North African Berber and Arab Influences in the Western Mediterranean Revealed by Y-Chromosome DNA Haplotypes

Human Biology, Jun 2006 by G�rard, Nathalie, Berriche, Sala, Aouiz�rate, Annie, Di�terlen, Florent, Lucotte, G�rard

Abstract

We have analyzed Y-chromosome diversity in the western Mediterranean area, examining p49a,f TaqI haplotype V and subhaplotypes Vb (Berber) and Va (Arab). A total of 2,196 unrelated DNA samples, belonging to 22 populations from North Africa and the southern Mediterranean coast of occidental Europe, have been typed. Subhaplotype Vb, predominant in a Berber population of Morocco (63.5%), was also found at high frequencies in southern Portugal (35.9%) and Andalusia (25.4%). The Arab subhaplotype Va, predominant in Algeria (53.9%) and Tunisia (50.6%), was also found at a relatively high frequency in Sicily (23.1%) and Naples (16.4%); its highest frequency in Iberia was in northern Portugal (22.8%) and Andalusia (15.5%). In Iberia there is a gradient of decreasing frequencies in latitude for both subhaplotypes Va and Vb, related to eight centuries of Muslim domination (8th to 15th centuries) in southern Iberia.

KEY WORDS: Y-CHROMOSOME HAPLOTYPES, P49a,f TaqI HAPLOTYPE V, SUBHAPLOTYPE Va (ARAB), SUBHAPLOTYPE Vb (BERBER), WESTERN MEDITERRANEAN AREA, IBERIA, MUSLIM DOMINATION IN SOUTHERN PORTUGAL AND SPAIN, ARABS, BERBERS.

During the 7th century A.D., Muslim people coming from the Arabian peninsula and the Middle East invaded North Africa. The most important population movement relating both sides of the Mediterranean Sea was the conquest of the Iberian peninsula by North African populations (with recruited Berbers), soon after the first Muslim invasion. More than eight centuries (8th to 15th centuries) of Muslim domination in the southern part of Iberia imparted an important cultural legacy (Conrad 1998) and probable gene exchanges between North African and Iberian populations.

Variations in DNA sequences specific to the nonrecombinant part of the Y chromosome, relating to paternal ancestry, are particularly interesting from a human population genetics point of view. The first published and most informative probe used in Southern blots for this objective is p49 (locus DYSl), which is able to identify at last five TaqI male-specific fragments (A, C, D, F, and I) that are polymorphic between individuals (Lucotte and Ngo 1985). Sixteen main corresponding haplotypes (numbered I-XVI) were identified using the p49 probe on DNA samples of unrelated males living in France (Ngo et al. 1986). Only recently has the molecular basis of the p49 TaqI polymorphisms been established (Jovelin et al. 2003); the polymorphisms correspond to variable TaqI sites located in the four DAZ genes located in the AZF-c region of the Y chromosome.

In fact, the conventional p49 TaqI polymorphisms were the most popular markers used in various populations because of their ability to detect more than 100 different haplotypes [for a compilation on the subject until the end of 1995, see Poloni et al. (1997)]. Haplotype XV (A3,C1,D2,F1,I1) was the most widespread haplotype in our initial study (Ngo et al. 1986). Haplotype XV was also predominant in the first European study we published (Lucotte and Hazout 1996), with elevated frequencies in French Basques. The geographic distribution of haplotype XV in Europe reveals a gradient of decreasing frequencies from this Basque focus toward eastern peripheral countries (Lucotte and Loirat 1999) but also toward southwestern countries. According to the Y Chromosome Consortium (2002) nomenclature, haplotype XV corresponds to the M173 lineage (Di�terlen and Lucotte 2005).

Haplotype V (A2,C0,D0,F1,I1) is the most frequent haplotype in North Africa (Lucotte et al. 2000), with a particularly high frequency (55%) in the populations with a relative predominance of Berber origin. Our previous study on the subject examined the relative frequencies of haplotype V in four Iberian populations compared with a Berber population living in North Africa (Lucotte et al. 2001). The highest frequency of haplotype V (68.9%) was observed in Berbers from Morocco, and the geographic distribution of haplotype V revealed a gradient of decreasing frequencies with latitude in Iberia (40.8% in Andalusia, 36.2% in Portugal, 12.1% in Catalonia, and 11.3% in the Basque Country) (Lucotte et al. 2001); such a cline of decreasing haplotype V frequencies from the south to the north in Iberia clearly established a gene flow from North Africa toward Iberia.

According to the Y Chromosome Consortium (2002) nomenclature, haplogroup E is characterized by the mutations SRY4064, M96, and P29 on a background defined by the insertion of an Alu element (YAP ). The third clade, E3 (defined by the mutation P2), of haplogroup E is further subdivided into two monophyletic forms, the second one (E3b) being characterized by mutations M35 and M125. All of the 110 p49 TaqI haplotype V subjects from Morocco (51 Berbers and 59 Arabs) that we had previously tested correspond to haplogroup E3b.

In the present study we have subdivided haplotype V into its Berber (Vb) and Arab (Va) components in order to distinguish the relative contributions of these two ethnicity-specific markers in the gene pools of the populations living in Iberia and in other populations in the northern part of the western Mediterranean area.