PROTEIN POLYMORPHISM IN 3 SOUTH-AMERINDIAN POPULATIONS

Electrophoretic polymorphism at loci coding for blood red cells and pl asma proteins was analysed in three native populations of South Americ a: Mataco and Maca (from the Gran Chaco), and Guayaki (from the Paragu ayan forest). Mean heterozygosity per locus varied from 0.024 and 0.07 3, the Maca being the most polymorphic population, probably reflecting admixture with the caucasoid population of Asuncion city. Although th e external phenotype, blood group frequencies and ethno-linguistic aff iliation of the Guayaki clearly differ from those of the Chaco tribes, Nei's genetic distances were very low and almost equidistant among th e three populations. Heterogeneity of F-ST values among poly morphic l oci would suggest the action of natural selection.