The Genetic Variability of Present-Day Bulgarians Captures Ancient and Recent Ancestral Contributions

Abstract

Objectives Thanks to its pivotal crossroad position, Bulgaria played a fundamental key role during all the migration processes that interested the continent through time. While the genetic variability of the country has been deeply investigated using uniparental markers, previous genome-wide autosomal-based surveys mainly consisted of wider-range analyzes on Europe and the whole Balkan Peninsula. Here, we specifically focused on the Bulgarian population to recapitulate the main patterns of genomic variation and the major events that shaped the present-day genetic landscape. Methods A total of 112 samples from seven highly representative areas of present-day Bulgaria were collected and genotyped for approximately 720 K genome-wide SNPs, and integrated with previously generated genomic data from wide modern and ancient reference panels to explore fine-scale relationship patterns and detail ancestral contributions. Results In addition to the combination of ancient ancestries related to the early Mesolithic hunter-gatherers, Neolithic farmers, and Bronze Age Steppe pastoralists, both haplotype-based analyzes on modern populations and the comparisons with ancient genomes suggest the contribution of population processes that have occurred after the Roman rule and during the Medieval period in shaping the current Bulgarian genetic pool. Conclusions Our results align with previous evidence highlighting the impact that some historical events may have had not only in contributing to the ethnical and socio-cultural richness of present-day populations, but also in participating in the formation of the current genomic landscape. By providing new data from modern highly-representative samples, this study integrates further research to provide a comprehensive overview of the genetic history of Bulgaria.