Reduced genetic structure of the Iberian peninsulawrote:The Iberian peninsula, at the Southwestern part of
Europe (Figure 1a), is considered to be the region with less
Neolithic impact, based on archaeological and genetic
evidence. Their Palaeolithic component, with the Basques
being the most outstanding representative, have been
pointed out by classical markers,7,11 mtDNA studies12 15
and Y-chromosome variation.10,16 18 Furthermore, Alonso
and Armour19 found that the Basques diverged from other
Europeans by retaining less diversity and having a greater
proportion of ancestral (Palaeolithic) autosomal alleles.
However, the presence in high frequency of a number of
rare haplotypes, both in mtDNA12,14 and Y-chromosome18
analysis, suggests that the action of genetic drift may have
accentuated their distinctiveness. Owing to their characteristic
genetic variation, the Basques have often received
considerable attention in genetic studies of Western
Europe, in detriment of the genetic characterization of
the rest of Iberian populations. Outside a European
context, some studies have investigated the degree of
African gene flow in Iberian populations.20 23 Although
classical markers have failed to detect this influence,11
roughly 10% of Iberian mtDNA and Y-chromosome
haplotypes have been found to be of African origin.
13,15,24 29 Moreover, unlike the rest of Europe, the
presence of markers with probable North African origin,
the mtDNA U613,30 and the Y-chromosome E3b,26 points to
a specific Northwest African influence in Iberia.4,25 29
revealed by Y-chromosome analysis: implications for
http://hpgl.stanford.edu/publications/E ... 2_p855.pdf
And here comes the shocker (quotes from Dienekes: http://dienekes.blogspot.com/2005/03/pr ... er-to.html):
Temporal Mitochondrial DNA Variation in the Basque Country: Influence of Post-Neolithic Events
http://www.ingentaconnect.com/content/b ... 6/art00006
mtDNA J, not to be confused with the Y-chrom. J which is also "Neolithic" in Europe:wrote:The first component, which accounts for 42.6% of the total variance, established a differentiation between the present-day populations of the Near East and those of Europe. Within Europe, the populations of the Mediterranean area (MdE, MdC and MdW) and those of Eastern Europe (NE and SE) are closer to those of the Near East. Regarding the prehistoric populations of the Basque Country, they are situated between the two groups (Europe and Near East), whereas the historical population of Aldaieta falls within the variability range of present-day European populations.
wrote:Haplogroup J has been the main lineage of mtDNA related to the Neolithic expansion from the Near East around 10,000 years ago (Richards et al. 1996, 2000). A lower frequency of J has been displayed in the present-day Basque population (2.4%), whereas in all other regions of Europe its frequency ranges between 7% and 14%. However, in certain prehistoric populations from the Basque Country (SJAPL and Pico Ramos), and in the historical population of Aldaieta, the presence of this haplogroup is greater than in the rest of the European populations studied, displaying values of around 16%, although it is absent in the prehistoric population of Longar (Table 4). Nevertheless, haplogroup J is of no relevance in either of the first two components in the PC analysis performed in this paper (Fig. 4b and 5b).
wrote:Bearing in mind this temporal variation in the frequency of haplogroup H in the Basque Country, it is not correct to state that the widespread situation in the Upper Palaeolithic involved the existence of high frequencies of haplogroup H, simply due to the fact that present-day Basques present this characteristic. Another example is the case of haplogroup J. Given that the present-day Basque population is an outlier regarding the Neolithic component, it has been proposed that this region experienced a smaller genetic impact from Neolithic farmers. But if we accept that lineage J is a marker of migrations of Neolithic populations from the Near East, then the Basque Country also experienced the impact of these peoples, as is shown by the high frequency of haplogroup J in certain ancient populations.
wrote:As advised by Vernesi et al. (2004), this leads us to reconsider the supposition whereby the genetic patterns of present-day populations reflect the evolutionary processes experienced by their predecessors (Sokal et al. 1991; Richards et al. 2000, 2002, amongst others). Up until now it was thought that there was no evolutionary process subsequent to the Neolithic that altered the genetic composition of European populations (Barbujani & Bertorelle, 2001). However, our data on ancient DNA (as well as those of Vernesi et al. 2004) reveal a discontinuity between prehistoric and present-day populations, which leads us to reconsider the limitations involved in the reconstruction of evolutionary history on the basis of the genetic patterns of present-day populations.