doi: 10.1046/j.1529-8817.2004.00096.x Mitochondrial DNA Heterogeneity in Tunisian Berbers K. Fadhlaoui-Zid 1,* , S. Plaza 2,* , F. Calafell 2 , M. Ben Amor 1 , D. Comas 2,** and A. Bennamar El gaaied 1 1 Laboratoire de G´ en´ etique Mol´ eculaire, Immunologie et Biotechnologie, Facult´ e des Sciences de Tunis, Universit´ e Tunis El Manar, 2092 Tunis, Tunisia 2 Unitat de Biologia Evolutiva. Universitat Pompeu Fabra. Doctor Aiguader 80, 08003 Barcelona, Spain Summary Berbers live in groups scattered across North Africa whose origins and genetic relationships with their neighbours are not well established. The first hypervariable segment of the mitochondrial DNA (mtDNA) control region was sequenced in a total of 155 individuals from three Tunisian Berber groups and compared to other North Africans. The mtDNA lineages found belong to a common set of mtDNA haplogroups already described in North Africa. Besides the autochthonous North African U6 haplogroup, a group of L3 lineages characterized by the transition at position 16041 seems to be restricted to North Africans, suggesting that an expansion of this group of lineages took place around 10500 years ago in North Africa, and spread to neighbouring populations. Principal components and the coordinate analyses show that some Berber groups (the Tuareg, the Mozabite, and the Chenini-Douiret) are outliers within the North African genetic landscape. This outlier position is consistent with an isolation process followed by genetic drift in haplotype frequencies, and with the high heterogeneity displayed by Berbers compared to Arab samples as shown in the AMOVA. Despite this Berber heterogeneity, no significant differences were found between Berber and Arab samples, suggesting that the Arabization was mainly a cultural process rather than a demographic replacement. Introduction Berbers inhabit scattered places in North Africa, from the Moroccan western coast to the oasis Siwa in Egypt, and from Tunisia in the north to the oases in the mid- Sahara. The origin of the Berber people is not clearly established. According to the archaeological record, North Africa has been peopled since Upper Palae- olithic times (Newman, 1995). The first well-defined Palaeolithic technology, the Aterian, dates back around 40,000 years ago, and is followed by the Iberomau- risian (∼ 22,000 years ago; Feremback, 1985; Close & Wendorf, 1990). The archaeological record then re- veals a Mesolithic culture, the Capsian (Brett & Fen- tress, 1996), which gave way to the Neolithic transition ∗ Both authors contributed equally to the present work ∗∗ Correspondence: David Comas, Unitat de Biologia Evolutiva, Facultat de Ci` encies de la Salut i de la Vida, Universitat Pompeu Fabra, Doctor Aiguader 80, 08003 Barcelona, Spain. Tel: +34 93 542 28 02; Fax: +34 93 542 28 44. E-mail: david.comas@upf.edu to agriculture that occurred around 9,500-7,000BC, spreading from the Near East to Egypt (Dupanloup, 1993). Berbers may be the descendants of Mesolithic Capsian populations, and/or of the later Neolithic peo- ple who came from the Middle East via Egypt and who possibly introduced the Afro-Asiatic languages to North Africa (Renfrew, 1991). Since then, the North African coast has known several invasions: Phoenicians, Ro- mans, Vandals, Byzantines, Arabs, Ottomans, Spanish and French have occupied the territory, although their demographic impact is not well established. In Tunisia, the first well-known post-Neolithic inva- sion was that of the Phoenicians coming from the East Mediterranean sea coast around 1,100BC. Nonetheless, their number was estimated at the end of their kingdom to be 100,000 compared to 500,000 Berbers living in Tunisia (Julien, 1961). The long dominations by the Ro- mans, Vandals and Byzantines had an even lesser demo- graphic impact. The Arab conquest in Tunisia started in the 7th century and was followed by a massive Bedouin 222 Annals of Human Genetics (2004) 68,222–233 C  University College London 2004