BackgroundHabitat quality is one main trigger for the persistence of butterflies. The effects of the influencing biotic and abiotic factors may be enhanced by the challenging conditions in high-alpine environments. To better our knowledge in this field, we performed a mark-release-recapture study with Boloria pales in the Southern Carpathians.MethodsWe analysed population structure, movement and foraging behaviour to investigate special adaptations to the alpine environment and to reveal differences between sexes. We compared these aspects in one sector with and one sector without grazing to address the effects of grazing intensity on habitat quality.ResultsWe observed “soft” protandry, in which only a small number of males appeared before females, and an extended emergence of individuals over the observed flight period, dividing the population’s age structure into three phases; both observations are considered adaptations to high mountain environments. Although both sexes were mostly sedentary, movement differences between them were obvious. Males flew larger distances than females and were more flight-active. This might explain the dimorphism in foraging behaviour: males preferred nectar sources of Asteraceae, females Caprifoliaceae. Transition from the grazed to the ungrazed sector was only observed for males and not for females, but the population density was higher and the flight distances of the individuals were significantly longer on the grazed sector compared with the ungrazed one.ConclusionSoft protandry, an extended emergence of the individuals and an adapted behavioural dimorphism between sexes render to represent a good adaptation of B. pales to the harsh environmental conditions of high mountain ecosystems. However, land-use intensity apparently has severe influence on population densities and movement behaviour. To protect B. pales and other high-alpine species from the negative consequences of overgrazing, areas without or just light grazing are needed.Electronic supplementary materialThe online version of this article (10.1186/s12983-018-0298-1) contains supplementary material, which is available to authorized users.

High mountain ecosystems are a challenge for the survival of animal and plant species, which have to evolve specific adaptations to cope with the prevailing extreme conditions. The strategies to survive may reach from opportunistic to highly adapted traits. One species successfully surviving under these conditions is the here studied butterfly Erebia nivalis. In a mark-release-recapture study performed in the Hohe Tauern National Park (Austria) from 22 July to 26 August 2013, we marked 1386 individuals and recaptured 342 of these. For each capture event, we recorded the exact point of capture and various other traits (wing conditions, behavior, nectar sources). The population showed a partial protandrous demography with the minority of males emerging prior to the females, but the majority being synchronized with them. Males and females differed significantly in their behavior with males being more flight active and females nectaring and resting more. Both sexes showed preferences for the same plant species as nectar sources, but this specialization apparently is the result of a rapid individual adaptation to the locally available flowers. Estimates of the realized dispersal distances predicted a comparatively high amount of long-distance flights, especially for females. Therefore, the adaptation of Erebia nivalis to the unpredictable high mountain conditions might be a mixture of opportunism and specialized traits.

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AimCold‐adapted species had their largest distribution areas during glacial periods, whereas the subsequent interglacials led to retreats of these taxa into mountain ranges and more northern regions, but existing data are not sufficient for generalizing these range dynamics. To improve our knowledge of the different phylogeographical patterns existing for cold‐adapted species, we examined two closely related butterfly species of the genus Boloria with alpine disjunct and arctic–alpine distribution respectively.LocationEurope: High mountain areas and Scandinavia.TaxaBoloria pales and B. napaea.MethodsWe sequenced two mitochondrial (COI, ND1/trRNA/16S region) and two nuclear genes (wingless and EF‐1α) for 182 B. pales specimens from 37 localities and 60 B. napaea specimens from 12 localities representing the whole distribution area of both species in Europe. We used existing and known calibration points to date the age of the relevant splits.ResultsWhile nuclear DNA showed no genetic structures, the mitochondrial loci revealed 91 haplotypes belonging to three well‐differenced genetic lineages: (a) all samples of B. napaea from the Alps and Scandinavia, (b) the samples of B. pales from the Alps, Carpathians, High Tatra, Pirin Mountains, Dinaric Alps in Montenegro and the Apennines and (c) all samples of B. pales from the Pyrenees. The time estimates for the splits between these three groups range from 1.3 to 0.84 million years ago (mya). The further within‐groups differentiations are not older than 0.32 mya, but reveal a subtle pattern among and within mountain ranges.Main conclusionsAllopatry during the mid‐Pleistocene has led to differentiation into three major genetic groups, each of which possibly representing a separate species today. Especially within the today widespread mountain group (i.e. the pales sensu stricto group), repeated expansion out of their Alpine centre and a number of different peri‐Alpine glacial distribution areas have produced the subtle genetic structure observed over the late Pleistocene. The two other groups also show substructures, but to a lesser degree, hence, calling for a less disrupted distribution pattern during the late Pleistocene. However, the arctic populations of B. napaea are not derived from the same source as the Alpine ones.

Sexual dimorphism is a widespread phenomenon in Lepidoptera. It is reflected in differences in life history, behavior and morphology. Analyses of differences in behavior are mostly difficult and time-consuming, especially in high mountain ecosystems. To enhance our knowledge on sexual dimorphisms of alpine butterflies, we performed a mark-release-recapture study on 2 species common in the Alps: Boloria pales and Boloria napaea. We analysed movement and foraging behavior to investigate differences between sexes. Both sexes were mostly sedentary and the movement distances of males and females similar. However, obvious differences in dispersal behavior between the sexes were found in the movement patterns. Three different patterns were distinguished. Most males showed intensive flight activity, but mostly flew only in a limited part of the entire habitat (i.e., their individual home range) searching for females, whereas females were less flight active and flew only to find places for oviposition or feeding. The third pattern, where individuals flew larger distances, was only observed in a small number of males, which always returned to their home range. Nearly all feeding was observed on Asteraceae. However, males preferred the genera Leontodon and Crepis, while females preferred Leontodon and Carduus. Apart from this sexual difference in foraging, individuals of both sexes were found to be more or less specialised on nectar sources. Flight activity was generally greater in males than females. Therefore, we think that sex-specific requirements in nectar ingredients exist, that is, sugar for the intensive flight activity of males and amino acids for egg production of females.