Geographic Sub-Structuring of The Island of Cres (Croatia) – Microsatellite Perspective

The island of Cres belongs to the group of Kvarner islands which is the most northern inhabited island group in the Croatian section of the Adriatic Sea. The population history of Cres provides relevant information for the interpretation of present day genetic relationships. There are many reasons why the island has been inhabited for thousands of years. First of all, the influence of world civilizations, important sea routes, the relatively high quality of natural resources and of the climate. The purpose of this anthropological and genetic study was to analyze genetic structure of the island of Cres by examining: 1) its sub-population level (eight settlements populations) 2) its relationship to five other Eastern Adriatic island populations, and 3) its relationship to the mainland Croatian population, which has substantially contributed to the current gene pool of the islands. We have analysed a sample of 122 unrelated autochthonous adult individuals from the island of Cres. Analysis of STR polymorphisms revealed genetic homogeneity among sub-populations of the island of Cres and small but significant levels of genetic heterogeneity among geographically distant Eastern Adriatic islands. Despite a considerable degree of genetic homogeneity among the studied Eastern Adriatic islands, small but significant differentiation between distant islands indicates geographic sub-structuring which follows the isolation by distance model. This study confirms that STR markers are useful tools for assessing levels of genetic differentiation between larger and geographically more distant populations.