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X-chromosome SNP analyses in 11 human Mediterranean populations show a high overall genetic homogeneity except in North-west Africans (Moroccans).

Tomas C, Sanchez JJ, Barbaro A, Brandt-Casadevall C, Hernandez A, Ben Dhiab M, Ramon M, Morling N - BMC Evol. Biol. (2008)

Bottom Line: A high overall homogeneity was found among the Mediterranean populations except for the population from Morocco, which seemed to differ genetically from the rest of the populations in the Mediterranean area.A very low genetic distance was found between populations in the Middle East and most of the western part of the Mediterranean Sea.A higher migration rate in females versus males was observed by comparing data from X-chromosome, mt-DNA and Y-chromosome SNPs both in the Mediterranean and a wider geographic area.Multilocus association was observed among the 25 SNPs on the X-chromosome in the populations from Ibiza and Cosenza.Our results support both the hypothesis of (1) a reduced impact of the Neolithic Wave and more recent migration movements in NW-Africa, and (2) the importance of the Strait of Gibraltar as a geographic barrier.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. carmen.tomas@forensic.ku.dk

ABSTRACT

Background: Due to its history, with a high number of migration events, the Mediterranean basin represents a challenging area for population genetic studies. A large number of genetic studies have been carried out in the Mediterranean area using different markers but no consensus has been reached on the genetic landscape of the Mediterranean populations. In order to further investigate the genetics of the human Mediterranean populations, we typed 894 individuals from 11 Mediterranean populations with 25 single-nucleotide polymorphisms (SNPs) located on the X-chromosome.

Results: A high overall homogeneity was found among the Mediterranean populations except for the population from Morocco, which seemed to differ genetically from the rest of the populations in the Mediterranean area. A very low genetic distance was found between populations in the Middle East and most of the western part of the Mediterranean Sea.A higher migration rate in females versus males was observed by comparing data from X-chromosome, mt-DNA and Y-chromosome SNPs both in the Mediterranean and a wider geographic area.Multilocus association was observed among the 25 SNPs on the X-chromosome in the populations from Ibiza and Cosenza.

Conclusion: Our results support both the hypothesis of (1) a reduced impact of the Neolithic Wave and more recent migration movements in NW-Africa, and (2) the importance of the Strait of Gibraltar as a geographic barrier. In contrast, the high genetic homogeneity observed in the Mediterranean area could be interpreted as the result of the Neolithic wave caused by a large demic diffusion and/or more recent migration events. A differentiated contribution of males and females to the genetic landscape of the Mediterranean area was observed with a higher migration rate in females than in males. A certain level of background linkage disequilibrium in populations in Ibiza and Cosenza could be attributed to their demographic background.

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Principal coordinate analyses plotted from pairwise Reynold's Fst values. a) The Mediterranean group analyzed by using 25 X-chromosome SNPs. b) All the 17 populations were represented, including those from the HapMap collection. Twenty-three X-chromosome SNPs were used. CEU: Utah residents with ancestry from western and northern Europe, DEN: Denmark, CHB: China, JPT: Japan, SOM: Somalia, YRI: Nigeria, CAT: Catanzaro, CSZ: Cosenza, IBZ: Ibiza, IRQ: Iraq, MAJ: Majorca, MOR: Morocco, RCA: Reggio di Calabria, SIC: Sicily, TUN: Tunisia, TKY: Turkey, VAL: Valencia
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Figure 1: Principal coordinate analyses plotted from pairwise Reynold's Fst values. a) The Mediterranean group analyzed by using 25 X-chromosome SNPs. b) All the 17 populations were represented, including those from the HapMap collection. Twenty-three X-chromosome SNPs were used. CEU: Utah residents with ancestry from western and northern Europe, DEN: Denmark, CHB: China, JPT: Japan, SOM: Somalia, YRI: Nigeria, CAT: Catanzaro, CSZ: Cosenza, IBZ: Ibiza, IRQ: Iraq, MAJ: Majorca, MOR: Morocco, RCA: Reggio di Calabria, SIC: Sicily, TUN: Tunisia, TKY: Turkey, VAL: Valencia

Mentions: In order to obtain a graphical representation of the genetic structure of the populations studied, a principal coordinate analysis (PCoA) was made from the pairwise Reynold's Fst matrix obtained using 25 or 21 X-chromosome SNPs in the Mediterranean (Figure 1a) and the 17 populations (Figure 1b), respectively.


X-chromosome SNP analyses in 11 human Mediterranean populations show a high overall genetic homogeneity except in North-west Africans (Moroccans).

Tomas C, Sanchez JJ, Barbaro A, Brandt-Casadevall C, Hernandez A, Ben Dhiab M, Ramon M, Morling N - BMC Evol. Biol. (2008)

Principal coordinate analyses plotted from pairwise Reynold's Fst values. a) The Mediterranean group analyzed by using 25 X-chromosome SNPs. b) All the 17 populations were represented, including those from the HapMap collection. Twenty-three X-chromosome SNPs were used. CEU: Utah residents with ancestry from western and northern Europe, DEN: Denmark, CHB: China, JPT: Japan, SOM: Somalia, YRI: Nigeria, CAT: Catanzaro, CSZ: Cosenza, IBZ: Ibiza, IRQ: Iraq, MAJ: Majorca, MOR: Morocco, RCA: Reggio di Calabria, SIC: Sicily, TUN: Tunisia, TKY: Turkey, VAL: Valencia
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2315647&req=5

Figure 1: Principal coordinate analyses plotted from pairwise Reynold's Fst values. a) The Mediterranean group analyzed by using 25 X-chromosome SNPs. b) All the 17 populations were represented, including those from the HapMap collection. Twenty-three X-chromosome SNPs were used. CEU: Utah residents with ancestry from western and northern Europe, DEN: Denmark, CHB: China, JPT: Japan, SOM: Somalia, YRI: Nigeria, CAT: Catanzaro, CSZ: Cosenza, IBZ: Ibiza, IRQ: Iraq, MAJ: Majorca, MOR: Morocco, RCA: Reggio di Calabria, SIC: Sicily, TUN: Tunisia, TKY: Turkey, VAL: Valencia
Mentions: In order to obtain a graphical representation of the genetic structure of the populations studied, a principal coordinate analysis (PCoA) was made from the pairwise Reynold's Fst matrix obtained using 25 or 21 X-chromosome SNPs in the Mediterranean (Figure 1a) and the 17 populations (Figure 1b), respectively.

Bottom Line: A high overall homogeneity was found among the Mediterranean populations except for the population from Morocco, which seemed to differ genetically from the rest of the populations in the Mediterranean area.A very low genetic distance was found between populations in the Middle East and most of the western part of the Mediterranean Sea.A higher migration rate in females versus males was observed by comparing data from X-chromosome, mt-DNA and Y-chromosome SNPs both in the Mediterranean and a wider geographic area.Multilocus association was observed among the 25 SNPs on the X-chromosome in the populations from Ibiza and Cosenza.Our results support both the hypothesis of (1) a reduced impact of the Neolithic Wave and more recent migration movements in NW-Africa, and (2) the importance of the Strait of Gibraltar as a geographic barrier.

View Article: PubMed Central - HTML - PubMed

Affiliation: Section of Forensic Genetics, Department of Forensic Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. carmen.tomas@forensic.ku.dk

ABSTRACT

Background: Due to its history, with a high number of migration events, the Mediterranean basin represents a challenging area for population genetic studies. A large number of genetic studies have been carried out in the Mediterranean area using different markers but no consensus has been reached on the genetic landscape of the Mediterranean populations. In order to further investigate the genetics of the human Mediterranean populations, we typed 894 individuals from 11 Mediterranean populations with 25 single-nucleotide polymorphisms (SNPs) located on the X-chromosome.

Results: A high overall homogeneity was found among the Mediterranean populations except for the population from Morocco, which seemed to differ genetically from the rest of the populations in the Mediterranean area. A very low genetic distance was found between populations in the Middle East and most of the western part of the Mediterranean Sea.A higher migration rate in females versus males was observed by comparing data from X-chromosome, mt-DNA and Y-chromosome SNPs both in the Mediterranean and a wider geographic area.Multilocus association was observed among the 25 SNPs on the X-chromosome in the populations from Ibiza and Cosenza.

Conclusion: Our results support both the hypothesis of (1) a reduced impact of the Neolithic Wave and more recent migration movements in NW-Africa, and (2) the importance of the Strait of Gibraltar as a geographic barrier. In contrast, the high genetic homogeneity observed in the Mediterranean area could be interpreted as the result of the Neolithic wave caused by a large demic diffusion and/or more recent migration events. A differentiated contribution of males and females to the genetic landscape of the Mediterranean area was observed with a higher migration rate in females than in males. A certain level of background linkage disequilibrium in populations in Ibiza and Cosenza could be attributed to their demographic background.

Show MeSH
Related in: MedlinePlus