Eastern Adriatic Islands are examples of Croatian population isolates with low genetic diversity resulting from geographic and reproductive isolation and high inbreeding level. We investigated the distribution of mtDNA haplogroups and their frequencies in two Croatian insular populations (Islands of Mljet and Lastovo) and one continental population (city of Dubrovnik). Since these two islands are part of Dubrovnik archipelago, it was interesting to compare the obtained results. We analysed 300 mtDNAs based on high resolution analysis of SNPs from the control and coding region (68 from Mljet, 51 from Lastovo and 181 from Dubrovnik) and our results confirmed the strong influence of evolutionary forces on the genetic structure of isolated populations. Although all typical European haplogroups were represented in the sample, a significantly higher prevalence of certain haplogroups and their subclades was detected - haplogroup H in general (73.5%) and H1b clade (30.9%) on Mljet, U haplogroup in general (23.5%) and U1 clade (5.9%) on Lastovo, in comparison with the mainland sample of Dubrovnik, where the haplogroup distribution and frequencies correspond to results from other European and Croatian mainland populations. Haplotype analysis revealed six possible founder lineages on Lastovo and only two on Mljet, accounting for almost half of its sample. Also, the Island of Mljet has the lowest reported gene diversity index among Croatian isolates. We can conclude that the observed impact of evolutionary forces in such small populations can cause significant departures from expected haplogroup frequencies and help us to understand still unrevealed parts of our demographic history. |
