Logically, genetics and ecology should be complementary disciplines - at least at the population biology level. In reality this is not the case, and the emphasis of genetical and ecological textbooks and courses are often so different that the disciplines in which they are taught can appear to be dealing with different concepts. This book in the BES Symposium series aims to dismantle specialist approach and to unify the two disciplines where possible and appropriate. This volume is divided into four sections. Section One discusses the influences of population genetics on our view of ecology. Part Two reviews the use of molecular methods in the investigation of adaptation and ecological processes. The third section discusses the integration of ecological principles with genetics, and the last section includes a brief description of molecular and genetical techniques appropriate and helpful in the work of ecologists.