Isolation by distance in Germany

The isonymy structure of Germany has been studied by using the surname distributions in private telephone users. Germany was subdivided in 50 adjacent rectangles having side 115x80 kms; at least the largest town in the rectangle was selected and the private telephone users in its district were included in the analysis. The number of different surnames found in the whole analysis was 462,580. Lasker's distance was found to be linearly and significantly correlated with the geographic distance, with r=0.51±0.010. A dendrogram was built with the matrix of isonymy distance, using the UPGMA method. It separates the German towns in two main clusters, one in the southern half of the country and the other in the northern. The two main clusters correspond fairly well to the north-south division of german sublanguages (Nieder and Mitteldeutsch in the North vs. Frankish-Alemannisch in the South). The other clusters are related to minor sublanguages. Comparisons with the results of a previous analysis, show that isolation by distance in Germany is less strong than in Switzerland and indicate that this Country has a fairly homogeneous isonymy structure.