Distinguishing between founder and host population mtDNA lineages in the Ashkenazi population

The size of the founding generation of founder populations is typically small. For example, studies estimate the Ashkenazi Jewish founder generation at around 150 families. Research has suggested that only a third of the original mitochondrial DNA (mtDNA) signatures survived. Unlike isolated populations, founder groups surrounded by larger populations tend to absorb mtDNA from the host population. A prior study reported that a significant portion of Ashkenazi Jews carry mtDNA of ancient European origin, leading to the hypothesis that the female founders were primarily European, while male founders were Near Eastern. This study presents a method to distinguish between founder and absorbed mtDNA lineages in contemporary Ashkenazi Jews. Adjusting the sample size, absorbed lineages appear as singletons, while founder lineages show multiple occurrences. Our analysis found that less than 15 % of current Ashkenazi Jews carry absorbed mtDNA, consistent with patterns seen in many founder populations, where absorbed matrilineal lineages outnumber founder ones. However, this does not support a non-Jewish European origin for the founding generation. Given that Y-chromosome analysis already confirms a Near Eastern origin for Ashkenazi paternal lineages, we propose that both maternal and paternal lineages share a common Near Eastern ancestry. This challenges the convoluted hypothesis of a mixed origin with Near Eastern paternal and predominantly European maternal founders.