Ancient Local Evolution of African mtDNA Haplogroups in Tunisian Berber Populations

Abstract

Our objective is to highlight the age of sub-Saharan gene flows in North Africa and particularly in Tunisia. Therefore we analyzed in a broad phylogeographic context sub-Saharan mtDNA haplogroups of Tunisian Berber populations considered representative of ancient settlement. More than 2,000 sequences were collected from the literature, and networks were constructed. The results show that the most ancient haplogroup is L3*, which would have been introduced to North Africa from eastern sub-Saharan populations around 20,000 years ago. Our results also point to a less ancient western sub-Saharan gene flow to Tunisia, including haplogroups L2a and L3b. This conclusion points to an ancient African gene flow to Tunisia before 20,000 BP. These findings parallel the more recent findings of both archaeology and linguistics on the prehistory of Africa. The present work suggests that sub-Saharan contributions to North Africa have experienced several complex population processes after the occupation of the region by anatomically modern humans. Our results reveal that Berber speakers have a foundational biogeographic root in Africa and that deep African lineages have continued to evolve in supra-Saharan Africa.

Genetic variation in Tunisia in the context of human diversity worldwide

“…It is bounded by the Sahara desert to the South, by the Mediterranean Sea on the North and East, and by Algeria to the West. Mitochondrial DNA evidence supports the idea that Tunisia was occupied more than 20,000 YBP by a group originating from sub-Saharan Africa (Frigi et al, 2010;Soares et al, 2012). By 15,000 YBP the Mechto€ ıdes, also known as Ibero-Maurisans, appear (Bedoui, 2002).…”

“…There are those who say that a civilization radiated to North Africa 40,000 years ago built by the Aterian, after which North Africa was depopulated (see the introduction to Rando et al, 1998). Indeed, uniparental genetic data support the arrival of sub-Saharans around 20,000 years ago according to Frigi et al (2010). Other studies show that the introduction of sub-Saharan mtDNA lineages in North Africa is older than 30,000 YBP (Soares et al, 2012).…”

Ancient and recent Middle Eastern maternal genetic contribution to North Africa as viewed by mtDNA diversity in Tunisian Arab populations

“…This was marked by the invasion of Bedouin tribes (Banu Hilal), followed by the Arabization and Islamization of many Berber populations. Even so, previous studies on Tunisian populations displayed the mosaic structure of the mitochondrial gene pool, which is characterized by an overall high frequency of Eurasian haplogroups (∼70%), followed by Sub‐Saharan L lineages (∼ 25%), and lesser frequencies of North African haplogroups U6 and M1 (5%) (Fadhlaoui‐Zid et al, ; Frigi et al, ; Kefi et al, ). However, of these mtDNA, only Fernandes et al () estimated the recent contribution of Near Eastern sublineages, i.e., K1a1, N1, T, J, R0a, U, and X, suggesting that they arrived around 2000 years ago, probably associated with Phoenician occupation.…”

“…Other studies revealed the arrival of some L sublineages in North Africa across the Sahel Belt during the Early Holocene at the beginning of the African Humid Period (11 000 years ago), particularly L1b and L3e5 which are commonly found in the Lake Chad Basin (Černý, Salas, Hájek, Žaloudková, & Brdička, ; Frigi et al, ; Hernández et al, ; Podgorná, Soares, Pereira, & Černý, ; Soares et al, ). Conversely, U6 and some L sublineages were introduced from northwest Africa into Iberia probably after the Younger Dryas period (Cerezo et al, ; Hernández et al, ; Podgorná et al, ; Secher et al, ; Soares et al, ).…”

“…Genetic analysis of mtDNA diversity in present‐day populations of North Africa suggested an early introduction of Sub‐Saharan lineages, with L3 arriving around 35 000 years ago (Soares et al, ) and L2a around 28 000 years ago (Frigi, Cherni, Fadhlaoui‐Zid, & Benammar Elgaaied, ). By contrast, haplogroups U6 and M1 show evidence of a westward human migration from the Near East, often described as the “Back to Africa” process (González et al, ; Olivieri et al, ), a process also suggested by nuclear genomic data (Haber et al, ; Henn et al, ).…”