Isonymy and migration distance

The distribution of surnames of the living immigrants in the population of the town of Ferrara was studied by sex of immigrants and by distance of their place of origin from Ferrara. It was found that isonymy decreases with distance from the place of origin and that there is sexual dimorphism in migration distance: females migrate preferentially at short distances and males at long and very long distances. As indicators of the abundance of surnames in a distribution, the common ecological indices derived from entropy were used, and compared between migration ranges. It was found that redundancy, like isonymy, decreases with migration distance, and that it may be useful in detecting very-long-distance migration.