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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]

Intraspecific variation in colour patterns may reflect adaptive responses to local environmental regimes that favour selection of different trade-offs between visual communication, thermoregulation, and anti-predatory functions. Understanding the drivers of colour pattern variation within species can therefore provide valuable insights about adaptation. However, the ecogeographic correlates, and thus the ecological drivers, associated with the segregation of different colour morphs for most reptile species, including snakes, are not well known. Here, we examined differences in environmental niches associated with occurrence records of preserved museum specimens and georeferenced photographic images of common egg-eaters (Dasypeltis scabra) to characterise ecogeographic divergence between typically patterned, patternless, and faintly marked individuals. We gathered 1707 records that we assigned as either patterned, plain, or intermediate morphs. Most records were of patterned individuals, which were widely distributed in southern Africa. Climate niches differed between morphs as plain and intermediate snakes were restricted to high-elevation areas in the Highveld grasslands of South Africa, and woodland-dominated areas in the central and eastern parts of both Zambia and Zimbabwe, but there were no areas where only plain or intermediate snakes occurred in isolation from patterned snakes. Environmental niche modelling predicted minimal areas suitable for co-habitation of colour morphs. We speculate that plain or weakly-marked colour patterns likely developed as an adaptation to increase camouflage ability in open areas in grassland and certain woodland habitats. [ABSTRACT FROM AUTHOR]

One of the most evident sources of phenotypic diversity within a population is colouration, as exemplified by colour polymorphism. This is relevant to a greater extent in animals with visually biased sensory systems. There is substantial evidence suggesting that different colour morphs can access a broader range of habitats or niches, leading to larger geographic range sizes. However, this hypothesis has been tested in few lineages, comprising species where colour is likely to be involved in sexual selection. Furthermore, some available evidence considers geographical variation as polymorphism, thus limiting our comprehension of how sympatric colour polymorphism can influence a species' geographic range. Through an extensive systematic literature review and a comparative analysis, we examined the relationship between colour polymorphism and range size or niche breadth in web-building spiders. We identified 140 colour polymorphic spider species, belonging mainly to the families Araneidae and Theridiidae. We found no evidence that colour polymorphic species differ significantly from non-polymorphic species in terms of range size and niche breadth, after accounting for phylogenetic relationships and other covariates. However, we did observe that colour polymorphic species were more likely to be found on islands compared to non-polymorphic species. Overall, our results indicate that the association between colour polymorphism and geographic range size may not exist among web-building spiders, or be as pronounced as in other lineages. This suggests that the strength of the association between colour polymorphism and ecological success might depend on the ecological role that colouration plays in each clade. [ABSTRACT FROM AUTHOR]

Understanding the maintenance of genetic variation in reproductive strategies and polymorphisms in the wild requires a comprehensive examination of the complex interactions between genetic basis, behaviour and environmental factors.We tested the association between three colour genotypes and variation in female pheromone signalling and male antennal morphology in the wood tiger moth (Arctia plantaginis). These moths have genetically determined white (WW, Wy) and yellow (yy) hindwings that are linked to mating success and fitness, with heterozygotes (Wy) having an advantage. We hypothesized that attractiveness and reproductive success are correlated, with Wy females being more attractive than the other two genotypes which could contribute to maintaining the polymorphism.Female attractiveness was tested by baiting traps with females of the three colour genotypes both in low‐ (i.e. field set‐up) and in high‐population density (i.e. large enclosure set‐up). Male's ability to reach females was correlated to their own colour genotype and antennal morphology (length, area and lamellae count).Contrary to our prediction, morph‐related reproductive success and attractiveness were not correlated. Heavier Wy females attracted a lower proportion of males compared to WW and yy females. Specifically, an increase in weight corresponded to a decreased Wy but increased yy female attractiveness. yy females were generally more attractive than others likely due to earlier pheromone release. In males, lamellae count and genetic colour morph were linked to the male's ability to locate females. Furthermore, male traits affected their ability to reach females in a context‐specific way. Males with denser antennae (i.e. higher lamellae count) and white males reached the females faster than yellows in the enclosure, while yellow males located females faster than whites in the field.Our results indicate that higher yy female attractiveness was likely affected by the combined effect of early pheromone release, female weight and higher population density. Males' searching success was affected by morph‐specific behavioural strategies and local population density. Ultimately, the combined effect of genotype‐related pheromone signalling strategies of females together with environment‐dependent male behaviour affect male response and potentially contribute to maintaining variation in fitness‐related traits. [ABSTRACT FROM AUTHOR]

Colour polymorphic species often exhibit variation in morphology, physiology, and behaviour among morphs. In particular, dominance status may be signalled by the interaction between behaviour and colour morph. Behavioural traits associated with dominance include boldness, exploration, and aggression, which influence access to preferred habitat, territorial defence, and mate acquisition. In ectotherms, the social structure associated with morphs may result in the exploitation of structural niches differing in thermal quality. Hence, social interactions among morphs may generate concordant variation in thermal preference and environmental temperature. However, few studies have assessed thermal preference variation in colour polymorphic species and its covariation with behaviour. Doing so can provide insight into niche specialization and the maintenance of colour polymorphism in populations. Here, we investigated the patterns of covariation in boldness behaviour, exploratory behaviour, and thermal preference in the tree lizard, Urosaurus ornatus. We assessed trait variation between territorial and non‐territorial male morphs and between orange and yellow female morphs. Boldness and exploratory behaviour were repeatable in male U. ornatus and bolder individuals were significantly more likely to incur tail loss, a potential consequence of bold behaviour. Territorial male morphs were significantly bolder and more exploratory and preferred higher body temperatures with a narrower Tset than non‐territorial morphs. Female morphs did not vary in behavioural or thermal traits. This study highlights behavioural mechanisms that underly ecological niche segregation and variable habitat use between morphs in a colour polymorphic species. [ABSTRACT FROM AUTHOR]

Sensory drive can lead to the evolution of signals that are optimized to the environment in which they are perceived. However, when environmental conditions change, the interactions between signal, environment, and receiver may also shift, leading to the evolution of a new signal optimum or more categorical shifts in sexual signals (gains or losses). We evaluated how visual systems have evolved following a change in environment and male signal, and whether visual system divergence contributes to reproductive isolation between ancestral and derived types in red and black morphs of Pacific Northwest freshwater threespine stickleback. We found that opsin sequence was tuned to enhance the perceived contrast of black fish on a red-shifted light background, whereas opsin expression was not. Further, we found no evidence for homotypic preferences or assortative mating between colour morphs; males of both morphs were equally successful in no-choice mating contexts, perhaps because black males are more vigorous courters. Together, our results suggest that habitat transitions in black stickleback have led to a shift in sensory-drive dynamics with some aspects of the visual system and behaviour evolving in response to other factors (foraging or predation) or lagging behind the evolution of opsin sequences in red-shifted environments. [ABSTRACT FROM AUTHOR]

How colour polymorphisms are maintained in natural populations constitutes a key subject of study for evolutionary ecologists. One of the mechanisms that has been put forward to explain this phenomenon is negative frequency-dependent selection, which can be caused by different mechanisms. Among these mechanisms is mate choice, or the selection as a potential mate of the rare or dissimilar colour morph by the choosy sex of a given species. In the context of colour polymorphism, mate choice predicts the occurrence of a negative assortative mating pattern, whereby different colour morphs mate more often than expected by chance alone. However, negative assortative mating can also result from other mechanisms, making it, at best, a fallible indicator of a mate choice-driven negative frequency-dependent selection. For this reason, experimental evidence explicitly connecting such a mating pattern to mate choice is necessary to claim that a particular colour polymorphism is being maintained by negative frequency-dependent selection. Here we present experimental evidence backing this relationship for the colour polymorphic marine gastropod Littorina saxatilis from the Ría de Vigo (NW Iberian Peninsula), although how specifically these organisms choose their mates remains unclear. This calls for further experimental efforts to clarify this issue and its relationship to the maintenance of colour polymorphism in L. saxatilis. [ABSTRACT FROM AUTHOR]

Colour signals play pivotal roles in different communication systems, and the evolution of these characters has been associated with behavioural ecology, integumentary production processes and perceptual mechanisms of the species involved. Here, we present the first insight into the molecular and histological basis of skin colour polymorphism within a miniaturized species of pumpkin toadlet, potentially representing the lowest size threshold for colour polytypism in tetrapods. Brachycephalus actaeus exhibits a coloration ranging from cryptic green to conspicuous orange skin, and our findings suggest that colour morphs differ in their capability to be detected by potential predators. We also found that the distribution and abundance of chromatophores are variable in the different colour morphs. The expression pattern of coloration related genes was predominantly associated with melanin synthesis (including dct, edn1, mlana, oca2, pmel, slc24a5, tyrp1 and wnt9a). Up‐regulation of melanin genes in grey, green and brown skin was associated with higher melanophore abundance than in orange skin, where xanthophores predominate. Our findings provide a significant foundation for comparing and understanding the diverse pathways that contribute to the evolution of pigment production in the skin of amphibians. [ABSTRACT FROM AUTHOR]

Trait polymorphisms can vary across different contexts of selection and be maintained through trade-offs between these contexts. For example, colour polymorphic variants may represent alternative strategies optimizing crypsis or thermoregulation in different populations. Here we use visual modelling to test the conspicuousness of different colour pattern morphs in males and females of an Australian lizard, Lampropholis delicata , to predators and conspecifics. We further assess differences in reflectance, microhabitat selection, and mate preference to determine the functional role of the polymorphism and explain its variable distribution across latitude and the sexes. Plain morphs are more conspicuous than striped morphs in both bird and lizard visual models, suggesting predation selection, and habitat structure varies among sex-morph types, but we find no difference in microhabitat selection or mate preference based on colour. We suggest that a combination of spatially varying selection, habitat preference, and context-specific behaviour may be necessary to explain spatial patterns of colour morph frequencies. [ABSTRACT FROM AUTHOR]

Geographical barriers like mountain ranges impede genetic exchange among populations, promoting diversification. The effectiveness of these barriers in limiting gene flow varies between lineages due to each species' dispersal modes and capacities. Our understanding of how the Andes orogeny contributes to species diversification comes from well‐studied vertebrates and a few arthropods and plants, neglecting organisms unable to fly or walk long distances. Some arachnids, such as Gasteracantha cancriformis, have been hypothesized to disperse long distances via ballooning (i.e. using their silk to interact with the wind). Yet, we do not know how the environment and geography shape its genetic diversity. Therefore, we tested whether the Andes contributed to the diversification of G. cancriformis acting as an absolute or semi‐permeable barrier to genetic connectivity between populations of this spider at opposite sides of the mountain range. We sampled thousands of loci across the distribution of the species and implemented population genetics, phylogenetic, and landscape genetic analyses. We identified two genetically distinct groups structured by the Central Andes, and a third less structured group in the Northern Andes that shares ancestry with the previous two. This structure is largely explained by the altitude along the Andes, which decreases in some regions, possibly facilitating cross‐Andean dispersal and gene flow. Our findings support that altitude in the Andes plays a major role in structuring populations in South America, but the strength of this barrier can be overcome by organisms with long‐distance dispersal modes together with altitudinal depressions. [ABSTRACT FROM AUTHOR]

Genetic diversity within a species can be shaped by abiotic factors, such as climate and geography. We aimed to ascertain the relative importance of these two abiotic factors to Indrella ampulla , a monotypic snail species from the Western Ghats, India, that has three colour morphs with some overlapping distributions. We also wanted to investigate whether these colour morphs represent divergent lineages or incipient species. We sequenced one nuclear and two mitochondrial genes from 32 individuals of I. ampulla. We used phylogenetic, population genetic, and niche modelling tools to address these questions. The results suggested that the colour morphs were not reciprocally monophyletic and exhibited considerable niche overlap, suggesting that they cannot be considered as incipient species. Furthermore, the results showed that the impact of palaeoclimatic oscillations in shaping the genetic diversity of this species cannot be determined conclusively. The Palghat Gap seems to have shaped the genetic diversity in this group to a certain degree. The colour morph distributed south of the Palghat Gap did not show admixture and exhibited the least amount of niche overlap with the other morphs. The geography of the landscape seems to have played a prominent role in shaping genetic diversity in this species. [ABSTRACT FROM AUTHOR]

The maintenance of polymorphisms often depends on multiple selective forces, but less is known on the role of stochastic or historical processes in maintaining variation. The common wall lizard (Podarcis muralis) is a colour polymorphic species in which local colour morph frequencies are thought to be modulated by natural and sexual selection. Here, we used genome‐wide single‐nucleotide polymorphism data to investigate the relationships between morph composition and population biogeography at a regional scale, by comparing morph composition with patterns of genetic variation of 54 populations sampled across the Pyrenees. We found that genetic divergence was explained by geographic distance but not by environmental features. Differences in morph composition were associated with genetic and environmental differentiation, as well as differences in sex ratio. Thus, variation in colour morph frequencies could have arisen via historical events and/or differences in the permeability to gene flow, possibly shaped by the complex topography and environment. In agreement with this hypothesis, colour morph diversity was positively correlated with genetic diversity and rates of gene flow and inversely correlated with the likelihood of the occurrence of bottlenecks. Concurrently, we did not find conclusive evidence for selection in the two colour loci. As an illustration of these effects, we observed that populations with higher proportions of the rarer yellow and yellow‐orange morphs had higher genetic diversity. Our results suggest that processes involving a decay in overall genetic diversity, such as reduced gene flow and/or bottleneck events have an important role in shaping population‐specific morph composition via non‐selective processes. [ABSTRACT FROM AUTHOR]

Animals can use different cues to memorise food resources, which can be broadly divided into spatial and feature cues. Differences in species-specific preferences for spatial or feature cues has been historically linked to their reliance on spatial information (food-caching and migratory species prefer spatial cues), but more recently, attention has shifted to procedural differences largely affecting the salience of cues. Here, we investigated cue preferences in the colour-polymorphic Gouldian Finch to test a range of hypotheses. Birds were trained to find food either in a white or coloured feeder always positioned in the same location. In experimental trials, feeders were swapped, dissociating the feature and the spatial cue from the feature cue rewarded. Similar numbers of birds preferred the feature or the spatial cue in the first experimental trial. Preferences were not affected by head colour morph, sex or age group. However, birds with a spatial preference changed their choices over time, resulting in a significant number of birds choosing the feature cue at the end of the experiment. These results indicate that Gouldian Finches have individual preferences for one cue type or the other but can change their preference flexibly depending on the salience of the cue.

Colour polymorphisms have long served as model systems in evolutionary studies and continue to inform about processes involved in the origin and dynamics of biodiversity. Modern sequencing tools allow for evaluating whether phenotypic differences between morphs reflect genetic differentiation rather than developmental plasticity, and for investigating whether polymorphisms represent intermediate stages of diversification towards speciation. We investigated phenotypic and genetic differentiation between two colour morphs of the butterfly Fabriciana adippe using a combination of ddRAD‐sequencing and comparisons of body size, colour patterns and optical properties of bright wing spots. The silvery‐spotted adippe form had larger and darker wings and reflected UV light, while the yellow cleodoxa form displayed more green scales and reflected very little UV, showcasing that they constitute distinct and alternative integrated phenotypes. Genomic analyses revealed genetic structuring according to source population, and to colour morph, suggesting that the phenotypic differentiation reflects evolutionary modifications. We report 17 outlier loci associated with colour morph, including ultraviolet‐sensitive visual pigment (UVRh1), which is associated with intraspecific communication and mate choice in butterflies. Together with the demonstration that the wings of the adippe (but essentially not the cleodoxa) morph reflect UV light, that UV reflectance is higher in females than males and that morphs differ in wing size, this suggests that these colour morphs might represent genetically integrated phenotypes, possibly adapted to different microhabitats. We propose that non‐random mating might contribute to the differentiation and maintenance of the polymorphism. [ABSTRACT FROM AUTHOR]

The persistence of non-neutral trait polymorphism is enigmatic because stabilizing selection is expected to deplete variation. In cryptically coloured prey, negative frequency-dependent selection due to search image formation by predators has been proposed to favour rare variants, promoting polymorphism. However, in a heterogeneous environment, locally varying disruptive selection favours patch type-specific optima, resulting in spatial segregation of colour variants. Here, we address whether negative frequency-dependent selection can overcome selection posed by habitat heterogeneity to promote local polymorphism using an individual-based model. In addition, we compare how prey and predator mobility may modify the outcome. Our model revealed that frequency-dependent predation could strongly promote local prey polymorphism, but only when differences between morphs in patch-specific fitness were small. The effect of frequency-dependent predation depended on the predator adjustment of search image and was hampered by the prey population structure. Gene flow due to prey movement counteracted local selection, promoted local polymorphism to some extent, and relaxed the conditions for polymorphism due to frequency-dependent predation. Importantly, abrupt spatial changes in morph frequencies decreased the probability that mobile frequency-dependent predators could maintain local prey polymorphism. Overall, our study suggests that in a spatially heterogeneous environment, negative frequency-dependent selection may help maintain local polymorphism but only under a limited range of conditions. [ABSTRACT FROM AUTHOR]

Dendropsophus molitor is a hylid frog endemic to the Eastern Cordillera of the Colombian Andes, where it exhibits extensive geographic variation in size and colour pattern. Previous multivariate analyses of acoustic and genetic data suggested that northern and southern populations of D. molitor were distinct lineages, and consequently, the northern populations were described as Dendropsophus luddeckei. In this study, we conducted morphometric and genetic analyses of populations of D. molitor and D. luddeckei to test the validity of this recent taxonomic split. We sequenced the mitochondrial genes 12S, 16S, and COI , and the nuclear marker POMC , and also tested whether variation in the MC1R gene was associated with colour polymorphism in these frogs. Phylogenetic analyses recovered D. molitor and D. luddeckei as polyphyletic and species delimitation tests failed to recover them as separate lineages. Genetic differentiation between populations was mostly explained by high intra- and interpopulation variation in the absence of a north-south split, and we found no differences in morphometry between northern and southern populations. In addition, the coding region of MC1R is not associated with colour polymorphism. Thus, multiple lines of evidence suggest that D. luddeckei is not a valid species and D. molitor should be considered a single species. Our study highlights the danger of taxonomic inflation in the face of limited geographic sampling and a lack of clear diagnostic characters. [ABSTRACT FROM AUTHOR]

Simple Summary: Remembering food resources is important for survival. Animals differ in their strategies to remember resources; some use spatial information, and others resource-specific information (colour, shape). Which strategy they use depends in part on their way of life (food-caching species and migratory species prefer spatial information), but is also affected by the salience of the information. Here, we investigated the strategy used in the colour-polymorphic Gouldian Finch by offering spatial and object (feature) cues. Birds were trained to find food either in a white or coloured feeder always positioned in the same location. In experimental trials, feeders were swapped, dissociating the feature and the spatial cues from the feature cue rewarded. Similar numbers of birds preferred the feature or the spatial cue in the first experimental trial, which was not affected by head colour morph, sex or age. However, birds with a spatial preference changed their choices over time, resulting in most birds choosing the feature cue at the end of the experiment. These results indicate that Gouldian Finches have individual preferences for one strategy or the other but can change their preference flexibly depending on the salience of the cue. Animals can use different cues to memorise food resources, which can be broadly divided into spatial and feature cues. Differences in species-specific preferences for spatial or feature cues has been historically linked to their reliance on spatial information (food-caching and migratory species prefer spatial cues), but more recently, attention has shifted to procedural differences largely affecting the salience of cues. Here, we investigated cue preferences in the colour-polymorphic Gouldian Finch to test a range of hypotheses. Birds were trained to find food either in a white or coloured feeder always positioned in the same location. In experimental trials, feeders were swapped, dissociating the feature and the spatial cue from the feature cue rewarded. Similar numbers of birds preferred the feature or the spatial cue in the first experimental trial. Preferences were not affected by head colour morph, sex or age group. However, birds with a spatial preference changed their choices over time, resulting in a significant number of birds choosing the feature cue at the end of the experiment. These results indicate that Gouldian Finches have individual preferences for one cue type or the other but can change their preference flexibly depending on the salience of the cue. [ABSTRACT FROM AUTHOR]

Artificial light at night (ALAN) disrupts biological processes across taxa and at all levels of organisation. Despite growing interest in this globally pervasive sensory pollutant, its impact on colour-guided processes remains largely unexplored. This is especially concerning given the rapid transition in recent years away from narrow-spectrum lighting and towards broad-spectrum options such as white LEDs, which are rich in the short wavelengths of light to which many taxa are particularly sensitive. Camouflage is particularly likely to be disrupted by broader spectra of ALAN due to changes in conspicuousness in background matching prey, which may alter prey recognition in visually guided predators. We simulated natural intensities of moonlight with and without ALAN, using both broad-spectrum (‘white’) ALAN and ALAN filtered to remove the characteristic short (blue) wavelength peak of broad-spectrum LEDs to test whether filtering might mitigate their effects. We tested how exposure to these light treatments impacted predator-prey interactions, using the intertidal crab Carcinus maenas and contrasting colour morphs of the colour-polymorphic snail Littorina obtusata as a model system. Exposure to broad-spectrum ALAN reduced overall predation and reversed the pattern of colour-based prey selection observed under control conditions. Snails were 55 % less likely to be attacked under broad-spectrum ALAN than in control conditions, with likelihood decreasing over 70 % for yellow snails. Yellow snails were over 26 % more likely to be attacked than brown ones under control conditions, but brown snails were over 40 % more likely to be attacked than yellow ones under broad-spectrum ALAN. Exposure to filtered ALAN removed any significant colour-based difference in prey recognition. Our results demonstrate that spectral composition is a crucial aspect of ALAN as a sensory pollutant, capable of instigating profound changes in predator-prey interactions that could drive changes in population demography and increase morphological homogeneity in species that depend on colour polymorphism for camouflage.

Artificial light at night (ALAN) disrupts biological processes across taxa and at all levels of organisation. Despite growing interest in this globally pervasive sensory pollutant, its impact on colour-guided processes remains largely unexplored. This is especially concerning given the rapid transition in recent years away from narrow-spectrum lighting and towards broad-spectrum options such as white LEDs, which are rich in the short wavelengths of light to which many taxa are particularly sensitive. Camouflage is particularly likely to be disrupted by broader spectra of ALAN due to changes in conspicuousness in background matching prey, which may alter prey recognition in visually guided predators. We simulated natural intensities of moonlight with and without ALAN, using both broad-spectrum ('white') ALAN and ALAN filtered to remove the characteristic short (blue) wavelength peak of broad-spectrum LEDs to test whether filtering might mitigate their effects. We tested how exposure to these light treatments impacted predator-prey interactions, using the intertidal crab Carcinus maenas and contrasting colour morphs of the colour-polymorphic snail Littorina obtusata as a model system. Exposure to broad-spectrum ALAN reduced overall predation and reversed the pattern of colour-based prey selection observed under control conditions. Snails were 55 % less likely to be attacked under broad-spectrum ALAN than in control conditions, with likelihood decreasing over 70 % for yellow snails. Yellow snails were over 26 % more likely to be attacked than brown ones under control conditions, but brown snails were over 40 % more likely to be attacked than yellow ones under broad-spectrum ALAN. Exposure to filtered ALAN removed any significant colour-based difference in prey recognition. Our results demonstrate that spectral composition is a crucial aspect of ALAN as a sensory pollutant, capable of instigating profound changes in predator-prey interactions that could drive changes in population demography and increase morphological homogeneity in species that depend on colour polymorphism for camouflage. [ABSTRACT FROM AUTHOR]

Unusual plumage colours are of interest for environmental and evolutionary questions. This brief article reappraised information on male western capercaillies Tetrao urogallus individuals with atypical white feathers. It was inspired by a casual observation of T. u. aquitanicus in the Pyrenees. The presence of colour aberrations has been reported for several body parts in male western capercaillies. Updated quantifications of this phenomenon and the understanding of its causal factors remain pending for this species. Monitoring individual variability in plumage in tetraonids could contribute to assessing potential signs of population deterioration in species that are currently faced with population and habitat fragmentation and subject to climate change.

The niche divergence hypothesis proposes that the evolution and maintenance of colour polymorphism is based on a mechanism of disruptive selection. In a trophic context, the hypothesis predicts that individuals differing in colour vary in their trophic niche, either because they differ in foraging efficiency or feed in different habitats. A major evolutionary conundrum is how these expectations are affected by variation in trophic quality. Using an owl species with colour plumage polymorphism, the Eurasian scops owl Otus scops, we examined diet and habitat segregation during reproduction in relation to plumage colouration and trophic quality. Intensive sampling revealed that trophic quality for scops owls (i.e. abundance of grasshoppers and locusts) varied more among territories than between years, but scops owls did not segregate among territories of different quality by their colouration. However, we found that sex, plumage colouration and territory differences in trophic quality explained differences in the degree of dietary specialization. Brownish males delivered a higher diversity of prey to the nest than greyish ones in high trophic quality territories. We also found that the more diverse the diet provided by males, the heavier the owlets at fledging. Our study provides evidence for a different sensitivity to trophic quality of the colour morphs with potential fitness consequences in scops owls. We highlight the importance of studying the mechanisms leading to the persistence of colour polymorphism in patchy environments, since segregation may pass otherwise unnoticed if only habitats or years with similar conditions are considered. [ABSTRACT FROM AUTHOR]

Colour has been hypothesized to play a crucial role in prey capture for sit-and-wait predators that rely on visual cues to deceive their prey. Prey capture success has been directly linked to colouration in spiders; however, evidence so far focuses mostly on dorsal colouration, excluding ventral patterns that are visible to prey and may be relevant for prey attraction. Here, we explored whether the dorsal and ventral colouration of a colour polymorphic spider is associated with light environment and prey capture success. We quantified the number of prey captured across three dorsal (black, white, and yellow) and two ventral (black and a mosaic yellow/orange pattern) morphs of Gasteracantha cancriformis, considering light intensity on dorsal and ventral sides. We found that spiders capture more prey in low light environments, and that individuals often expose their dorsal colouration towards low light levels. We did not find significant differences in prey capture rate between morphs dorsally or ventrally. These results indicate that how and where spiders position their web can be more important for prey capture than colouration. Alternative hypotheses such as aposematism, camouflage and thermoregulation deserve more attention in future studies that aim to understand the role of colouration in spiders and the factors causing spider colour polymorphisms. [ABSTRACT FROM AUTHOR]

Abstract For many species, the ability to rapidly adapt to changes in seasonality is essential for long‐term survival. In the Arctic, seasonal moulting is a key life‐history event that provides year‐round camouflage and thermal protection. However, increased climatic variability of seasonal events can lead to phenological mismatch. In this study, we investigated whether winter‐white (white morph) and winter‐brown (blue morph) Arctic foxes (Vulpes lagopus) could adjust their winter‐to‐summer moult to match local environmental conditions. We used camera trap images spanning an eight‐year period to quantify the timing and rate of fur change in a polymorphic subpopulation in south‐central Norway. Seasonal snow cover duration and temperature governed the phenology of the spring moult. We observed a later onset and longer moulting duration with decreasing temperature and longer snow season. Additionally, white foxes moulted earlier than blue in years with shorter periods of snow cover and warmer temperatures. These results suggest that phenotypic plasticity allows Arctic foxes to modulate the timing and rate of their spring moult as snow conditions and temperatures fluctuate. With the Arctic warming at an unprecedented rate, understanding the capacity of polar species to physiologically adapt to a changing environment is urgently needed in order to develop adaptive conservation efforts. Moreover, we provide the first evidence for variations in the moulting phenology of blue and white Arctic foxes. Our study underlines the different intraspecific selective pressures that can exist in populations where several morphs co‐occur, and illustrates the importance of integrating morph‐based differences in future management strategies of such polymorphic species.

Animals adapt to their environments in the course of evolution. One effective approach to elucidate mechanisms of adaptive evolution is to compare closely related species with model organisms in which knowledge of the molecular and physiological bases of various traits has been accumulated. Drosophila elegans and its close relatives, belonging to the same species group as the model organism D. melanogaster, exhibit various unique characteristics such as flower-breeding habit, courtship display, territoriality, sexual dimorphism, and colour polymorphism. Their ease of culturing and availability of genomic information makes them a useful model for understanding mechanisms of adaptive evolution. Here, we review the morphology, distribution, and phylogenetic relationships of D. elegans and related species, as well as their characteristic flower-dependent biology, food habits, and life-history traits. We also describe their unique mating and territorial behaviours and note their distinctive karyotype and the genetic mechanisms of morphological diversity that have recently been revealed.

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]

A comprehensive updated review of published literature on xanthochromic malpigmentation in wild marine fishes is provided for the first time, with 68 species reported, including seven elasmobranchs and 61 teleosts. The revision highlights the difficulty in separating similar natural colourings from abnormal ones, the presence of some probably misidentified species and the higher occurrence of this phenomenon in some taxonomic groups. The capture of a specimen of the sharpsnout seabream Diplodus puntazzo with abnormal skin coloration is reported. The specimen was caught in northern Spain (Galician waters, North-eastern Atlantic) in 2022 with gillnets. The general yellow-orange pigmentation, lead us to consider the specimen as xanthochromic. This is the first case of xanthism in Diplodus puntazzo and the third record of this colour aberration in the family Sparidae. The identification of the specimen was made based on morphological characters and confirmed by DNA barcoding. A description of the anomalous compared to normal colouration was also carried out. [ABSTRACT FROM AUTHOR]

For many species, the ability to rapidly adapt to changes in seasonality is essential for long‐term survival. In the Arctic, seasonal moulting is a key life‐history event that provides year‐round camouflage and thermal protection. However, increased climatic variability of seasonal events can lead to phenological mismatch. In this study, we investigated whether winter‐white (white morph) and winter‐brown (blue morph) Arctic foxes (Vulpes lagopus) could adjust their winter‐to‐summer moult to match local environmental conditions. We used camera trap images spanning an eight‐year period to quantify the timing and rate of fur change in a polymorphic subpopulation in south‐central Norway. Seasonal snow cover duration and temperature governed the phenology of the spring moult. We observed a later onset and longer moulting duration with decreasing temperature and longer snow season. Additionally, white foxes moulted earlier than blue in years with shorter periods of snow cover and warmer temperatures. These results suggest that phenotypic plasticity allows Arctic foxes to modulate the timing and rate of their spring moult as snow conditions and temperatures fluctuate. With the Arctic warming at an unprecedented rate, understanding the capacity of polar species to physiologically adapt to a changing environment is urgently needed in order to develop adaptive conservation efforts. Moreover, we provide the first evidence for variations in the moulting phenology of blue and white Arctic foxes. Our study underlines the different intraspecific selective pressures that can exist in populations where several morphs co‐occur, and illustrates the importance of integrating morph‐based differences in future management strategies of such polymorphic species. [ABSTRACT FROM AUTHOR]

In Lepidoptera, as an explanation for darker phenotypes occurring in colder areas, wing melanism has been proposed to increase solar thermal gain. Alternatively, trade-offs with aposematic signalling and ultraviolet protection have been proposed as explanations for variation in melanism. To investigate the roles of temperature, humidity, solar radiation and predation in driving melanism in the Ranchman's tiger moth (Arctia virginalis), we characterized wing melanism in 23 populations across the range. We also conducted predation experiments using artificial moths and carried out genetic analyses to examine population structure and to test whether wing coloration was hereditary. We found that wing melanism was positively associated with mean temperature during the flight season, which was the best predictor of melanism rates. Wing melanism also exhibited a negative association with humidity and a weak positive association with insolation. We also found two loci weakly associated with wing melanism and showed that melanism is likely to be highly hereditary but not closely associated with population differentiation. Our results contrast with previous findings that melanism is associated with colder conditions and higher predation risk and suggest that humidity and protection against ultraviolet radiation are potential drivers of variation in wing melanism that have been overlooked. [ABSTRACT FROM AUTHOR]

Simple Summary: Authentic species-level identification is key to many fields of entomology, especially insect pest management and biosecurity. Bamboo, known as "Poor Man's Timber" and "Green Gold", is one of the fastest growing plants on earth. Bamboo and food grain crops (rice and wheat, for example) belong to the same family (Poaceae), so there is a chance of host shift because of global climate change and extensive cultivation. In the present study, the colour polymorphism of the bamboo-feeding leafhopper Mukaria splendida is highlighted, along with additional geographical distribution records. The integration of the morpho-molecular data confirmed that all the colour morphs belonged to the same species, M. splendida. The leafhopper species, Mukaria splendida Distant, is economically important due to itsstatus as a pest on bamboo and was recently reported to bea vector for phytoplasmal disease. Morphological identification is often difficult and requires a high level of taxonomic expertise, with misidentifications causing problematic false-positive/negative results. In this paper, colour polymorphism was recorded in the bamboo-feedingleafhopper M. splendida (Distant, 1908), which is a major insect pest in the bamboo ecosystem based on explorations conducted in different locations of India. Ten morphs were identified for each sex of M. splendida Distant based on the colour pattern on the pronotum and forewings. However, in view of the economic importance of the species, the morphological studies were integrated with the molecular data for the accurate identification of the species. The morphological characteristics and sequence results of the amplified product of the mitochondrial cytochrome oxidase subunit I (mtCOI) gene confirmed that all the morphs were M. splendida and the pairwise distance matrix showed a negligible genetic distance in the COI mtDNA gene. Simulated future predictions, along with detailed notes on the colour polymorphic forms with illustrations, and additional distribution records as well as thebiology of M. splendida were discussed in light of the available literature, all of which will aid the authentic identification of this species. [ABSTRACT FROM AUTHOR]

Categorizing individuals into discrete forms in colour polymorphic species can overlook more subtle patterns in coloration that can be of functional significance. Thus, quantifying inter‐individual variation in these species at both within‐ and between‐morph levels is critical to understand the evolution of colour polymorphisms. Here we present analyses of inter‐individual colour variation in the Reunion grey white‐eye (Zosterops borbonicus), a colour polymorphic wild bird endemic to the island of Reunion in which all highland populations contain two sympatric colour morphs, with birds showing predominantly grey or brown plumage, respectively. We first quantified colour variation across multiple body areas by using a continuous plumage colour score to assess variation in brown‐grey coloration as well as smaller scale variation in light patches. To examine the possible causes of among‐individual variation, we tested if colour variation in plumage component elements could be explained by genotypes at two markers near a major‐effect locus previously related to back coloration in this species, and by other factors such as age, sex and body condition. Overall, grey‐brown coloration was largely determined by genetic factors and was best described by three distinct clusters that were associated to genotypic classes (homozygotes and heterozygote), with no effect of age or sex, whereas variation in smaller light patches was primarily related to age and sex. Our results highlight the importance of characterizing subtle plumage variation beyond morph categories that are readily observable since multiple patterns of colour variation may be driven by different mechanisms, have different functions and will likely respond in different ways to selection. [ABSTRACT FROM AUTHOR]

Differential predation on species with intraspecific colour variation has been explored in various systems and is often implicated as the driving force behind colour polymorphism maintenance.Here, investigation done on whether predation contributes to the maintenance of extensive colour variation in the Neotropical tortoise beetle, Chelymorpha alternans (Chrysomelidae). Recorded predation rates on different colour pattern phenotypes by three common, generalist invertebrate predators, and identified potential chemical signals of unpalatability.Predaceious mantids (Orthoptera, Mantidae) consumed no beetles, regardless of phenotype, whereas the giant orb‐weaving spider (Trichonephila clavipes; Araneidae) consumed all three beetle phenotypes. The carton‐nest ant, Azteca chartifex (Formicidae), displayed differential predation; the rufipennis phenotype of C. alternans was sometimes consumed, the metallic phenotype was never consumed, and the veraguensis phenotype was consumed in the first three encounters and subsequently discarded, suggesting a learned avoidance behaviour.Using gas chromatography–mass spectrometry, it was determined that cuticular hydrocarbon profiles were similar between the metallic and militaris‐a phenotypes. The rufipennis phenotype showed pronounced differences and displayed the greatest among‐individual variation in elytral cuticular profiles.Between‐phenotype variation in chemical cues, and differences in how predators receive those cues, may mediate predator response, and play a role in maintaining colour variation in this species. [ABSTRACT FROM AUTHOR]

Context: Among processes involved in colour polymorphism, geographic variation in morph composition and frequency has been attracting interest since it reflects morph local adaptation. A recent study in the Pyrenees associated the pattern of geographic variation in morph frequency of the common wall lizard with the divergence in climatic niches, supporting the hypothesis that morphs represent alternative local climatic adaptations. However, the Pyrenees represent only a small portion of the species range. Aims: We modelled the ecological niches of Italian morphs using the same procedure adopted for the Pyrenees to check whether the effects detected at local scales (i.e. the Pyrenees) were repeatable at regional scales (i.e. Italy). This generalisation is needed to investigate how natural selection maintains locally adapted polymorphisms. Methods: We classified each locality (120 populations) according to the presence/absence of morphs, and independent Ecological Niche Models (ENMs) against the same background were fitted. Receiver Operating Curves accounting for sampling biases, equivalency and similarity tests were used to check and compare models accounting for spatial distribution of data. Key results: Morph-specific ENMs did not reproduce any of the patterns detected in the Pyrenees. Any difference among morphs disappeared after controlling for morph spatial distribution. Since occurrence points of the rarest morphs were a subsample of the occurrence points of the most common morph, it is not possible to separate the effects of true ecological differences among morphs from the effects of the spatial distribution patterns of morph occurrence. Conclusions: Using presence data not specifically collected for ENM comparisons does not allow reliable assessments of morph niche segregation. Our analysis points out the need to be very cautious in ecological interpretations of ENMs built on presence/background or presence-only data when occurrences are spatially nested. Implications: When dealing with data not specifically collected according to a targeted design, it is not legitimate to compare ENMs with completely nested occurrence points, because this approach can not exclude the possibility that ENM differences were the result of a spatial subsampling. This type of bias is probably largely underestimated, and it may lead to serious misinterpretations as shown in this study. Sampling procedures not exactly designed for a specific purpose ('opportunistic' data) are commonly used to model species distribution and analyse niche segregation among species. By analysising niche overlap among morphs in a polymorphic lizard, we show how opportunistically collected data have serious limitations without properly accounting for the spatial structure of the data. We point out the need of being cautious in interpretation of ENMs when occurrences are spatially nested. Photography by Roberto Sacchi [ABSTRACT FROM AUTHOR]

Simple Summary: This study examines colour variation in the highly endangered crocodile lizard, Shinisaurus crocodilurus. Both males and females vary in the extent to which their throats and venters are red. Their colouration is easily visible to a lizard receiver, and we found evidence that colour signals individual quality. Females with red venters had larger heads while females with red throats had greater bite force. In males, redder individuals were older. Finally, we found links between colour and fitness in males but not females. Aspects of male colouration were linked to reproductive output such that they sired offspring from heavier litters. The potential fitness consequences of colour should be considered in captive breeding and release programs. Colour plays a key role in animal social communication including as an indicator of individual quality. Using spectrophotometry, we examined colour variation in the throat and venter of the crocodile lizard (Shinisaurus crocodilurus), an endangered species native to southern China and northern Vietnam. We detected two broad colour variants, individuals with and without red, for each body region and each sex. A cluster analysis of spectral colour measurements (hue, chroma, luminance) revealed discrete throat and ventral morphs when measured in a single snapshot in time. However, photographic evidence revealed that the amount of red relative to body size increased as they got older. Individuals with red were equally likely to be male or female and throat colour was unrelated to ventral colour. Therefore, it is premature to claim that crocodile lizards have discrete colour morphs. We used visual modelling to show that the throat and venter were easily discriminable to a lizard visual system, suggesting they function in social communication. We also asked whether colour variation signalled individual quality. Females with red throats had greater bite force while males with red throats were older. In addition, females with red venters had larger heads. We also detected differences in morphology linked to colour. Females with red throats had slender bodies and longer tails, while individuals lacking red on their throats were stouter and had shorter tails. Finally, throat and ventral colour were unrelated to reproductive output (litter size and mass) in females. Males with greater ventral luminance contrast sired offspring from litters with greater litter mass (including stillborns), while males with greater ventral chromatic contrast sired offspring whose collective live mass (excluding stillborns) was greater. Males with greater luminance contrast also sired more live offspring (excluding stillborns). Collectively, these results suggest that male ventral colour signals individual quality in males. Conservation initiatives should take colour variation into account when planning future captive breeding and release programs for this endangered species. [ABSTRACT FROM AUTHOR]

Space is a limited resource in which many animals need to perform basic functions such as feeding and reproducing. Competition over access to space can induce a variety of behaviours that may result in differential access to crucial resources related to survival and fitness. The Aegean wall lizard, Podarcis erhardii , is a colour-polymorphic lizard that inhabits dry stone walls where they access food, safely thermoregulate, shelter from predators and interact with other lizards. Many colour-polymorphic species have morphs with distinct behavioural strategies, which may play a role in morph evolution and maintenance. Here, we conducted the first behavioural experiments on P. erhardii colour morphs. Our goal was to compare morph competitive ability and characterize morph differences in social behaviours using laboratory contest experiments over limited heated space on a stone wall in a neutral arena. Contest experiments revealed that colour morph, not size, predicted intermorph contest outcomes. White and yellow morphs were associated with winning and the orange morph was associated with losing contests. Male colour morphs exhibited different levels of aggressive, boldness, chemical signalling and visual signalling behaviours depending on which morph they were in contest with. White morphs always performed aggressive and scent-marking behaviours more frequently during contests with other morphs. Yellow morphs performed aggressive, bold, chemical signalling and visual signalling behaviours at intermediate frequencies relative to other morphs. Orange morphs performed aggressive behaviours equally often when in contest with yellow morphs but performed all other behaviours less frequently against yellow and white morphs. Considering these results, behavioural variation among P. erhardii colour morphs may promote morph maintenance. • Male lizard colour morphs differed in their ability to win staged contests for space. • White and yellow morphs were associated with winning contests over space. • Larger orange morphs were associated with losing and were the least aggressive. • White morphs were the most aggressive and scent-marked territories often. • Different social strategies among morphs may help maintain polymorphism. [ABSTRACT FROM AUTHOR]

Abstract Background Host-associated microbiota are integral to the ecology of their host and may help wildlife species cope with rapid environmental change. Urbanization is a globally replicated form of severe environmental change which we can leverage to better understand wildlife microbiomes. Does the colonization of separate cities result in parallel changes in the intestinal microbiome of wildlife, and if so, does within-city habitat heterogeneity matter? Using 16S rRNA gene amplicon sequencing, we quantified the effect of urbanization (across three cities) on the microbiome of eastern grey squirrels (Sciurus carolinensis). Grey squirrels are ubiquitous in rural and urban environments throughout their native range, across which they display an apparent coat colour polymorphism (agouti, black, intermediate). Results Grey squirrel microbiomes differed between rural and city environments; however, comparable variation was explained by habitat heterogeneity within cities. Our analyses suggest that operational taxonomic unit (OTU) community structure was more strongly influenced by local environmental conditions (rural and city forests versus human built habitats) than urbanization of the broader landscape (city versus rural). The bacterial genera characterizing the microbiomes of built-environment squirrels are thought to specialize on host-derived products and have been linked in previous research to low fibre diets. However, despite an effect of urbanization at fine spatial scales, phylogenetic patterns in the microbiome were coat colour phenotype dependent. City and built-environment agouti squirrels displayed greater phylogenetic beta-dispersion than those in rural or forest environments, and null modelling results indicated that the phylogenetic structure of urban agouti squirrels did not differ greatly from stochastic expectations. Conclusions Squirrel microbiomes differed between city and rural environments, but differences of comparable magnitude were observed between land classes at a within-city scale. We did not observe strong evidence that inter-environmental differences were the result of disparate selective pressures. Rather, our results suggest that microbiota dispersal and ecological drift are integral to shaping the inter-environmental differences we observed. However, these processes were partly mediated by squirrel coat colour phenotype. Given a well-known urban cline in squirrel coat colour melanism, grey squirrels provide a useful free-living system with which to study how host genetics mediate environment x microbiome interactions.

Intraspecific colour morphs usually differ in more traits than just colour. These traits can manifest as differences in morph physiology, behaviour, and ecology. Ecological differences among colour morphs, such as the degree of parasitism, can influence the evolution, maintenance, and loss of morphs from populations. High ectoparasite load can directly and deleteriously impact host fitness, and thus could influence colour morph persistence in populations if certain morphs are more frequently exposed to parasites or are more susceptible to parasitism. The Aegean wall lizard, Podarcis erhardii , is a colour polymorphic island lizard that is parasitized externally by ticks and mites. These ectoparasites can affect aspects of host lizard behaviour and physiology – including thermoregulation and body mass – and therefore are an important factor influencing the ecology and fitness of P. erhardii. We find that among sympatric colour morphs, ectoparasite loads differ; namely, monochromatic orange morphs have the highest numbers of ectoparasites, and in general, morphs with orange alleles (orange, orange-white, and orange-yellow) are more heavily parasitized by ticks and mites than the other morphs. Our results indicate that morphs with orange alleles tend to occupy microhabitats with significantly more vegetation cover and thus may increase their exposure to ticks and mites. Ecological differences between morphs could be an important factor contributing to demonstrated patterns of orange morph rarity and loss in P. erhardii populations. [ABSTRACT FROM AUTHOR]

Flower colour has played a decisive role as an evolutionary force in many groups of plants by driving speciation. A well-known example of colour polymorphism is found across the Mediterranean populations of Lysimachia arvensis and L. monelli , in which blue- and red-flowered plants can be found. Previous studies recognized two lineages within L. arvensis differing in flower colour, but this variation has not yet been considered in a phylogenetic context. We have reconstructed the ancestral states of flower colour across Mediterranean Lysimachia spp. aiming at understanding its phylogenetic signal using the nuclear internal transcribed spacer (ITS) sequences and three plastid markers. All blue- and red-flowered specimens were nested in different clades in the ITS tree, thus supporting that L. arvensis and L. monelli are polyphyletic, whereas low phylogenetic resolution was found in plastid markers. Monophyly was reconstructed for blue-flowered L. arvensis and L. monelli samples, and similarly for red-flowered individuals of each species: (1) blue-flowered L. arvensis was reconstructed as sister to the strictly blue-flowered L. talaverae in a monophyletic clade sister to remaining Lysimachia ; (2) red-flowered L. arvensis was resolved as sister to red-flowered L. monelli in a monophyletic clade; and (3) clade 2 was sister to blue-flowered L. monelli and the strictly blue-flowered L. foemina. Our results suggest that colour lineages in L. arvensis and L. monelli constitute different species, but flower colour did not promote the separation of these lineages. We propose a new name for blue-flowered L. arvensis (L. loeflingii) and a new combination for red-flowered L. monelli (L. collina), maintaining L. arvensis for red-flowered plants and L. monelli for blue-flowered plants. [ABSTRACT FROM AUTHOR]

Social and aggressive behaviours often affect the fitness of multiple interacting individuals simultaneously. Here, we assessed dyadic interactions in a colour-polymorphic cichlid fish, the red devil, Amphilophus labiatus. We found that sub-adult red devil pairs of smaller body size interacted more, and were more aggressive towards each other, than pairs comprising larger individuals. Interactions did not significantly differ between colour morphs, i.e. between dark, gold and heterotypic pairs. Interestingly, within a broad range of parameters, an automated measure of time that the two fish spent in close proximity was an accurate proxy for their level of aggression, as measured by an observer from video recordings. These results show that, between sub-adult red devils, (aggressive) interactions significantly depend on body size, but not colour morph, of the interacting individuals. In addition, the results support the use of automated data-gathering approaches as an appropriate tool for studies of aggression. [ABSTRACT FROM AUTHOR]

The growing global prevalence of energy efficient broad spectrum lighting threatens to disrupt an array of visually guided ecological processes. Broad spectrum lighting likely better enables the discrimination of colour, yet it is potential to increase the conspicuousness of camouflaged prey at night remains little explored.Using a well‐established visual model, we quantified the impacts of four spectrally distinct narrow and broad spectrum lighting technologies on the conspicuousness of three different polymorphic colour variations of intertidal littorinid snail, as viewed by three model predators.Modern broad spectrum lighting technologies increased the conspicuousness of prey compared to 20th‐century narrow spectrum lighting. This effect was most prominent in the yellow colour morphs due to greater contrast with their natural fucoid seaweed background.Synthesis and applications. Our results provide evidence that the global transition to broad spectrum lighting will decrease the efficacy of camouflage at night in nature, potentially altering selective predation, population dynamics and the genetic structure of polymorphic populations. These findings highlight the need for further consideration in environmental management and planning, to ensure habitats are protected from unnecessary exposure to artificial light. [ABSTRACT FROM AUTHOR]

We report the assembly and annotation of the complete mitochondrial genome of the warningly-coloured wood tiger moth (Arctia plantaginis) and investigate its phylogenetic position within Arctiinae. The A.plantaginis mitogenome is 15,479 bp long with 13 protein-coding genes, 22 transfer RNAs, 2 ribosomal RNA genes, and an A + T-rich region (D-loop). The phylogenetic analyses based on 13 protein-coding genes showed A.plantaginis clustering within a clade of species with white wings and yellow or red bodies. This result can be useful in understanding the evolution of coloration in Arctiid moths.

Intraspecific colour polymorphisms (CPs) present unique opportunities to study fundamental evolutionary questions, such as the link between ecology and phenotype, mechanisms maintaining genetic diversity and their putative role in speciation. Wrasses are highly diverse in ecology and morphology and harbour a variety of colour‐polymorphic species. In the Mediterranean Sea, wrasses of the tribe Labrini evolved two species radiations each harbouring several species with a brown and a green morph. The colour morphs occur in complete sympatry in mosaic habitats with rocky outcrops and Neptune grass patches. Morph‐specific differences had not been characterized yet and the evolutionary forces maintaining them remained unknown. With genome‐wide data for almost all Labrini species, we show that species with CPs are distributed across the phylogeny, but show evidence of hybridization. This suggests that the colour morphs are either ancient and have been lost repeatedly, that they have evolved repeatedly or have been shared via hybridization. Focusing on two polymorphic species, we find that each colour morph is more common in the microhabitat providing the best colour match and that the morphs exhibit additional behavioural and morphological differences further improving crypsis in their respective microhabitats. We find little evidence for genetic differentiation between the morphs in either species. Therefore, we propose that these colour morphs represent a multi‐niche polymorphism as an adaptation to the highly heterogeneous habitat. Our study highlights how colour polymorphism (CP) can be advantageous in mosaic habitats and that Mediterranean wrasses are an ideal system to study trans‐species polymorphisms, i.e. polymorphisms maintained across several species, in adaptive radiations. [ABSTRACT FROM AUTHOR]

The distribution of the iridescent dung beetle Bolbites onitoides can be divided, based on dorsal colouration, into a blue western-half and a red eastern-half. This has raised the question, in 1959, of whether the two colour variants could represent distinct subspecies. Having examined ~1200 specimens and evaluated the proposal under both an ontological and an operational subspecies concept, we conclude that B. onitoides should continue to be treated as a single monotypic species because: (1) two kinds of colour intermediates were found living among populations of the two main variants; (2) the distribution of the variants overlaps; (3) no other characters were seen to vary consistently in accordance with the colour variants; (4) the overall geographical pattern can be explained by phenomena other than (incipient) speciation, such as phenotypic plasticity and distinct selective regimes; and (5) colour has been extensively shown not to be a reliable indicator of speciation processes among dung beetles. By comparing our findings with other cases of polychromatism among scarabaeines, we discuss publications proposing subspecies taxa relying uniquely upon colour variants. We contend that, due to the often continuous, populational, polytopic and, several times, clinal nature of the intraspecific geographical variation, subspecies classification schemes should not be established simply to classify variation across a species range without a commitment to the reality as evolutionary entities of the taxa being proposed. The alternative stance championed by many contemporary authors to give trinomina to conspecific (meta)population lineages, in turn, may eventually prove to be adequate, but we express some of our concerns as to the feasibility of this practice. Whether these intraspecific taxa should be ranked in a Linnaean hierarchy – e.g. as subspecies – is equally an open question. We also elaborate on an evolutionary scenario where the role of the iridescence in sexual selection, as hypothesized in a previous work, may be an exaptation, not an adaptation, among the horned Phanaeina. [ABSTRACT FROM AUTHOR]

A new genus, Pericallea gen. n., is described to accommodate the new species Pericallea katherina sp. n., a species endemic to inland districts of south-western Western Australia. Relationships of the new genus are discussed, and the male calling song of the new species is described and analysed. [ABSTRACT FROM AUTHOR]

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Climate‐modulated parasitism is driven by a range of factors, yet the spatial and temporal variability of this relationship has received scant attention in wild vertebrate hosts. Moreover, most prior studies overlooked the intraspecific differences across host morphotypes, which impedes a full understanding of the climate–parasitism relationship. In the common lizard (Zootoca vivipara), females exhibit three colour morphs: yellow (Y‐females), orange (O‐females) and mixed (mixture of yellow and orange, M‐females). Zootoca vivipara is also infested with an ectoparasite (Ophionyssus mites). We therefore used this model system to examine the intraspecific response of hosts to parasitism under climate change. We found infestation probability to differ across colour morphs at both spatial (10 sites) and temporal (20 years) scales: M‐females had lower parasite infestations than Y‐ and O‐females at lower temperatures, but became more susceptible to parasites as temperature increased. The advantage of M‐females at low temperatures was counterbalanced by their higher mortality rates thereafter, which suggests a morph‐dependent trade‐off between resistance to parasites and host survival. Furthermore, significant interactions between colour morphs and temperature indicate that the relationship between parasite infestations and climate warming was contingent on host morphotypes. Parasite infestations increased with temperature for most morphs, but displayed morph‐specific rates. Finally, infested M‐females had higher reductions in survival rates than infested Y‐ or O‐females, which implies a potential loss of intraspecific diversity within populations as parasitism and temperatures rise. Overall, we found parasitism increases with warming temperatures, but this relationship is modulated by host morphotypes and an interaction with temperature. We suggest that epidemiological models incorporate intraspecific diversity within species for better understanding the dynamics of wildlife diseases under climate warming. [ABSTRACT FROM AUTHOR]

Resources allocated in reproduction are traded off against those invested in self‐maintenance such as antioxidant response. Glutathione (GSH) is an intracellular antioxidant defence that scavenges reactive oxygen species, the deleterious byproducts of oxygen consumption. Given the role of intracellular GSH in pheomelanogenesis, a trade‐off in GSH allocation between resistance in oxidative stress and melanin production may take place. To investigate how intracellular GSH is regulated in differently coloured individuals at the time of reproduction (in adults) and of intense melanogenesis (in nestlings), we measured the total pool of GSH produced (tGSH), consumed (oxGSH) and available (redGSH) in adult tawny owls and their offspring which were cross‐fostered between randomly chosen nests. Our goal was to describe potential correlations between resistance in oxidative stress and colour morphs in natural conditions. Nestling GSH levels were correlated with GSH levels in their genetic and foster parents suggesting that producing GSH is genetically and environmentally determined (although the effect of the foster nest seemed stronger). This species shows continuous variation in pheomelanin reddish colouration, which is associated with life‐history strategies. Based on the hypothesis of GSH dependence of pheomelanism, we expected a greater amount of oxGSH in dark compared to light pheomelanic nestlings, which was not the case. In contrast, light melanic breeding adults had higher levels of tGSH and redGSH than dark breeders probably because of a higher investment in antioxidant capacity. The link between pheomelanism and GSH may therefore be due to the fact that differently colored individuals have different life‐history strategies rather than because the production of pheomelanin pigments requires GSH. [ABSTRACT FROM AUTHOR]

Different physical structures play a central role in animal camouflage. However, in evolutionary studies of mimicry, the ecological and evolutionary significance of such structures has been poorly investigated. Larvae of long-bodied craneflies, Cylindrotominae, are all obligate herbivores and resemble plants. They are distinctively characterized by possessing numerous elongated cuticular lobes on the integument. A comprehensive overview of the biology and morphology of cylindrotomids, particularly their larval stages, is laid out, providing original data on nine species. To explore the ecological background of moss resemblance, host-plants of most examined species are clarified, revealing that terrestrial moss-feeding species tend to use specific groups of mosses, either belonging to Bryales or Hypnales. However, the evolution of cryptic forms remains paradoxical, due to the apparent absence of visual predators. Based on histological examinations, extensive internal musculatures within the cuticular lobes on the lateral side are discovered, shedding new light on their function in locomotion. Traditional functional explanations for these lobes, particularly as devices for respiration, locomotion and attachment, are challenged. This study promotes our understanding of the ecomorphology of mimicry devices, which is an angle often dismissed in evolutionary studies of mimicry. [ABSTRACT FROM AUTHOR]