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Abstract
This study examines the genetic variation in Basque Y chromosome lineages using data on 12 Y-short tandem repeat (STR) loci in a sample of 158 males from four Basque provinces of Spain (Alava, Vizcaya, Guipuzcoa, and Navarre). As reported in previous studies, the Basques are characterized by high frequencies of haplogroup R1b (83%). AMOVA analysis demonstrates genetic homogeneity, with a small but significant amount of genetic structure between provinces (Y-short tandem repeat loci STRs: 1.71%, p = 0.0369). Gene and haplotype diversity levels in the Basque population are on the low end of the European distribution (gene diversity: 0.4268; haplotype diversity: 0.9421). Post-Neolithic contribution to the paternal Basque gene pool was estimated by measuring the proportion of those haplogroups with a Time to Most Recent Common Ancestor (TMRCA) previously dated either prior (R1b, I2a2) or subsequent to (E1b1b, G2a, J2a) the Neolithic. Based on these estimates, the Basque provinces show varying degrees of post-Neolithic contribution in the paternal lineages (10.9% in the combined sample).
KEY WORDS: SPAIN, BASQUES, Y-CHROMOSOME, Y-SHORT TANDEM REPEAT LOCI, HAPLOTYPES, POPULATION GENETICS.
The debate concerning the genetic composition of the modern European gene pool is currently a matter of degree. Did the Paleolithic inhabitants of Europe contribute to the modern gene pool? If so, how much? Or are modern Europeans the result of a replacement of the Paleolithic groups by technologically advanced Neolithic farmers? Two models have been proposed to explain the patterns of gene distribution found in Europe. The demie diffusion model (DDM) states that the majority of genetic variation present in modern Europeans is the result of Neolithic farmers spreading their technology (and genes) into Europe with the advent of agriculture (Ammerman and Cavalli-Sforza 1984). The cultural diffusion model (CDM) posits that while technology spread into Europe 10,000 years ago, people did not, leaving the Paleolithic gene pool largely intact (Novelletta 2007). Genetic evidence is used in support of both models. Synthetic gene map analyses based on classical markers exhibit a cline for several loci in the first principal component, accounting for approximately 27% of the total variation and spreading from southeast to northwest through Europe (CavalliSforza et al. 1994). This cline has been interpreted as a genetic signature of the DDM model, with a correlation...