Micro-geographical differentiation in Northern Iberia revealed by Y-chromosomal DNA analysis.

Y-chromosome diversity has been analyzed at a micro-geographical level, examining 10 binary polymorphisms and 7 short tandem repeats (STRs) in 443 samples belonging to 11 populations from two regions of Northern Spain, Galicia and Cantabria. Both regions, as a whole, cluster with other Iberian populations. However, some individual populations, particularly that from the Pas Valley in Cantabria, depart markedly from this general pattern, with higher genetic distances and reduced diversity. This unusual population is even more distinct than the Basques from their Iberian neighbors. Genetic drift in a small isolated population could explain this special behavior, and in addition to its anthropological interest, this finding has important forensic implications.