This volume contains the papers presented at a symposium on popula tion biology sponsored by the Deutsche Forschungsgemeinschaft. It was . held at the guest house of the University of Ttibingen at Oberjoch on May 15-19, 1983. Prior to this conference a small group of European biologists had met in Berlin (June 1981) and Pavia (September 1982) to discuss re search problems on the borderline between population genetics and evolutionary ecology. From the contributions and discussions at these meetings it became evident that the unification of approaches to evolutionary problems in population...