Phylogeography of E1b1b1b-M81 Haplogroup and Analysis of Its Subclades in Morocco

Abstract

In this study we analyzed 295 unrelated Berber-speaking men from northern, central, and southern Morocco to characterize frequency of the E1b1b1b-M81 haplogroup and to refine the phylogeny of its subclades: E1b1b1b1-M107, E1b1b1b2-M183, and E1b1b1b2a-M165. For this purpose, we typed four biallelic polymorphisms: M81, M107, M183, and M165. A large majority of the Berber-speaking male lineages belonged to the Y-chromosomal E1b1b1b-M81 haplogroup. The frequency ranged from 79.1% to 98.5% in all localities sampled. E1b1b1b2-M183 was the most dominant subclade in our samples, ranging from 65.1% to 83.1%. In contrast, the E1b1b1b1-M107 and E1b1b1b2a-M165 subclades were not found in our samples. Our results suggest a predominance of the E1b1b1b-M81 haplogroup among Moroccan Berber-speaking males with a decreasing gradient from south to north. The most prevalent subclade in this haplogroup was E1b1b1b2-M183, for which differences among these three groups were statistically significant between central and southern groups.

The tree of binary polymorphisms in the nonrecombining portion of the human Y chromosome provides important insights to trace the pattern of demographic history of human populations and to help decipher paternal genetic relationships among human populations. According to the hierarchical phylogenetic nomenclature of the Y chromosome tree reported by Underhill et al. (2001) and updated by the Y Chromosome Consortium (2002) and Karafet et al. (2008), the E major haplogroup was observed in Africa, Europe, and the Near East (Semino et al. 2004). The most widespread and frequent cluster among its clades was E1b1b1-M35 at this level of molecular resolution, and the main derivative haplogroups were E1b1b1a-M78 in eastern Africa, E1b1b1c-M123 in the Near East, and E1b1b1b-M81 among male lineages in northwestern Africa (Semino et al. 2004). The E1b1b1b-M81 haplogroup can be further characterized by unique event polymorphism markers E1b1b1b*, E1b1b1b1 given by M107, and E1b1b1b2 given by M183; at this level we can find E1b1b1b2* and E1b1b1b2a given by M165 (Figure 1).

The Berber-speaking ethnic group represents the ancient inhabitants of northwestern Africa. In Morocco, Berber groups speak several dialects; the three main spoken dialects are Tarifit, Tamazight, and Tachelhit, respectively distributed in the northern, central, and southern parts of the country.

To further describe the Y-chromosomal E1b1b1b-M81 haplogroup and its subclades among Moroccan Berber-speaking groups, we typed four biallelic polymorphisms, M81, M107, M183, and M165, in samples of the Berber-speaking groups collected from different regions of Morocco. We also give an overview of the distribution of this lineage in the Mediterranean area in relation to historical events.

Figure 1.

Phylogeny of E1b1b1b-M81 haplogroup.

Subjects and Methods

Subjects

We analyzed samples of 295 unrelated Moroccan men who spoke Berber as a first dialect: 43 men from the northern (Rif) region who spoke Tarifit, 187 men from the central region who spoke Tamazight, and 65 men from the southern region who spoke Tachelhit (Figure 2). These samples were collected from individuals who reported that their four grandparents lived in the same geographic location. DNA was extracted from fresh peripheral blood by standard phenol-chloroform protocols. Appropriate informed consent was obtained from all participants in this study. This study was carried out after obtaining permission from the Ministry of Health of Morocco.

Figure 2.

Geographic locations of the populations studied.

Biallelic Polymorphisms Typing

All biallelic polymorphisms were amplified by PCR using the primers described by Underhill et al. (2001) (Table 1). The standard PCR protocol was modified to give a final volume of 25 µL; the composition of the reaction mix was the same for all reactions: 400 nM of each primer, 200 µM dNTP, 1 U Taq DNA polymerase, 100 ng nuclear DNA, 1.5 mmol/L MgCl₂, and 2.5 µL 10× PCR buffer. The M81, M107, and M165 markers were analyzed by restriction fragment length polymorphism using the restriction enzymes HpyCH4IV (ACG...