Population study of Aymara Amerindians for the PCR-DNA polymorphisms HUMTH01, HUMVWA31A, D3S1358, D8S1179, D18S51, D19S253, YNZ22 and HLA-DQalpha

Autosomal STR genetic variability in the Gran Chaco native population: Homogeneity or heterogeneity?

To investigate the population structure and variation in Gran Chaco's Amerindian population, data from 15 short tandem repeats (STRs) were determined in 128 individuals from three tribes of the Argentinean part of this region. STR genotypic differences, structure analysis, and multidimensional plot for the D(A) distances indicated that (1) Wichí from the Chaco Province are genetically distinct from the other populations, but still preserve a fair amount of genetic similarity with Wichí from Formosa; (2) the Toba populations studied are genetically indistinguishable; and (3) Toba subjects from Formosa are similar to the Pilagá of the same linguistic group (Guaykurú) and to the Wichí from Formosa who speak a Mataco language. This similarity could be due to their past mobility and the custom of absorbing females taken as prisoners from groups raided by them. Language, geography, and genetics seem to play similar roles in determining the population structure of these groups. Analyses of molecular variance and G(ST)' values calculated considering three South American regions indicated that the Argentinean Chaco is genetically homogeneous; addition of the Ayoreo Amerindians of the Paraguayan Chaco, however, led to diversity values that are not much different from those of South Amerindians in general. The present data contribute to efforts that try to understand in what way groups with diverse sociocultural settings (tribal, agricultural, and industrial) differ in genetic structure.

Genetic analysis of the Amerindian Kichwas and Afroamerican descendents populations from Ecuador characterised by 15 STR-PCR polymorphisms

Allele frequency data for the 15 STR systems and Amelogenine were determined in a population sample of healthy Amerinidian Kichwas and Blacks individuals. All loci met Hardy-Weinberg expectations and the high discrimination power of combined system showed the forensic efficiency of these genetic markers.

The acute hypoxic ventilatory response: testing the adaptive significance in human populations

The acute Hypoxic Ventilatory Response (HVR) is an important component of human hypoxia tolerance, hence presumably physiological adaptation to high altitude. We measured the isocapnic HVR (L min(-1) %(-1)) in two genetically divergent low altitude southern African populations. The HVR does not differ between African Xhosas (X) and Caucasians (C) (X:-0.34+/-0.36; C:-0.42+/-0.33; P > 0.34), but breathing patterns do. Among all Xhosa subjects, size-independent tidal volume was smaller (X: 0.75+/-0.20; C: 1.11+/-0.32 L; P < 0.01), breathing frequency higher (X: 22.2+/-5.7; C: 14.3+/-4.2 breaths min(-1); P < 0.01) and hypoxic oxygen saturation lower than among Caucasians (X: 78.4+/-4.7%; C: 81.7+/-4.7%; P < 0.05). The results remained significant if subjects from Xhosa and Caucasian groups were matched for gender, body mass index and menstrual cycle phase in the case of females. The latter also employed distinct breathing patterns between populations in normoxia. High repeatability (intra-class correlation coefficient) of the HVR in both populations (0.77-0.87) demonstrates that one of the prerequisites for natural selection, consistent between-individual variation, is met. Finally, we explore possible relationships between inter-population genetic distances and HVR differences among Xhosa, European, Aymara Amerindians, Tibetan and Chinese populations. Inter-population differences in the HVR are not attributable to genetic distance (Mantel Z-test, P = 0.59). The results of this study add novel support for the hypothesis that differences in the HVR, should they be found between other human populations, may reflect adaptation to hypoxia rather than genetic divergence through time.

Characterisation of three Amerindian populations from Hidalgo State (Mexico) by 15 STR-PCR polymorphisms

The purpose of this study is to report allele frequency data of three ethnic Amerindian population samples: the Otomi (Hna-hnu) from eastern Sierra Madre and Ixmiquilpan valley and the Huasteco from La Huasteca. These groups were characterised by 15 STR-PCR polymorphisms (HumTH01, HumvWA, D18S51, HumTPOX, D19S433, D16S539, D13S317, D8S1179, D7S820, D5S818, HumFGA, CSF1PO, D2S1338, D3S1358 and D21S11). No significant deviations in observed allelic frequencies from Hardy-Weinberg equilibrium were found for all the studied systems. From the forensic point of view, the heterozygosity value, power of discrimination and the a priori chance of exclusion were calculated.