Das Projekt "Genetische Auswirkungen auf kleine, zersplitterte Vogelpopulationen" wird vom Umweltbundesamt gefördert und von Universität Basel, Departement Integrative Biologie, Zoologisches Institut durchgeführt. 1. How does the spatial structure of the habitat and gene flow influence local genetic diversity? 2. Does inbreeding in wild birds lead to a decline in reproductive success that could cause local extinctions? Conservation biologists have become increasingly concerned about reductions in genetic variability, individual survival, and fecundity that occur due to inbreeding (inbreeding depression), particularly in small populations of endangered species. However, the extent of inbreeding depression in the wild is still unknown mostly due to the general lack of relevant data. Our project investigates genetic effects in small, subdivided populations, using Song Sparrows as a model. The existing pedigree is based on 20 years of research on a met population of Song Sparrows on the West Coast of Canada and allows an analysis of inbreeding and fitness. We also use micro satellite markers to examine the genetic variation. Our preliminary results show that inbreeding reduced the survival of juvenile Song Sparrows over the whole study period. In particular, inbred birds were five times less likely to survive a severe bottleneck caused by a winter storm than were non-inbred birds. Thus, inbreeding depression was expressed in the face of a common environmental challenge, and one that is also likely to be faced by inbred populations of endangered species. Complementary information: One of the major human impacts on natural populations is loss and fragmentation of habitats. The local populations which result from the sub-division may become so small that stochastic effects on the population dynamics cause the extinction of these local populations. Hence, we must understand the ecological and evolutionary dynamics of small, subdivided populations to manage and preserve them. Extinction is fundamentally a demographic process, influenced by genetic and environmental effects. Genetical effects on the demography of small populations have been neglected. We propose research to examine genetical effects in two small, subdivided populations of birds. We apply for support to improve our basic knowledge of the interactions between and significance of reproductive isolation through habitat fragmentation, different kinds of genetic variation and the level of gene flow for population dynamics, particularly met population dynamics. We will 1. Examine the importance of dispersal, gene flow and the source/sink characteristics of the local populations for the dynamics of the met population using an approach combining description and field experiments. 2. Assess the effects of inbreeding on reproductive success. We will use extensive existing data sets for pedigree analysis and examine experimentally the effects of close inbreeding on reproductive success.