Population ecology is the study of the abundance and distribution of organisms at the scale of a group or groups of organisms that are related to each other taxonomically or functionally. As such it represents the bulk of ecological research and is a fundamental discipline for courses in ecology degrees at the senior undergraduate and beginning graduate level. This book is for undergraduate or graduate students who have had a basic course in ecology and are ready for a more advanced examination of population ecology.  After more than 35 years of teaching population ecology the authors approach is not to teach theory for the sake of theory, but rather to allow students to apply population principles to real-life problems. This book teaches students to integrate population ecology with the challenges presented by work in conservation and environmental biology. The first edition was unique and successful because of the emphasis on interactions beyond the usual competitive and predator-prey interactions.   Graphs, simulations, sample problems and other aids were included to help students visualize what the equations were trying to tell them these are expanded in this edition. Each chapter continues to feature laboratory and field studies to illustrate how theory can translate into a better understanding of the natural world. There are up-to-date examples of laboratory and field work, including field studies using new molecular based and GIS based methodologies. The first edition is currently used all over the world.