Molecular variability in Amerindians: widespread but uneven information

Abstract

A review was made in relation to the molecular variability present in North, Central, and South American Indian populations. It involved results from ancient DNA, mitochondrial DNA in extant populations, HLA and other autosomal markers, X and Y chromosome variation, as well as data from parasitic viruses which could show coevolutionary changes. The questions considered were their origin, ways in which the early colonization of the continent took place, types and levels of the variability which developed, peculiarities of the Amerindian evolutionary processes, and eventual genetic heterogeneity which evolved in different geographical areas. Although much information is already available, it is highly heterogeneous in relation to populations and types of genetic systems investigated. Unfortunately, the present trend of favoring essentially applied research suggest that the situation will not basically improve in the future.

Color and genomic ancestry in Brazilians

“…As pointed out by Cavalli-Sforza et al (25), the enormous amounts of genetic drift existent in many South American native groups has generated exceptional gene-frequency variation (reviewed in ref. 26) that severely weakens or renders invalid admixture inferences. Even if we averaged gene frequencies over extant populations, we could have no idea how these frequencies were in the past, when the admixture took place.…”

A great diversity of Amerindian mitochondrial DNA ancestry is present in the Mexican mestizo population

“…53,57 The frequencies of haplogroup D1 in Amerindian populations are lower in Central America and higher in North and South America. 15,16,58 Genetic diversity of mitochondrial Amerindian haplogroups Molecular diversity indexes were calculated for each Amerindian haplogroup (see Table 2). Interestingly, although haplogroup A2 was the most frequent in the whole sample, it had a significantly lower mean number of pairwise differences (4.7) and nucleotide diversity (0.027) compared with the B2 (5.8; 0.034) and C1 (5.9; 0.034) haplogroups (Po0.01, Student's t-test).…”

Polymorphic Alu insertions among Mayan populations

“…Widespread genetic information on Native Americans has been collected and reviewed (Salzano and Callegari-Jacques 1988;Crawford 1998;Salzano 2002). The last author evaluated the molecular variation among (i.e., G st ) North, Central and South Native American populations and found that the levels of inter-population variation is higher in comparison to other worldwide groups.…”

“…In addition, limited variation within populations (i.e., H t ) is found in American natives as a whole when HLA polymorphisms (Black 1991;Arnaiz-Villena et al 2000), polymorphic Alu insertions (PAIs) (Novick et al 1998;Mateus-Pereira et al 2005), mitochondrial DNA (Bonatto and Salzano 1997;Silva et al 2002) and Y-chromosome data (Santos et al 1996;Bianchi et al 1997Bianchi et al , 1998 are examined, supporting the idea of a limited number of entries of founders into the American continent. However, the genetic information is highly heterogeneous with respect to the populations and types of genetic systems investigated (Salzano 2002). In an effort to better understand the genetics of Mesoamerican groups, we undertook this study of the Mayans.…”