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Euclides
Wednesday, April 14th, 2004, 06:00 PM
Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of
a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many
founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Ychromosomal
biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes
belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly
nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five
of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide
and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and
are more regionally restricted and are likely to reflect distinct population movements, including one from north of
the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography,
rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and
highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation
between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of
patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that
the demographic history of Europe has been complex and influenced by other major population movements, as
well as by linguistic and geographic heterogeneities and the effects of drift.


Am. J. Hum. Genet. 67:1526–1543, 2000

( I can´t post the pdf - 4, 62Mb)

Euclides
Sunday, April 18th, 2004, 09:03 PM
Network Analyses of Y-Chromosomal Types in Europe, Northern Africa, and Western Asia Reveal Specific Patterns of Geographic Distribution

Patrizia Malaspina,1 Fulvio Cruciani,2 Bianca Maria Ciminelli,1 Luciano Terrenato,1
Piero Santolamazza,2 Antonio Alonso,33 Juraj Banyko,4 Radim Brdicka,5 Oscar García,6 Carlo Gaudiano,7 Ginevra Guanti,8 Kenneth K. Kidd,9 João Lavinha,10 Madalena Avila,10 Paola Mandich,11 Pedro Moral,12 Raheel Qamar,13 Syed Q. Mehdi,13 Angela Ragusa,14 Gheorghe Stefanescu,15 Maria Caraghin,15 Chris Tyler-Smith,16 Rosaria Scozzari,2
Andrea Novelletto1

1Department of Biology, University "Tor Vergata," and 2Department of Genetics and Molecular Biology, University "La Sapienza," Rome; 3Instituto Nacional de Toxicologia, Madrid; 4Department of Anthropology, University of P. J. Safarik, Kosice, Slovak Republic; 5Institute for Haematology and Blood Transfusion, Prague; 6Basque Country Police, Bilbao, Spain; 7Azienda Sanitaria Locale 4, Centro Lotto alle Microcitemie, Matera, Italy; 8University of Bari, Bari, Italy; 9Department of Genetics, Yale University School of Medicine, New Haven; 10Instituto Nacional de Saúde, Lisbon; 11I. Bi. G., University of Genoa, Genoa; 12Departmento de Biologia Animal, Universitat de Barcelona, Barcelona; 13A. Q. Khan Research Laboratories, Islamabad; 14Oasi Institute, Troina, Italy; 15Institutul de Cercetari Biologice, Iasi, Romania; and 16Department of Biochemistry, University of Oxford, Oxford

Received December 5, 1997; accepted for publication June 22, 1998; electronically published August 21, 1998.

Summary

In a study of 908 males from Europe, northern Africa, and western Asia, the variation of four Y-linked dinucleotide microsatellites was analyzed within three "frames" that are defined by mutations that are nonrecurrent, or nearly so. The rapid generation and extinction of new dinucleotide length variants causes the haplotypes within each lineage to diverge from one another. We constructed networks of "adjacent" haplotypes within each frame, by assuming changes of a single dinucleotide unit. Two small and six large networks were obtained, the latter including 94.9% of the sampled Y chromosomes. We show that the phenetic relationships among haplotypes, represented as a network, result largely from common descent and subsequent molecular radiation. The grouping of haplotypes of the same network thus fits an evolutionarily relevant criterion. Notably, this method allows the total diversity within a sample to be partitioned. Networks can be considered optimal markers for population studies, because reliable frequency estimates can be obtained in small samples. We present synthetic maps describing the incidence of different Y-chromosomal lineages in the extant human populations of the surveyed areas. Dinucleotide diversity also was used to infer time intervals for the coalescence of each network.

Euclides
Wednesday, May 26th, 2004, 05:59 AM
''Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift.''

Euclides
Wednesday, May 26th, 2004, 06:03 AM
Geographic patterns of mtDNA diversity in Europe.

Simoni L, Calafell F, Pettener D, Bertranpetit J, Barbujani G.

Department of Evolutionary and Experimental Biology, University of Bologna, Bologna, Italy.

Genetic diversity in Europe has been interpreted as a reflection of phenomena occurring during the Paleolithic ( approximately 45,000 years before the present [BP]), Mesolithic ( approximately 18,000 years BP), and Neolithic ( approximately 10,000 years BP) periods. A crucial role of the Neolithic demographic transition is supported by the analysis of most nuclear loci, but the interpretation of mtDNA evidence is controversial. More than 2,600 sequences of the first hypervariable mitochondrial control region were analyzed for geographic patterns in samples from Europe, the Near East, and the Caucasus. Two autocorrelation statistics were used, one based on allele-frequency differences between samples and the other based on both sequence and frequency differences between alleles. In the global analysis, limited geographic patterning was observed, which could largely be attributed to a marked difference between the Saami and all other populations. The distribution of the zones of highest mitochondrial variation (genetic boundaries) confirmed that the Saami are sharply differentiated from an otherwise rather homogeneous set of European samples. However, an area of significant clinal variation was identified around the Mediterranean Sea (and not in the north), even though the differences between northern and southern populations were insignificant. Both a Paleolithic expansion and the Neolithic demic diffusion of farmers could have determined a longitudinal cline of mtDNA diversity. However, additional phenomena must be considered in both models, to account both for the north-south differences and for the greater geographic scope of clinical patterns at nuclear loci. Conversely, two predicted consequences of models of Mesolithic reexpansion from glacial refugia were not observed in the present study.