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84 results for “melanin”
Evolution of a conspicuous melanin-based ornament in gulls Laridae
<p>Melanin- and carotenoid-based ornaments often signal different aspects of individual quality or similar aspects under different environmental conditions and, thus, they may become evolutionarily integrated into a composite sexual trait. On the other hand, functionally and developmentally different characters (e.g. coloration characters of different developmental origin) are more likely to evolve independently from each other than more similar traits. Here, we examined evolutionary correlations between the occurrence of a conspicuous melanin-based ornament (hood) and carotenoid-based bare-part ornaments within gull family. We also aimed to identify major ecological, life-history, and biogeographical predictors of hood occurrence and reconstruct evolutionary history of this ornament. We found that hood occurrence was associated with red or dark coloration of unfeathered traits (bill and legs), while combinations of hood with yellow carotenoid-based coloration of integument were evolutionarily avoided. Also, hood occurrence correlated negatively with the occurrence of other melanin-based plumage character (mantle). Breeding latitude and habitat were identified as major predictors of hood occurrence in gulls, as hoods were recorded more frequently in low-latitude and inland (rather than marine) species. Finally, our analysis provided support for evolutionary lability in hood occurrence, with a dominance of transitions towards hood loss in the evolutionary history of gulls. The results of our study provide one of the first evidence for a correlated evolution of melanin- and carotenoid-based ornaments in an avian lineage, which supports evolutionary modularity of developmentally and functionally different coloration traits.</p>
Data from: The meaning of melanin, carotenoid, and pterin pigments in the bluefin killifish, Lucania goodei
Male bluefin killifish (Lucania goodei) exhibit extensive color variation in their fins, but the utility of this variation has not yet been determined. We collected males from multiple populations and spectrophotometrically determined the pigment types responsible for fin coloration. We determined that the orange coloration in the caudal fin is caused by carotenoid pigmentation. In contrast, color in the anal fin is either pterin based (yellow and red) or structural (blue) with a melanic fin border. As these colors have different developmental origins, the potential for complex signaling is high. Therefore, we sought to determine whether behavior, reproductive success, or health correlated with pigmentation. Males with more melanin on the anal fin were more dominant and had higher spawning success. Male–male aggression was greater between males with similar-sized melanic borders, indicating that melanic markings function as badges of status between males. Caudal carotenoid pigmentation did not correlate with dominance, but this highly labile ornament was correlated with body condition, parasite infection, and spawning success, suggesting a role in intersexual selection by signaling health to potential mates. Similar results were found for caudal fin coloration using digital photography. Pterin pigmentation in the anal fin was not related to dominance but was related to overall spawning levels and parasite infection, suggesting that pterin pigmentation may also signal immune status. Thus, the coloration of male bluefin killifish provides multiple messages to multiple receivers through these 3 pigments (melanin, pterin, and carotenoid) that have distinct developmental origins.
Data from: Melanin-specific life-history strategies
The maintenance of genetic variation is a long-standing issue because the adaptive value of life-history strategies associated with each genetic variant is usually unknown. However, evidence for the coexistence of alternative evolutionary fixed strategies at the population level remains scarce. Because in the tawny owl (Strix aluco) heritable melanin-based coloration shows different physiological and behavioral norms of reaction, we investigated whether coloration is associated with investment in maintenance and reproduction. Light melanic owls had lower adult survival compared to dark melanic conspecifics, and color variation was related to the trade-off between offspring number and quality. When we experimentally enlarged brood size, light melanic males produced more fledglings but in poorer condition, and they were less often recruited in the local breeding population than those of darker melanic conspecifics. Our results also suggest that dark melanic males allocate a constant effort to raise their brood independently of environmental conditions, whereas lighter melanic males finely adjust reproductive effort in relation to changes in environmental conditions. Color traits can therefore be associated with life-history strategies, and stochastic environmental perturbation can temporarily favor one phenotype over others. The existence of fixed strategies implies that some phenotypes can sometimes display a "maladapted" strategy. Long-term population monitoring is therefore vital for a full understanding of how different genotypes deal with trade-offs.
Data from: Melanin-based colouration and host-parasite interactions under global change
The role of parasites in shaping melanin-based colour polymorphism, and the consequences of colour polymorphism for disease resistance, remain debated. Here we review recent evidence of the links between melanin-based colouration and the behavioural and immunological defences of vertebrates against their parasites. First we propose that (1) differences between colour morphs can result in variable exposure to parasites, either directly (certain colours might be more or less attractive to parasites) or indirectly (variations in behaviour and encounter probability). Once infected, we propose that (2) immune variation between differently coloured individuals might result in different abilities to cope with parasite infection. We then discuss (3) how these different abilities could translate in variable sexual and natural selection in environments varying in parasite pressure. Finally, we address (4) the potential role of parasites in the maintenance of melanin-based colouration polymorphism, especially in the context of global change and multiple stressors in human-altered environments. Because global change will likely affect both colouration and the spread of parasitic diseases in the next decades, future studies should take into account melanin-based colouration to better predict the evolutionary responses of animals to changing disease risk in human-altered environments.
Data from: Melanin-based coloration of sneaker male Atlantic salmon is linked to viability and emergence timing of their offspring
The 'good genes' hypothesis of sexual selection predicts that male ornaments are favoured by female mate choice because male ornament reveals genetic quality. In species with different male reproductive tactics, variation in genetic quality among 'sneaking' males has rarely been investigated, as usually 'sneakers' are thought not to be chosen by females. Here we focused on the alternative reproductive tactic in Atlantic salmon (Salmo salar Linnaeus, 1758) to test whether the skin colour of sneakers may reveal the performance traits of their offspring. A fully factorial breeding design was realized between 20 sneakers and two females using in vitro fertilization. We quantified the red and dark colorations of males and measured the survival of their progeny under semi-natural conditions. In addition, the size of offspring and their emergence timing from the gravel nest were monitored in the laboratory. We found that darker males sired more viable offspring, whereas red coloration was negatively correlated with offspring survival. Nevertheless, darker and redder male pigmentations were linked to a delay in offspring emergence. These results demonstrate that colours can reveal individual genetic quality in an alternative male reproductive tactic, with male melanin-based coloration being linked to both beneficial and detrimental effects for the offspring. Our results imply that sneaker ornaments may potentially play a role in both intra- and intersexual selection.
Data from: Oxidative stress is related to both melanin- and carotenoid-based ornaments in the common yellowthroat
Male ornaments are hypothesized to signal the ability of males to produce an effective immune response without extensive oxidative stress and damage to DNA. We examined this hypothesis in male common yellowthroats (Geothlypis trichas), which have two ornaments, a black (eumelanin-based) facial mask and a yellow (carotenoid-based) bib. In our study population, only the black mask is sexually selected. As predicted by the oxidative stress hypothesis, males with larger black masks were more resistant to oxidative stress, as measured by an in vitro assay of the resistance of erythrocytes to haemolysis by free radicals. Furthermore, males with larger masks also tended to have lower levels of glutathione, which was predicted because glutathione inhibits eumelanin production. In contrast, mask size was not related to absolute levels of oxidative stress measured in the plasma. Although the yellow bib is not under sexual selection in our population, males with larger bibs and feathers with greater carotenoid chroma had lower levels of oxidative stress. The oxidative stress hypothesis was first proposed for carotenoid-based ornaments. However, our results suggest that, even in the same individuals, carotenoid and eumelanin-based plumage ornaments may both signal the ability of males to resist or manage oxidative stress.
Data from: Effect of the MC1R gene on sexual dimorphism in melanin-based colorations
Variants of the melanocortin-1 receptor (MC1R) gene result in abrupt, naturally selected colour morphs. These genetic variants may differentially affect sexual dimorphism if one morph is naturally selected in the two sexes but another morph is naturally or sexually selected only in one of the two sexes (e.g. to confer camouflage in reproductive females or confer mating advantage in males). Therefore, the balance between natural and sexual selections can differ between MC1R variants, as suggest studies showing interspecific correlations between sexual dimorphism and the rate of nonsynonymous vs. synonymous amino acid substitutions at the MC1R. Surprisingly, how MC1R is related to within-species sexual dimorphism, and thereby to sex-specific selection, has not yet been investigated. We tackled this issue in the barn owl (Tyto alba), a species showing pronounced variation in the degree of reddish pheomelanin-based coloration and in the number and size of black feather spots. We found that a valine (V)-to-isoleucine (I) substitution at position 126 explains up to 30% of the variation in the three melanin-based colour traits and in feather melanin content. Interestingly, MC1R genotypes also differed in the degree of sexual colour dimorphism, with individuals homozygous for the II MC1R variant being 2 times redder and 2.5 times less sexually dimorphic than homozygous individuals for the VV MC1R variant. These findings support that MC1R interacts with the expression of sexual dimorphism and suggest that a gene with major phenotypic effects and weakly influenced by variation in body condition can participate in sex-specific selection processes.
Data from: Feather melanin and micro-structure variation in dark-eyed junco (Junco hyemalis) across an elevational gradient in the Selkirk Mountains
Variation in feather melanism and microstructure can arise through sexual selection and ecological functional drivers. Melanin-based plumage traits are associated with sexual dichromatism and the intensity of sexual selection in many avian species, but also have several ecological benefits such as protection against ultra-violet (UV) radiation, camouflage, and feather strength. Additionally, feather microstructure influences thermoregulation. Plumage variation across species is well documented; however, the relative role of sexual selection and ecological drivers in intra-specific and within-population variation is less established. We investigated UV reflectance, melanism, and feather microstructure in a population of Oregon dark-eyed juncos Junco hyemalis oreganus between high (1900–2200 m a.s.l.) and low (450–800 m a.s.l.) elevations in the Selkirk Mountains to evaluate potential sexual selection and ecological drivers of variation. We found no difference in UV reflectance or lightness (melanism) of head feathers between elevations, but individuals at high elevation had lighter (less melanism) and less brown (less pheomelanin) body contour feathers than at low elevations. High elevation individuals also had longer contour feathers with more pronounced plumulaceous regions. Sexual dichromatism did not vary between elevations, leading us to reject sexual selection in favour of ecological functional drivers of plumage variation in this system. To our knowledge, this is the first study to identify within-population differences in feather melanism and microstructure between different elevations.
Goldenberg, J., Bisschop, K., Bruni, G., Di Nicola, M. R., Banfi, F., Faraone, F. P. "Replication Data for: Melanin-based color variation in response to changing climates in snakes"
<p>This repository contains the data used to produce the manuscrpit "Melanin-based color variation in response to changing climates in snakes" by Goldenberg, J., Bisschop, K., Bruni, G., Di Nicola, M. R., Banfi, F., Faraone, F. P.</p> <p>Article DOI: 10.1002/ece3.11627</p> <p>Journal: Ecology and Evolution</p>
Data from: Melanin in a changing world: brown trout coloration reflects alternative reproductive strategies in variable environments
Melanins are the most widespread pigments in animals but their adaptive significance remains elusive. Recent studies suggest that intraspecific variation in melanin-based coloration reflects individual genetic-based alternative strategies to cope with environment variability, which could be crucial for their responses to climate changes. However, empirical evidence is still scarce. In this study, we tested how skin coloration in natural populations of brown trout Salmo trutta fario would reflect alternative reproductive strategies in different environments. We experimentally manipulated the flow regime (constant vs. variable) in artificial streams and compared the reproductive investment (body mass and plasma triglyceride variations), innate immunity (variations in plasma peroxidase and lysozyme activity) and reproductive success (number of mates and offspring) of differently colored brown trout over 2 reproductive seasons. Results show that darker males had a higher reproductive investment, but similar immune variations during reproduction compared to paler males. In addition, this reproductive investment was higher in variable environments. However, this did not translate into a higher reproductive success in variable environments, as darker males had a similar number of mates and offspring compared to their paler counterparts under a variable water flow. Since climate change will likely lead to an increased flow variability in the next decades, this suggests that darker brown trout could incur a higher energetic cost of reproduction and could be more impacted by climate changes than their paler counterparts. This highlights the need to take into account intraspecific variability to better forecast the response of natural populations to climate changes.
Data from: The size of a melanin-based plumage ornament correlates with glucocorticoid receptor concentrations in the skin of that ornament
Glucocorticoid hormones such as corticosterone (CORT) play crucial roles in many physiological processes. CORT's actions are primarily mediated via binding to two receptors (glucocorticoid receptors (GR) and mineralocorticoid receptors (MR)) in different target tissues. CORT receptors can be independently regulated from circulating hormone titers, from tissue to tissue and even within different regions of the same tissue type. Increasing evidence has shown relationships between circulating CORT and melanin-based pigmentation in skin and feathers, yet to our knowledge there have been no studies of CORT receptors in the skin of melanized ornaments. Male house sparrows (Passer domesticus) have a black, melanized bib, and evidence suggests that bib size is an important intraspecific signal. We examined the relationship between bib area and tissue sensitivity to CORT by quantifying GR and MR in bib skin and in adjacent paler-feathered belly skin (as a control tissue) at different life history stages using radioligand binding assays. Males with larger bibs relative to their life history stage had less GR in bib skin, but not belly skin, than males with smaller bibs. These results suggest a connection between the size of a melanin-based ornament and the underlying tissue's responsiveness to CORT.
Roy et al. 2023 Supplemental Information for "Sediment-encased pressure–temperature maturation experiments elucidate the impact of diagenesis on melanin-based fossil color and its paleobiological implications."
<p><em>Supplemental Information for</em></p> <p>Sediment-encased pressure–temperature maturation experiments elucidate the impact of diagenesis on melanin-based fossil color and its paleobiological implications.</p> <p>Arindam Roy<em><sup>*</sup></em> (<a href="https://orcid.org/0000-0002-4890-6851">https://orcid.org/0000-0002-4890-6851</a>)</p> <p>Michael Pittman<em><sup>*</sup></em> (<a href="https://orcid.org/0000-0002-6149-3078">https://orcid.org/0000-0002-6149-3078</a>)</p> <p>Thomas G. Kaye (<a href="https://orcid.org/0000-0001-7996-618X">https://orcid.org/0000-0001-7996-618X</a>)</p> <p>Evan T. Saitta (<a href="https://orcid.org/0000-0002-9306-9060">https://orcid.org/0000-0002-9306-9060</a>)</p> <p>*Corresponding author(s)</p> <p><strong>Email: </strong><a href="mailto:ar15313@bristol.ac.uk">ar15313@bristol.ac.uk</a> ; <a href="http://palaeopittman.com/2022/03/27/lab-members/mpittman@cuhk.edu.hk">mpittman@cuhk.edu.hk</a></p> <p>The Dataset contains two files, (1) Supporting Information and (2) Supporting Data PCA worksheet. </p> <p>The first contains Supplementary tables and figures (.docx file) while the structural organisation of the second (.xlsx file) is provided below:</p> <p>We received ToF-SIMS data (Samples 1–30, 36–51) pertaining to purified melanosome extracts of modern bird feathers (both fresh and capsule-matured) from Caitlin Colleary (Associate Curator of Vertebrate Paleontology, Cleveland Museum of Natural History), based on their previous work (Colleary et al. 2015). Citation below:</p> <p> </p> <p>Colleary, C., A. Dolocan, J. Gardner, S. Singh, M. Wuttke, R. Rabenstein, J. Habersetzer, S. Schaal, M. Feseha, M. Clemens, B. F. Jacobs, E. D. Currano, L. L. Jacobs, R. L. Sylvestersen, S. E. Gabbott, and J. Vinther. 2015. Chemical, experimental, and morphological evidence for diagenetically altered melanin in exceptionally preserved fossils. Proceedings of the National Academy of Sciences USA 112(41):12592-7. doi: https://doi.org/10.1073/pnas.1509831112</p> <p> </p> <p>We further augmented this data set by adding ToF-SIMS spectra from our own samples (31-34, 52-79) pertaining to sediment encased maturation experiments (190ºC to 300ºC) and fossilised feathers of paravian dinosaurs housed at the Shandong Tianyu Museum of Natural History, Linyi Shi, Shandong, China.</p> <p>We conducted Principal Components Analysis with this Data and this dataset effectively serves as a PCA worksheet. The file can be opened/edited using Microsoft 365 Excel (.xlsx) with the following organisation of sheets.</p> <p>Sheets:</p> <p><strong>|----- PCA All</strong> : contains Sample ID, treatment categories, mass by charge (m/z) ratios of 55 peaks, peak identity and raw intensity counts</p> <p><strong>|-----PCA All Normalised</strong> : same data as PCA All but peak raw intensity counts normalised.</p> <p><strong>|-----PCA All Mean Centered</strong>: same data as PCA Normalised but with peak raw intensity mean centered.</p> <p><strong>|-----PCA All Loading Matrix:</strong> Loading matrix for PCA All using all 55 peaks.</p> <p><strong>|-----PCA All Eigen Vectors: </strong>Eigen vectors for PCA All.</p> <p><strong>|-----PCA All Scores: </strong> PCA scores for all 55 peaks.</p> <p><strong>|-----PCA No Lipids RAW</strong>: same data as PCA All but without peaks suspected to arise from lipids (e.g., CxH-).</p> <p><strong>|-----PCA No Lipids Normalised:</strong> same data as PCA without Lipids RAW but with peak raw intensity counts normalised.</p> <p><strong>|-----PCA No Lipids MeanCentred:</strong> same data as PCA without Lipids Norm but with peak raw intensity counts mean centered.</p> <p><strong>|-----PCA No Lipids Loading Matrix:</strong> Loading matrix for PCA All excluding peaks of lipid origin (CxH-).</p> <p><strong>|-----PCA No Lipids Eigen Vectors: </strong>Eigen vectors for PCA No Lipids Eigen Vectors.</p> <p><strong>|-----PCA No Lipids Scores:</strong> PCA scores for all peaks excluding those of lipid origin (CxH-).</p> <p> </p> <p>The dataset has been created in Microsoft Office 365 (Excel: .xlsx file). The file can also be also be opened and edited using the following softwares.</p> <p>1. Google Sheets</p> <p>2. Apache Open Office</p> <p>3. Libre Office</p> <p>4. PAST 4 (free software for scientific data analysis, with functions for data manipulation, plotting, univariate and multivariate statistics, ecological analysis, time series and spatial analysis, morphometrics and stratigraphy)."</p>
Melanin Recurrence in Scalpel and LASER Gingival Depigmentation in Thin and Thick Phenotypes.
ClinicalTrials.gov study NCT06886100. IPD Sharing: UNDECIDED. Countries: 1. Publications: 1.
Comparison of Er,Cr:YSGG Laser and Diode Laser in the Treatment of Gingival Melanin Pigmentation
ClinicalTrials.gov study NCT05304624. IPD Sharing: NO. Countries: 1. Publications: 1.
Melanin Index in Those With Fitzpatrick Skin Phototypes I-VI
ClinicalTrials.gov study NCT01124513. IPD Sharing: Not stated. Countries: 1. Publications: 1.
Data from: Melanin-based colouration and host-parasite interactions under global change
Open the record for dataset details and reuse information.
Data from: Effect of the MC1R gene on sexual dimorphism in melanin-based colorations
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Data from: The size of a melanin-based plumage ornament correlates with glucocorticoid receptor concentrations in the skin of that ornament
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Data from: Candidate gene analysis suggests untapped genetic complexity in melanin-based pigmentation in birds
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Data from: The meaning of melanin, carotenoid, and pterin pigments in the bluefin killifish, Lucania goodei
Open the record for dataset details and reuse information.
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