The influence of populations substructuring on statistical forensic parameters of genetic STR markers in the area of South-Eastern Europe

Population substructuring due to organization into small groups has probably been a characteristic demographic feature during the vast majority of human population history, and persists today to a greater or lesser extent in many rural areas. As some of the few persisting isolates among contemporary South-Eastern European (SE European) human groups, isolated Croatian islands are among the most suitable models for theoretical analyses differentiation and substructuring. In this study the data obtained by means of the analysis of 9 autosomal STR loci of microsatellite DNA in Croatian islands and Slovenian populations were integrated with the published data from other Croatian islands and wide SE European region. The sample was defined hierarchically and the influence of isolation of the Croatian insular populations on substructuring of the population of Croatia, as well as the influence of the regional population groups on substructuring of South- Eastern Europe was detected. Due to the decreased influence of endogamy, lower genetic differentiation was detected at the higher level of grouping of SE European populations (FST = 0, 002) than at the level of sub-populations of Croatia (FST = 0, 005). Finally, the influence of substructuring of the aforementioned levels on the calculation of forensic statistical parameters was determined. It was found that the isolation of Croatian insular populations affects the value of forensic parameters. This led to the modelling of adequate sampling of the entire population when creating the DNA database of genetic STR markers that would reflect all characteristics of its subpopulations.