Distribution of blood groups among indians in South America. VI. In Paraguay

Genetic studies in French Guiana populations: Synthesis

Twelve blood group and protein systems from a total of 819 individuals from six tribal groups (Apalaí-Wayana, Emerillon, Kaliña, Palikur Wayampi, and Wayana) living in French Guiana and Brazil were compared with each other and integrated with previous results from 17 other South Amerindian populations studied for the same genetic markers. Using correspondence analysis, map methodologies, and maximum linkage cluster analysis developed with the UPGMA method, we attempted to establish the genetic position of these tribes among South American Indians. Peripheral positions for the Emerillon and the Palikur were observed. Ethnohistorical data in French Guiana suggest that a strong founder effect for the former and endogamy for the latter could have generated the genetic differentiation of these two ethnic groups. However, when considered in a wider context, all French Guiana Natives cluster together in an intermediate position as compared with 17 other Amerindian groups studied for the comparison.

Mitochondrial DNA andAlu insertions in a genetically peculiar population: The Ayoreo Indians of Bolivia and Paraguay

A total of 91 Ayoreo individuals previously studied for blood groups and protein markers, living in two Bolivian and one Paraguayan communities, were extensively investigated in relation to the hypervariable 1 segment of the control and eight coding regions of their mitochondrial DNA (mtDNA). They show an extremely reduced mtDNA variability, the observed haplotypes being classifiable in just two haplogroups (C and D). They were also variously studied in relation to six Alu insertions; in this case, however, the prevalences found did not depart markedly from those obtained in other populations of this ethnic group. To assess the Ayoreo position in relation to these populations, 11 other groups that had also been studied for these systems and for blood groups and proteins were selected. The dendrograms obtained with two of the three sets of markers showed distinct patterns, but the Ayoreo were placed in a central position in both the blood group + proteins and Alu insertions trees. Therefore, they are clearly distinct in relation to their mtDNA only, suggesting a strong founder effect and/or random loss of variability in this system.

New genetic data on Amerindians from the Paraguayan Chaco

New data on 17 blood group and protein genetic systems obtained among the Ayoreo and Lengua Indians of Paraguay are presented. They include the first report on the red cell band-3 protein investigated among South American Indians. This information was integrated with previous results available for these two and four other groups. Five of the six populations reside in the Chaco area, while the sixth was included as an outgroup living elsewhere in Paraguay. Four of the five Chaco tribes exhibit good genetic homogeneity, but the Ayoreo are somewhat different. The results confirm the Chaco as a distinct biological (as well as cultural and economic) region, which should be considered in evaluations of genetic variability among South American Indians.

Genetic relationships between Amerindian populations of Argentina

A total of 495 individuals from five different Argentinian tribes was examined for variation in 23 blood group and protein genetic systems, and the results were integrated with previous data on some of these systems. These tribes generally present RH * R1, PGM1 * 1, and ACP * A frequencies lower and RH * R2, ESD * 1, and GLO * 1 prevalences higher than those observed in other South American Indian groups. Earlier studies with mitochondrial DNA showed that haplogroup A was present in low frequencies in these tribes, but haplogroup B showed a high prevalence among the Mataco. Average heterozygosities are very similar in the five tribes, while estimates of non-Indian ancestry are generally low. Both the blood group and protein, as well as the mtDNA data sets, divide the five tribes into two groups, and the relationships obtained with the blood group and protein systems are exactly those expected on the basis of geography and language. However, the topology obtained with the mtDNA results was different, possibly due to sampling effects or diverse patterns of exchange between the groups related to sex.

Protein polymorphism in three South Amerindian populations

Electrophoretic polymorphism at loci coding for blood red cells and plasma proteins was analysed in three native populations of South America: Mataco and Macá (from the Gran Chaco), and Guayaki (from the Paraguayan forest). Mean heterozygosity per locus varied from 0.024 and 0.073, the Macá being the most polymorphic population, probably reflecting admixture with the caucasoid population of Asuncion city. Although the external phenotype, blood group frequencies and ethno-linguistic affiliation of the Guayaki clearly differ from those of the Chaco tribes, Nei's genetic distances were very low and almost equidistant among the three populations. Heterogeneity of F(ST) values among polymorphic loci would suggest the action of natural selection.

Patterns and correlates of genetic variation in South Amerindians

Gene frequency data from six polymorphic blood group systems in 70 South American Indian populations are used to derive synthetic gene frequency maps that document the geographical pattern of genetic variation. Additional analyses are directed toward the elucidation of mechanisms that give rise to or maintain the observed distributions. Variables of local ecology do not appear to explain gene frequency distributions in South America. Instead, local isolation and the action of stochastic forces appears to be the most parsimonious explanation of the observed geographical patterns. This is distinctly different from the geographical patterns of genetic variation seen in other continents.

Restriction and persistence of polymorphisms of HLA and other blood genetic traits in the Parakanã Indians of Brazil

Results concerning HLA types and 22 other blood genetic systems are reported for the Parakanã Indians of northern Brazil, a tribe that is notable for the light color and pilosity of some of its members. No clear evidence of Caucasoid admixture was found, but the Parakanã show unusual frequencies in the EsD1, PGM1(1) Gc2, CpB, Fya, Dia, and LM genetic markers. In addition, the very rare Rh allele ry is present, as well as what seems to be a new PGM2 variant. There is very limited heterogeneity in the HLA system. All these distinctive features may have arisen through a combination of founder effects and genetic drift. However, low FIS values, as well as higher mean ages in heterozygous as compared to homozygous persons, suggest that an heterotic effect is counteracting these dispersive forces.