The model of the Belgorod oblast population has been used to demonstrate different effects of administrative reforms on microevolution in human populations. For the populations that formerly belonged to Kursk oblast, changes in the regional administrative structure (after which some of them remained in Kursk oblast and others were included into Belgorod oblast) have lead to an increase in the genetic distances between them. However, other populations (formerly belonging to Voronezh oblast) have become genetically closer to one another, although these populations now belong to different administrative regions (Belgorod and Voronezh oblasts).