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The water vole (Arvicola amphibius) is widespread throughout Eurasia. In 2020, 17 specimens were collected from the islands of the White Sea during the field expedition of the Karelian Research Centre. It was the first record of this species for White Sea island fauna since the 1950s. Among the captured voles, there were two different colour variants of the animals: almost black and reddish-brown. We tend to classify the black type of colour as melanism. This type of colouration is new for the species in the region, according to data from long-term monitoring of continental populations of small mammals. All reddish-brown samples, with the exception of one juvenile male, presented white spots on various parts of the body. The white-spotting patterns of reddish-brown colouration were also first recorded for water voles in the region. Individuals with different colouration types inhabited islands separated by about 50 kms of water. [ABSTRACT FROM AUTHOR]

Background and Aim: Colour polymorphic populations constitute excellent model systems for testing ecological and evolutionary hypotheses, as alternate colourations are associated with differences in various biological, behavioural and life‐history traits. Melanism is the most common and most obvious form of polymorphism. In reptiles in general (and snakes in particular), thermal melanism has been a popular hypothesis used to explain the appearance of black individuals. It suggests that a trade‐off exists between superior thermoregulation and reduced protection through the loss of crypsis. Surprisingly, despite the growing body of literature available, to date, there are only two qualitative reviews on the evolutionary significance of melanism in reptiles and no quantitative synthesis. We conducted the first systematic review and meta‐analysis summarising the current knowledge on melanism in polymorphic terrestrial snakes and synthesised the evidence for an adaptive advantage of the melanistic morph. Location: Northern Hemisphere. Taxon: Polymorphic terrestrial snakes. Results: Mean prevalence of melanism is 31% with no significant differences between species. Annual precipitation was a significant moderator of melanism prevalence. Our results revealed no significant differences in odds ratios of melanism between sexes or in mean body size. Main Conclusions: Environmental plasticity can be considered the primary cause of melanism, possibly as a result of seasonal climatic variations, a result corroborated by the formal meta‐analysis conducted. Conclusions from the meta‐analysis are that melanism in snakes follows Gloger's rule, as is the case in birds and mammals, and as opposed to the thermal melanism hypothesis. Further, our findings do not lend support for other predictions from the thermal melanism hypothesis, such as skewed frequency of melanistics in favour of males or females, or larger body sizes in black individuals. Our results hold implications for the future diversity of animal populations, as climate change is predicted to decrease the degree of colour variation. [ABSTRACT FROM AUTHOR]

Variations in colouration patterns have been reported in numerous wildlife species, particularly birds. However, the increased use of camera traps for wildlife monitoring has enabled the detection of elusive species and phenotypic variations that might otherwise go undetected. Here, we compiled records of unusual colouration patterns in terrestrial mammals, documented through camera-trap studies over a 12-year period in the Llanganates-Sangay Connectivity Corridor, in the Tropical Andes of Ecuador. We identified colour variations in seven species of terrestrial mammals, including disorders, such as melanism, white spotting/ piebaldism, xanthocromism and progressive greying. Notably, we reported a high prevalence of melanism in wild populations of the clouded oncilla, along with observations on the species' activity patterns. Approximately half of the recorded clouded oncillas were melanistic. We detected significant differences in activty patterns between melanistic and non-melanistc clouded oncilla, with melanistic morphs showing a peak of activity between 3 a.m. and before dawn. The proportion of melanistic individuals suggests that melanism is widespread throughout the corridor. However, its impact on the species' fitness remains unclear.

ABSTRACT Aim Location Taxon Methods Results Main Conclusions Colour polymorphism within ectothermic species and populations is shaped by multiple selection pressures that can vary geographically. Here, we tested different hypotheses to better understand this variation in colour polymorphism. The thermal melanism hypothesis predicts that darker colouration is beneficial in colder regions, due to enhanced heat absorption, while the predation pressure hypothesis predicts that melanistic individuals are exposed to a higher predation risk because they are more visible to predators. Additionally, temperature, land cover and predation pressure could interact to influence colour morph frequencies due to trade‐offs regarding thermoregulation and predation risk.Eurasia.European adder (Vipera berus).We compiled a dataset of > 7000 citizen observations across the entire distribution of the European adder, scoring adder colouration to test the above‐mentioned hypotheses concerning geographic variation in colour polymorphism, using Bayesian generalised nonlinear regression models.We found support for the thermal melanism hypothesis, with the frequency of melanism increasing in colder regions. Moreover, in colder areas, the proportion of melanistic snakes increased with avian predator density, whereas this pattern was weaker in warmer areas, potentially because melanistic snakes spend less time basking and therefore experience reduced predation rates compared to brown and grey snakes. Finally, we found the proportion of melanistic individuals to decline at higher elevations (> 1000 m), potentially due to increased access to basking opportunities or because higher elevations facilitate easier detection of melanistic snakes by predators.Combined, our results emphasise the large potential of citizen observations to obtain novel insights concerning biogeographic patterns of morphological divergence in colouration. Our findings increase the understanding of the underlying mechanisms affecting colour polymorphism in ectothermic animals, providing valuable information to predict how species might respond to global change. [ABSTRACT FROM AUTHOR]

Fire events change background color, impairing camouflage strategies. However, selection for polymorphic populations may increase camouflage and survival by reducing predation risks. We conducted experiments addressing background selection and predation pressures on the effectiveness of arthropod camouflage against predation in burned and unburned trunks. We tested color and luminance contrasts, as well as trunk preferences, in a color polymorphic grasshopper and praying mantis species with melanic and brown morphs, and a spider species with a single dark color. To expand the scope of our study, we used two distinct visual models of avian predators: ultraviolet sensitive and violet sensitive. We also performed predation experiments using theoretical prey exhibiting black and brown color and human "predators" to understand the effectiveness of color polymorphism against different trunk conditions. Melanic morphs had lower achromatic contrast in burned backgrounds for both visual systems, suggesting that melanism promotes advantages against predation over long distances. However, only spiders actively selected the low-contrasting burned trunks, indicating habitat specialization. The predation experiments showed that black models benefited from camouflage on burned trunks. Conversely, brown models elicited more time and reduced distance in predator searching compared with the black targets on unburned trunks. We suggest that postfire effects can enhance color contrasts and increase predation over color-mismatching individuals, which translates into selection pressures for color polymorphism and matching background choices. [ABSTRACT FROM AUTHOR]

Simple Summary: An updated classification system for the Aporia agathon group is proposed after the re-examination of a long series of specimens with mitogenomic data. Our results showed that A. japfuensis, A. bifurcata, A. moltrechti, A. kuangtungensis, and A. omotoi should be recognised as full species, while lemoulti, gigantea, and fanjinensis should be recognized as subspecies of A. largeteaui. In addition, two subspecies, A. kuangtungensis yufeii and A. kuangtungensis josephi, are described herein. Pierid species of the Aporia agathon group are among the largest Sino-Himalayan members of genus Aporia, with four conventionally recognised species, namely A. agathon, A. largeteaui, A. gigantea, and A. lemoulti. Recent publications indicated that some of these species may contain more than one species despite their similar morphological characters. The present research analysed this group of butterflies using mitogenomic data, and proved that A. japfuensis stat. nov., A. bifurcata stat. nov., A. moltrechti reinst. stat., A. kuangtungensis stat. nov. and A. omotoi stat. nov. should be recognised as distinct species, while lemoultistat. rev., gigantea stat. nov. and fanjinensis stat. rev. should be subspecies of A. largeteaui. Two new subspecies, namely A. kuangtungensis yufeii ssp. nov. and A. kuangtungensis josephi ssp. nov. were described. Illustrations of specimens and male and female genitalia of each taxon were provided in this article with an updated classification system. Variable melanism and yellow tinge are two major factors causing historical taxonomic confusion; thus, such characters should be less crucial for this species group. Future research is still necessary to elucidate the evolutionary history of these species along with other Aporia taxa, as well as the mechanism of variable melanism and yellow coloration. [ABSTRACT FROM AUTHOR]

Melanism in Echis carinatus has been observed on Sheedvar Island in the Persian Gulf. A comparative analysis between melanistic and non-melanistic individuals showed no significant morphological or genetic differences. The evolution of melanism in E. carinatus may serve as camouflage or aid in predator avoidance, similar to other nocturnal viper species. However, a deeper understanding of the ecological role of melanism in nocturnal vertebrates, including E. carinatus, requires further investigation to clarify its broader significance. [ABSTRACT FROM AUTHOR]

The tomato leafminer (Tuta absoluta) is a highly destructive global quarantine pest. The methoprene-tolerant (Met) protein, a member of the bHLH/PAS family of transcription factors, forms complexes with other family members to transduce the juvenile hormone signal, which regulates insect growth and development. However, the functions of the TaMet gene have rarely been studied in T. absoluta. Herein, we investigated the significance of TaMet in T. absoluta. Spatiotemporal expression analysis revealed that TaMet exhibited comparable expression patterns in males and females, with high expression levels during the early pupal and early adult stages. TaMet was predominantly expressed in the female ovary and male wing. TaMet knockdown impaired ovarian development in female adults, causing irregular arrangement and increased spacing of the egg epithelial cells in the ovary. Silencing TaMet also led to a 67.25% reduction in female spawning and a 67.21% decrease in the offspring hatching rate. Furthermore, the vitellogenin content was significantly diminished, and the expression levels of vitellogenin (Vg) and vitellogenin receptor (VgR) genes were significantly downregulated. In contrast, silencing TaMet in 3-day-old male pupae resulted in an 80% mortality rate and various phenotypic abnormalities, including body melanism, molting defects, and wing deformities. Moreover, the expression levels of wing development and chitin metabolism genes decreased significantly after knocking down TaMet. Our results indicate that TaMet plays a significant dual role in male molting and female reproduction of T. absoluta. [ABSTRACT FROM AUTHOR]

The two-spot ladybird, Adalia bipunctata, is polymorphic for elytral colour pattern. Whilst colour pattern polymorphism is complex, there are two predominant morphs: melanic and typical, which vary spatially in frequency. In the UK the melanic form has historically been most common in the industrialized North West of England. Evidence from industrial midland populations showed a decline in melanic frequency between 1960 and 1986 concordant with de-industrialization. We resampled the population of Merseyside in the North West of England, where the highest frequencies of melanic forms were historically observed, and compared our samples to data previously collected in 19621963. Data was consistent with a decline in frequency of melanics in the 60 year interval, but the melanic form was nevertheless still observed at around 30% frequency. We estimate the melanic allele has declined from 60-67% frequency to 13-18% frequency over the last 60 years, and that selection favouring the typical form has been of the order of 5-7% per generation. We note that selection against melanics in Wirral/Merseyside has been less strong than that observed in other Northern populations. We conclude that the decline in the melanic form is consistent with industrial thermal melanism as a primary factor driving melanism, but de-industrialization has not been suffi cient to cause complete loss of the melanic allele in this location. [ABSTRACT FROM AUTHOR]

In the northern portions of its range, Abert's Squirrel (Sciurus aberti) has two color morphs: a wild-type gray morph and a melanistic morph. Using camera traps, citizen science data and in-person observations in and near Boulder, Colorado (USA), we compared current color morph frequencies to those reported in a 1969–1971 study. At all study sites, we observed a large and statistically significant increase in the frequency of the melanistic morph compared to historic data. We hypothesize that this increase may be due to selection favoring the melanistic morph in a changing forest environment. [ABSTRACT FROM AUTHOR]

Variations in colouration patterns have been reported in numerous wildlife species, particularly birds. However, the increased use of camera traps for wildlife monitoring has enabled the detection of elusive species and phenotypic variations that might otherwise go undetected. Here, we compiled records of unusual colouration patterns in terrestrial mammals, documented through camera-trap studies over a 12-year period in the Llanganates-Sangay Connectivity Corridor, in the Tropical Andes of Ecuador. We identified colour variations in seven species of terrestrial mammals, including disorders, such as melanism, white spotting/ piebaldism, xanthocromism and progressive greying. Notably, we reported a high prevalence of melanism in wild populations of the clouded oncilla, along with observations on the species' activity patterns. Approximately half of the recorded clouded oncillas were melanistic. We detected significant differences in activty patterns between melanistic and non-melanistc clouded oncilla, with melanistic morphs showing a peak of activity between 3 a.m. and before dawn. The proportion of melanistic individuals suggests that melanism is widespread throughout the corridor. However, its impact on the species' fitness remains unclear. [ABSTRACT FROM AUTHOR]

Melanism drives both crypsis and mimicry in butterflies and moths. To date, melanism has been mapped to a structural gene called cortex , but now more detailed work shows that in fact it is controlled by non-coding RNAs at the same locus. [ABSTRACT FROM AUTHOR]

The study of colour, including physical properties and patterns, is an essential step in comprehensively understanding the role, evolution and diversification of this trait involved in functions like survival, performance, reproductive success and communication. While quantitative studies on colour have primarily focused on colour attributes, such as hue or brightness, the quantitative assessment of how colours are distributed across an organism's body (i.e. pattern) has received less attention despite its high functionality irrespective and together with colour. This gap is particularly noticeable in amphibians, especially in highly polymorphic, continuously variable species. In this study, we use the urodele Salamandra salamandra as a study model to apply an analytical approach for extracting and quantifying colour proportions and patterns variation using the recently developed R packages patternize and recolorize to precisely describe and compare colour distribution at both taxonomic and habitat levels. We first assessed the potential application of this workflow in taxonomic studies by examining its accuracy and sensitivity in differentiating morphs, using S. s. bernardezi and S. s. gallaica subspecies. Subsequently, we applied the same analytical approach to compare colour and colour pattern shifts among population of S. s. bernardezi within an urban–forest system. Our results demonstrated that this methodological workflow effectively detects differences in colour patterns at the taxonomic and habitat levels, confirming its utility in different fields, from systematics to eco‐evolutionary studies. Furthermore, our results revealed an increased prevalence of melanistic colouration and a less homogeneous colour pattern within urban settings, contributing to the limited number of studies about amphibian colouration in anthropic habitats. We outline and discuss alternative hypotheses to explain these patterns, although further investigation is necessary to address several new questions that arise from our results. [ABSTRACT FROM AUTHOR]

In mammals, hair and skin colour play crucial roles in concealing individuals from predators, facilitating communication within and between species, and contributing to essential physiological functions like thermoregulation. However, certain individuals exhibit abnormal colouration patterns due to either an excess (melanism) or deficiency (albinism, leucism, or piebaldism) in melanin production. Despite the prevalence of chromatic disorders in mammals, instances of species displaying colour anomalies remain infrequent. Here, we report the occurrence of colour anomalies in eight small mammal species (Microtus hartingi, M. dogramacii, M. schidlovskii, M. levis, Mus macedonicus, Sorex sp., Apodemus sp., Nannospalax sp.). In some specimens with colour abnormalities (M. hartingi, M. schidlovskii and M. dogramacii), species identification was confirmed by molecular analysis (cyt b gene region). An individual of M. dogramacii exhibiting colour anomaly was compared with the M. dogramacii species displaying normal colouration through multivariate morphometric analysis and was found to be in the normal range for the species. [ABSTRACT FROM AUTHOR]

Reef manta rays (Mobula alfredi) face threats from human exploitation and activity in several regions of the world and crucial information on the ecology of the species is needed. The species is observed at several sites in all parts of the archipelago of New Caledonia where anthropogenic influence is presumed to be minimal. This study is the first to investigate the population of New Caledonia and focuses on its characteristics and its habitat use. Photographs of reef manta rays were collected directly from the authors (14.4%) between 2017 and 2020 and gathered from recreational divers and snorkelers (85.6%) from 11 sites around New Caledonia. The authors used the unique ventral coloration patterns of the manta rays that were clearly identifiable from 1741 of these photographs to identify 391 individuals and record their physical characteristics (sex, injuries, and colour morph) and resighting rates. These results highlight the widespread distribution of the species in the archipelago (11 sites) with little connectivity between all aggregations sites, with only 5.4% of the individuals observed at more than one site. Strong and long-term site fidelity was recorded at all studied sites through re-sighting rates (52.2% overall) and residency analysis. The population also records the world highest known proportion of melanistic manta rays (43%) to date, and a balanced male: female ratio (1.0:1.15). The analysis of injuries reported that 44.8% of all reef manta rays identified (n = 391) had noticeable wounds or injuries with no significant difference in the proportions of males and females injured. From these injured individuals only 9.8% of injuries judged to be of anthropogenic origin and 29.7% from attempted predation. Our study complements and correlates previous findings on this population that revealed strong site fidelity and low connectivity. The different characteristics of this population of reef manta rays also emphasize that concerns about species in New Caledonia are limited and that such favourable context needs to be preserved as reference for conservation. [ABSTRACT FROM AUTHOR]

Melanin-based color polymorphism is predicted to evolve and maintain through differential fitness of morphs in different environments, and several empirical studies indicate that life history strategies, physiology, and behavior vary among color morphs. Sex allocation theory predicts that parents should adjust their sex allocation based on differential costs of raising sons and daughters, and therefore, color morphs are expected to modify their brood sex ratio decisions. In color polymorphic tawny owls (Strix aluco), the pheomelanistic brown morph is associated with higher energy requirements, faster growth, and higher parental effort than the gray morph. As hypothesized, we find that brown tawny owl mothers produced more daughters in early broods and more males in late broods, whereas gray mothers did the opposite. At fledging, daughters of early broods and of brown mothers were heavier than those of late broods or gray mothers. Hence, larger and more costly daughters appeared to benefit more than males from being born to brown mothers early in the season. Brown mothers breeding later in the season produced more cheap sons, while gray mothers face fewer challenges under limited resources and favor daughters. These findings suggest that environmental conditions influence brood sex allocation strategies of genetically determined color morphs differently. [ABSTRACT FROM AUTHOR]

Aim: To better understand the potential impact of climate change on butterfly assemblages across a tropical island, we model the potential for taxonomic and functional homogenization and determine climate‐ and trait‐mediated shifts in projected species distributions. Location: Puerto Rico. Methods: We used thousands of museum records of diurnal Lepidoptera to model current (1970–2000) and forecast future (2061–2080) species distributions and combined these to test for taxonomic and functional homogenization. We then quantified climatic‐mediated effects on current and forecasted taxonomic and functional composition and, specifically, whether temperature was a primary driver, as predicted by the temperature–size rule and the thermal melanism hypotheses. Finally, we measured wing traits important in thermoregulation (size and colour) and determined trait‐mediated changes in forecasted species distributions over time. Results: Based on ensemble model outputs, taxonomic and functional richness and turnover were predicted to vary across the island's complex topography. Our models projected an increase in taxonomic and functional richness over time, and a decrease in taxonomic and functional turnover – a signature of biotic homogenization. Under future climate scenarios, models projected a decrease in wing length and an increase in wing brightness at higher elevations. One variable, temperature seasonality, was the strongest predicted driver of both the current spatial distribution and the projected per cent change over time for not only wing traits but also taxonomic and functional richness and turnover. Main conclusions: The species distribution models generated here identify several priority regions and species for future research and conservation efforts. Our work also highlights the role of seasonality and climatic variability on diverse tropical Lepidoptera assemblages, suggesting that climatic variability may be an important, albeit overlooked, driver of climate change responses. [ABSTRACT FROM AUTHOR]

Melanism, the process of heavier melanin deposition, can interact with climate variation at both micro and macro scales, ultimately influencing color evolution in organisms. While the ecological processes regulating melanin production in relation to climate have been extensively studied, intraspecific variations of melanism are seldom considered. Such scientific gap hampers our understanding of how species adapt to rapidly changing climates. For example, dark coloration may lead to higher heat absorption and be advantageous in cool climates, but also in hot environments as a UV or antimicrobial protection mechanism. To disentangle such opposing predictions, here we examined the effect of climate on shaping melanism variation in 150 barred grass snakes (Natrix helvetica) and 383 green whip snakes (Hierophis viridiflavus) across Italy. By utilizing melanistic morphs (charcoal and picturata in N. helvetica, charcoal and abundistic in H. viridiflavus) and compiling observations from 2002 to 2021, we predicted that charcoal morphs in H. viridiflavus would optimize heat absorption in cold environments, while offering protection from excessive UV radiation in N. helvetica within warm habitats; whereas picturata and abundistic morphs would thrive in humid environments, which naturally have a denser vegetation and wetter substrates producing darker ambient light, thus providing concealment advantages. While picturata and abundistic morphs did not align with our initial humidity expectations, the charcoal morph in N. helvetica is associated with UV environments, suggesting protection mechanisms against damaging solar radiation. H. viridiflavus is associated with high precipitations, which might offer antimicrobial protection. Overall, our results provide insights into the correlations between melanin‐based color morphs and climate variables in snake populations. While suggestive of potential adaptive responses, future research should delve deeper into the underlying mechanisms regulating this relationship. [ABSTRACT FROM AUTHOR]

ABSTRACT Here we present melanic forms of ants belonging to the light-colored Neotropical species Heteroponera dolo (Ectatomminae) and Prionopelta punctulata (Amblyoponinae). We also discuss the intraspecific variation regarding body color for both species and provide the dominant colors for the light and dark forms based on the amount of red, blue and green tones generated from the HEX code.

Colour aberrations are rare conditions in birds that are caused by genetic as well as environmental factors. Among the colour aberrations in birds, albino, leucism, progressive greying, brown, dilution, ino, and melanism are the best known. This report describes an observation of colour aberration in a Spotted Dove (Spilopelia chinensis suratensis) from India. It was recorded in the Deobali Jalah (an IBA site) of Nagaon district, Assam. The recorded individual exhibited a pale plumage with normal eyes and some light brown colour in some of the feathers, indicating this to be a form of dilution. The report also represents the first photographic documentation of colour aberration in Spotted Doves from Brahmaputra Valley of Assam, India. Further research is necessary to comprehend the causes of colour aberration in Spotted Doves. [ABSTRACT FROM AUTHOR]

A robust understanding of an organism's behavioural and ecological characteristics is an integral part of conservation; unfortunately, many of New Zealand's native insect fauna still show a degree of data deficiency in these areas. Predator avoidance behaviours are one such area, and where there are colour morphs in New Zealand native and threatened insects, potential differences in the behaviour of these morphs can often be under investigated. The mountain stone wētā (Hemideina maori) possesses two distinct colour morphs, melanic and yellow, though the reason for this distinction is unclear. This study uses laboratory based assays to compare the behaviour of the morphs, including activity, refuge seeking, cohabitation, emergence and defensive behaviour. We observed emergence and cohabitation regularly, used video recordings to assay activity and refuge seeking behaviours, and measured defensive behaviours by probing individuals until a defensive response was displayed. Differences in all tested behaviours between colour morphs were non-significant; however, there were significant differences in defensive behaviour between sexes. We also discuss how defensive behaviours of H. maori compare with another tree wētā. Overall, the colour morphs in H. maori are similar in their predator responses and there may be a driving factor for melanism other than predation pressure. urn:lsid:zoobank.org:pub:D54E864D-844F-4619-84E6-44BBAC1DE4E5 [ABSTRACT FROM AUTHOR]

For decades, the evolutionary role of melanism in reptiles has been highly debated. According to the thermal melanism hypothesis, melanistic phenotypes should provide thermal advantages, thus positively impacting various biological aspects of these individuals. Nevertheless, these benefits seem to be countered by environmental constraints and predatory pressure. Here, we mapped for the first time the distribution of the melanistic phenotypes in the highly polymorphic asp viper (Vipera aspis). We focused our research effort on the Italian peninsula, where this species reaches its highest level of taxonomic diversity with three currently described subspecies. Furthermore, we investigated via bioclimatic niche modelling, the influence of a wide array of bioclimatic variables on the distribution of melanism in Italian asp vipers. In general, our results seem to support the implications of the thermal melanism hypothesis, highlighting the central influence of mean annual temperature and elevation on the geographic distribution of melanistic V. aspis. At the finest scale, our analyses have highlighted a distinction in bioclimatic niches among the three assessed subspecies. However, further fine-scale investigations are needed in order to exclude the potential influence of latitude and elevation on the observed the intersubspecific bioclimatic niche segregation pattern. [ABSTRACT FROM AUTHOR]

The occurrence of a small specimen of Lepidion guentheri (Giglioli, 1880) (Gadiformes: Moridae) with an unusual dark colouration in the Porcupine Bank is reported. A single specimen of 114.2 mm of total length was caught in 2023 in a bottom trawl at a depth of 1168 m. The specimen was initially identified morphologically and later confirmed by molecular taxonomy using DNA barcoding. Its dark colouration pattern is discussed in the context of the known colouration patterns. Although a complete melanosis is possible, ontogenetic colouration is proposed as the most likely cause. DNA barcoding suggests the presence of Lepidion guentheri in the southern Indian and southwestern Pacific Oceans. [ABSTRACT FROM AUTHOR]

In insects, melanism, a fundamental pigmentation process, is of significant importance in evolutionary biology due to its complex genetic foundation. We investigated the role of the RNA‐binding gene Musashi (msi) in melanism in Laodelphax striatellus, a Hemiptera species. We identified a single L. striatellus msi homolog, Lsmsi, encoding a 357 amino acid protein with 2 RNA recognition motifs. RNA interference‐mediated knockdown of LsMsi resulted in complete body melanism and increased cuticular permeability. Additionally, we found the involvement of G protein‐coupled receptor A42 and tyrosine hydroxylase (Th) in L. striatellus melanism. Knockdown of LsTh lightened the epidermis, showing dehydration signs, while LsA42 knockdown enhanced LsTh expression, leading to melanism. Surprisingly, Lsmsi knockdown decreased both LsA42 and LsTh expression, which was expected to cause whitening but resulted in melanism. Further, we found that Lsmsi influenced downstream genes like phenoloxidase homolog LsPo and dopa decarboxylase (Ddc) homolog LsDdc in the tyrosine‐mediated melanism pathway. Extending to Nilaparvata lugens and Sogatella furcifera, we demonstrated the conserved role of msi in melanism among Delphacidae. Given MSI proteins’ roles in cancer and tumors in vertebrates, our study is the first to link msi in insects to Delphacidae body color melanization via the tyrosine‐mediated pathway, offering fresh perspectives on the genetic basis of insect melanism and msi functions. [ABSTRACT FROM AUTHOR]

Phenotypic plasticity is the ability of an organism to alter its phenotype in response to environmental cues. This can be adaptive if the cues are reliable predictors of impending conditions and the alterations enhance the organism's ability to capitalize on those conditions. However, since traits do not exist in isolation but as part of larger interdependent systems of traits (phenotypic integration), trade‐offs between correlated plastic traits can make phenotypic plasticity non‐ or maladaptive. We examine this problem in the seasonally plastic wing melanism of a pierid (Order Lepidoptera, Family Pieridae) butterfly, Pieris rapae L. Several wing pattern traits are more melanized in colder than in warmer seasons, resulting in effective thermoregulation through solar absorption. However, other wing pattern traits, the spots, are less melanized during colder seasons than in warmer seasons. Although spot plasticity may be adaptive, reduced melanism of these spots could also be explained by resource‐based trade‐offs. Theory predicts that traits involved in resource‐based trade‐offs will be positively correlated when variation among individuals in resource acquisition is greater than variation among individuals in resource allocation strategies, and negatively correlated when variation in allocation is greater than variation in acquisition. Using data from both field studies and laboratory studies that manipulate dietary tyrosine, a melanin precursor, we show that when allocation to thermoregulatory melanism (ventral hindwing, and basal dorsal fore‐ and hindwing "shading") varies substantially this trait is negatively correlated with spot melanism. However, when there is less variation in allocation to thermoregulatory melanism we find these traits to be positively correlated; these findings are consistent with the resource‐based trade‐off hypothesis, which may provide a non‐ or maladaptive hypothesis to explain spot plasticity. We also show that increased dietary tyrosine results in increased spot melanism under some conditions, supporting the more general idea that melanism may involve resource‐based costs. [ABSTRACT FROM AUTHOR]

Animal colour is a highly adaptive phenotypic trait that can respond to several selection pressures, including those facilitated by variations in climate. The thermal melanism hypothesis predicts that for ectotherms, selection for darker phenotypes should be highest in cooler areas because darker pigmentation should provide thermoregulatory advantages. We tested whether intraspecific variation in colour distribution of Cape Cobras (Naja nivea) conforms to this hypothesis using a dataset of ∼800 georeferenced photographs of cobras available from community science platforms. We scored the dorsal colouration of snakes in each photograph and tested for associations between snake colours and climate variables at those locations. Our results provide strong evidence to suggest that temperature and solar radiation are important predictors of N. nivea colour occurrence, whereas elevation and precipitation are not. Overall, darker snakes have a significantly higher probability of occurrence in colder areas with low solar radiation than lighter snakes, which are more likely to occur in hotter areas with more solar radiation. Our study is the first to provide evidence for thermal melanism in a sub-Saharan African snake species, which was made possible by the availability of community science data. [ABSTRACT FROM AUTHOR]

Coloration in wildlife serves numerous biological purposes, including sexual selection signaling, thermoregulation, and camouflage. However, the physical appearance of wildlife also influences the ways in which humans interact with them. Wildlife conservation has largely revolved around humans' propensity to favor charismatic megafauna, but human perceptions of wildlife species extend beyond conservation measures into our everyday interactions with individual wildlife. Our aesthetic appreciation for different species interplays with culture, lore, and the economic interest they carry. As such, one characteristic that may underpin and interact with social drivers of perception is the coloration of a particular individual. We provide case studies illustrating the dynamism in interactions people have with conspicuously colored wildlife – i.e., individuals that vary from their species-typical coloration. We focus on melanism, leucism, and albinism across four species commonly thought of as pests in the United States: coyotes (Canis latrans), eastern gray squirrels (Sciurus carolinensis), white-tailed deer (Odocoileus virginianus), and black-tailed deer (O. hemionus). [ABSTRACT FROM AUTHOR]

Snake venom is an ecologically relevant functional trait directly linked with a snake’s fitness and survival, facilitating predation and defence. Snake venom variation occurs at all taxonomic levels, but the study at the intraspecific level is still in its early stages. The common adder (Vipera berus) exhibits considerable variation in colour phenotypes across its distribution range. Melanistic (fully black) individuals are the subject of myths and fairytales, and in German folklore such ‘hell adders’ are considered more toxic than their normally coloured conspecifics despite any formal investigation. Here, we provide the first comparative analysis of venoms from melanistic and normally coloured common adders. Specifically, we compared the venom profiles by sodium dodecylsulfate polyacrylamide gel electrophoresis and reversed-phase high-performance liquid chromatography and tested the venoms’ protease, phospholipase A2 and cytotoxic activities. Phospholipase A2 activity was similar in both phenotypes, whereas general protease activity was higher in the melanistic venom, which was also more cytotoxic at two concentrations (6.25 and 12.5 µg ml−1). These minor differences between the venoms of melanistic and normally coloured adders are unlikely to be of clinical relevance in the context of human envenomation. In light of our results, the claim that melanistic adders produce more toxic venom than their normally coloured conspecifics appears rooted entirely in folklore.

The variegated toad-headed agama, Phrynocephalus versicolor, lives in the arid landscape of the Chinese Gobi Desert. We analyzed populations from three different locations which vary in substrate color and altitude: Heishankou (HSK), Guazhou County (GZ), and Ejin Banner (EJN). The substrate color is either light-yellow (GZ-y), yellow (EJN-y), or black (HSK-b); the corresponding lizard population colors largely match their substrate in the degree of melanism. We assembled the P. versicolor genome and sequenced over 90 individuals from the three different populations. Genetic divergence between populations corresponds to their geographic distribution. We inferred the genetic relationships among these populations and used selection scans and differential expression to identify genes that show signatures of selection. Slc2a11 and akap12, among other genes, are highly differentiated and may be responsible for pigment adaptation to substrate color in P. versicolor.

On 28th January 2023 at 02:30 PM first author (PC) recorded and photographed the completely black in colour cat species during the jungle safari in the Great Rann of Kutch, Gujarat, India. Based on the photographic evidence we identified the species as Jungle cat (Felis chaus), which was affected by melanism. In this note, we highlighted the importance of color aberration on wild animals in their natural habitats. This is necessary for a better understanding of this phenomenon and its insights into the ecological and physiological implications of this condition considerably affecting animal survival.

Island organisms often evolve phenotypes divergent from their mainland counterparts, providing a useful system for studying adaptation under differential selection. In the white-winged fairywren (Malurus leucopterus), subspecies on two islands have a black nuptial plumage whereas the subspecies on the Australian mainland has a blue nuptial plumage. The black subspecies have a feather nanostructure that could in principle produce a blue structural color, suggesting a blue ancestor. An earlier study proposed independent evolution of melanism on the islands based on the history of subspecies divergence. However, the genetic basis of melanism and the origin of color differentiation in this group are still unknown. Here, we used whole-genome resequencing to investigate the genetic basis of melanism by comparing the blue and black M. leucopterus subspecies to identify highly divergent genomic regions. We identified a well-known pigmentation gene ASIP and four candidate genes that may contribute to feather nanostructure development. Contrary to the prediction of convergent evolution of island melanism, we detected signatures of a selective sweep in genomic regions containing ASIP and SCUBE2 not in the black subspecies but in the blue subspecies, which possesses many derived SNPs in these regions, suggesting that the mainland subspecies has re-evolved a blue plumage from a black ancestor. This proposed re-evolution was likely driven by a preexisting female preference. Our findings provide new insight into the evolution of plumage coloration in island versus continental populations, and, importantly, we identify candidate genes that likely play roles in the development and evolution of feather structural coloration. [ABSTRACT FROM AUTHOR]

Simple Summary: Melanism, or the overexpression of melanin resulting in dark pigmentation, is fairly common among tree squirrels. The mutation that causes melanism has been discovered in two out of twelve species of tree squirrel that are known to have a melanistic phenotype. In this study, we identified the mutation that appears to cause melanism in a third species, Abert's Squirrel (Sciurus aberti). The mutation is a previously unknown mutation apparently unique to Abert's Squirrel, which suggests this mutation evolved independently from the other known mutations. Considering that three separate mutations are now known, it is likely there is a benefit for tree squirrels of having a dark, melanistic coat in certain environments. Melanism is widespread in different taxa and has been hypothesized to provide adaptive benefits in certain environments. Melanism is typically caused by mutations in one of two regulatory genes: the Melanocortin 1 Receptor (MC1R) or the Agouti Signaling Protein (ASIP). Melanism has repeatedly evolved among tree squirrels and their relatives (tribe Sciurini) in at least 12 different species based on our review of the literature. The causal mutations for melanism have been characterized in two species so far. This study examines Abert's Squirrel (Sciurus aberti), which has a melanistic morph whose genetic basis has not yet been established. We sequenced the MC1R and ASIP genes for five wild-type and seven melanistic S. aberti individuals to search for melanism-associated mutations. A novel single base pair mutation in the ASIP gene, unique to S. aberti, was found to be associated with melanism in the species, indicating that melanism in S. aberti evolved independently from other tree squirrels and thus represents an example of convergent evolution. The independent evolution of melanism in this species suggests that there is an adaptive advantage to the melanistic phenotype. The geographic range and habitat of S. aberti suggest possible benefits associated with thermoregulation, post-forest-fire camouflage, or other untested hypotheses. [ABSTRACT FROM AUTHOR]

Speciation is the fundamental process that underlies the diversification of species. Different steps of speciation, such as reproductive isolation or ecological niche separation, can evolve in different orders and over different time scales. The two subspecies of the green whip snake, Hierophis viridiflavus viridiflavus and Hierophis viridiflavus carbonarius , sometimes considered as separate species, are ideal to study speciation because they diverged in isolated glacial refugia. So far, little is known about whether these two subspecies are reproductively isolated from each other. Furthermore, it is unknown whether the common melanism of the subspecies H. v. carbonarius might be genetically encoded. We quantified gene flow along two transects across the contact zone of the two subspecies using double-digest restriction site-associated DNA. Our analyses implicated the existence of two well-defined clades that experience substantial gene flow along a contact zone that is ~300 km wide. We detected a clear association between the genetic assignment and the quantitative extent of melanism within the contact zone, which is likely to be genetically polygenic. Given the level of gene flow, it seems that strong postzygotic reproductive barriers have not evolved. We conclude that the two subspecies represent evolutionarily significant units for conservation and suggest treating them taxonomically as subspecies. [ABSTRACT FROM AUTHOR]

Opisina arenosella (Lepidoptera: Oecophoridae) is a major leaf-feeding pest of palm crops that has invaded several tropical and subtropical countries or regions. Habrobracon hebetor (Hymenoptera: Braconidae) is a parasitoid of O. arenosella larvae whose efficiency in controlling its hosts is inhibited by high temperatures. The body color of this wasp exhibits a plastic response to temperature (melanin fades with increasing temperature). Based on the thermal melanism hypothesis, we proposed that H. hebetor adults with lighter body color would have better biological performance at high temperatures. This paper established the link between the parasitoid's body color phenotype and biological performance. Our results show that exposure to 32°C for more than 3 d during the pupal stage induced almost complete loss of abdominal melanin in H. hebetor adults. At the population level, when adults were held under heat stress (34°C), the percentage of abdominal melanin in the parasitoids was negatively correlated with parasitoid longevity and the number of paralyzed hosts, But, in contrast, melanization was positively correlated with parasitoid fecundity. The yellow-biotype of H. hebetor has higher host control potential in tropical regions. Related aspects of our results also improve understanding the biological significance of plastic body color in insects and provide information on host control by H. hebetor in tropical environments. [ABSTRACT FROM AUTHOR]

We document the presence of bobcats (Lynx rufus) that demonstrate melanism in the Greater Everglades. The South Florida landscape is driven by a myriad of disturbance regimes particularly that of short fire intervals. We monitored 180 camera traps for 3 years and obtained 9503 photographs of bobcats 25 (<0.5%) of these detections included melanistic individuals. Our observations and historical accounts suggest melanism is a phenotype that persists, albeit it at an exceedingly low frequency, in bobcats in the region. While we do not know if the expression of melanism conferred a fitness benefit in our system, the vegetation structure that was characterized by frequently burned uplands and low‐light and densely vegetated swamps produced conditions that may render a benefit from melanism through enhanced crypsis. The investigation of rare phenomenon in ecology is important yet difficult within a given field study, but reporting novel observations, like melanism in bobcats, allows for science to gain insight across studies that would not be otherwise possible. [ABSTRACT FROM AUTHOR]

Aberrant colouration in birds is relatively common but melanism occurs infrequently. We report an observation of a melanistic Razorbill Alca torda attending the nesting colony at Machias Seal Island, Bay of Fundy in 2022 and 2023. This is the third reported occurrence of a melanistic Razorbill and the first in over 100 years. [ABSTRACT FROM AUTHOR]

Avian deformities have been recorded in a variety of bird species all over the world. However, they have not been studied in Nepal, although there are increasing sightings of these deformities. Injuries, genetic mutations, environmental factors, infections, radiation, and other factors can cause deformities. In our study, we collected data from numerous field trips, conversations with bird watchers and experts, and social media posts in Nepal. We reported 24 cases of avian deformities in 16 different bird species across 12 districts in Nepal, suggesting that certain abnormalities persist in a high proportion of previously unstudied birds. We discovered different types of color abnormalities (6 cases of leucism, 3 albinism, 4 partial leucism, 1 brown mutation, 1 melanism, and 3 unidentified color aberration), 5 cases of avian keratin disorder (AKD), and 1 case of both leucism and AKD. The majority of these cases affected corvids and other birds frequently living and nesting near human settlements, indicating that causative agents such as anthropogenic toxicants and environmental degradation could be important contributors. There is a scarcity of research on avian deformities and diseases in Nepal, thus more research on avian abnormalities, such as the pathophysiology of AKD and genetic studies, should be performed. [ABSTRACT FROM AUTHOR]

Melanism is the presence of an excess of dark pigmentation in an animal, which causes a total or partial blackening of the skin. In fish, melanosis has been reported for a few species, indicating that it is not a common aspect and that it more frequently affects limnic species. The capture of a Sebastes oculatus female specimen, with complete melanism, is reported. The individual was captured by hand line, in the town of Isla Pájaro II, northern Chile. Its standard length is 31.5 cm and its total weight is 993 g. The general coloration of the body is dark gray. The fins do not have the orange hue characteristic of the species at their ends. The melanic condition in S. oculatus is very rare, it is the second time that it has been reported for this species, where the expression of a dark color would be beneficial for specimens that inhabit bottoms with little vegetation and between cracks. [ABSTRACT FROM AUTHOR]

Parallel colour/pattern polymorphism has been reported in the three sympatric spittlebug species Philaenus spumarius, P. signatus and Mesoptyelus impictifrons in the Mediterranean region of Türkiye. In our study, the colour phenotypes POP (populi) and TYP (typicus) are shared by all three species, whereas the phenotypes MEL (melanocephalus), PRA (praeustus) and LCE (leucocephalus) were found only in M. impictifrons. MAR (marginellus), FLA (flavicollis) and LOP (leucophthalmus) were found only in P. signatus, and TRI (trilineatus) and LAT (lateralis) were found only in P. spumarius. In combination with previous results, we show that P. spumarius and P. signatus share all eight common phenotypes except for LAT. The genetic basis of this polymorphism is well understood only for P. spumarius, yet the evolutionary strategies governing this phenomenon found in both sympatric and allopatric populations of the three species remain unknown. As the same visible elytral colour/pattern morphs occur in all three species, it will be interesting to investigate the genetic bases of these polymorphisms with further laboratory crossbreeding experiments. [ABSTRACT FROM AUTHOR]

Gentoo Penguin (Pygoscelis papua) is a species that reproduces in Antarctica and sub-Antarctic islands. During 2022 a Gentoo Penguin with an unusual plumage coloration was recorded at Esperanza/Hope Bay, north of the Antarctic Peninsula (63°24′ S, 57°01′ W). The coloring of plumage is achieved by two types of pigments known as carotenoids and melanins. Two different types of melanin (phaeomelanin and eumelanin) are responsible of producing different pigmentation patterns that oscillates between reddish-blackish coloration. The unusual coloration of the penguin was identified as melanism, a genetic condition that causes an excess of melanin pigment in feathers. This particular individual appeared to be in good health and exhibited normal behavior. As far as we know this is the second official report of melanism for the species since the first one in 1997 and it is the first report for the colony. [ABSTRACT FROM AUTHOR]

The evolution of Batesian mimicry – whereby harmless species avoid predation through their resemblance to harmful species – has long intrigued biologists. In rare cases, Batesian mimicry is linked to intraspecific colour variation, in which only some individuals within a population resemble a noxious 'model'. Here, we assess intraspecific colour variation within a widespread New Zealand stonefly, wherein highly melanized individuals of Zelandoperla closely resemble a chemically defended aposematic stonefly, Austroperla cyrene. We assess convergence in the colour pattern of these two species, compare their relative palatability to predators, and use genome‐wide association mapping to assess the genetic basis of this resemblance. Our analysis reveals that melanized Zelandoperla overlap significantly with Austroperla in colour space but are significantly more palatable to predators, implying that they are indeed Batesian mimics. Analysis of 194,773 genome‐wide SNPs reveals an outlier locus (ebony) strongly differentiating melanic versus non‐melanic Zelandoperla. Genotyping of 338 specimens from a single Zelandoperla population indicates that ebony explains nearly 70% of the observed variance in melanism. As ebony has a well‐documented role in insect melanin biosynthesis, our findings indicate this locus has a conserved function across deeply divergent hexapod lineages. Distributional records suggest a link between the occurrence of melanic Zelandoperla and the forested ecosystems where the model Austroperla is abundant, suggesting the potential for adaptive shifts in this system underpinned by environmental change. [ABSTRACT FROM AUTHOR]

The coloration pattern alteration occurs at a low frequency in fish. The excesses of dark pigments in living organisms are known as melanism or melanosis, but a total blackening of the skin is known as hyper melanism or hyper melanosis. Little is known about why the extreme conditions of albinism and melanosis occur among fish. To date, there are no records of melanism for the genus Sebastes. Here, we report the first case of hyper melanosis in rockfish Sebastes oculatus (Patagonian redfish) in the southeastern Pacific Ocean. In 2005, small-scale fishers from Quintay Beach (Valparaiso, Chile) captured a single individual of Patagonian redfish covered with an excess of dark pigmentation. The specimen had a total length of 35.5 cm, and we followed the literature available to determine its morphometric and meristic features. The measurements led us to conclude that the specimen was a black S. oculatus with a rare melanosis condition. Our finding contributes to the knowledge of this species, and we infer that this melanosis case was caused by genetic heritage or some intergenetic hybridization. Still, genetic studies are necessary to confirm this hypothesis. [ABSTRACT FROM AUTHOR]

We conducted genetic and morphological investigations on a snake specimen initially identified as the venomous species Walterinnesia morgani (Mocquard, 1905) from the family Elapidae, primarily based on its dark colouration. However, subsequent genetic analysis revealed a clear affiliation with the family Colubridae, specifically Hemorrhois nummifer (Reuss, 1834), which shares a partially sympatric distribution with the previously mentioned species in Iraq. This discovery represents the first documented record of such a coloured specimen of H. nummifer in Iraq, raising additional questions regarding possible mimicry and the possibility of confusion in species identifications. [ABSTRACT FROM AUTHOR]

We examined the mitochondrial identity of Aegean Natrix natrix moreotica representing different morphotypes, with a focus on new material from Milos and Skyros. We found no correlation between distinct morphotypes and mitochondrial identity. Our results support that grass snake populations are polyphenetic and that southern subspecies, including island populations, show a higher variability than northern ones. [ABSTRACT FROM AUTHOR]

We report the first record of a melanistic individual of the critically endangered Pampa cat (Leopardus munoai), from July 8th, 2021, at 10:45 am (coordinates 30.096288° S; 54.941139° W) in the area of the Brazilian army, known as Campo de Instrução Barão de São Borja (CIBSB), popularly known as Saicã. [ABSTRACT FROM AUTHOR]

According to Gloger's rule, animal colouration is expected to be darker in wetter and warmer climates. Such environmental clines are predicted to occur in colour polymorphic species and to be shaped by selection if colour morphs represent adaptations to different environments. We studied if the distribution of the colour polymorphic tawny owl (Strix aluco) morphs (a pheomelanic brown and a pale grey) across Europe follow the predictions of Gloger's rule and if there is a temporal change in the geographical patterns corresponding to regional variations in climate change. We used data on tawny owl museum skin specimen collections. First, we investigated long‐term spatiotemporal variation in the probability of observing the colour morphs in different climate zones. Second, we studied if the probability of observing the colour morphs was associated with general climatic conditions. Third, we studied if weather fluctuations prior to the finding year of an owl explain colour morph in each climate zone. The brown tawny owl morph was historically more common than the grey morph in every studied climate zone. Over time, the brown morph has become rarer in the temperate and Mediterranean zone, whereas it has first become rarer but then again more common in the boreal zone. Based on general climatic conditions, winter and summer temperatures were positively and negatively associated with the proportion of brown morph, respectively. Winter precipitation was negatively associated with the proportion of brown morph. The effects of 5‐year means of weather on the probability to observe a brown morph differed between climate zones, indicating region‐dependent effect of climate change and weather on tawny owl colouration. To conclude, tawny owl colouration does not explicitly follow Gloger's rule, implying a time and space‐dependent complex system shaped by many factors. We provide novel insights into how the geographic distribution of pheomelanin‐based colour polymorphism is changing. [ABSTRACT FROM AUTHOR]

In this short note we present unique and new records of a marine fish pigmentation abnormalities, including a case of an albino-melanistic fish, combining leucism and melanism, the first record of a leucistic individual of the iconic and critically endangered great hammerhead shark (Sphyrna mokarran), first record of leucistic Almaco jacks (Seriola rivoliana) and the first melanistic giant manta (Mobula birostris) in the north Atlantic. We speculate that these new records of pigmentary abnormalities may be related to significant population declines and isolation of remote populations.