Abstract
Background: Many Croatian islands are examples of genetic isolates, with low level of heterozygosity and high level of inbreeding, due to practice of endogamy.
Aim: The aim was to study the genetic structure of two insular and one mainland population through high-resolution phylogenetic analysis of mitochondrial DNA (mtDNA).
Subjects and methods: MtDNA polymorphisms were explored in 300 unrelated individuals from Mljet, Lastovo and the coastal city of Dubrovnik, based on SNP polymorphisms.
Results: All mtDNA haplogroups found in the sample were of typical European origin. However, the frequency distribution of their subclades differed significantly from other Croatian and European populations. MtDNA haplotype analysis revealed only two possible founder lineages on Mljet and six on Lastovo, accounting for almost half of the sample on both islands. The island of Mljet also has the lowest reported haplotype and nucleotide diversity among Croatian isolates and the island of Lastovo, a new sublineage of a usually quite rare U1b clade.
Conclusion: The results can be explained by the effect evolutionary forces have on genetic structure, which is in line with the specific demographic histories of the islands. An additional research value of these two island isolates is the appearance of certain Mendelian disorders, highlighting their importance in epidemiological studies.
Acknowledgements
This study was supported by the Croatian Ministry of Science, Education and Sports, project: ‘Population structure of Croatia – Anthropogenetic approach’, project number: 196-1962766-2751, grant to P.R. Molecular analyses were performed in the Estonian Biocentre and the Institute of Molecular and Cell Biology, University of Tartu, Tartu. The funding was provided by the European Commission, Directorate-General for Research for FP7 Ecogene grant 205419, Estonian Basic Research grant SF0182474 to R.V. and E.M. and Estonian Science Foundation grant (7858) to E.M. We are thankful to Henry Harpending for the program POPSTR, which we used for the construction of the PC plot. We would also like to thank O. Balanovski for allowing us insight into his mtDNA database and Lena Kushniarevich and Lejla Kovačević for their unselfish help and suggestions. Special gratitude goes to Miro Auguštin, for his immense effort and help in modifying and refining the figures for the manuscript.
Declaration of interest: The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.