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Geoffrey E. Hill - One of the best experts on this subject based on the ideXlab platform.
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effects of diet on Plumage Coloration and carotenoid deposition in red and yellow domestic canaries serinus canaria
The Wilson Journal of Ornithology, 2016Co-Authors: Rebecca E. Koch, Kevin J. Mcgraw, Geoffrey E. HillAbstract:ABSTRACT Atlantic Canaries (Serinus canaria) are the most commonly kept caged bird with extensive carotenoid-based Plumage Coloration. Domestic strains of canaries have been bred for a variety of colors and patterns, making them a valuable model for studies of the genetic bases for feather pigmentation. However, no detailed account has been published on feather pigments of the various strains of this species, particularly in relation to dietary pigments available during molt. Moreover, in the twentieth century, aviculturists created a red canary by crossing Atlantic Canaries with Red Siskins (Carduelis cucullata). This “red-factor” canary is reputed to metabolically transform yellow dietary pigments into red ketocarotenoids, but such metabolic capacity has yet to be documented in controlled experiments. We fed molting yellow and red-factor canaries seed diets supplemented with either β-carotene, lutein/zeaxanthin, or β-cryptoxanthin/β-carotene and measured the Coloration and carotenoid content of newly gr...
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rapid evolution of bright monochromatism in the domestic atlantic canary serinus canaria
The Wilson Journal of Ornithology, 2015Co-Authors: Rebecca E. Koch, Geoffrey E. HillAbstract:ABSTRACT Males exhibit more colorful Plumage than females in many bird species. Phylogenetic reconstructions indicate that transitions from dichromatism to monochromatism are not uncommon and that monochromatism can result from the evolution of brighter Plumage in females. To better understand the time scale over which such changes in dichromatism can evolve, we used a reflectance spectrophotometer to quantify feather Coloration in the Atlantic Canary (Serinus canaria), a species that is sexually dichromatic in the wild but that has been under strong artificial selection for color in both sexes for several centuries. We measured the Plumage Coloration of males and females in the wild progener population of canaries, in captive canaries bred for bright yellow or red Plumage Coloration, and in Black-hooded Red Siskins (Carduelis cucullata), which were hybridized with yellow canaries to produce red canaries. We show that domestic canaries evolved from dichromatism to monochromatism under strong selection for...
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Effects of diet on Plumage Coloration and pigment deposition in red and yellow domestic canaries
bioRxiv, 2015Co-Authors: Rebecca E. Koch, Kevin J. Mcgraw, Geoffrey E. HillAbstract:The Atlantic Canary (Serinus canaria) is the most common caged bird with extensive carotenoid Plumage Coloration. Domestic strains of canaries have been bred for a range of colors and patterns, making them a valuable model for studies of the genetic bases for feather pigmentation. However, no detailed account has been published on the feather pigments of the various strains of this species, particularly in relation to dietary pigments available during molt. Moreover, in the twentieth century, aviculturists created a red canary by crossing Atlantic Canaries with Red Siskins (Carduelis cucullata). This red-factor canary is reputed to metabolically transform yellow dietary pigments into red ketocarotenoids, but such metabolic capacity has yet to be documented in controlled experiments. We fed molting yellow and red-factor canaries seed diets supplemented with either B-carotene, lutein/zeaxanthin, or B-cryptoxanthin/B-carotene and measured the Coloration and carotenoid content of newly grown feathers. On all diets, yellow canaries grew yellow feathers and red canaries grew red feathers. Yellow canaries deposited dietary pigments and metabolically derived canary xanthophylls into feathers. Red-factor canaries deposited the same Plumage carotenoids as yellow canaries, but also deposited red ketocarotenoids. Red-factor canaries deposited higher total amounts of carotenoids than yellow canaries, but otherwise there was little effect of diet treatment on feather hue or chroma. These observations indicate that canaries can use a variety of dietary precursors to produce Plumage Coloration and that red canaries can metabolically convert yellow dietary carotenoids into red ketocarotenoids.
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effect of prenatal and natal administration of testosterone on production of structurally based Plumage Coloration
Physiological and Biochemical Zoology, 2013Co-Authors: Lynn Siefferman, Mark Liu, Kristen J Navara, Mary T Mendonca, Geoffrey E. HillAbstract:AbstractTestosterone has been implicated as a developmental mechanism involved in the organization and expression of sexually dimorphic traits, such as Plumage Coloration, in birds. Although research findings relating testosterone levels to Plumage expression is equivocal, few studies have investigated how testosterone may influence the expression of structurally based Plumage Coloration. Here, we use experimental and correlational evidence to test the hypothesis that testosterone influences the development and maintenance of structurally based Plumage Coloration in a wild-breeding population of eastern bluebirds (Sialia sialis). First, we experimentally manipulated yolk testosterone and measured the effect on the development of Plumage Coloration of nestlings. Second, we implanted juvenile bluebirds with testosterone and measured the effect on nestling growth, body condition, and Plumage Coloration of nestlings. Third, we measured covariation between circulating testosterone and Plumage Coloration of bre...
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influence of hatch order on begging and Plumage Coloration of nestling eastern bluebirds
The Wilson Journal of Ornithology, 2011Co-Authors: Nathan Soley, Lynn Siefferman, Kristen J Navara, Geoffrey E. HillAbstract:Abstract Hatching asynchrony in altricial songbirds can influence the morphology and behavior of nestling birds. We compared the position of nestling Eastern Bluebirds (Sialia sialis) in the hatching hierarchy to their (1) position in the egg-laying order, (2) rate of nestling begging, (3) circulating corticosterone, (4) size, and (5) Plumage Coloration. Most nestlings hatched within 36 hrs of each other, and nestlings hatched in the order in which eggs were laid. Early-hatched nestlings were heavier than late-hatched nestlings for the duration of the growth period and begged less intensely than their late-hatched siblings. There was little evidence of severe effects of hatch order. Hatch order did not influence nestling corticosterone levels nor did we find effects of hatch order on ornamental Plumage Coloration. Our data suggest no long-term effect of hatching asynchrony on the development of sexually selected Plumage Coloration.
Kevin J. Mcgraw - One of the best experts on this subject based on the ideXlab platform.
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effects of diet on Plumage Coloration and carotenoid deposition in red and yellow domestic canaries serinus canaria
The Wilson Journal of Ornithology, 2016Co-Authors: Rebecca E. Koch, Kevin J. Mcgraw, Geoffrey E. HillAbstract:ABSTRACT Atlantic Canaries (Serinus canaria) are the most commonly kept caged bird with extensive carotenoid-based Plumage Coloration. Domestic strains of canaries have been bred for a variety of colors and patterns, making them a valuable model for studies of the genetic bases for feather pigmentation. However, no detailed account has been published on feather pigments of the various strains of this species, particularly in relation to dietary pigments available during molt. Moreover, in the twentieth century, aviculturists created a red canary by crossing Atlantic Canaries with Red Siskins (Carduelis cucullata). This “red-factor” canary is reputed to metabolically transform yellow dietary pigments into red ketocarotenoids, but such metabolic capacity has yet to be documented in controlled experiments. We fed molting yellow and red-factor canaries seed diets supplemented with either β-carotene, lutein/zeaxanthin, or β-cryptoxanthin/β-carotene and measured the Coloration and carotenoid content of newly gr...
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Effects of diet on Plumage Coloration and pigment deposition in red and yellow domestic canaries
bioRxiv, 2015Co-Authors: Rebecca E. Koch, Kevin J. Mcgraw, Geoffrey E. HillAbstract:The Atlantic Canary (Serinus canaria) is the most common caged bird with extensive carotenoid Plumage Coloration. Domestic strains of canaries have been bred for a range of colors and patterns, making them a valuable model for studies of the genetic bases for feather pigmentation. However, no detailed account has been published on the feather pigments of the various strains of this species, particularly in relation to dietary pigments available during molt. Moreover, in the twentieth century, aviculturists created a red canary by crossing Atlantic Canaries with Red Siskins (Carduelis cucullata). This red-factor canary is reputed to metabolically transform yellow dietary pigments into red ketocarotenoids, but such metabolic capacity has yet to be documented in controlled experiments. We fed molting yellow and red-factor canaries seed diets supplemented with either B-carotene, lutein/zeaxanthin, or B-cryptoxanthin/B-carotene and measured the Coloration and carotenoid content of newly grown feathers. On all diets, yellow canaries grew yellow feathers and red canaries grew red feathers. Yellow canaries deposited dietary pigments and metabolically derived canary xanthophylls into feathers. Red-factor canaries deposited the same Plumage carotenoids as yellow canaries, but also deposited red ketocarotenoids. Red-factor canaries deposited higher total amounts of carotenoids than yellow canaries, but otherwise there was little effect of diet treatment on feather hue or chroma. These observations indicate that canaries can use a variety of dietary precursors to produce Plumage Coloration and that red canaries can metabolically convert yellow dietary carotenoids into red ketocarotenoids.
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evolution of carotenoid pigmentation in caciques and meadowlarks icteridae repeated gains of red Plumage Coloration by carotenoid c4 oxygenation
Evolution, 2014Co-Authors: Nicholas R Friedman, Kevin J. Mcgraw, Kevin E OmlandAbstract:Many animals use carotenoid pigments to produce yellow, orange, and red Coloration. In birds, at least 10 carotenoid compounds have been documented in red feathers; most of these are produced through metabolic modification of dietary precursor compounds. However, it is poorly understood how lineages have evolved the biochemical mechanisms for producing red Coloration. We used high-performance liquid chromatography to identify the carotenoid compounds present in feathers from 15 species across two clades of blackbirds (the meadowlarks and allies, and the caciques and oropendolas; Icteridae), and mapped their presence or absence on a phylogeny. We found that the red Plumage found in meadowlarks includes different carotenoid compounds than the red Plumage found in caciques, indicating that these gains of red color are convergent. In contrast, we found that red Coloration in two closely related lineages of caciques evolved twice by what appear to be similar biochemical mechanisms. The C4-oxygenation of dietary carotenoids was responsible for each observed transition from yellow to red Plumage Coloration, and has been commonly reported by other researchers. This suggests that the C4-oxygenation pathway may be a readily evolvable means to gain red Coloration using carotenoids.
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Carotenoids in bird testes: links to body carotenoid supplies, Plumage Coloration, body mass and testes mass in house finches (Carpodacus mexicanus).
Comparative biochemistry and physiology. Part B Biochemistry & molecular biology, 2012Co-Authors: Melissah Rowe, Elizabeth A Tourville, Kevin J. McgrawAbstract:Carotenoid pigments can be allocated to different parts of the body to serve specific functions. In contrast to other body tissues, studies of carotenoid resources in the testes of animals are relatively scarce. We used high-performance liquid chromatography to determine the types and concentrations of carotenoids in the testes of house finches (Carpodacus mexicanus). Additionally, we examined the relationships between testes carotenoid concentrations and carotenoid pools in other body tissues, as well as body mass, testes mass and Plumage Coloration. We detected low concentrations of several carotenoids - lutein (the predominant carotenoid), zeaxanthin, anhydrolutein, β-cryptoxanthin, β-carotene and an unknown carotene - in the testes of wild house finches. We also found that testes lutein levels were significantly and positively associated with circulating lutein levels, while the concentration of zeaxanthin in testes was positively associated with zeaxanthin levels in liver, though in this instance the relationship was much weaker and only marginally significant. Furthermore, lutein levels in testes were significantly negatively associated with testes mass. Finally, Plumage Coloration was not associated with either the concentration of carotenoids in the testes or relative testes mass. These results suggest that testes carotenoids are reflective of the pool of circulating carotenoids in house finches, and that Plumage Coloration is unlikely to signal either the carotenoid content of testes tissue or a male's capacity for sperm production.
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carotenoids bolster immunity during moult in a wild songbird with sexually selected Plumage Coloration
Biological Journal of The Linnean Society, 2011Co-Authors: Kevin J. Mcgraw, Paul M Nolan, Ondi L CrinoAbstract:Carotenoid-based colours in animals are valuable models for testing theories of sexual selection and life-history trade-offs because the pigments used in Coloration are chemically tractable in the diet and in the body, where they serve multiple purposes (e.g. health enhancement, photoprotection). An important assumption underlying the hypothesized signalling value of carotenoid Coloration is that there is a trade-off in carotenoid pigment allocation, such that not all individuals can meet the physiological/morphological demands for carotenoids (i.e. carotenoids are limited) and that only those who have abundant supplies or fewer demands become the most colourful. Studies of carotenoid trade-offs in colourful animals have been limited largely to domesticated species, which may have undergone artificial selection that changed the historical/natural immunomodulatory roles of carotenoids, to young animals lacking carotenoid-based signals or to species displaying carotenoid-based skin and bare parts. We studied the health benefits of carotenoids during moult in house finches (Carpodacus mexicanus), which display sexually selected, carotenoid-based Plumage Coloration. We manipulated dietary carotenoid availability during both winter (nonmoult) and autumn (moult) in captive males and females and found that carotenoid-supplemented birds mounted stronger immune responses (to phytohemagglutinin injection and to a bacterial inoculation in blood) than control birds only during moult. This study provides experimental, seasonal support for a fundamental tenet of Lozano's ‘carotenoid trade-off’ hypothesis and adds to a growing list of animal species that benefit immunologically from ingesting higher dietary carotenoid levels. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 560–572.
Lynn Siefferman - One of the best experts on this subject based on the ideXlab platform.
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the separate effects of egg size and parental quality on the development of ornamental Plumage Coloration
Ibis, 2014Co-Authors: Lynn Siefferman, Thomas J Robinson, Alexandra B Bentz, Thomas S RischAbstract:The fitness-related consequences of egg size, independent of the influences of parental quality, are poorly understood in altricial birds. Not only can egg size and parental quality influence growth and survival, but each could influence the development of condition-dependent Plumage Coloration in offspring. The Eastern Bluebird Sialia sialis is an altricial, multi-brooded, cavity-nesting passerine in which juveniles display dichromatic UV-blue Plumage. Previous research suggests that Plumage Coloration acts as a signal of individual quality among juvenile and adult Eastern Bluebirds. Here, we separate the effects of egg size and parental quality (defined by egg size laid) on nestling growth and Plumage ornamentation by exchanging clutches of large eggs with clutches of small eggs. Nestlings were significantly larger immediately post-hatching when hatched from a large egg, but to maintain a larger size, nestlings needed to have hatched from a large egg and to have been reared by high-quality parents. Nestlings were brighter when reared by high-quality parents and this relationship was strongest later in the breeding season. Nestlings exhibited greater UV chroma if hatched early in the season, but UV chroma was not significantly affected by egg size or parental quality. These findings demonstrate varying influences of both egg size and parental quality on offspring growth and Plumage ornamentation but suggest that quality of post-hatching investment is more influential than pre-hatching investment.
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effect of prenatal and natal administration of testosterone on production of structurally based Plumage Coloration
Physiological and Biochemical Zoology, 2013Co-Authors: Lynn Siefferman, Mark Liu, Kristen J Navara, Mary T Mendonca, Geoffrey E. HillAbstract:AbstractTestosterone has been implicated as a developmental mechanism involved in the organization and expression of sexually dimorphic traits, such as Plumage Coloration, in birds. Although research findings relating testosterone levels to Plumage expression is equivocal, few studies have investigated how testosterone may influence the expression of structurally based Plumage Coloration. Here, we use experimental and correlational evidence to test the hypothesis that testosterone influences the development and maintenance of structurally based Plumage Coloration in a wild-breeding population of eastern bluebirds (Sialia sialis). First, we experimentally manipulated yolk testosterone and measured the effect on the development of Plumage Coloration of nestlings. Second, we implanted juvenile bluebirds with testosterone and measured the effect on nestling growth, body condition, and Plumage Coloration of nestlings. Third, we measured covariation between circulating testosterone and Plumage Coloration of bre...
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age dependent relationships between Coloration and reproduction in a species exhibiting delayed Plumage maturation in females
Journal of Avian Biology, 2013Co-Authors: Alexandra B Bentz, Lynn SieffermanAbstract:Males of many bird species exhibit delayed Plumage maturation (DPM), a condition in which young individuals display an immature Plumage. Several adaptive hypotheses have been suggested for the signaling utility of DPM in males. Tree swallows Tachycineta bicolor, however, are one of the few bird species to exhibit DPM in females, but not in males. Few studies have focused on the age-dependent signaling function of female Plumage traits due to the uncommon nature of DPM in females. Therefore, we used reflectance spectrometry and scanning electron microscopy of sub-adult (melanin-based brown) and adult (iridescent-blue structural) female tree swallows to characterize Plumage Coloration. Next, we asked whether variation in Plumage Coloration in females reflects condition and reproductive performance between and within age classes. We found that older females were in better body condition and laid eggs earlier in the season compared to young females; however, average egg mass and reproductive success (number of offspring fledged and offspring condition) did not differ between age classes. There were significant relationships indicating that young females with more-ornamented (darker brown melanin) Plumage laid smaller eggs, but hatched eggs earlier in the season leading to nestlings in better condition compared to less-ornamented young females. Older females that were more ornamented (brighter, greater blue chroma, and lower hues in iridescent Plumage) laid heavier eggs, but ornamentation was negatively associated with immune function, health, and reproductive success. Together, these data suggest that female ornamentation reflects reproductive performance and that there are complicated relationships between Plumage Coloration, condition, and reproductive performance that ultimately influence reproductive success.
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influence of hatch order on begging and Plumage Coloration of nestling eastern bluebirds
The Wilson Journal of Ornithology, 2011Co-Authors: Nathan Soley, Lynn Siefferman, Kristen J Navara, Geoffrey E. HillAbstract:Abstract Hatching asynchrony in altricial songbirds can influence the morphology and behavior of nestling birds. We compared the position of nestling Eastern Bluebirds (Sialia sialis) in the hatching hierarchy to their (1) position in the egg-laying order, (2) rate of nestling begging, (3) circulating corticosterone, (4) size, and (5) Plumage Coloration. Most nestlings hatched within 36 hrs of each other, and nestlings hatched in the order in which eggs were laid. Early-hatched nestlings were heavier than late-hatched nestlings for the duration of the growth period and begged less intensely than their late-hatched siblings. There was little evidence of severe effects of hatch order. Hatch order did not influence nestling corticosterone levels nor did we find effects of hatch order on ornamental Plumage Coloration. Our data suggest no long-term effect of hatching asynchrony on the development of sexually selected Plumage Coloration.
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A field test of female mate preference for male Plumage Coloration in eastern bluebirds
Animal behaviour, 2009Co-Authors: Mark Liu, Lynn Siefferman, Herman L. Mays, John E. Steffen, Geoffrey E. HillAbstract:A growing body of evidence shows that female birds use male Plumage Coloration as an important criterion in mate choice. In the field, however, males with brighter Coloration may both compete better for high quality territories and be the object of female choice. Positive associations between territory quality, male-male competitive ability, and female preferences can make it difficult to determine whether females actively choose the most ornamented males. Male eastern bluebirds (Sialia sialis) display brilliant ultraviolet (UV)-blue Plumage Coloration on their heads, backs, wings, and tails, and chestnut Coloration on their breasts which is positively correlated with condition, reproductive effort, and reproductive success. We tested the hypothesis that female bluebirds prefer males that display brighter and more chromatic Coloration by widowing males in the field and allowing replacement females to choose partners. We controlled for the influence of territory quality on female choice by widowing dyads of males with adjacent territories. We found no evidence that UV-blue or chestnut Plumage Coloration, body size, or body condition predicted the male with which females would pair. We found no support for the hypothesis that the Coloration of male eastern bluebirds functions as a criterion in female mate choice.
Juan Carlos Senar - One of the best experts on this subject based on the ideXlab platform.
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age and sex differences in niche use at molt and its effect on Plumage Coloration characteristics in a bird
Current Zoology, 2019Co-Authors: Emilio Paganinunez, Craig A Barnett, Juan Carlos SenarAbstract:Bird Plumage is often very colorful and can communicate the quality of the bearer to conspecifics. These Plumage-based signals of quality are composed of multiple pigments (e.g., melanin and carotenoids). Therefore, sex and age classes, which often show marked differences in Plumage Coloration, may have different dietary needs for the different Plumage components and this might promote preferences for different dietary niches at different molting stages. However, no study has addressed the role that changes in niche use play in the expression of multiple component Plumage signals in birds. We used stable isotope analysis to test the hypothesis that niche use is related to age and sex and to differently cultured Plumage patches, yellow carotenoid-based and black melanin-based, in great tits Parus major. We recorded high niche overlap between Plumage patches, although δ15N was higher in black than yellow Plumage. Niche overlap was relatively low for age classes and relatively high for sex classes, and age classes showed a contrasting pattern of niche overlap between carotenoid- and melanin-based Plumages. Moreover, δ13C, but not δ15N, had a significant negative relationship with carotenoid-based Plumage, which was only apparent in juveniles. Taken together, our results demonstrate that niche use had a moderate influence on Plumage Coloration characteristics of great tit individuals, mostly associated with δ13C rather than with δ15N and with age rather than with sex. Therefore, our study is significant because it confirms the relevance of niche use during ornament production in free-living birds.
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Plumage Coloration of the blue grosbeak has no dual function a test of the armament ornament model of sexual selection
The Condor, 2013Co-Authors: Javier Quesada, Juan Carlos Senar, Carlos A Chavezzichinelli, Jorge E SchondubeAbstract:Abstract. Although Plumage Coloration has been widely used as a model in studies of the evolution of signaling, the role of Plumage in intrasexual communication has been less studied, especially in cases of the structural Plumage color. The aim of our study was to use choice trials and Plumage manipulation to test whether or not the structural blue color of the male Blue Grosbeak (Passerina caerulea) works as a signal of social status. Additionally, we tested whether or not females exploit signals used in aggression between males. If they do, it suggests that Plumage Coloration is also used in mate choice. In 2007, we captured males and females from two different populations. We performed two choice experiments by manipulating Plumage color: (1) a status-signaling experiment, in which a male had to choose one of two other males, and (2) a mate-choice experiment, in which a female had to choose one of two males. Males clearly foraged near less blue birds during their first encounter and on the first day. H...
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changes in carotenoid based Plumage colour in relation to age in european serinsserinus serinus age related differences in Plumage Coloration
Ibis, 2012Co-Authors: Emilio Paganinunez, Juan Carlos SenarAbstract:Yearling birds generally display duller colours than adults. This may be due to selection favouring birds with more intensely coloured Plumage or to an increase in colour after the first complete moult. Most research to date on the topic has been carried out on species with structural Plumage Coloration or with carotenoid-based Coloration that is produced by the unmodified deposition of pigments. However, no study has been carried out on species whose carotenoids are metabolically modified before deposition. In this study, we assess age-related changes in the carotenoid-based Coloration of European Serins, a species that metabolically processes carotenoids before they can be deposited into feathers. Birds were captured over consecutive years and we carried out both cross-sectional and longitudinal analysis. Adults had significantly greater values of lightness and chroma than yearling birds. However, there were no changes in Plumage colour when analysing the same individuals captured in subsequent seasons. Plumage lightness and chroma of adult males after moult were related to body mass, suggesting a role of body condition on Plumage Coloration. Our results suggest that changes in Plumage Coloration with age in European Serins are due to a selection process that favours more intensely coloured individuals.
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the role of melanin and carotenoid based Plumage Coloration in nest defence in the great tit
Ethology, 2007Co-Authors: Javier Quesada, Juan Carlos SenarAbstract:Although Plumage Coloration is recognized to convey valuable information about the bearer’s parental abilities, few studies have explored the relationship between Coloration and nest defence. In this study in Great Tit Parus major, we analysed the relationship between nest defence and melanin- as well as carotenoid-based Plumage Coloration, after controlling for ecological variables known to influence nest defence. A principal components analysis was applied to classify birds according to how vigorously they defended the nest, and the intensity of nest defence was tested against Plumage Coloration. Males with a large black tie defended their nests more vigorously, but no such effect was found for yellow breast Coloration. This suggests that melanin-based Coloration in the Great Tit is associated with aggression, including both dominanceaggression and nest defence, whereas carotenoid-based Coloration is not. The challenge in future studies will be to demonstrate whether females use this trait as an ornament to assess male quality and whether they trade off between the different ornaments a male may exhibit.
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comparing Plumage colour measurements obtained directly from live birds and from collected feathers the case of the great tit parus major
Journal of Avian Biology, 2006Co-Authors: Javier Quesada, Juan Carlos SenarAbstract:Birds frequently display a colourful Plumage which is important both in inter and intraespecific communication, and either in sexual and social contexts. In last years some methodologies have been developed to analyse Plumage Coloration, but the use of the spectrometers has been particularly important for UV range. Measurement of Plumage Coloration with the spectrometer may be taken directly on the bird or, alternatively by collecting some feathers and measuring them later in the laboratory. However, few is known about the reliability of measures obtained from feathers and whether these are really representative of Plumage Coloration. We tested this assumption analysing measurements of carotenoids-based Coloration components (lightness, chroma and hue) and lutein peak of the yellow breast of the great tit Parus major. We used two spectrometers (Ocean optics and Minolta) which calculate differently the colour components. Our results showed that direct measurement of bird was highly repeatable to determine lightness, chroma and hue for both spectrometers. Similar results we found for collected feathers procedure for both devices. Collected feathers provided high representative measurements of colour values with Minolta spectrometer. Lightness was highly repeatable when we used Ocean optic spectrometer, but chroma and hue were moderate. Lutein peak was also highly repeatable in all cases. The number of feathers used to measure Plumage Coloration in collected feathers procedure strongly influenced values of colour Plumage variables. In general, values of lightness, chroma and hue stabilised when more than 1015 feathers were used although we found slight differences between spectrometers. However, only four feathers were needed for lutein peak. Thus, our results stress the need to use a minimum number of feathers in measuring Plumage Coloration from collected feathers.
Borja Mila - One of the best experts on this subject based on the ideXlab platform.
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Differential gene regulation underlies variation in melanic Plumage Coloration in the dark-eyed junco ( Junco hyemalis )
Molecular Ecology, 2018Co-Authors: Mikus Abolins-abols, Mark Peterson, Etienne Kornobis, Paolo Ribeca, Kazumasa Wakamatsu, Ellen Ketterson, Borja MilaAbstract:Colour plays a prominent role in species recognition; therefore, understanding the proximate basis of pigmentation can provide insight into reproductive isolation and speciation. Colour differences between taxa may be the result of regulatory differences or be caused by mutations in coding regions of the expressed genes. To investigate these two alternatives, we studied the pigment composition and the genetic basis of Coloration in two divergent dark-eyed junco (Junco hyemalis) subspecies, the slate-coloured and Oregon juncos, which have evolved marked differences in Plumage Coloration since the Last Glacial Maximum. We used HPLC and light microscopy to investigate pigment composition and deposition in feathers from four body areas. We then used RNA-seq to compare the relative roles of differential gene expression in developing feathers and sequence divergence in transcribed loci under common-garden conditions. Junco feathers differed in eumelanin and pheomelanin content and distribution. Within subspecies, in lighter feathers melanin synthesis genes were downregulated (including PMEL, TYR, TYRP1, OCA2 and MLANA), and ASIP was upregulated. Feathers from different body regions also showed differential expression of HOX and WNT genes. Feathers from the same body regions that differed in colour between the two subspecies showed differential expression of ASIP and three other genes (MFSD12, KCNJ13 and HAND2) associated with pigmentation in other taxa. Sequence variation in the expressed genes was not related to colour differences. Our findings support the hypothesis that differential regulation of a few genes can account for marked differences in Coloration, a mechanism that may facilitate the rapid phenotypic diversification of juncos.
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a role for differential gene regulation in the rapid diversification of melanic Plumage Coloration in the dark eyed junco junco hyemalis
bioRxiv, 2018Co-Authors: Mikus Abolinsabols, Ellen D. Ketterson, Etienne Kornobis, Paolo Ribeca, Kazumasa Wakamatsu, Mark P Peterson, Borja MilaAbstract:Color plays a prominent role in reproductive isolation, therefore understanding the proximal basis of pigmentation can provide insight into speciation. Subspecies of the dark-eyed junco (Junco hyemalis) have evolved marked differences in Plumage Coloration since the Last Glacial Maximum, yet whether color differences are caused by mutations in coding regions of expressed genes or are instead the result of regulatory differences remains unknown. To address this question, we studied the pigment composition and the genetic basis of Coloration in two divergent subspecies, the slate-colored and Oregon juncos. We used HPLC and light microscopy to investigate pigment composition and deposition in feathers from four body areas. We then used RNAseq to compare the relative roles of differential gene expression in developing feathers and sequence divergence in transcribed loci under common garden conditions. Junco feathers differed in eumelanin and pheomelanin content and distribution. Within subspecies, in lighter feathers melanin synthesis genes were downregulated (including PMEL, TYR, TYRP1, OCA2, MLANA), ASIP was upregulated. Feathers from different body regions also showed differential expression of HOX and Wnt genes. Feathers from the same body regions that differed in color between the two subspecies showed differential expression of ASIP and three other genes (MFSD12, KCNJ13, HAND2) associated with pigmentation in other taxa. Sequence variation in the expressed genes was not related to color differences. Our findings support the hypothesis that differential regulation of a few genes can account for marked differences in Coloration, a mechanism that may underlie the rapid diversification of juncos.