This textbook helped to define the field of Behavioural Ecology. In this fourth edition the text has been completely revised, with new chapters and many new illustrations and full colour photographs. The theme, once again, is the influence of natural selection on behaviour – an animal's struggle to survive and reproduce by exploiting and competing for resources, avoiding predators, selecting mates and caring for offspring, – and how animal societies reflect both cooperation and conflict among individuals. Stuart A. West has joined as a co-author bringing his own perspectives and work on microbial systems into the book. Written in the same engaging and lucid style as the previous editions, the authors explain the latest theoretical ideas using examples from micro-organisms, invertebrates and vertebrates. There are boxed sections for some topics and marginal notes help guide the reader. The book is essential reading for students of behavioural ecology, animal behaviour and evolutionary biology. Key Features: Long-awaited new edition of a field-defining textbookNew chapters, illustrations and colour photographsNew co-authorFocuses on the influence of natural selection on behavior, and how animal societies reflect both cooperation and conflict among individuals "The long-awaited update to a classic in this field is now here, presenting new directions in thinking and addressing burning questions. Richly informed by progress in many other disciplines, such as sensory physiology, genetics and evolutionary theory, it marks the emergence of behavioural ecology as a fully fledged discipline.... This is a marvellous book, written in a lucid style. A must-read for those in the field, it is also a cornucopia of new thinking for anyone interested in evolution and behaviour."—Manfred Milinski, Nature, 2012