Intraspecific variation in sex-biased dispersal of a threatened ecotone butterfly between forest patches in a mosaic landscape.

Forest patches are vital for saving biodiversity in fragmented temperate agricultural landscapes. They support threatened species, e.g. the charismatic Clouded Apollo butterfly, Parnassius mnemosyne, which lives at forest-meadow edges as it requires resources available in both of these biotopes. Dispersal is a key process to ensure gene flow and the colonization of vacant patches, hence knowledge on mobility is key in the context of conservation. Using intensive mark-recapture sampling, we investigated a lowland metapopulation inhabiting a complex of coppiced forest patches and adjacent grasslands in NE Poland. In order to account for intra-specific variability in movement abilities, three size groups based on their wing length were distinguished. Large males covered significantly longer distances than small ones. In turn, larger females undertook dispersal most frequently, but also experienced significantly higher mortality compared to all other groups of both sexes. This implies that higher emigration propensity (at least in females) do not necessarily translate into greater dispersal success. The movements of all butterflies were relatively short, which indicates restricted dispersal, despite the lack of clear barriers. The current forest management appears optimal, but changes in the use of open spaces may lead to a loss of connectivity within the focal system.