Geographical repartition of surnames and genetic structure in the French county of Ardeche at the beginning of the XXth century.

The analysis of the geographical distribution of surnames (whose transmissi on in the European societies is similar to that of the Y chromosome) allows to study in an exhaustive way the spatial and temporal human population st ructure and the influence of environmental variations on this structure. Th e genetic structure of the Ardeche county was analysed through a study of t he surname characteristics (diversity, frequency, geographical dispersion, etc.) of individuals born between 1891 and 1915. The estimation of the intr a-community average consanguinity and the inter-district genetic relationsh ips reveals a clear differentiation between populations of the mountainous part (geographically isolated, highly inbreeded) and those of the Rhone val ley (less isolated, weakly inbreeded). As predicted by the isolation by dis tance model, inter-population coefficients of kinship decreases as distance increases, confirming the presence of a spatial structure, characterized b y neighborhood exchange and resulting from former migratory flow. (C) 2001 Academie des sciences/Editions scientifiques et medicales Elsevier SAS.