Fine-scale genetic structure in an eastern Alpine black grouse Tetrao tetrix metapopulation

Understanding genetic consequences of habitat fragmentation is crucial for the management and conservation of wildlife populations, especially in case of species sensitive to environmental changes and landscape alteration. In central Europe, the Alps are the core area of black grouse Tetrao tetrix distribution. There, black grouse dispersal is limited by high altitude mountain ridges and recent black grouse habitats are known to show some degree of natural fragmentation. Additionally, substantial anthropogenic fragmentation has occurred within the past ninety years. Facing losses of peripheral subpopulations and ongoing range contractions, we explored genetic variability and the fine-scale genetic structure of the Alpine black grouse metapopulation at the easternmost fringe of the species' Alpine range. Two hundred and fifty tissue samples and non-invasive faecal and feather samples of eleven a priori defined subpopulations were used for genetic analysis based on nine microsatellite loci. Overall, eastern Alpine black grouse show similar amounts of genetic variation (H-O = 0.65, H-E = 0.66) to those found in more continuous populations like in Scandinavia. Despite of naturally and anthropogenically fragmented landscapes, genetic structuring was weak (global F-ST < 0.05), suggesting that the actual intensity of habitat fragmentation does not completely hamper dispersal, but probably restricts it to some extent. The most peripheral subpopulations at the edge of the species range show signs of genetic differentiation. The present study gives new insights into the population genetic structure of black grouse in the eastern Alps and provides a more fine-scale view of genetic structure than previously available. Our findings will contribute to monitor the current and future status of the population under human pressures and to support supra-regional land use planning as well as decision making processes in responsibilities of public administration.