Sabeh Frigi

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.

ABSTRACT Objectives North Africa has a complex demographic history of migrations from within Africa, Europe, and the Middle East. However, population genetic studies, especially for autosomal genetic markers, are few relative to other world regions. We examined autosomal markers for eight Tunisian and Libyan populations in order to place them in a global context. Materials and Methods Data were collected by TaqMan on 399 autosomal single nucleotide polymorphisms on 331 individuals from Tunisia and Libya. These data were combined with data on the same SNPs previously typed on 2585 individuals from 57 populations from around the world. Where meaningful, close by SNPs were combined into multiallelic haplotypes. Data were evaluated by clustering, principal components, and population tree analyses. For a subset of 102 SNPs, data from the literature on seven additional North African populations were included in analyses. Results Average heterozygosity of the North African populations is high relative to our global samples, consistent with a complex demographic history. The Tunisian and Libyan samples form a discrete cluster in the global and regional views and can be separated from sub‐Sahara, Middle East, and Europe. Within Tunisia the Nebeur and Smar are outlier groups. Across North Africa, pervasive East‐West geographical patterns were not found. Discussion Known historical migrations and invasions did not displace or homogenize the genetic variation in the region but rather enriched it. Even a small region like Tunisia contains considerable genetic diversity. Future studies across North Africa have the potential to increase our understanding of the historical demographic factors influencing the region. Am J Phys Anthropol 161:62–71, 2016.

Assessing human genetic diversity in Tunisian Berber populations by Alu insertion polymorphisms

Background: The most recent Alu insertions reveal different series of characteristics such as stability that make them particularly suitable genetic markers for human biological studies. Aim: Six human-specific Alu insertion polymorphisms were typed in two Tunisian Berber populations with the aim of analysing the genetic diversity of these two communities and the genetic relationships between this region of North Africa and other populations. Subjects and methods: Forty-seven Berbers from Sejnane and 33 from Takrouna were sampled. Alu insertion polymorphism was analysed using PCR with loci specific primers. Results: A similar level of gene diversity was detected in Sejnane and Takrouna populations. PC results revealed genetic affinities between these two populations and some Eurasian populations (Germany, Genova and Syria). In contrast, there is a differentiation between these two Berber communities and North African and Iberian populations. Conclusion: The results of this study confirm the heterogeneity of Berbers in North Africa, which suggests their diverse origins. In the case of Sejnane and Takrouna populations, these results are in line with an ancient Euro Mediterranean background that has already been studied by archaeologists, particularly for the population of Sejnane.

Human Alu Insertion Polymorphisms in North African Populations

Abstract Several features make Alu insertions a powerful tool used in population genetic studies: the polymorphic nature of many Alu insertions, the stability of an Alu insertion event and, furthermore, the ancestral state of an Alu insertion is known to be the absence of the Alu element at a particular locus and the presence of an Alu insertion at the site that forward mutational change. This study analyses seven Alu insertion polymorphisms in a sample of 297 individuals from the autochthonous population of Tunisia (Thala, Smar, Zarzis, and Bou Salem) and Libya with the aim of studying their genetic structure with respect to the populations of North Africa, Western, Eastern and Central Europe. The comparative analyses carried out using the MDS and AMOVA methods reveal the existence of spatial heterogeneity, and identify four population groups. Study populations (Libya, Smar, Zarzis, and Bou Salem) are closest to North African populations whereas Thala is isolated and is closest to Western European populations. In conclusion, Results of the present study support the important role that migratory movements have played in the North African gene pool, at least since the Neolithic period.

Mitochondrial DNA analysis of Tunisians reveals a mosaic genetic structure with recent population expansion

Tunisia is a country of great interest for human population genetics due to its strategic geographic position and rich human settlement history. These factors significantly contributed to the genetic makeup of present-day Tunisians harbouring components of diverse geographic origins. Here, we investigated the genetic structure of Tunisians by performing a mitochondrial DNA (mtDNA) comparison of 15 Tunisian population groups, in order to explore their complex genetic landscape. All Tunisian data were also analysed against 40 worldwide populations. Statistical results (Tajimas D and Fus FS tests) suggested recent population expansion for the majority of studied populations, as well as showed (AMOVA test) that all populations were significantly different from each other, which is evidence of population structure even if it is not guided by geographic and ethnic effects. Gene flow analysis revealed the assignment of Tunisians to multiple ancestries, which agrees with their genetic heterogeneity. The resulting picture for the mtDNA pool confirms the evidence of a recent expansion of the Tunisian population and is in accordance with a mosaic structure, composed by North African, Middle Easterner, European and Sub-Saharan lineages, resulting from a complex settlement history.

An investigation of the genetic diversity of the Kerkennah islands and Mahdia (Tunisia) using biparental markers

Abstract Background: Kerkennah is one of the main inhabited islands of Tunisia. The origin of the population of Kerkennah has not been established and no well-defined ethnic groups have been identified nor are genetic studies available. Mahdia, a Tunisian coastal city, has a long history dating back to ancient times. Aim: To discover the genetic diversity of the two studied populations and analyse their relationships with other Mediterranean populations. Subject and methods: Seven human-specific Alu insertion polymorphisms were typed in 99 individuals born in Kerkennah and Mahdia. Results: A neighbour-joining tree and MDS multidimensional scaling analysis showed that these Tunisian populations are scattered amongst North African and Europeans populations, indicating their high genetic diversity and mosaic aspect. The important finding of this study was the proximity of Kerkennah to Moroccans. Hence, the actual gene pool of this insular population may descend from the ancestral population known to be of Moroccan origin. Concerning Mahdia, its closeness to Eurasian populations and some Tunisian groups reflected a high Eurasian genetic component for North African populations and confirmed their heterogeneity. Conclusion: The strategic location of the two studied populations and their fortifications have allowed them to play a leading role in the Mediterranean basin.