Y-chromosomal diversity in Lebanon is structured by recent historical events

Abstract

Lebanon is an eastern Mediterranean country inhabited by approximately four million people with a wide variety of ethnicities and religions, including Muslim, Christian, and Druze. In the present study, 926 Lebanese men were typed with Y-chromosomal SNP and STR markers, and unusually, male genetic variation within Lebanon was found to be more strongly structured by religious affiliation than by geography. We therefore tested the hypothesis that migrations within historical times could have contributed to this situation. Y-haplogroup J*(xJ2) was more frequent in the putative Muslim source region (the Arabian Peninsula) than in Lebanon, and it was also more frequent in Lebanese Muslims than in Lebanese non-Muslims. Conversely, haplogroup R1b was more frequent in the putative Christian source region (western Europe) than in Lebanon and was also more frequent in Lebanese Christians than in Lebanese non-Christians. The most common R1b STR-haplotype in Lebanese Christians was otherwise highly specific for western Europe and was unlikely to have reached its current frequency in Lebanese Christians without admixture. We therefore suggest that the Islamic expansion from the Arabian Peninsula beginning in the seventh century CE introduced lineages typical of this area into those who subsequently became Lebanese Muslims, whereas the Crusader activity in the 11(th)-13(th) centuries CE introduced western European lineages into Lebanese Christians.

Figure 1

Map of Lebanon and Its Surrounding Regions Showing Historically Documented Migrations into Lebanon

Figure 2

Y-Chromosomal Haplogroups Identified in Lebanese Subpopulations The phylogenetic tree defined by the markers used is shown on the left, and the haplogroup names are given in the middle. Nomenclature is based on the 2003 YCC tree, with departures indicated by “/-”. The absolute number of chromosomes within each haplogroup in the entire sample is shown in the “Lebanon” column, and the relative frequency within each of the three religious groups is shown on the right by the relative sizes of the circles.

Figure 3

Network of STR Variation within Haplogroup R1b Circles represent haplotypes defined by nine STRs; area is proportional to frequency, and color indicates the region of origin. Lines represent the mutational differences between haplotypes.

Figure 4

Geographical Distribution of WES1, the Most Common R1b Haplotype in Lebanese Christians This haplotype is DYS19, DYS389I, DYS389b, DYS390, DYS391, DYS392, DYS393 14, 12, 16, 24, 10, 13, 13. Population samples containing the haplotype are shown in red, and those lacking it are shown in blue. Note the highly specific western European distribution and the absence of the haplotype from populations near Lebanon. Data are from YHRD.