Systems of interconnected populations (metapopulations) are likely to be the rule rather than the exception in nature. Nevertheless, the study of natural systems of interconnected populations has lagged behind theoretical demonstrations of their potential importance. Coloniation, extinction, and population interconnectedness play an important role in the dynamics of the Silence alba/Ustilago violacea plant-fungal pathosystem. This system is experimentally tractable and shows host genetic variation in resistance and susceptibility,. The proposed research will continue the long-term monitoring of metapopulation processes in natural populations, assess the effect of population connectedness on local dynamics using experimental populations, and investigate empirically and theoretically the effects of genetic compostion on metapopulation dynamics of host-pathogen systems. The results will provide information on the degree to which metapopulation processes influence host-pathogen systems and how genetic variation in the component species affects these processes. This system is of general interest because the metapopulation concept provides a framework for understanding the consequences of habitat fragmentation.
