Alu insertion polymorphisms in NW Africa and the Iberian Peninsula

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Hum Genet. 2000 Oct;107(4):312-9.

Alu insertion polymorphisms in NW Africa and the Iberian Peninsula: evidence for a strong genetic boundary through the Gibraltar Straits.

Comas D, Calafell F, Benchemsi N, Helal A, Lefranc G, Stoneking M, Batzer MA, Bertranpetit J, Sajantila A.

Unitat de Biologia Evolutiva, Facultat de Ciencies de la Salut i de la Vida, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain.

An analysis of 11 I Alu insertion polymorphisms (ACE, TPA25, PV92, APO, FXIIIB, D1, A25, B65, HS2.43, HS3.23, and HS4.65) has been performed in several NW African (Northern, Western, and Southeastern Moroccans, Saharawi; Algerians; Tunisians) and Iberian (Basques, Catalans, and Andalusians) populations. Genetic distances and principal component analyses show a clear differentiation of NW African and Iberian groups of samples, suggesting a strong genetic barrier matching the geographical Mediterranean Sea barrier. The restriction to gene flow may be attributed to the navigational hazards across the Straits, but cultural factors must also have played a role. Some degree of gene flow from sub-Saharan Africa can be detected in the southern part of North Africa and in Saharawi and Southeastern Moroccans, as a result of a continuous gene flow across the Sahara desert that has created a south-north cline of sub-Saharan Africa influence in North Africa. Iberian samples show a substantial degree of homogeneity and fall within the cluster of European-based genetic diversity.

source : http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Citation


The complete study can found here :

http://www.eva.mpg.de/genetics/pdf/C...umGen.2000.pdf


It's now 6 years old. How's this study up to date, outdated?

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Coll Antropol. 2003 Dec;27(2):491-500. Related Articles, Links

Alu insertions in the Iberian Peninsula and north west Africa--genetic boundaries or melting pot?

Gonzalez-Perez E, Via M, Esteban E, Lopez-Alomar A, Mazieres S, Harich N, Kandil M, Dugoujon JM, Moral P.

Department of Anthropology, Faculty of Biology, University of Barcelona, Barcelona, Spain.

The Western Mediterranean Basin joins a set of ethnically different populations as Iberians and Basques in the North shore and Berbers and Arab-speakers in the South one. In spite of this differentiation, they have maintained historical contacts since ancient times. The existence of a possible common genetic background (specially for Berbers and Iberians) together with the genetic impact of the Islamic occupation of the Iberian Peninsula during 7 centuries are some of the intriguing anthropological questions that have been studied in this area using several classical and DNA markers. The aim of this work is to present the results on a survey of polymorphic Alu elements in 10 human populations of the Western Mediterranean. Recent Alu subfamilies include a significant number of polymorphic Alu insertions in humans. The polymorphic Alu elements are neutral genetic markers of identical descent with known ancestral states. This fact turns Alu insertions into useful markers for the study of human population genetics. A total number of 14 Alu insertions were analyzed in 5 Iberian populations, 3 Berber groups from North-Western Africa, an Arab-speaker population from Morocco and a sub-Saharan ethnic group from Ivory Coast. The results of this study allow the genetic characterization of Berber populations, which show a certain degree of differentiation from Arab-speaking groups of the same geographic area. Furthermore, a closer genetic distance between South Spain and Moroccan Berbers as compared with other Spanish samples supports a major genetic influx consistent with some (but not all) previous genetic studies on populations from the two shores of the Gibraltar Straits.

PMID: 14746135 [PubMed - indexed for MEDLINE]

source :http://www.ncbi.nlm.nih.gov/entrez/q...&dopt=Citation

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ARTICLE

Reduced genetic structure of the Iberian peninsula revealed by Y-chromosome analysis: implications for population demography

1Departamento de Gene´tica, Universidad de La Laguna, Tenerife E-38271, Spain; 2 Unidad de Investigacio´n, Hospital Universitario N.S. de Candelaria, Tenerife 38010, Spain; 3 Stanford Genome Technology Center, 855 California Ave., Palo Alto, CA 94304, USA; 4Hospital del FREMAP, Departamento de Salud Laboral, Sevilla E-41012, Spain; 5 Department of Genetics, Stanford University, 300 Pasteur Dr., Stanford, CA 94305-5120, USA

Europe has been influenced by both intra- and intercontinental migrations. Since the Iberian peninsula was a refuge during the Last Glacial Maximum, demographic factors associated with contraction, isolation, subsequent expansion and gene flow episodes have contributed complexity to its population history. In this work, we analysed 26 Y-chromosome biallelic markers in 568 chromosomes from 11 different Iberian population groups and compared them to published data on the Basques and Catalans to gain insight into the paternal gene pool of these populations and find out to what extent major demographic processes account for their genetic structure. Our results reveal a reduced, although geographically correlated, Y-chromosomal interpopulation variance (1.2%), which points to a limited heterogeneity in the region. Coincidentally, spatial analysis of genetic distances points to a focal distribution of Y-chromosome haplogroups in this area. These results indicate that neither old or recent Levantine expansions nor North African contacts have influenced the current Iberian Y-chromosome diversity so that geographical patterns can be identified.

European Journal of Human Genetics (2004) 12, 855–863. doi:10.1038/sj.ejhg.5201225

Published online 28 July 2004 nature.

source : http://hpgl.stanford.edu/publication...4_v12_p855.pdf

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Am. J. Hum. Genet., 68:1019-1029, 2001
0002-9297/2001/6804-0022$02.00
© 2001 by The American Society of Human Genetics. All rights reserved.


High-Resolution Analysis of Human Y-Chromosome Variation Shows a Sharp Discontinuity and Limited Gene Flow between Northwestern Africa and the Iberian Peninsula


Elena Bosch,1,* Francesc Calafell,1 David Comas,1 Peter J. Oefner,2 Peter A. Underhill,3 and Jaume Bertranpetit1

1Unitat de Biologia Evolutiva, Facultat de Ciències de la Salut i de la Vida, Universitat Pompeu Fabra, Barcelona; 2Stanford DNA Sequencing and Technology Center, Palo Alto, CA; and 3Department of Genetics, Stanford University, Stanford, CA


Received December 27, 2000; accepted for publication February 14, 2001; electronically published March 14, 2001.


In the present study we have analyzed 44 Y-chromosome biallelic polymorphisms in population samples from northwestern (NW) Africa and the Iberian Peninsula, which allowed us to place each chromosome unequivocally in a phylogenetic tree based on >150 polymorphisms. The most striking results are that contemporary NW African and Iberian populations were found to have originated from distinctly different patrilineages and that the Strait of Gibraltar seems to have acted as a strong (although not complete) barrier to gene flow. In NW African populations, an Upper Paleolithic colonization that probably had its origin in eastern Africa contributed 75% of the current gene pool. In comparison, 78% of contemporary Iberian Y chromosomes originated in an Upper Paleolithic expansion from western Asia, along the northern rim of the Mediterranean basin. Smaller contributions to these gene pools (constituting 13% of Y chromosomes in NW Africa and 10% of Y chromosomes in Iberia) came from the Middle East during the Neolithic and, during subsequent gene flow, from Sub-Saharan to NW Africa. Finally, bidirectional gene flow across the Strait of Gibraltar has been detected: the genetic contribution of European Y chromosomes to the NW African gene pool is estimated at 4%, and NW African populations may have contributed 7% of Iberian Y chromosomes. The Islamic rule of Spain, which began in A.D. 711 and lasted almost 8 centuries, left only a minor contribution to the current Iberian Y-chromosome pool. The high-resolution analysis of the Y chromosome allows us to separate successive migratory components and to precisely quantify each historical layer.

* Present affiliation: Department of Genetics, University of Leicester, Leicester, United Kingdom.

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source : http://www.journals.uchicago.edu/AJH...720269654Guest

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