Counting the founders: the matrilineal genetic ancestry of the Jewish Diaspora

Abstract

The history of the Jewish Diaspora dates back to the Assyrian and Babylonian conquests in the Levant, followed by complex demographic and migratory trajectories over the ensuing millennia which pose a serious challenge to unraveling population genetic patterns. Here we ask whether phylogenetic analysis, based on highly resolved mitochondrial DNA (mtDNA) phylogenies can discern among maternal ancestries of the Diaspora. Accordingly, 1,142 samples from 14 different non-Ashkenazi Jewish communities were analyzed. A list of complete mtDNA sequences was established for all variants present at high frequency in the communities studied, along with high-resolution genotyping of all samples. Unlike the previously reported pattern observed among Ashkenazi Jews, the numerically major portion of the non-Ashkenazi Jews, currently estimated at 5 million people and comprised of the Moroccan, Iraqi, Iranian and Iberian Exile Jewish communities showed no evidence for a narrow founder effect, which did however characterize the smaller and more remote Belmonte, Indian and the two Caucasus communities. The Indian and Ethiopian Jewish sample sets suggested local female introgression, while mtDNAs in all other communities studied belong to a well-characterized West Eurasian pool of maternal lineages. Absence of sub-Saharan African mtDNA lineages among the North African Jewish communities suggests negligible or low level of admixture with females of the host populations among whom the African haplogroup (Hg) L0-L3 sub-clades variants are common. In contrast, the North African and Iberian Exile Jewish communities show influence of putative Iberian admixture as documented by mtDNA Hg HV0 variants. These findings highlight striking differences in the demographic history of the widespread Jewish Diaspora.

Figure 1. A median joining network representing all founding lineages found among Jewish communities and comprised of the 49 novel complete mtDNA sequences from non-Ashkenazi Jews and the four Ashkenazi lineages previously reported by Behar et al. .

The nodes represent the Jewish communities in which the lineages were found. The network should not be regarded as demonstrating all nested bifurcations known to exist under each Hg, but as a schematic tree indicating the wide range of Jewish lineages spread throughout the human mtDNA phylogeny. Nucleotide positions in red correspond to the diagnostic positions inferred from the complete sequences information and checked in all samples suspected as a monophyletic lineage from the control region information. The three complete sequences that could not be clearly proved as monophyletic lineages are marked by an asterisk. Mutations are transitions, unless the base change is explicitly indicated. Deletions are indicated by a “d” following the deleted nucleotide position. Insertions are indicated by a dot followed by number and type of inserted nucleotide(s). The background colorization denotes the gross affiliation of the lineages into the following geographic mtDNA gene pools: green for West Eurasia, pink for Africa and blue for South Asia/ India. The information of the reported samples is presented in Table 2. To create the topology map we have applied the reduced median algorithm (r = 2), followed by the median-joining algorithm (epsilon = 2) as described at the Fluxus Engineering Website (www.fluxus-engineering.com).

Figure 2. Phylogeny networks of the Azerbaijani (a), Georgian (b) and Libyan (c) Jewish case studies.

The trees encompasses the coding region diagnostic positions (in bold) derived from the complete sequence information and the HVS-I information of all samples included. The same considerations detailed in figure 1 are relevant here. Circle sizes are proportional to the haplotype frequency in the sample.