Mitochondrial DNA Variability among Six South American Amerindian Villages from the Pano Linguistic Group

Abstract

Although scattered throughout a large geographic area, the members of the Pano linguistic group present strong ethnic, linguistic, and cultural homogeneity, a feature that causes them to be considered components of a same “Pano” tribe. Nevertheless, the genetic homogeneity between Pano villages has not yet been examined. To study the genetic structure of the Pano linguistic group, four major Native American mitochondrial DNA (mtDNA) founder haplogroups were analyzed in 77 Amerindians from six villages of four Pano tribes (Katukina, Kaxináwa, Marúbo, and Yaminawa) located in the Brazilian Amazon. The central position of these tribes in the continent makes them relevant for attempts to reconstruct population movements in South America. Except for a single individual that presented an African haplogroup L, all remaining individuals presented one of the four Native American haplogroups. Significant heterogeneity was observed across the six Pano villages. Although Amerindian populations are usually characterized by considerable interpopulational diversity, the high heterogeneity level observed is unexpected if the strong ethnic, linguistic, and cultural homogeneity of the Pano linguistic group is taken into account. The present findings indicate that the ethnic, linguistic, and cultural homogeneity does not imply genetic homogeneity. Even though the genetic heterogeneity uncovered may be a female-specific process, the most probable explanation for that is the joint action of isolation and genetic drift as major factors influencing the genetic structure of the Pano linguistic group.

The central west region of the Brazilian Amazon attracts attention because of its central position in South America, which makes it relevant for attempts to reconstruct the population movements and biological relationships of South American indigenous populations. Many tribes inhabit the western part of the northern region of Brazil, including several that are classified as Pano. They descend from populations that used to inhabit the eastern Andean slopes of Ecuador. At the end of the seventeenth century, they experienced some migrational events that culminated in their distribution along the Juruá and Purus Rivers in the Brazilian territory and in adjacent portions of Peru (Mohrenweiser et al. 1979; Salzano and Jacques 1979).

At that time, they suffered a series of fissions that gave rise to the current tribes (Salzano and Jacques 1979). In spite of their large geographic distribution, the Pano group attracts attention for its remarkable ethnic homogeneity, reinforced by outstanding cultural and linguistic cohesion (Erikson 1998). For instance, a linguistic analysis based on the cognate density disclosed a high degree of mutual intelligibility (Mohrenweiser et al. 1979), even greater than that encountered among the various subdivisions of the Yanomami (Spielman et al. 1974). Therefore, the several Pano groups are sometimes considered as members of a single Pano tribe (Mohrenweiser et al. 1979; Salzano and Jacques 1979).

The genetic structure of the Pano group has not been comprehensively studied. So far, analyses of classical genetic markers, including both blood groups and erythrocyte and serum proteins (ABO, Kell, MNSs, P, Rh, Duffy, Kidd, Diego, haptoglobin, GC, transferrin, albumin, Lewis, ceruloplasmin, Gm, Km, phosphoglucomutase, acid phosphatase, galactose-1-phosphate uridyltransferase, and esterase D), revealed that the Brazilian and Peruvian Kaxináwa (one of the Pano tribes) can be grouped in a common gene pool, while Kaxináwa and Katukina (another Pano tribe) are somewhat more heterogeneous (Salzano and Jacques 1979). The only DNA markers that were exhaustively studied in Pano populations were two HLA-G polymorphisms: a cytosine deletion (ΔC) at codon 130 in exon 3 that determines a premature stop codon (Mendes-Junior et al. 2007a) and a 14-bp insertion/ deletion polymorphism at exon 8 of the HLA-G gene (Mendes-Junior et al. 2007b). While the ΔC was not observed in the four Pano tribes, the 14-bp insertion/deletion polymorphism revealed heterogeneous insertion frequencies that ranged from 36.11% (Marúbo) to 77.78% (Kaxináwa) (Mendes-Junior et al. 2007a, 2007b).

Mitochondrial DNA (mtDNA) haplogroups, which present a matrilineal pattern of inheritance, have yet to be extensively analyzed among the Pano Indians. Although mtDNA markers have already been analyzed in many South American...