Millennia of Mitochondrial Change: Tracing Haplogroup Variation in Lithuania

Background. The mitochondrial DNA (mtDNA) of modern-day Lithuanians has been previously studied, and ancient samples have provided insights into earlier populations; however, a comprehensive temporal analysis of haplogroup variation across Lithuanian history remains limited. Therefore, this study investigates the mtDNA haplogroup landscape during the Iron Age compared to the new mtDNA modern data from Lithuania. Methods. Remains of individuals from the Roman (n = 29), Migration (n = 48), and Viking (n = 24) periods spanning Eastern, Central, and Western Lithuania were processed using protocols from Witas et al. (2015). For the modern-day Lithuanian population sample (n = 279), DNA was extracted from venous blood and mtDNA sequenced (352x coverage). Haplogroups were assigned using 36 loci with Haplogrep v2. Results. Fourteen distinct haplogroups in the Iron Age group were identified. Haplogroup H consistently dominated across all periods. The L haplogroup, present during the Roman and Viking periods, was not found in the modern-day Lithuanian population. Despite temporal variation, the top three haplogroups remained relatively stable (H, U, T). Conclusions. mtDNA haplogroup variation landscape over time reveals both persistence and transformation in haplogroup composition. And while haplogroup H remained stable, haplogroup L vanished over time, confirming a dynamic population history. Together with previous ancient mtDNA studies, our results show an influx of haplogroup H into the territory of present-day Lithuania in the late Bronze Age and the early Iron Age.