Distribution of isonymy index in the territory of Ukraine

Purpose of the study: to calculate the irrationality index Ir for the population of the region level, to analyze the regularity of distribution of its values in the territories of Ukraine, which differ in geographical conditions and previous history of population formation. Methods. Using total names, isonymy indices for the entire population of Ukraine, individual regions and oblasts are calculated. Results. The Ir index for the whole population of Ukraine is 2,13×10-4. In some regions of Ukraine it has the following meanings: east – 2,69×10-4, south - 2,23×10-4, center - 3,15×10-4, north - 3,40×10-4, west – 2,40×10-4. The Ir frequency distribution map for regional populations shows a gradient of this index rising from the southeast to the northwest of the country. The minimum Ir value is observed in the Crimea (1,61×10-4), the maximum in the Volyn region (7,14×10-4). Conclusions. The Ukrainian population isonymy index is of the same order of magnitude as in other European countries. The territorially dependent variation of the isonymy index is explained in the peculiarities of the history and landscape of the area. Keywords: population, isonymy, surnames, migration, genetic drift.