This award will support a two-year U.S.-Japan cooperative science research project between Dr. Hal Caswell, Biology Department, Woods Hole Oceanographic Institution, and Dr. Nanako Shigesada, Department of Biophysics, Kyoto University. The investigators will collaborate on the development of mathematical population models. The models are intended to simulate population processes more realistically than current models through the incorporation of the effects of spatial structuring in local populations. Dr. Caswell specializes in discrete models, while Dr. Shigesada specializes in continuous models. The objective of the research is to investigate the relationships among different classes of spatio-temporal models, particularly contrasting and comparing discrete and continuous approaches. By clarifying the conditions under which different kinds of models are appropriate, the work will be of widespread applicability to ecologists interested in population modelling.