Genetic structure of Quechua-speakers of the Central Andes and geographic patterns of gene frequencies in South Amerindian populations

A sample of 141 Quechua-speaking individuals of the population of Tayacaja, in the Peruvian Central Andes, was typed for the following 16 genetic syst ems: ABO, Rh, MNSs, P, Duffy, AcP1, EsD, GLOI, PGTM1, AK, B-PGD, Wp, Gc, Pi , C3, and Bf. The genetic structure of the population was analyzed in relat ion to the allele frequencies available for other South Amerindian populati ons, using a combination of multivariate and multivariable techniques. Spat ial autocorrelation analysis was performed independently for 13 alleles to identify patterns of gene flow in South America as a whole and in more spec ific geographic regions. We found a longitudinal dine for the AcP1*a and EsD*1 alleles which we inte rpreted as the result of an ancient longitudinal expansion of a putative an cestral population of modern Amerindians. Monmonnier's algorithm, used to i dentify areas of sharp genetic discontinuity, suggested a clear east-west d ifferentiation of native South American populations, which was confirmed by analysis of the distribution of genetic distances. We suggest that this pa ttern of genetic structures is the consequence of the independent peopling of western and eastern South America or to low levels of gene flow between these regions, related to different environmental and demographic histories . (C) 2000 Wiley-Liss, Inc.