In search of the pre- and post-neolithic genetic substrates in Iberia: evidence from Y-chromosome in Pyrenean populations.

The male-mediated genetic legacy of the Pyrenean population was assessed through the analysis of 12 Y-STR and 27 Y-SNP loci in a sample of 169 males from 5 main geographical areas in the Spanish Pyrenees: Cinco Villas (Western Pyrenees), Jacetania and Valle de Arán (Central Pyrenees) and Alto Urgel and Cerdaña (Eastern Pyrenees). In the Iberian context, the Pyrenean samples present some specificities, being characterizeded by a high proportion of chromosomes R1b1b2-M269 (including the usually uncommon R1b1b2d-SRY(2627) and R1b1b2c-M153 types) or I2a2-M26 and low proportions of other haplogroups. Our results indicate that an old pre-Neolithic substrate is preponderant in populations of the whole Pyrenean fringe. However, AMOVA revealed a high level of substructure within Pyrenean populations, partially explained by drift effects as well as by the signature of an ancient genetic differentiation between Western and Eastern Pyrenees.