Population analysis of Volyn region based on surname data

The aim of this study was to obtain indicators characterizing the genetic structure of the populations in Volyn Region based on surname distribution. The study utilized the surnames of 1 050 021 residents of Volyn as recorded at the beginning of the 21st century, according to the 2001 population census. The analysis employed the methodology proposed by I. Barrai et al. (1992). The total surname diversity in the region comprised 59 545 unique surnames. The surname diversity index in the general population of Volyn was α = 14,0×102, while in the urban population of Lutsk, it was slightly higher at α = 15,9×102. In district populations, the number of unique surnames was lower, ranging from 1 811 in Shatsk District to 10 578 in Ivanichi District, with surname diversity indices of α = 2,5×102 and α = 11,3×102, respectively. The isonymy index in the overall population of Volyn was I = 7,1×10⁻4, whereas in Lutsk, it was lower at I = 6,3×10⁻4, reflecting greater heterogeneity in the urban population. In district populations, this indicator varied from I = 8,9×10⁻4 in Ivanichi District to I = 40,5×10⁻4 in Shatsk District. The coefficient of random inbreeding (FST) in the general population was FST = 17,9×10⁻5, while in Lutsk, it was slightly lower at FST = 15,84×10⁻5. The highest values of FST were observed in Shatsk (FST = 101,3×10⁻5), Ratne (FST = 89,1×10⁻5), and Liubeshiv (FST = 83.9×10⁻5) districts, indicating a greater degree of genetic isolation. The population structure was also assessed using the surname redundancy index (R), which quantifies deviations from an even surname frequency distribution. In the general population of Volyn, this index was R = 36,0. In Lutsk, surname distribution was more uniform, with R = 28,0. In district populations, this index ranged from 27,2 to 41,8. The migration index (v) reflects the population’s ability to maintain its genetic structure despite the influx of migrants. In the general population of Volyn, this index was v = 13,3×10⁻4, whereas in Lutsk, it was substantially higher at v = 78,1×10⁻4. Among district populations, v varied significantly, from 55,0×10⁻4 in Ratne District to 232,9×10⁻4 in Turiisk District. These findings indicate that smaller populations have a lower capacity to preserve their genetic structure in response to migration flows.