Genetic differentiation between individuals


François Rousset Laboratoire Génétique et Environement, Istitut des Sciences de l‘Évolution, CC065, USTL, Place E. Bataillon, 34095 Montpellier Cedex 05, France, Tel: +33 67 14 46 30; fax: +33 67 14 36 22; e-mail:


I describe a method of analysis of genetic differentiation which is suitable for the comparison of genetic and demographic estimates of the ‘neighborhood size’– more precisely the product of density and second moment of dispersal distance σ2– in continuous populations sampled at the smallest scale. This method is based on results of models of isolation by distance common to a wide variety of dispersal distances. The performance of this method is tested by simulation for some highly leptokurtic dispersal distributions, and it is applied to a previous study of a kangaroo-rat (Dipodomys spectabilis) population. In this case, genetic and demographic estimates are within a factor of two from each other. Thus, in line with some previous examples, this study shows that a better agreement may be attained than is usually recognized between genetic and demographic estimates.