Dispersal

Dispersal is one of the most central concepts in ecology and evolutionary biology, and aects the ecology and distribution of individuals, populations and communities, as well as genetic dierentiation, local adaptation and evolutionary persistence of populations and species. Despite this wideranging and long-recognised signi®cance, the mechanisms and extent of dispersal are not well understood, in part because its measurement has traditionally presented considerable diculties. Recent advances in ecological and genetic methods, and in the theoretical basis of computer models, however, now allow a more thorough and integrated approach to the investigation of dispersal. In this multi-authored book, Clobert et al. bring together population ecologists, molecular and quantitative geneticists, computer modellers, evolutionary biologists and conservationists, thus providing the basis for an interdisciplinary discussion of dispersal. It is this interdisciplinarity that makes the book a particularly valuable addition to the bookshelf, providing `intellectual dispersal opportunities for an unusually broad range of ideas' (foreword by Peter Waser). The book concentrates on reviews of speci®c aspects of dispersal, including its measurement, causes and mechanisms, and its evolutionary and applied signi®cance, with a few interesting case studies illustrating pertinent points. The language in most chapters is suciently simple to allow nonexpert readers an understanding and assessment of the topic, an important aspect in an interdisciplinary book. Extensive cross-referencing among chapters provides helpful links and aids the crossing of disciplinary boundaries. Perhaps the most useful features of the book are the conclusions in many (unfortunately not all) chapters, which not only summarise the information presented, but also point out gaps in knowledge and future research directions. The book therefore provides an outlook on potential developments in the ®eld, a topic sadly missing in many other books and review papers. Can Dispersal tell us everything there is to know about dispersal? Perhaps because of the wide coverage of disciplines and methods in the book, its scope of ecological systems and factors aecting dispersal is remarkably narrow considering the very general and non-descriptive title. As the editors state in their introduction, the inclusion of all aspects of dispersal would be far too ambitious, and under-representation of some taxa and systems is almost inevitable. However, the book concentrates very much on biotic factors aecting active dispersal, including condition, behaviour, intraand interspeci®c competition, predation, parasitism and others. Much less consideration is given, for example, to features facilitating (e.g. currents, air ̄ow etc.) or hindering (e.g. geographic barriers, hydrographic fronts) passive dispersal, for example in many invertebrate and plant species. Given the extensive literature on marine dispersal, the shortage of examples from aquatic species, and factors aecting their dispersal is unfortunate. Furthermore, there is little discussion of how phylogeography and population history may aect extant patterns of genetic dierentiation and thus estimates of dispersal. While such biases do not necessarily compromise the value of the book, a more speci®c title better describing its scope would have been useful. On balance, I highly recommend the book for scientists who are interested in an integration of genetic, demographic and theoretical approaches, and who want exciting perspectives on the future in the ®eld. However, people looking for an exhaustive review on all aspects of dispersal, especially in aquatic and plant systems, may be disappointed.