelengths ant that parents use this UV reflectance in food allocation decisions. Résumé Certains comportements et structures chez les animaux agissent, pour ceux qui les émettent, comme des signaux permettant d'augmenter leur fitness en altérant les comportements de ceux qui les perçoivent. Une grande partie des études sur la sélection sexuelle s'est focalisée sur les ornements mâles. Ces études ont démontré que ces ornements pouvaient signaler la qualité de celui qui les porte et influencer le choix des femelles. Bien que les femelles puissent aussi présenter des traits voyants, les études sur leurs ornements font défaut. Dans le chapitre 1 de ce travail, nous montrons que les étourneaux femelles sont plus voyantes que les mâles sur la base de la blancheur de la poitrine. De plus la blancheur des femelles peut signaler leur condition au début de la saison de reproduction et ainsi être corrélée avec leur fitness. Nous mettons aussi en évidence que la densité et l'abrasion des plumes sont des facteurs importants, contrôlant l'expression de la blancheur de la poitrine. Ceci suggère que des études futures pourraient examiner le rôle des facteurs environnementaux et physiologiques qui influencent la condition des plumes pour mieux comprendre l'évolution de la blancheur chez les étourneaux. Le plumage subit des dommages à travers l'abrasion et probablement aussi par l'activité de dégradation de bactéries. Dans le chapitre 2 de ce travail, nous nous intéressons aux facteurs qui influencent les communautés de bactéries dégradant les plumes. Nous basant sur l'hypothèse selon laquelle il existe un compromis entre les soins parentaux et la maintenance corporelle, nous montrons qu'une manipulation de la taille de nichée modifie la structure des communautés de bactéries dégradant les plumes ainsi que les densités de bactéries libres présentes sur le plumage. Ainsi nous mettons en évidence un coût encore peu connu des activités de reproduction. Dans le même contexte, nous montrons, dans le chapitre 3, que des variations individuelles dans l'énergie et/ou le temps alloué dans les activités de reproduction sont associés, chez les femelles, à un niveau proximal à l'hormone prolactine. Cette relation n'est pas présente chez les mâles. Cette étude montre que la relation entre la taille de nichée et les niveaux de prolactine diffère avec le sexe des individus. Les oiseaux utilisent des comportements de nettoyage associés aux sécrétions de la glande uropygiale afin de préserver la condition de leurs plumes. Dans le chapitre 4 de ce travail, nous décrivons une méthode qui permet de mesurer la taille de la glande in situ. Puis nous caractérisons certains facteurs écologiques et physiologiques qui expliquent les variations de la taille de la glande chez des individus capturés dans leur environnement. Les parents nourrissent leur progéniture en réponse à des signaux émis par ceux-ci. Dans le chapitre 5 de ce travail, nous démontrons que les commissures et la peau sur le corps des oisillons reflètent la lumière dans l'ultraviolet. Nous montrons que les parents utilisent cette réflexion dans l'ultraviolet lors de l'allocation de nourriture pour leurs jeunes.

Different colors of light lead to different adaptation and activation as determined by high-density EEG.

Light adaptation is crucial for coping with the varying levels of ambient light. Using high-density electroencephalography (EEG), we investigated how adaptation to light of different colors affects brain responsiveness. In a within-subject design, sixteen young participants were adapted first to dim white light and then to blue, green, red, or white bright light (one color per session in a randomized order). Immediately after both dim and bright light adaptation, we presented brief light pulses and recorded event-related potentials (ERPs). We analyzed ERP response strengths and brain topographies and determined the underlying sources using electrical source imaging. Between 150 and 261ms after stimulus onset, the global field power (GFP) was higher after dim than bright light adaptation. This effect was most pronounced with red light and localized in the frontal lobe, the fusiform gyrus, the occipital lobe and the cerebellum. After bright light adaptation, within the first 100ms after light onset, stronger responses were found than after dim light adaptation for all colors except for red light. Differences between conditions were localized in the frontal lobe, the cingulate gyrus, and the cerebellum. These results indicate that very short-term EEG brain responses are influenced by prior light adaptation and the spectral quality of the light stimulus. We show that the early EEG responses are differently affected by adaptation to different colors of light which may contribute to known differences in performance and reaction times in cognitive tests.

Projecte Rambla de la Mina. Colors per trepitjar

Aquest projecte deriva d'alguns dels resultats del conjunt de tallers de participació que, amb el nom de Cartografies de La Mina vàrem desenvolupar entre el 2002 i el 2005 amb diversos grups de veïns i veïnes del barri i que queden sintetitzats en el Pla d¿accions de barri en Espai Públic, que vàrem lliurar al Consorci del Barri de La Mina l'abril del 2006.

Owl melanin-based plumage redness is more frequent near than away from the equator: implications on the effect of climate change on biodiversity

Climate change acts as a major new selective agent on many organisms, particularly at high latitudes where climate change is more pronounced than at lower latitudes. Studies are required to predict which species are at a high risk of extinction and whether certain phenotypes may be more affected by climate change than others. The identification of susceptible phenotypes is important for evaluating the potential negative effect of climate change on biodiversity at the inter- and intraspecific levels. Melanin-based coloration is an interesting and easily accessible candidate trait because, within certain species, reddish pheomelanin-based coloration is associated with adaptations to warm climates. However, it is unclear whether the same holds among species. We tested one prediction of this hypothesis in four owl genera (wood, scops, screech, and pygmy owls), namely that darker reddish species are more prevalent near the equator than polewards. Our comparative analysis is consistent with this prediction for the northern hemisphere, suggesting that pale reddish species may be adapted to cold climates and dark reddish species to warmer climates. Thus, climate change may have a larger negative impact on pale pheomelanic owls and favour dark pheomelanic species.

Projecte Rambla de la Mina. Colors per trepitjar

Aquest projecte deriva d'alguns dels resultats del conjunt de tallers de participació que, amb el nom de Cartografies de La Mina vàrem desenvolupar entre el 2002 i el 2005 amb diversos grups de veïns i veïnes del barri i que queden sintetitzats en el Pla d¿accions de barri en Espai Públic, que vàrem lliurar al Consorci del Barri de La Mina l'abril del 2006.