Maternal genetic legacy of the eastern Adriatic island of Krk--an interplay of evolutionary forces and island's historical events in shaping the genetic structure of contemporary island population.

This study presents genetic diversity and structure of contemporary Krk islanders revealed by high-resolution mitochondrial DNA analysis on a sample of 132 unrelated autochthonous adults from seven different settlements and regions of the island. Relatively high level of haplogroup and haplotype diversity in the overall island sample is an indicator of numerous migrations and gene flows throughout the history. Expectedly, the results show the highest frequency of haplogroup H (33.3%), yet this value is much lower compared to different Croatian and other European mainland populations. An interesting finding refers to highly elevated frequencies of some haplogroups, otherwise rare in Croatia and most of the Europe, such as I (11.3%) and W (7.6%) in Krk population, especially pronounced in some settlements. At the level of settlements, many of the major European haplogroups were found to be absent from their mtDNA gene pools, whereas several others show a pronounced deviation from an average. Overall, our results suggest a tangled interplay of different evolutionary forces, such as founder effects and a few strong bottlenecks, presumably due to epidemics, which have occurred in various periods of the island's history. Cultural customs, such as frequent endogamy in some regions of the island during past centuries, have additionally shaped its genetic structure into the observed present-day diversity patterns.