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.

Understanding how large-scale environmental variability may shape the distribution of phenotypic variation remains central to evolutionary biology. Across-species comparisons of trait variation alongside environmental gradients may offer valuable insights into how different species may respond to similar selective pressures. We conducted a comparative morphological study (>32° latitude and >47° longitude) on three closely related Argynnini butterfly species, Speyeria aglaja, Fabriciana adippe, and F. niobe . We measured wing size and coloration to assess (1) whether they respond similarly or differently to environmental factors (longitude, latitude, altitude, temperature, precipitation, solar radiation, wind speed); (2) if these factors correspond with those associated with the species’ genetic structure based on a previous study; and (3) whether correlations between phenotypic traits within individuals are species-specific. We found common and species-specific associations of climatic (precipitation, wind speed) and geographic (longitude, altitude) factors with the composite phenotypic variation. Wing size was associated with different variables in the studied species, while melanisation mainly increased in cooler regions in all species, suggesting that the need for temperature regulation is a strong selective pressure on melanisation. Wing size was associated with the genetic structure in all species, highlighting the functional importance of this trait. The environmental drivers associated with the phenotypic variation in S. aglaja and F. adippe were largely the same as those associated with their genetic structure, hinting at a genetic underpinning of the observed morphological variation due to local adaption. We report some distinct intraspecific trait correlations in S. aglaja and F. adippe , indicative of independent phenotypic integration. These phenotypes seem to be associated with protection against predators and thermal regulation in the respective habitats of both species, suggesting that similar selective pressures have resulted in the evolution of different trait combinations. Some of the inter-specific differences could be related to diverging niche breadths and dispersal capacities, exemplifying that the evolution of trait integration and spatial phenotypic differentiation may differ between closely related species with overlapping distribution ranges. Our findings highlight the importance of comparative assessments of variation, and demonstrate that the relative effects of drivers of variability may vary between sister species.

Understanding which factors and processes are associated with genetic differentiation within and among species remains a major goal in evolutionary biology. To explore differences and similarities in genetic structure and its association with geographical and climatic factors in sympatric sister species, we conducted a large-scale (>32° latitude and >36° longitude) comparative phylogeographical study on three Argynnini butterfly species (Speyeria aglaja, Fabriciana adippe and F. niobe) that have similar life histories, but differ in ecological generalism and dispersal abilities. Analyses of nuclear (ddRAD-sequencing derived SNP markers) and mitochondrial (COI sequences) data revealed differences between species in genetic structure and how genetic differentiation was associated with climatic factors (temperature, solar radiation, precipitation, wind speed). Geographical proximity accounted for much of the variation in nuclear and mitochondrial structure and evolutionary relationships in F. adippe and F. niobe, but only explained the pattern observed in the nuclear data in S. aglaja, for which mitonuclear discordance was documented. In all species, Iberian and Balkan individuals formed genetic clusters, suggesting isolation in glacial refugia and limited postglacial expansion. Solar radiation and precipitation were associated with the genetic structure on a regional scale in all species, but the specific combinations of environmental and geographical factors linked to variation within species were unique, pointing to species-specific responses to common environments. Our findings show that the species share similar colonization histories, and that the same ecological factors, such as niche breadth and dispersal capacity, covary with genetic differentiation within these species to some extent, thereby highlighting the importance of comparative phylogeographical studies in sympatric sister species.

Ecological theory postulates that the size and isolation of habitat patches impact the colonization/extinction dynamics that determine community species richness and population persistence. Given the key role of lotic habitats for life-history completion in rheophilic fish, evaluating how the distribution of swift-flowing habitats affects the abundance and dynamics of subpopulations is essential. Using extensive electrofishing data, we show that merging island biogeography with meta-population theory, where lotic habitats are considered as islands in a lentic matrix, can explain spatio-temporal variation in occurrence and density of brown trout ( Salmo trutta ). Subpopulations in larger and less isolated lotic habitat patches had higher average densities and smaller between-year density fluctuations. Larger lotic habitat patches also had a lower predicted risk of excessive zero-catches, indicative of lower extinction risk. Trout density further increased with distance from the edge of adjacent lentic habitats with predator ( Esox lucius ) presence, suggesting that edge- and matrix-related mortality contributes to the observed patterns. These results can inform the prioritization of sites for habitat restoration, dam removal and reintroduction by highlighting the role of suitable habitat size and connectivity in population abundance and stability for riverine fish populations.

We tracked the movements of adult Ringlet butterflies (Lepidoptera, Nymphalidae, Erebia Dalman, 1816) in high-elevation (> 1800 meters a.s.l.) grasslands in the Austrian Alps in order to test if an anthropogenic boundary (= an asphalt road) had a stronger effect on butterfly movement than natural habitat boundaries (trees, scree, or dwarf shrubs surrounding grassland sites). 373 individuals (136 females, 237 males) belonging to 11 Erebia species were observed in one flight season (July–August 2013) while approaching or crossing habitat edges. Erebia pandrose (Borkhausen, 1788) was the most abundant species with 239 observations. All species studied were reluctant to cross habitat boundaries, but permeability was further strongly affected by the border type. Additional variables influencing movement probability were species identity and the time of the day. In E. pandrose, for which we had sufficient observations to analyse this, individuals were more likely to cross a boundary in the morning and in the late afternoon than at midday. Erebia euryale (Esper, 1805) and E. nivalis Lorković & de Lesse, 1954 were more likely to leave a habitat patch than their studied congeners. The key result of our study is that the paved road had the lowest permeability among all edge types (0.1 likelihood of crossing when approaching the edge). A road cutting across a conservation area (viz. a national park) thus hinders inter-patch exchange among Ringlet butterflies in the alpine zone, even though theoretically they ought to be able to fly across.

Mobility may affect species' distribution patterns in heterogeneous landscapes, and it might impact fitness by influencing mating success, predation avoidance, and foraging success. Here, we studied causes and consequences of mobility patterns in butterflies: Argynnis adippe, a specialist constrained to warm microhabitats within woodland landscapes, and A. aglaja, a relative generalist that also inhabits grasslands, and tolerates lower temperatures. We explored associations of movement and occurrence patterns, population size and density, niche breadth, wing size, and different types of behaviour prior to capture by conducting a mark‐release‐recapture study on the Swedish island Öland. We marked 1 935 A. aglaja and 123 A. adippe and achieved recapture rates of 9.5% (A. aglaja), and 8.9% (A. adippe). Estimated population densities were 5 066 and 814 individuals per km2, for A. aglaja and A. adippe, respectively. Argynnis aglaja was less likely to perform long‐distance flights according to estimated dispersal kernels, hinting at negative density‐dependent dispersal in these species. Although we detected the longest flight distances ever in these species in MRR studies (11.9 km for A. aglaja and 3.7 km for A. adippe), most butterflies were recaptured within 200 meters (60–80%). Low recapture rates along with low estimated residence times and the potential for long movement might indicate that many individuals left the study area, and that the species form open populations, stretching over large areas. Despite significant differences in wing size and behaviour types, mean observed flight distances were similar in these species.

Animal colour patterns long have provided information about key processes that drive the ecological and evolutionary dynamics of biological diversity. Theory and empirical evidence indicate that variation in colour patterns and other traits among individuals generally improves the performance of populations and species, for example by reducing predation risk, increasing establishment success, improving resilience to environmental change, and decreasing risk of extinction. However, little is known about whether and how variation in colour pattern among species is associated with variation in other phenotypic dimensions. To address this issue, we analysed associations of colour pattern with morphological, behavioural and life‐history traits on the basis of data for nearly 400 species of noctuid moths. We found that moths with more variable colour patterns had longer flight activity periods, more diverse habitats and a greater number of host plant species than species with less variable colour patterns. Variable coloration in adult noctuid moths therefore can be considered as indicative of broader niches and generalist diets. Colour pattern variability was not significantly associated with overwintering stage or body size (wing span), and it was independent of whether the colour pattern of the larvae was non‐variable, variable or highly variable. Colour pattern variation during the larval stage tended to increase as the duration of the flight activity period increased, but was independent of the length of the larval period, diet breadth and habitat use. The realization that information on colour pattern variation in adult moths, and possibly other organisms, offers a proxy for niche breadth and dietary generalization can inform management and conservation biology.

Dispersal is a crucial feature for the long-term survival of metapopulations. Each individual that leaves the habitat and enters the matrix takes a risk. Consequently, even winged organisms, like butterflies, are often extremely sedentary and spend much of their lifetime in very restricted areas. For such species, large roads may be a serious obstacle for movement. Here, we aim to study if a large and highly frequented road in an alpine environment hinders the movement of relatively sedentary butterflies of the genus Erebia. We conducted a mark-release-recapture study on six alpine Erebia species (E. eriphyle, E. epiphron, E. gorge, E. pharte, E. pandrose and E. nivalis) in the Hohe Tauern National Park, Austria. We measured the following variables which we hypothesize to affect movement probability: (a) species identity, (b) nectar resource availability, (c) butterfly age or (d) patch isolation through the road. Population density estimates ranged from 230 ± 35 individuals for E. pharte to 1,316 ± 205 individuals for E. epiphron per hectare. More than 50 percent of recaptured butterflies were tracked within distances of <25 m. The maximum flight distance recorded was 332 m (E. epiphron). Our data indicate that species identity generally did not have a significant effect on mobility patterns in the studied Erebia butterflies. Only one species, E. pharte, was more likely to change the plot than the others. High resource availability decreased butterfly movement. Age influenced mobility, with mid-aged butterflies being most likely to move between patches. The road hindered dispersal. Butterflies which had to cross the road to get to another suitable habitat patch were less likely to move than butterflies that did not have to cross the road.

Dispersal is a crucial feature for the preservation of butterfly metapopulations, which can be affected by habitat fragmentation. Each individual that enters the matrix takes a risk. Therefore, even winged organisms, like butterflies, are often extremely sedentary and spend their whole lifetime in a relatively small area. For such species, large roads may constitute a real obstacle for movement. We conducted a mark-release-recapture study on six alpine Erebia species in the Hohe Tauern National Park in order to investigate if theGroßglocknerHochalpenstraße – a large and highly frequented road in an alpine environment – acts as a barrier to movement for these relatively sedentary butterflies. We aimed at analysing which of the following variables predicts movement probability: (a) species membership, (b) ecological specialization, (c) nectar availability, (d) age or (e) patch isolation. We marked a total of 429 individuals, of which 113 were recaptured. Our data indicates that neither body-size nor ecological specialization significantly influenced mobility patterns in these Erebia butterflies.Butterflies that were on a patch with a high nectar level were less likely to leave the patch. Age influenced mobility with mid-aged butterflies being most likely to change between patches. The road, however, seemed to be a barrier for dispersal. We found that butterflies that had to cross the road to get to another suitable habitat patch were less likely to leave the patch than butterflies that did not have to cross the road.

Ausbreitung ist eine wesentliche Eigenschaft fur den Erhalt von Schmetterlings-Metapopulationen, welche durch Habitatfragmentierung beeintrachtigt werden kann. Jedes Individuum, das das Habitat verlasst und in die Matrix eintritt, geht ein Risiko ein. Deshalb sind sogar oft geflugelte Organismen wie Schmetterlinge sehr sedentar und verbringen ihr gesamtes Leben auf relativ kleinen Flachen. Fur solche Arten konnen grose Strasen ein betrachtliches Hindernis fur die Fortbewegung darstellen. Ich fuhrte eine Fang-Wiederfang-Studie an sechs verschiedenen alpinen Erebia Arten im Nationalpark Hohe Tauern durch, um herauszufinden ob die Grosglockner Hochalpenstrase – eine breite, hochfrequentierte Strase in alpiner Umgebung – eine Barriere fur die Fortbewegung dieser Schmetterlinge darstellt. Indem ich sechs Arten untersuchte, die sich in Korpergrose und ihren okologischen Anspruchen unterscheiden, beabsichtigte ich aufzuklaren, welche der folgenden Variablen die Wahrscheinlichkeit fur Fortbewegung voraussagen: (a) Artzugehorigkeit, (b) okologische Spezialisierung, (c) Ressourcenangebot, (d) Alter oder (e) Habitatisolierung. Ich schatzte auserdem die Populationsgrosen dieser sechs Erebia Arten. Insgesamt wurden 429 Individuen gefangen, von welchen 113 wiedergefangen wurden. Meine Daten weisen darauf hin, dass weder Korpergrose noch okologische Spezialisierung die Mobilitatsmuster in diesen Mohrenfaltern signifikant beeinflussen. Die Strase jedoch schien ein Hindernis fur die Ausbreitung zu sein. Ich zeigte, dass Schmetterlinge, die die Strase uberqueren mussten um zu einem geeigneten Habitat-Patch zu kommen, mit geringerer Wahrscheinlichkeit den Habitat-Patch verliesen als Schmetterlinge, die die Strase nicht uberqueren mussten. Schmetterlinge, die sich auf einem Habitat-Patch mit einem hohen Nektaranteil befanden, verliesen mit geringerer Wahrscheinlichkeit den Patch. Das Alter beeinflusste die Mobilitat dahingehend, dass Schmetterlinge mittleren Alters mit der hochsten Wahrscheinlichkeit zwischen den Patches wechselten.