Y-chromosome polymorphisms and the origins of the European gene pool

Gradients of allele frequencies have long been considered the main genetic characteristic of the European population, but mitochondrial DNA diversity seems to be distributed differently. One Alu insertion (YAP), five tetranuc leotide (DYS19, DYS389B, DYS390, DYS391 and DYS393) and one trinucleotide ( DYS392) microsatellite loci of the Y chromosome were analysed for geographi cal patterns in 59 European populations. Spatial correlograms showed dines for most markers, which paralleled the gradients previously observed for tw o restriction fragment length polymorphisms. Effective separation times bet ween populations were estimated from genetic distances at microsatellite lo ci. Even after correcting for the possible effects of continuous local gene flow, the most distant Indo-European-speaking populations seem to have sep arated no more than 7000 years ago. The clinal patterns and the estimated, recent separation times between populations jointly suggest that Y-chromoso me diversity in Europe largely reflects a directional demic expansion, whic h is unlikely to have occurred before the Neolithic period.