Evolution Of Pigmentation Research Articles

Continental variation in wing pigmentation inCalopteryxdamselflies is related to the presence of heterospecifics

Wing pigmentation in Calopteryx damselflies, caused by the deposition of melanin, is energetically expensive to produce and enhances predation risk. However, patterns of melanisation are used in species identification, greater pigmentation is an accurate signal of male immune function in at least some species, and there may be a role for pigment in thermoregulation. This study tested two potential hypotheses to explain the presence of, and variation in, this pigmentation based on these three potential benefits using 907 male specimens of Calopteryx maculata collected from 49 sites (34 discrete populations) across the geographical range of the species in North America: (i) pigmentation varies with the presence of the closely related species, Calopteryx aequabilis, and (ii) pigment increases at higher latitudes as would be expected if it enhances thermoregulatory capacity. No gradual latitudinal pattern was observed, as might be expected if pigmentation was involved in thermoregulation. However, strong variation was observed between populations that were sympatric or allopatric with C. aequabilis. This variation was characterised by dark wings through allopatry in the south of the range and then a step change to much lighter wings at the southern border of sympatry. Pigmentation then increased further north into the sympatric zone, finally returning to allopatry levels at the northern range margin. These patterns are qualitatively similar to variation in pigmentation in C. aequabilis, meaning that the data are consistent with what would be expected from convergent character displacement. Overall, the results corroborate recent research that has suggested sexual selection as a primary driver behind the evolution of wing pigmentation in this group.

Vitamin D, folate, and potential early lifecycle environmental origin of significant adult phenotypes

Vitamin D and folate are highly UV sensitive, and critical for maintaining health throughout the lifecycle. This study examines whether solar irradiance during the first trimester of pregnancy influences vitamin D receptor (VDR) and nuclear folate gene variant occurrence, and whether affected genes influence late-life biochemical/clinical phenotypes. 228 subjects were examined for periconceptional exposure to solar irradiance, variation in vitamin D/folate genes (polymerase chain reaction (PCR)), dietary intake (food frequency questionnaire (FFQ)) and important adult biochemical/clinical phenotypes. Periconceptional solar irradiance was associated with VDR-BsmI (P = 0.0008(wk7)), TaqI (P = 0.0014(wk7)) and EcoRV (P = 0.0030(wk6)) variant occurrence between post-conceptional weeks 6-8, a period when ossification begins. Similar effects were detected for other VDR gene polymorphisms. Periconceptional solar irradiance was also associated with 19 bp del-DHFR (P = 0.0025(wk6)), and to a lesser extent C1420T-SHMT (P = 0.0249(wk6)), a folate-critical time during embryogenesis. These same genes were associated with several late-life phenotypes: VDR-BsmI, TaqI and ApaI determined the relationship between dietary vitamin D and both insulin (P < 0.0001/BB, 0.0007/tt and 0.0173/AA, respectively) and systolic blood pressure (P = 0.0290/Bb, 0.0299/Tt and 0.0412/AA, respectively), making them important early and late in the lifecycle. While these and other phenotype associations were found for the VDR variants, folate polymorphism associations in later-life were limited to C1420T-SHMT (P = 0.0037 and 0.0297 for fasting blood glucose and HbA1c levels, respectively). We additionally report nutrient-gene relationships with body mass index, thiol/folate metabolome, cognition, depression and hypertension. Furthermore, photoperiod at conception influenced occurrence of VDR-Tru9I and 2R3R-TS genotypes (P = 0.0120 and 0.0360, respectively). Findings identify environmental and nutritional agents that may interact to modify gene-phenotype relationships across the lifecycle, offering new insight into human ecology. This includes factors related to both disease aetiology and the evolution of skin pigmentation.

The evolution of skin pigmentation and hair texture in people of African ancestry.

Our species, Homo sapiens, evolved in Africa, and humanity's highest levels of genetic diversity are maintained there today. Underlying genetic diversity combined with the great range of solar regimes and climatic conditions found in Africa has contributed to a wide range of human integumentary phenotypes within the continent. Millions of Africans have moved, voluntarily and involuntarily, to other continents in the past 2000 years, and the range of integumentary phenotypes among admixed African diaspora populations is enormous. In this contribution, we do not catalog this variation, but provide basic evolutionary background as to how it developed in the first place.

Pigmentation inXiphophorus: An Emerging System in Ecological and Evolutionary Genetics

The genus Xiphophorus has great potential to contribute to the study of vertebrate pigmentation and elucidating the relative influence of ecology, physiology, and behavior on evolution at the molecular level. More importantly, the association between pigmentation and a functional oncogene offers the potential to understand the evolution and maintenance of cancer-causing genetic elements. Using criteria laid out recently in the literature, I demonstrate the power of the Xiphophorus system for studying pigment evolution through integrative organismal biology. Using the most recent phylogeny, the phylogenetic distribution of several important pigmentation loci are reevaluated. I then review support for existing hypotheses of the functional importance of pigmentation. Finally, new observations and hypotheses regarding some of the characteristics of pigment patterns in natural populations and open questions and future directions in the study of the evolution of these traits are discussed.

IL-17 and TNF Synergistically Modulate Cytokine Expression while Suppressing Melanogenesis: Potential Relevance to Psoriasis

Inflammation-associated pigmentation changes are extremely common, but the etiology behind this clinical observation remains elusive. Particularly, it is unclear how the myriad of cytokines known to be involved in inflammatory skin processes affect epidermal melanocytes. We sought to determine how IL-17 and TNF influence normal human melanocytes, as these two cytokines have been implicated in various skin diseases. IL-17 and TNF jointly stimulated broad inductions of cytokines , including melanoma mitogens CXCL1 and IL-8. Moreover, IL-17 and TNF synergistically inhibited pigmentation-related signaling and melanin production, and induced keratinocytes production of β-defensin 3, an antagonist for melanocortin-receptor 1. When analyzing psoriasis lesions that are known to over express IL-17 and TNF, we observed an increase in melanocyte number and a simultaneous decrease in pigmentation signaling. Furthermore, therapeutic neutralization of TNF and IL-17 with mAbs results in a rapid recovery of pigment gene expression in psoriasis lesions. These results demonstrate that IL-17 and TNF can impact both the growth and pigment production of melanocytes, which may contribute to the pigmentation changes associated with psoriasis. These findings may allow the development of novel therapeutics for pigmentary disorders and bring new insights into the immune milieu surrounding melanocytes and related neoplasms.

A life history perspective on skin cancer and the evolution of skin pigmentation

The ancestral state of human skin pigmentation evolved in response to high ultraviolet radiation (UVR) stress. Some argue that pigmentation evolved to limit folate photolysis, therein limiting neural tube defects. Pigmentation also protects against sunburn which decreases the efficiency of sweating and potentiates skin infection. Pigmentation increases the efficacy of skin as a barrier to infection. Skin cancer has been rejected or minimized as a selective pressure because it is believed to have little or no effect on mortality during reproductive years. This argument ignores evidence of human longevity as a derived life history trait and the adaptive value of investment in offspring and kin, particularly during the post-reproductive lifespan. Opponents argue that lifespan in prehistoric hunter-gatherers was too short to be relevant to the evolution of skin pigmentation. This argument is flawed in that it relies on estimates of longevity at birth rather than adolescence. When appropriate estimates are used, it is clear that human longevity has a deep evolutionary history. We use a life history perspective to demonstrate the value of skin pigmentation as an adaptation to skin cancer with the following points: UVR exposure increases dysregulation of gene expression in skin cells leading to immortal cell lines; cutaneous malignant melanoma (CMM) affects individuals throughout reproductive years; and lifespan was longer than has previously been acknowledged, providing the opportunity for kin selection. This hypothesis is not at odds with the folate or barrier hypotheses. We stress that the evolution of skin pigmentation is complex and is an ongoing process.

Fluorescence Approach for Measuring Anthocyanins and Derived Pigments in Red Wine

A novel fluorescence approach to monitor the evolution of anthocyanins and derivatives in red wine was developed. Some red table wines and Port wine with different vintage years were first tested with the aim to determine the ideal fluorescent conditions. The fluorescence contribution of both monomeric and polymeric anthocyanins was studied by comparing their emission spectra. By measuring the F700/F560 ratio on different wine samples and applying an inverted exponential function, it was possible to estimate the monomeric/polymeric anthocyanin absorbance ratio that is proportional to the relative content of the two classes of compounds. The methodology was further developed by using pure compounds representative of monomeric anthocyanins and anthocyanin-pyruvic acid adducts, namely, by using malvidin-3-O-glucoside and vitisin A. A fluorescence excitation ratio (FER350/550) was considered for estimating the absorbance ratio between vitisin A and malvidin-3-O-glucoside. Overall, this work aims to use fluorescence to monitor the evolution of anthocyanin derivatives and to distinguish them from their anthocyanin precursors, thereby allowing the evolution of anthocyanin pigments during wine aging to be monitored, but it also may be useful to determine age markers or even geographical markers.

Ecology and Sexual Selection: Evolution of Wing Pigmentation in Calopterygid Damselflies in Relation to Latitude, Sexual Dimorphism, and Speciation

Our knowledge about how the environment influences sexual selection regimes and how ecology and sexual selection interact is still limited. We performed an integrative study of wing pigmentation in calopterygid damselflies, combining phylogenetic comparative analyses, field observations and experiments. We investigated the evolutionary consequences of wing pigmentation for sexual dimorphism, speciation, and extinction and addressed the possible thermoregulatory benefits of pigmentation. First, we reconstructed ancestral states of male and female phenotypes and traced the evolutionary change of wing pigmentation. Clear wings are the ancestral state and that pigmentation dimorphism is derived, suggesting that sexual selection results in sexual dimorphism. We further demonstrate that pigmentation elevates speciation and extinction rates. We also document a significant biogeographic association with pigmented species primarily occupying northern temperate regions with cooler climates. Field observations and experiments on two temperate sympatric species suggest a link between pigmentation, thermoregulation, and sexual selection, although body temperature is also affected by other phenotypic traits such as body mass, microhabitat selection, and thermoregulatory behaviors. Taken together, our results suggest an important role for wing pigmentation in sexual selection in males and in speciation. Wing pigmentation might not increase ecological adaptation and species longevity, and its primary function is in sexual signaling and species recognition.

Slc45a2 and V‐ATPase are regulators of melanosomal pH homeostasis in zebrafish, providing a mechanism for human pigment evolution and disease

We present here the positional cloning of the Danio rerio albino mutant and show that the affected gene encodes Slc45a2. The human orthologous gene has previously been shown to be involved in human skin color variation, and mutations therein have been implicated in the disease OCA4. Through ultrastructural analysis of the melanosomes in albino alleles as well as the tyrosinase-deficient mutant sandy, we add new insights into the role of Slc45a2 in the production of melanin. To gain further understanding of the role of Slc45a2 and its possible interactions with other proteins involved in melanization, we further analyzed the role of the V-ATPase as a melanosomal acidifier. We show that it is possible to rescue the melanization potential of the albino melanosomes through genetic and chemical inhibition of V-ATPase, thereby increasing internal melanosome pH.

The Timing of Pigmentation Lightening in Europeans

The inverse correlation between skin pigmentation and latitude observed in human populations is thought to have been shaped by selective pressures favoring lighter skin to facilitate vitamin D synthesis in regions far from the equator. Several candidate genes for skin pigmentation have been shown to exhibit patterns of polymorphism that overlap the geospatial variation in skin color. However, little work has focused on estimating the time frame over which skin pigmentation has changed and on the intensity of selection acting on different pigmentation genes. To provide a temporal framework for the evolution of lighter pigmentation, we used forward Monte Carlo simulations coupled with a rejection sampling algorithm to estimate the time of onset of selective sweeps and selection coefficients at four genes associated with this trait in Europeans: KITLG, TYRP1, SLC24A5, and SLC45A2. Using compound haplotype systems consisting of rapidly evolving microsatellites linked to one single-nucleotide polymorphism in each gene, we estimate that the onset of the sweep shared by Europeans and East Asians at KITLG occurred approximately 30,000 years ago, after the out-of-Africa migration, whereas the selective sweeps for the European-specific alleles at TYRP1, SLC24A5, and SLC45A2 started much later, within the last 11,000-19,000 years, well after the first migrations of modern humans into Europe. We suggest that these patterns were influenced by recent increases in size of human populations, which favored the accumulation of advantageous variants at different loci.

Phylogenetic signal and variation of visceral pigmentation in eight anuran families

Provete, D. B, Franco‐Belussi, L., de Souza Santos, L. R., Zieri, R., Moresco, R. M., Martins, I. A., de Almeida, S. C., &amp; de Oliveira, C. (2012). Phylogenetic signal and variation of visceral pigmentation in eight anuran families. —Zoologica Scripta, 41, 547‐556.Visceral pigmentation is found in several organs and structures of ectothermic animals, comprising the extracutaneous pigmentary system. Its function is not well defined, although it is known that melanin is produced and stored inside pigmented cells. Previous studies demonstrated that the distribution of visceral pigmentation is neither homogeneous among organs among anuran species. We described the diversity of visceral pigmentation in 12 organs/structures from 32 anuran species belonging to eight families in a phylogenetic context. We also determined in which node(s) of the phylogeny there is more variation in the pigmentation and whether this variation has phylogenetic signal. The visceral pigment cells in organs and structures of the abdominal cavity varied among genera. All species had pigmentation in the urogenital and cardiorespiratory systems, whereas the stomach lacks pigmentation in all species. We also found a phylogenetic signal for pigmentation in all organs and structures taken together, besides heart, testes, lumbar parietal peritoneum and lumbar nerve plexus when considered separately. Overall, considering all organs, the highest diversity of categories of pigmentation was found in the nodes corresponding to Cruciabatrachia and Athesphatanura. This study constitutes the first step towards understanding the evolution of visceral pigmentation in anurans.

The evolution of human skin colouration and its relevance to health in the modern world

Functionally naked skin which comes in a range of colours is unique to the human species. This review summarises current evidence pertaining to the evolution of these attributes. The biggest changes in the integument occurred during the course of human evolution in equatorial Africa, under regimes of high daytime temperatures and high ultraviolet radiation (UVR). Loss of most functional body hair was accompanied by the evolution of an epidermis with a specialised stratum corneum and permanent, protective, eumelanin pigmentation. The main reason for the evolution of dark pigmentation was to protect against folate deficiency caused by elevated demands for folate in cell division, DNA repair, and melanogenesis stimulated by UVR. Dispersal out of tropical Africa created new challenges for human physiology especially because of lower and more seasonal levels of UVR and ultraviolet B (UVB) outside of the tropics. In these environments, the challenge of producing a vitamin D precursor in the skin from available UVB was met by natural selection acting on mutations capable of producing varying degrees of depigmentation. The range of pigmentation observed in modern humans today is, thus, the product of two opposing clines, one favoring photoprotection near the equator, the other favoring vitamin D photosynthesis nearer the poles. Recent migrations and changes in lifestyle in the last 500 years have brought many humans into UVR regimes different from those experienced by their ancestors and, accordingly, exposed them to new disease risks, including skin cancer and vitamin D deficiency.

Evolution of phenols and pigments in extra virgin olive oil from irrigated super‐intensive orchard

AbstractPhenolic compounds have a high importance in olive oil because of their effect on shelf life and sensory properties. This study reports on the HPLC profiles of the phenolic compounds of virgin olive oils obtained from Arbequina olives from the harvesting in a super‐intensive orchard under a linear irrigation system. In addition, phenolic content, carotenoid and chlorophyllic pigments, and oxidative stability were analyzed. Total phenol content and 3,4‐DHPEA‐EDA increased up to a maximum throughout the ripening process. The simple phenols tyrosol and hydroxytyrosol acetate increased throughout the ripening process, however, there was not found a clear trend in hydroxytyrosol content. Minor constituents such as vanillic acid and p‐coumaric acid increased up to a maximum and then decreased, since vanillin decreased progressively throughout the time of harvest. 3,4‐DHPEA‐EDA and lignans were present in considerable amounts in the studied samples, while oleuropein aglycone was present in a low amount. Total phenol content and oil stability followed the same trend throughout the study, so a very good correlation was established between them. Total secoiridoids and, specifically, 3,4‐DHPEA‐EDA seemed to be responsible for oil stability. The pigment content decreased during ripening, and not a positive correlation was found between pigments and oil stability.Practical applications: The results can be used to determine the best time for harvesting in order to obtain olive oils with different phenols and pigment contents. This is important for sensory characteristics of the olive oils and also for olive oil stability.

Adaptive evolution of facial colour patterns in Neotropical primates

The rich diversity of primate faces has interested naturalists for over a century. Researchers have long proposed that social behaviours have shaped the evolution of primate facial diversity. However, the primate face constitutes a unique structure where the diverse and potentially competing functions of communication, ecology and physiology intersect, and the major determinants of facial diversity remain poorly understood. Here, we provide the first evidence for an adaptive role of facial colour patterns and pigmentation within Neotropical primates. Consistent with the hypothesis that facial patterns function in communication and species recognition, we find that species living in smaller groups and in sympatry with a higher number of congener species have evolved more complex patterns of facial colour. The evolution of facial pigmentation and hair length is linked to ecological factors, and ecogeographical rules related to UV radiation and thermoregulation are met by some facial regions. Our results demonstrate the interaction of behavioural and ecological factors in shaping one of the most outstanding facial diversities of any mammalian lineage.

Convergent, modular expression of ebony and tan in the mimetic wing patterns of Heliconius butterflies

The evolution of pigmentation in vertebrates and flies has involved repeated divergence at a small number of genes related to melanin synthesis. Here, we study insect melanin synthesis genes in Heliconius butterflies, a group characterised by its diversity of wing patterns consisting of black (melanin), and yellow and red (ommochrome) pigmented scales. Consistent with their respective biochemical roles in Drosophila melanogaster, ebony is upregulated in non-melanic wing regions destined to be pigmented red whilst tan is upregulated in melanic regions. Wing regions destined to be pigmented yellow, however, are downregulated for both genes. This pattern is conserved across multiple divergent and convergent phenotypes within the Heliconii, suggesting a conserved mechanism for the development of black, red and yellow pattern elements across the genus. Linkage mapping of five melanin biosynthesis genes showed that, in contrast to other organisms, these genes do not control pattern polymorphism. Thus, the pigmentation genes themselves are not the locus of evolutionary change but lie downstream of a wing pattern regulatory factor. The results suggest a modular system in which particular combinations of genes are switched on whenever red, yellow or black pattern elements are favoured by natural selection for diverse and mimetic wing patterns.

Molecular phylogeny of the subfamily Amphistichinae (Teleostei: Embiotocidae) reveals parallel divergent evolution of red pigmentation in two rapidly evolving lineages of sand-dwelling surfperch

Pigment evolution was reconstructed in the subfamily Amphistichinae, a six-species clade of the surfperches, family Embiotocidae. Assignment was confirmed for all species within the subfamily, but low levels of differentiation were found among species within the subfamily, suggesting a recent radiation. The new phylogeny differs from previous hypotheses by the placement of the spotfin surfperch Hyperprosopon anale at the base of the subfamily, while still preserving the calico surfperch Amphistichus koelzi and the redtailed surfperch Amphistichus rhodoterus as sister species. Phenotypically, A. rhodoterus, A. koelzi and the silver surfperch Hyperprosopon ellipticum express high levels of red pigmentation. The barred surfperch, Amphistichus argenteus and the walleye surfperch Hyperprosopon argenteum express little to no red pigment, while basal H. anale expresses an intermediate amount of red pigment. Red pigmentation is proposed to have experienced parallel divergent evolution in each genus within the subfamily.

Comparative Changes in Color Features and Pigment Composition of Red Wines Aged in Oak and Cherry Wood Casks

The color features and the evolution of both the monomeric and the derived pigments of red wines aged in oak and cherry 225 L barriques have been investigated during a four months period. For cherry wood, the utilization of 1000 L casks was tested as well. The use of cherry casks resulted in a faster evolution of pigments with a rapid decline of monomeric anthocyanins and a quick augmentation formation of derived and polymeric compounds. At the end of the aging, wines stored in oak and cherry barriques lost, respectively, about 20% and 80% of the initial pigment amount, while in the 1000 L cherry casks, the same compounds diminished by about 60%. Ethyl-bridged adducts and vitisins were the main class of derivatives formed, representing up to 25% of the total pigment amount in the cherry aged samples. Color density augmented in both the oak and cherry wood aged samples, but the latter had the highest values of this parameter. Because of the highly oxidative behavior of the cherry barriques, the use of larger casks (e.g., 1000 L) is proposed in the case of prolonged aging times.

Complex pigment evolution in the Caryophyllales

Carotenoids and flavonoids including anthocyanins are the predominant pigments in flowering plants, where they play important roles in pollination, seed dispersal, protection against stress and signalling. In certain families within the Pentapetalae order Caryophyllales, an unusual class of pigments, known as betalains, replaces the more common anthocyanins. This isolated occurrence of betalains in the Caryophyllales has stimulated over half a century of debate and experimentation. Numerous hypotheses have been suggested to explain the phylogenetically restricted occurrence of betalains and their apparent mutual exclusion with anthocyanins. In this review, we evaluate these hypotheses in the face of a changing interpretation of Caryophyllales phylogeny and new comparative genetic data. Phylogenetic analyses expose substantial gaps in our knowledge of the early evolution of pigments in the Caryophyllales and suggest pigmentation to be much more labile than previously recognized. Reconstructions of character evolution imply multiple switches from betalain to anthocyanin pigmentation, but also allow for possible multiple origins of betalains. Comparative genetic studies propose possible mechanisms underlying switches between pigment types and suggest that transcriptional down-regulation of late-acting enzymes is responsible for a loss of anthocyanins. Given these insights from molecular phylogenetics and comparative genetics, we discuss outstanding questions and define key goals for future research.

Photoaging under recreational sunbeds

Artificial sources of restricted light wavelength, particularly tanning beds, are progressively gaining importance in photoaging. To assess the kinetics and the long-term evolution of skin pigmentation and tensile functions in sunbed worshippers over a period of 8 years. Photoaging was explored in women who were both sunshine and sunbed worshippers. A series of 65 phototype III women aged 31-46 years completed a 100-month survey. Quarterly assessments were performed on the forearms to measure (a) the skin color individual typology angle (ITA°), (b) the extent in mottled subclinical melanoderma (MSM) using the ultraviolet light-enhanced visualization method and (c) the rheological properties of skin. A progressive increase in both skin extensibility and hysteresis was observed, contrasting with a decrease in biologic elasticity. These rheological changes were correlated with the ITA° changes, but not with the MSM extent. The kinetics of evolution of each test variable were distinct over time. This work is the first attempt at evaluating the kinetics of changes in physical parameters during a long period of frequent exposures to tanning sunbeds and sunshine for lifestyle purposes. The alterations were quite important in the color, MSM and rheological functions of the skin.

Adaptive Diversity: Hormones and Metabolism in Freshwaters

Genes underlying the evolution of morphological traits have recently been identified in a number of model species. In the stickleback, the metabolic adaptations to a freshwater habitat have now been linked to a well-known hormonal system.