A revival for group living Living in Groups by Jens Krause and Graeme D. Ruxton. Oxford University Press, 2002. £24.95, pbk (210 pages) ISBN 0 1985 0818 2

View Large Image | Download PowerPoint SlideThis slender volume critically reviews exciting issues and outlines areas for further research in the field of group living. The authors first thought of writing a book about shoaling in fish but were persuaded instead to write this conceptual book, and I am glad that they did. Although the title echoes Bertram's review in the first edition of Krebs and Davies [1xLiving in groups: predators and prey. Bertram, B.C.R. : 64–96See all References[1], this new book takes a fresh look at some of the classic issues in behavioral ecology, including the costs and benefits of grouping. I envisage that Living in Groups will become a benchmark for the next generation of studies within behavioral ecology.The authors begin by stating the topics that they will cover and referring readers elsewhere for topics, such as reciprocal altruism and social insects, that do not quite fit in this book. They then define groups based on exchange of information between group members, leaving each reader to find a working definition for a group of their particular study organism. I agree that information exchange is the principle for delineating groups and foresee that we will learn much about our organisms as we endeavor to apply this principle.The book can be divided into three parts. The first deals with the costs and benefits of grouping, including how attacks can be avoided, diluted, or abated by grouping, a framework that applies to parasites as well as to predators. There is little in this section about the costs of group living, reflecting how little we know about this subject. The authors call on researchers to correct this imbalance as it is important to our understanding of group living in general.The middle section of the book discusses the size and composition of groups. After explaining some old arguments about why the equilibrium size of groups will often be larger than the optimal size, the authors call for critical tests of group size and calling that recruits others to food. I found the authors' thoughts to be clear and refreshing. In particular, I agree that experimental manipulations of group size are the way to expose the costs and benefits of living in groups of different sizes. These issues are affected by the distribution of costs and benefits among group members. Within groups, different positions often have different foraging and predation consequences. When different kinds of organism gather together, the problems are compounded. Among many cogent points in this section, I particularly enjoyed the discussion of oddity effects. Predators might target the odd member of a group for attack but evidence indicates that such an individual can still be safer in a group than on its own.The final section deals with evolutionary considerations, environmental effects and mechanisms. These chapters contain many gems but I most remember a few pages of commentary about cooperative breeding, multi-level selection models and self-organization. I was impressed at the amount of thought that the authors had invested into each of these topics, even though they could have completed the book without mentioning them.Living in Groups brims with suggestions for further research and concludes with a sketch for a research program. The thoughtful analysis and genuine excitement found throughout the book culminate in the closing remarks. The authors summarize the field as being full of ‘vibrant science going on and many interesting questions that have still to be addressed’ and call upon readers to ‘help make this book out of date’! I am excited by the prospects, particularly for experimental and comparative studies. This will be the first book that I hand to a new graduate student and I recommend it to all biologists who think about animals that live in groups.