Wing Color Research Articles

Convergent morphology and divergent phenology promote the coexistence of Morpho butterfly species

The coexistence of closely-related species in sympatry is puzzling because ecological niche proximity imposes strong competition and reproductive interference. A striking example is the widespread wing pattern convergence of several blue-banded Morpho butterfly species with overlapping ranges of distribution. Here we perform a series of field experiments using flying Morpho dummies placed in a natural habitat. We show that similarity in wing colour pattern indeed leads to interspecific territoriality and courtship among sympatric species. In spite of such behavioural interference, demographic inference from genomic data shows that sympatric closely-related Morpho species are genetically isolated. Mark-recapture experiments in the two most closely-related species unravel a strong temporal segregation in patrolling activity of males. Such divergence in phenology reduces the costs of reproductive interference while simultaneously preserving the benefits of convergence in non-reproductive traits in response to common ecological pressures. Henceforth, the evolution of multiple traits may favour species diversification in sympatry by partitioning niche in different dimensions.

Solving the cryptic diversity of the genus Manerebia Staudinger in northern Peru: description of new species and considerations on the biogeographical role of the Huancabamba Deflection (Nymphalidae: Satyrinae: Pronophilina).

The Huancabamba Deflection in the Andes of northern Peru and southern Ecuador is a pivotal area for Neotropical biogeography, where exceptional biodiversity coincides with high rates of endemism. These characteristics are well illustrated within the montane butterfly genus Manerebia Staudinger (Nymphalidae, Satyrinae). Here, six new, apparently endemic species, and two new subspecies, are described from this region: M. inducta Pyrcz Willmott n. sp., M. ronda Pyrcz Boyer, n. sp., M. ronda amplia Pyrcz Boyer, n. ssp., M. punku Pyrcz Farfn n. sp., M. huamanii Cerdea Pyrcz n. sp., M. placida Pyrcz Willmott n. sp., M. granatus Willmott, Radford Pyrcz n. sp. and M. prattorum udima Pyrcz Boyer, n. ssp. A total of 22 species of Manerebia is reported from the study region, as much as half the total number of species in this genus distributed throughout the tropical Andes. The alpha-taxonomy of Manerebia is particularly demanding, as colour patterns have apparently converged among different species making identification virtually impossible in some cases without comparison of their genitalia, which prove taxonomically and phylogenetically highly valuable. On the other hand, several species differ markedly in wing colour patterns and occur at different elevations but have identical genitalia. Furthermore, our data show that DNA barcoding is only partly viable as an alpha-taxonomic tool, as some markedly different species of Manerebia, in terms of external morphology and ecological preferences, are genetically not separable using only COI markers. On the other hand, several species barely differing morphologically are identified based on barcode. Barcodes of 26 species, including 18 from the northern Andes, are studied here, showing strong differences within some taxa previously considered conspecific based on morphological characters, suggesting that their taxonomic status needs to be re-evaluated. In particular, M. trimaculata and the widely distributed polytypic M. inderena may be highly variable species or complexes of several species. A total of 16 species are found north of the Chamaya valley in southern Ecuador and extreme northern Peru, compared to 14 species south of it in northern Peru. The faunal (Jaccard) similarity coefficient of the two adjacent regions is low (0.3), reflecting the role of the Huancabamba Deflection as a biogeographical barrier.

Morphological characterization of Moringa oleifera seeds from different crops of Mexico

Objective: to characterize the seeds of Moringa oleifera present in various crops in Mexico morphologically.
 Design / Methodology / Approach: An analysis of variance, principal components, and conglomerates of qualitative morphological descriptors (shape, color, presence of wings and wing color) and quantitative (length, width, and weight) were carried out.
 Results: Significant statistical differences (P˂0.05) were found in the seeds' length, width, weight, and almonds. The principal component analysis indicated that components 1 (70.58%) and 2 (25.59%) contributed 96.17% of the variation, and the cluster analysis identified four groups. The evaluated populations showed qualitative variation (shape, color, presence of wings, and color of wings) and quantitative (length, width, and weight).
 Study limitations/implications: the germination percentage could not be evaluated because no information was obtained on the age of the seed and the storage conditions. Result/Finding:Conclusion: This information enriches the knowledge of Moringa oleifera in Mexico and serves as a basis for selecting materials of most significant interest.

In Search of an Honest Butterfly: Sexually Selected Wing Coloration and Reproductive Traits From Wild Populations of the Cabbage White Butterfly

Abstract Sexual selection is central to many theories on mate selection and individual behavior. Relatively little is known, however, about the impacts that human-induced rapid environmental change are having on secondary sexually selected characteristics. Honest signals function as an indicator of mate quality when there are differences in nutrient acquisition and are thus potentially sensitive to anthropogenically altered nutrient inputs. We used the cabbage white butterfly, Pieris rapae (L.) (Lepidoptera: Pieridae), to investigate differences in color and testes size in a system that is often exposed to agricultural landscapes with nitrogen addition. We collected individuals from four sites in California and Nevada to investigate variation in key traits and the possibility that any relationship between wing color and a reproductive trait (testes size) could vary among locations in the focal butterfly. Coloration variables and testes size were positively albeit weakly associated across sites, consistent with the hypothesis that females could use nitrogen-based coloration in the cabbage white as an indicator for a male mating trait that has the potential to confer elevated mating success in progeny. However, variation in testes size and in the relationship between testes size and wing color suggest complexities that need exploration, including the possibility that the signal is not of equal value in all populations. Thus these results advance our understanding of complex relationships among environmental change and sexual selection in the wild.

Comparative transcriptome analysis at the onset of speciation in a mimetic butterfly-The Ithomiini Melinaea marsaeus.

Ecological speciation entails divergent selection on specific traits and ultimately on the developmental pathways responsible for these traits. Selection can act on gene sequences but also on regulatory regions responsible for gene expression. Mimetic butterflies are a relevant system for speciation studies because wing colour pattern (WCP) often diverges between closely related taxa and is thought to drive speciation through assortative mating and increased predation on hybrids. Here, we generate the first transcriptomic resources for a mimetic butterfly of the tribe Ithomiini, Melinaea marsaeus, to examine patterns of differential expression between two subspecies and between tissues that express traits that likely drive reproductive isolation; WCP and chemosensory genes. We sequenced whole transcriptomes of three life stages to cover a large catalogue of transcripts, and we investigated differential expression between subspecies in pupal wing discs and antennae. Eighteen known WCP genes were expressed in wing discs and 115 chemosensory genes were expressed in antennae, with a remarkable diversity of chemosensory protein genes. Many transcripts were differentially expressed between subspecies, including two WCP genes and one odorant receptor. Our results suggest that in M.marsaeus the same genes as in other mimetic butterflies are involved in traits causing reproductive isolation, and point at possible candidates for the differences in those traits between subspecies. Differential expression analyses of other developmental stages and body organs and functional studies are needed to confirm and expand these results. Our work provides key resources for comparative genomics in mimetic butterflies, and more generally in Lepidoptera.

Novel wing display and divergent agonistic behaviors of two incipient Psolodesmus damselflies.

Sexual selection via male competition is a strong evolutionary force that can drive rapid changes in competitive traits and subsequently lead to population divergence and speciation. Territorial males of many odonates are known to use their colorful wings as visual signals and to perform agonistic displays toward intruders. Psolodesmus mandarinus dorothea and Psolodesmus mandarinus mandarinus are two parapatrically distributed sister damselflies that share similar ecological characteristics but differ markedly in wing coloration. The wings of P. m. dorothea are mostly clear, whereas those of P. m. mandarinus have a large area of black pigmentation and a central white patch. We investigated whether territorial males of the two damselflies at breeding sites display distinct agonistic behaviors associated with their respective wing colors. Behavioral interactions between territorial and intruder males and their wing kinematics were filmed and analyzed for P. m. dorothea in Lienhuachih of central Taiwan, and P. m. mandarinus in Tianxiyuan andFusan of northern Taiwan. We observed that the P. m. mandarinus males exhibited a novel set of perched wing displays, which was not only absent in its sister P. m. dorothea but also previously unknown in Odonata. At breeding sites, perched rival males of P. m. mandarinus with pigmented wings exhibited escalating agonistic wing-flapping and wing-hitting displays toward each other. In contrast, territorial males of P. m. dorothea with clear wings engaged only in aerial chase or face-to-face hovering when intruder males approached from the air. These results indicate that the two sister P. mandarinus damselflies diverged behaviorally in territorial contests and support the hypothesis of coadaptation on the basis of wing colors and types of wing movement in Odonata. Our findings further suggest that divergent agonistic wing displays may play a pivotal role in the speciation mechanism of P. mandarinus damselflies. The sequential analyses of behavioral characteristics and progression suggest that P. m. mandarinus damselflies likely use mutual assessment of rivals in territorial contests.

True UV color vision in a female butterfly with two UV opsins.

In true color vision, animals discriminate between light wavelengths, regardless of intensity, using at least two photoreceptors with different spectral sensitivity peaks. Heliconius butterflies have duplicate UV opsin genes, which encode ultraviolet and violet photoreceptors, respectively. In Heliconius erato, only females express the ultraviolet photoreceptor, suggesting females (but not males) can discriminate between UV wavelengths. We tested the ability of H. erato, and two species lacking the violet receptor, Heliconius melpomene and Eueides isabella, to discriminate between 380 and 390 nm, and between 400 and 436 nm, after being trained to associate each stimulus with a sugar reward. We found that only H. erato females have color vision in the UV range. Across species, both sexes show color vision in the blue range. Models of H. erato color vision suggest that females have an advantage over males in discriminating the inner UV-yellow corollas of Psiguria flowers from their outer orange petals. Moreover, previous models ( McCulloch et al., 2017) suggested that H. erato males have an advantage over females in discriminating Heliconius 3-hydroxykynurenine (3-OHK) yellow wing coloration from non-3-OHK yellow wing coloration found in other heliconiines. These results provide some of the first behavioral evidence for female H. erato UV color discrimination in the context of foraging, lending support to the hypothesis ( Briscoe et al., 2010) that the duplicated UV opsin genes function together in UV color vision. Taken together, the sexually dimorphic visual system of H. erato appears to have been shaped by both sexual selection and sex-specific natural selection.

Mathematical modeling of the eyespots in butterfly wings

Butterfly wing color patterns are a representative model system for studying biological pattern formation, due to their two-dimensional simple structural and high inter- and intra-specific variabilities. Moreover, butterfly color patterns have demonstrated roles in mate choice, thermoregulation, and predator avoidance via disruptive coloration, attack deflection, aposematism, mimicry, and masquerade. Because of the importance of color patterns to many aspects of butterfly biology and their apparent tractability for study, color patterns have been the subjects of many attempts to model their development. Early attempts focused on generalized mechanisms of pattern formation such as reaction-diffusion, diffusion gradient, lateral inhibition, and threshold responses, without reference to any specific gene products. As candidate genes with expression patterns that resembled incipient color patterns were identified, genetic regulatory networks were proposed for color pattern formation based on gene functions inferred from other insects with wings, such as Drosophila. Particularly detailed networks incorporating the gene products, Distal-less (Dll), Engrailed (En), Hedgehog (Hh), Cubitus interruptus (Ci), Transforming growth factor-β (TGF-β), and Wingless (Wg), have been proposed for butterfly border ocelli (eyespots) which helps the investigation of the formation of these patterns. Thus, in this work, we develop a mathematical model including the gene products En, Hh, Ci, TGF-β, and Wg to mimic and investigate the eyespot formation in butterflies. Our simulations show that the level of En has peaks in the inner and outer rings and the level of Ci has peaks in the inner and middle rings. The interactions among these peaks activate cells to produce white, black, and yellow pigments in the inner, middle, and outer rings, respectively, which captures the eyespot pattern of wild type Bicyclus anynana butterflies. Additionally, our simulations suggest that lack of En generates a single black spot and lack of Hh or Ci generates a single white spot, and a deficiency of TGF-β or Wg will cause the loss of the outer yellow ring. These deficient patterns are similar to those observed in the eyespots of Vanessa atalanta, Vanessa altissima, and Chlosyne nycteis. Thus, our model also provides a hypothesis to explain the mechanism of generating the deficient patterns in these species.

Mimicry: just wing it. Wing shape comparison between a mimicking swallowtail and its toxic model

Abstract Female eastern tiger swallowtails (Papilio glaucus) are well-known wing coloration mimics of the toxic pipevine swallowtail (Battus philenor). Given that forewing shape is an important component of butterfly flight behaviour found in unpalatable species, we hypothesized that the mimicking females also mimic the forewing shape of their poisonous model. Thus, we predicted that mimicking eastern tiger swallowtails have a more similar wing shape to their model compared with their non-mimicking conspecific morphs. In order to test this, we compared the forewing of the model with mimicking and non-mimicking eastern tiger swallowtail morphs using a standard geometric morphometrics approach. Contrary to our hypothesis, we found significant differences of forewing shape between the two species, with no overlap, regardless of the morph. However, mimicking and non-mimicking female eastern tiger swallowtails were significantly different from each other in wing shape. This indicates that either pleiotropic effects, possibly owing to wing coloration mimicry, or selection for different flight patterns in mimics informed the evolution of forewings in this species. Additionally, we found sexual dimorphism in forewing shape within each species, which supports research indicating that both sexual selection and sex-specific natural selection are important drivers in wing shape evolution.

New mimarachnids (Hemiptera, Fulgoromorpha, Fulgoroidea) in mid-Cretaceous Burmese amber.

A new genus and species, Multistriaorthotropagen. et sp. nov., and a new species, Dachibangushuisp. nov., of Mimarachnidae are described from the mid-Cretaceous Burmese amber. These new taxa display unique wing color patterns and extend the Mesozoic diversity of Mimarachnidae. The evolution of wing venation, phylogenetic placement of Mimarachnidae, and anti-predation defenses of this family in Burmese amber forest are briefly discussed.

Butterflies see wing colours change as mother-of-pearls flutter by

For centuries, our predecessors experimented with exotic pigments to create opulent ceramics and illuminated manuscripts. It was only in the 18th century that we discovered Mother Nature's alternative colour palette, produced by light reflecting from microscopic layers in feathers, skin and insect shells in a similar way to the shimmering rainbow hues of soap bubbles and oil films. ‘Earlier in my career, I was devoted to insect vision, but I was also constantly intrigued by the often brilliant colours of butterflies’, says Doekele Stavenga, from the University of Groningen, The Netherlands, who became increasingly fascinated by the intriguing physics of these so-called ‘structural colours’. After decades of investigating the startling shades of butterflies from all over the globe, he most recently turned his attention to the shimmering common mother-of-pearl butterfly (Protogoniomorpha parhassus) from Africa in the hope of discovering how they produce their opalescent glow.As butterfly wings are coated in scales, Stavenga suspected that thin layers in these structures were the cause of the mother-of-pearl butterfly's delicate iridescent pink hue. However, to be sure, he first had to shine light through the fragile wings. ‘The structural coloration of the wings was immediately and strikingly clear when comparing light reflecting from the wing with light that passed through it’, says Stavenga, who saw the rosy shade vanish when the wing was illuminated from beneath. And when Bodo Wilts, a colleague from the University of Fribourg, Switzerland, scrutinised the scales in fine detail using an electron microscope, they could clearly see box-like structures in the scales that would scatter light to produce the butterfly's pearlescence. Next, Stavenga focused a spot of bright white light on a wing from above, producing a fuchsia-coloured beam as the structures in the scales reflected only red and blue wavelengths, confirming that the delicate colour is produced by reflecting structures in the scales and not a rose-toned pigment in the wing.However, Stavenga also knew that the tones produced by these light-reflecting colour-generating structures depend on the position of a viewer relative to the structure, potentially altering the colour of an object as it moves. Could the wings of mother-of-pearl butterflies flash different tones as the animals flutter by? This time, Stavenga shone white light at angles ranging from directly above the wing to almost horizontally to one side (an oblique angle of 70 deg), recording the wavelengths that were reflected by the scales to find out whether the shade varied from different angles. Impressively, the wing's hue switched from pink to yellow as the light shifted from above to one side. And, when he calculated how the colours would change in the eyes of a butterfly – which see UV tones but not the red hues that we can see – the wings became a brighter shade of yellow and the light was more strongly polarized, making the wings stand out for creatures such as butterflies that see polarization.The mother-of-pearl butterfly's wings are perfectly tuned to generate flashes of colour as they flit past, and Stavenga suggests that the fluttering insect's flickering light show could help them to stand out from the crowd. ‘Only in the last decade has the importance of butterfly wing scales acting as thin film reflectors like soap bubbles become well recognized, and the mother-of-pearl butterfly is certainly the brightest, exemplary case’, he says.

Novel Doublesex Duplication Associated with Sexually Dimorphic Development of Dogface Butterfly Wings.

Sexually dimorphic development is responsible for some of the most remarkable phenotypic variation found in nature. Alternative splicing of the transcription factor gene doublesex (dsx) is a highly conserved developmental switch controlling the expression of sex-specific pathways. Here, we leverage sex-specific differences in butterfly wing color pattern to characterize the genetic basis of sexually dimorphic development. We use RNA-seq, immunolocalization, and motif binding site analysis to test specific predictions about the role of dsx in the development of structurally based ultraviolet (UV) wing patterns in Zerene cesonia (Southern Dogface). Unexpectedly, we discover a novel duplication of dsx that shows a sex-specific burst of expression associated with the sexually dimorphic UV coloration. The derived copy consists of a single exon that encodes a DNA binding but no protein-binding domain and has experienced rapid amino-acid divergence. We propose the novel dsx paralog may suppress UV scale differentiation in females, which is supported by an excess of Dsx-binding sites at cytoskeletal and chitin-related genes with sex-biased expression. These findings illustrate the molecular flexibility of the dsx gene in mediating the differentiation of secondary sexual characteristics.

Cortex cis-regulatory switches establish scale colour identity and pattern diversity in Heliconius.

In Heliconius butterflies, wing colour pattern diversity and scale types are controlled by a few genes of large effect that regulate colour pattern switches between morphs and species across a large mimetic radiation. One of these genes, cortex, has been repeatedly associated with colour pattern evolution in butterflies. Here we carried out CRISPR knockouts in multiple Heliconius species and show that cortex is a major determinant of scale cell identity. Chromatin accessibility profiling and introgression scans identified cis-regulatory regions associated with discrete phenotypic switches. CRISPR perturbation of these regions in black hindwing genotypes recreated a yellow bar, revealing their spatially limited activity. In the H. melpomene/timareta lineage, the candidate CRE from yellow-barred phenotype morphs is interrupted by a transposable element, suggesting that cis-regulatory structural variation underlies these mimetic adaptations. Our work shows that cortex functionally controls scale colour fate and that its cis-regulatory regions control a phenotypic switch in a modular and pattern-specific fashion.

Biomimicry of Blue Morpho butterfly wings: An introduction to nanotechnology through an interdisciplinary science education module

AbstractBiomimicry is the practice of imitating naturally occurring bio‐designs through engineering and invention. For instance, Blue Morpho butterfly wing colors are a result of the reflection and refraction of nanostructures embedded in the wing and have inspired practical applications in nanofabrication and photonics. Interdisciplinary science educational materials have been developed that demonstrate the cross‐disciplinary aspects and biomimetic properties used in designing nano‐based devices. The unique optical properties of the Blue Morpho wing provides an excellent source of demonstrating how aspects of chemistry, biology, physics, and nanotechnology relate. Specifically, these educational tools demonstrate concepts including natural selection, chemical and physical properties, structure at the nanoscale, optical, and electromagnetic design. In addition, the engaging activities are correlated to how nanotechnology drives invention and provides students a mechanism to be introduced to the possibilities nanotechnology provides. A comprehensive combination of lab, cleanroom, and classroom activities are suggested to promote remote learning.

Hidden in the wing dots: Disentangling mimetic sister species of butterflies (Riodinidae: Stalachtis) with an integrative approach

The high resemblance between closely related mimetic species poses a challenge to taxonomists who describe and define these species. An emblematic example is found within Stalachtis Hübner, 1818 (Lepidoptera: Riodinidae), a small Neotropical genus of brightly colored butterflies engaged in mimicry rings. Its systematic position within Riodinidae is difficult to define based on morphology alone, and while its taxonomy is inflated due to intraspecific color polymorphisms, phenotypic variation might be concealing cryptic species. Thus, we examined the subspecific diversity within S. phlegia (Cramer, 1779) through an integrative approach based on both molecular and morphological data, aiming to investigate taxon limits. Both morphology and molecular data support the status of S. phlegia and Stalachtis susannastat. rev. as distinct species. S. susannastat. rev. is a medium sized butterfly with an orange-black wing color pattern with a few white dots. Furthermore, S. susannastat. rev. has no subspecies, and is endemic to the Atlantic Forest, while the four subspecies within S. phlegia are widely distributed throughout the Amazon, the Cerrado savanna and in parts of the Atlantic Forest. We consider S. phlegia a promising model for studies of the effect of deforestation on mimetic color patterns in the Amazon–Cerrado transition.

Engaging the Community in Pollinator Research: The Effect of Wing Pattern and Weather on Butterfly Behavior

Community science, which engages students and the public in data collection and scientific inquiry, is often integrated into conservation and long-term monitoring efforts. However, it has the potential to also introduce the public to, and be useful for, sensory ecology and other fields of study. Here we describe a community science project that exposes participants to animal behavior and sensory ecology using the rich butterfly community of Northwest Arkansas, United States. Butterflies use visual signals to communicate and to attract mates. Brighter colors can produce stronger signals for mate attraction but can also unintentionally attract negative attention from predators. Environmental conditions such as weather can affect visual signaling as well, by influencing the wavelengths of light available and subsequent signal detection. However, we do not know whether the signals butterflies present correlate broadly with how they behave. In this study, we collaborated with hundreds of students and community members at the University of Arkansas (UARK) and the Botanical Gardens of the Ozarks (BGO) for over 3.5 years to examine relationships among wing pattern, weather, time of day, behavior, and flower choice. We found that both weather and wing color influenced general butterfly behavior. Butterflies were seen feeding more on cloudy days than on sunny or partly cloudy days. Brown butterflies fed or sat more often, while white butterflies flew more often relative to other butterfly colors. We also found that there was an interaction between the effects of weather and wing color on butterfly behavior. Furthermore, butterfly color predicted the choice of flower colors that butterflies visited, though this effect was influenced by the observer group (UARK student or BGO participant). These results suggest that flower choice may be associated with butterfly wing pattern, and that different environmental conditions may influence butterfly behavior in wing-pattern-specific ways. They also illustrate one way that public involvement in behavioral studies can facilitate the identification of coarse-scale, community-wide behavioral patterns, and lay the groundwork for future studies of sensory niches.

Haplotype tagging reveals parallel formation of hybrid races in two butterfly species

Genetic variation segregates as linked sets of variants or haplotypes. Haplotypes and linkage are central to genetics and underpin virtually all genetic and selection analysis. Yet, genomic data often omit haplotype information due to constraints in sequencing technologies. Here, we present "haplotagging," a simple, low-cost linked-read sequencing technique that allows sequencing of hundreds of individuals while retaining linkage information. We apply haplotagging to construct megabase-size haplotypes for over 600 individual butterflies (Heliconius erato and H. melpomene), which form overlapping hybrid zones across an elevational gradient in Ecuador. Haplotagging identifies loci controlling distinctive high- and lowland wing color patterns. Divergent haplotypes are found at the same major loci in both species, while chromosome rearrangements show no parallelism. Remarkably, in both species, the geographic clines for the major wing-pattern loci are displaced by 18 km, leading to the rise of a novel hybrid morph in the center of the hybrid zone. We propose that shared warning signaling (Müllerian mimicry) may couple the cline shifts seen in both species and facilitate the parallel coemergence of a novel hybrid morph in both comimetic species. Our results show the power of efficient haplotyping methods when combined with large-scale sequencing data from natural populations.

Revised species definitions and nomenclature of the blue and purple/rose Cithaerias/ butterflies (Lepidoptera, Nymphalidae, Satyrinae).

This study reassesses the taxonomic status of Neotropical blue and purple/rose-colored Cithaerias butterflies, thus complementing a previous study of the rose-colored species. Based on comparative study of wing coloration and genitalia morphology, I revise species definitions and the taxonomic status of: Cithaerias andromeda, C. azurina STAT. REV., C. esmeralda STAT. REV., C. bandusia STAT. REV., C. pyropina, and C. songoana STAT. REV. Photographs of adults and illustrations of male and female genitalia are provided for all species. Of particular importance are the genitalia illustrations of male and female C. azurina, presented here for the first time, as well as finding a putative first female of Ecuadorean subspecies C. pyropina julia.

Comparison of Courtship Behavior in Fourteen Butterfly Species

Courtship behavior was observed for 14 butterfly species, including seven species belonging to tribe Theclini, Lycaenidae, to address whether males of sexually dichromatic species perform more active demonstration of their wing surface to the female than those of monochromatic species do. Males in nearly half of the dichromatic species kept their wings closed on the thorax throughout most of a courtship, indicating no general relationship between the mode of wing coloration and courtship behavior. The results obtained are discussed from ecological and phylogenetic points of view, and it is inferred that the wing-closed courtship has developed in the Theclini group as adaptation to predation pressure in the woodland habitat.

Geographical disjunction and environmental conditions drive intraspecific differentiation in the chalk-hill blue butterfly

Abstract Drivers of evolution are often related to geographical isolation and/or diverging environmental conditions. Spatial variation in neutral genetic markers mostly reflects past geographical isolation, i.e. long-lasting allopatry, whereas morphology is often driven by local environmental conditions, resulting in more rapid evolution. In Europe, most thermophilic species persisted during the past glacial periods in geographically disjunct refugia, representing long-lasting isolates, frequently with diverging environmental conditions. This situation has driven the evolution of intraspecific signatures in species. Here, we analysed wing shape and wing pigmentation of the chalk-hill blue butterfly, Polyommatus coridon, across its entire distribution range restricted to the western Palaearctic. In addition, we compiled abiotic environmental parameters for each sampling site. Wing colour patterns differentiated a western and an eastern lineage. These lineages might represent two main Pleistocene refugia and differentiation centres, one located on the Italian Peninsula and the other in the Balkan region. The two lineages showed evidence of hybridization across Central Europe, from the Alps and across Germany. The intraspecific differentiation was strongest in the width of the brown band on the outer margin of the wings. The morphological structures obtained are in line with genetic signatures found in previous studies, but the latter are more fine-grained. Current environmental conditions, such as mean temperatures, were only marginally correlated with colour patterns. Our study underlines that Pleistocene range shifts, often resulting in allopatric isolation, shape intraspecific phenotypic structures within species; that pigmentation responds in a more sensitive manner to spatial disjunction than wing shape; and that morphometric and genetic structures in P. coridon provide concordant patterns and thus support identical biogeographical conclusions.