We aim to understand how propagule banks contribute to demography and genetic diversity through a combined empirical and modelling approach. The genetic structure of sediment bound propagules and of populations from different years will be characterized in bryozoan and plant systems. Models will predict temporal changes in genotype frequencies and the proportions deriving from propagule banks. Stage structured model simulations will identify key parameters that influence demography. Our study would have broad implications regarding the ecological significance of temporal gene flow in taxa ranging from zooplankton and plants to microbes, and a mechanistic basis for characterizing demographic contributions from propagule banks.