Clinal variation of YAP(+) Y-chromosome frequencies in Western Iberia

The potential of Y-chromosome biallelic marker haplotypes to infer populati on affiliations and structures was exploited to analyze four populations fr om the southwestern edge of Europe, namely north, central, and south Portug al and Galicia. Three markers subdividing the YAP(+) lineage were analyzed: the YAP Alu element insertion itself and the SRY8299 and sY81 base substit utions; these respectively define three haplotypes known as 4, 21, and 8, O nly haplotype 21 was detected presenting an increasing north-to-south frequ ency gradient, from 9.6% (Galicia) to 24.5% (South Portugal). This clinal d istribution most likely reflects the genetic input associated with the Neol ithic spread of agriculture, but we cannot exclude other. movements as pote ntial contributors to the distribution. In this context, it is interesting to note the consistency between the clinal variation and the population mov ement associated with Islamic rule in Iberia. The absence of haplotype 8, a marker of sub-Saharan populations, suggests that, despite the massive intr oductions of African slaves in historical times, there was little admixture between the African males and Western Iberian populations.