Mitochondrial DNA structure in the Arabian Peninsula

Khaled K Abu-Amero,Ana M González,Vicente M Cabrera,José M Larruga

doi:10.1186/1471-2148-8-45

Khaled K Abu-Amero, Ana M González + Show 2 more

Open Access

https://doi.org/10.1186/1471-2148-8-45

Copy DOI

Abstract

BackgroundTwo potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. These are the two natural passageways that connect both continents: the northern route through the Sinai Peninsula and the southern route across the Bab al Mandab strait. Recent archaeological and genetic evidence have favored a unique southern coastal route. Under this scenario, the study of the population genetic structure of the Arabian Peninsula, the first step out of Africa, to search for primary genetic links between Africa and Eurasia, is crucial. The haploid and maternally inherited mitochondrial DNA (mtDNA) molecule has been the most used genetic marker to identify and to relate lineages with clear geographic origins, as the African Ls and the Eurasian M and N that have a common root with the Africans L3.ResultsTo assess the role of the Arabian Peninsula in the southern route, we genetically analyzed 553 Saudi Arabs using partial (546) and complete mtDNA (7) sequencing, and compared the lineages obtained with those present in Africa, the Near East, central, east and southeast Asia and Australasia. The results showed that the Arabian Peninsula has received substantial gene flow from Africa (20%), detected by the presence of L, M1 and U6 lineages; that an 18% of the Arabian Peninsula lineages have a clear eastern provenance, mainly represented by U lineages; but also by Indian M lineages and rare M links with Central Asia, Indonesia and even Australia. However, the bulk (62%) of the Arabian lineages has a Northern source.ConclusionAlthough there is evidence of Neolithic and more recent expansions in the Arabian Peninsula, mainly detected by (preHV)1 and J1b lineages, the lack of primitive autochthonous M and N sequences, suggests that this area has been more a receptor of human migrations, including historic ones, from Africa, India, Indonesia and even Australia, than a demographic expansion center along the proposed southern coastal route.

Highlights

Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed
A total of 365 different mitochondrial DNA (mtDNA) haplotypes were observed in 553 Saudi Arab sequences. 299 of them (82%) could have been detected using only the hypervariable segment I (HVSI) sequence information and 66 (18%) when the hypervariable segment II (HVSII) information was taken into account
This fact is graphically reflected in the Multidimensional scaling (MDS) plot (Figure 6) where all the Arabian Peninsula samples are compared with samples from East Africa, the Near East and the Caucasus areas

Summary

Introduction

Two potential migratory routes followed by modern humans to colonize Eurasia from Africa have been proposed. A more recent analysis, based on a greater number of sequences, pushed back the lower bound of the out-of-Africa migration, signed by the L3 radiation, to around 85 kya [13] This date is no so far from the above commented presence of modern humans in the Levant about 100–125 kya. This migration is in frame with the putative presence of modern humans in Eritrean coasts [14], and corresponds with an interglacial period (OIS 5), when African faunas expanded to the Levant [15] After that, it seems that, at least in the Levant, there was a long period of population bottleneck, as there is no modern human evidence in the area until 50 kyr later, again in a relatively warm period (OIS 3). This contraction phase might be reflected in the basal roots of M and N lineages by the accumulation of 4 and 5 mutations before their radiation around 60 kya [13]

Methods

Results

Discussion

Conclusion