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.
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.
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.
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°
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.
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