Why did I leave home

Dispersaledited by J. Clobert, E. Danchin, A.A. Dhondt and J.D. Nichols.Oxford University Press, 2001. £45.00 (xxi + 452 pages)ISBN 0 19 850660 0In nearly all living organisms, at least some offspring settle and breed in a location at some distance from that of their progenitor or parents (a pattern generally termed ‘natal dispersal’). This fundamental biological phenomenon leads the editors of Dispersal to claim that ‘dispersal is probably the most important life history trait involved in both species persistence and evolution’. This collection of reviews, models and perspectives, however, is not simply ‘another book on dispersal’, as the editors humbly state. Dispersal is a collection of some of the most sophisticated essays in behavioral ecology and evolutionary biology.This sophistication comes at a cost. Those searching for basic ideas about dispersal could become lost among the diversity of concepts that are explored. None of the chapters provides a simple and clear historical overview of basic concepts and questions, and some background reading might be necessary before tackling the various advanced topics of the book (e.g. 1xDispersal in stable habitats. Hamilton, W.D. and May, R.M. Nature. 1977; 269: 578–581Crossref | Scopus (669)See all References, 2xMating systems, philopatry and dispersal in birds and mammals. Greenwood, P.J. Anim. Behav. 1980; 28: 1140–1162Crossref | Scopus (1910)See all References, 3xOn territorial behaviour and other factors influencing habitat distribution in birds. I. Theoretical development. Fretwell, S.D. and Lucas, H.L. Acta Biotheoretica. 1970; 19: 16–36Crossref | Scopus (2133)See all References, 4xSources, sinks, and population regulation. Pulliam, H.R. Am. Nat. 1988; 132: 652–661CrossrefSee all References, 5xSystems of mating. Wright, S. Genetics. 1921; 6: 111–178PubMedSee all References, 6xThe interpretation of population structure by F-statistics with special regard to systems of mating. Wright, S. Evolution. 1965; 19: 395–420CrossrefSee all References).Among the wide range of topics covered, several chapters address basic evolutionary hypotheses about natal dispersal that invoke influences of inbreeding avoidance, competition for resources (among kin and nonkin), and influences of mating systems (namely competition for mates and sexual asymmetries in investment in offspring). The presentation of evolutionarily stable strategies (ESS) models of the evolution of natal dispersal by Perrin and Goudet is particularly exciting, because they integrate the influences of inbreeding, kin competition, mating systems and their interactions into a general theoretical framework. There are also several chapters on habitat selection, which occurs at the end of the dispersal process. Danchin et al. explore the interesting possibility that ‘public information’, such as the reproductive success of conspecifics, might strongly influence whether an individual emigrates from the natal area, as well as settlement (‘habitat selection’) in a new patch of breeding habitat. Additional topics include measurement of dispersal (e.g. through direct tracking or indirect estimates via genetic markers), mechanisms leading to dispersal (e.g. genetic dispersal morphs, dependence on individual and environmental condition and hormonal mechanisms), the influence of trophic interactions (e.g. parasite–host and predator–prey), and the interactions of dispersal, gene dynamics and metapopulations.Most of the 25 chapters of the book are primarily review essays (13 chapters) or model presentations (five chapters, with three additional chapters that combine reviews with modeling). Chapters with new empirical work are few (five chapters) and still present more empirical review than novel data. This focus on theoretical development rather than new data gives the volume much of its sophistication, and renders it extremely thought provoking. For example, a thoughtful essay by Wiens on the spatial scale of investigation raises the possibility that extinctions of local populations might have had more influence on the evolution of dispersal patterns than is generally recognized. This idea is supported by the modeling of Gandon and Michalakis, and mentioned in other chapters. There is also an heroic attempt at synthesis of the disparate topics of the volume by Ronce et al. There are enough good ideas in this latter chapter to serve as the basis for several doctoral dissertations. Dispersal is certain to be widely cited, and should be read in many graduate seminars.