LTREB: Genetic analysis of metapopulation processes in the Silene-microbotryum host-pathogen system

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

In nature, populations of organisms are generally clustered into distinct patches that, over time, exchange migrants and perhaps suffer extinction and later recolonization. The genetic consequences of this dynamic population fragmentation has been studied in theory, but experimental studies have lagged behind because of the large quantity of long-term data that are required. The proposed research will close this gap using nearly three decades of data collected from hundreds of populations of a plant (white campion) and an associated disease (anther smut). With these data, we will be able to follow the genetics of local populations as they are born, exchange migrants, and possibly go extinct. These observations are important for understanding how genetics affects extinction and colonization success. More broadly, understanding the dynamics of interconnected populations is fundamental to predicting how disease outbreaks can occur from local patches, how invasive species spread, or how the genetics of species can be altered when they are rare or occur in fragmented habitats. The major objective of the proposed research is to follow the process of extinction and colonization in interconnected populations and study how these processes create and destroy genetic diversity. This proposal builds on a now 28-year study of the numerical dynamics of Silene latifolia (white campion) and its pathogen Microbotryum violaceum (anther smut). This project uses a long-term population genetic approach to characterize numerous colonization and extinction events and to follow populations through time. Methods used will include long-term monitoring (eventually more than over 800 populations for >30 yrs) and continued genetic sampling (eventually >15yrs). High throughput genomic studies of Silene populations will provide unprecedented resolution of changes in genetic divergence, the parentage of newly established populations, gene flow during population expansion or contraction, the genetic consequences of seed banks and the importance of inbreeding and genetic rescue for population persistence. Also, broad demographic shifts have occurred during the course of this study, opening up the potential to explore the population genetics of non-equilibrium systems of both the host plant and the disease. The Silene/Microbotryum system has become a model for numerous labs, and this research will provide a publicly available long-term data set of demographic and genomic data, living collections, and DNA samples. This study will provide scientific training in timely important fields of ecology, genomics, bioinformatics, and computational biology.