Natural killer cell immunoglobulin-like receptors (KIRs) mediate cell lysis through the recognition of human leukocyte antigen class I complexes in target cells, playing an important role in innate immune response. In this context, disease-based selective pressures could be relevant, leaving signatures detected by population studies. However, most population studies on KIR variability have focused on Europe and Asia, while Americas, Oceania, and Africa remain poorly studied. The aim of this study was to analyze the variability of KIR genes in Amerindian tribes from the Amazon region to infer about their evolutionary history. KIR profiles were estimated in 40 individuals from six Amazonian Amerindian tribes using single specific primer polymerase chain reaction. Twenty-five different profiles were identified, and surprisingly, the haplogroup A frequency was the lowest observed in human populations (16%). Results showed also that KIR variability was higher in this group in contrast to Venezuelan Amerindians. Principal components analysis evidenced that Amerindians formed a separated group from other worldwide populations and showed a higher intraethnic differentiation in comparison to other ethnic groups. Such pattern may reflect small effective size and intense genetic drift. However, because of the role of KIR in immune response, selective pressures cannot be entirely ruled out.
tupí linguistic groups display a wide geographical dispersion in south America, probably originated, as pointed by linguistic, from Madeira-Guaporé region (MGr) in Brazil. the present study reviewed genetic data on tupians for autosomal and uniparental (Y-chromosome and mtdnA) markers, using it to evaluate tupians geographic origin as well as the demographic dynamics of their dispersion from a genetic point of view. Comparison of genetic variability and mtdnA haplogroups d frequencies suggests a scenario where MGr is the tupí homeland. the relationship between five estimators of genetic variability (thetas-s, -Pi, -m2, -H and -k) shows that tupí groups from MGr and non-MGr experienced different patterns of demographic dynamics, with an ancient tupí expansion in MGr, followed by dispersion to other south America regions, probably associated to depopulation/founder effect events. furthermore, other recent depopulation events could also be detected in both regions. finally, the dispersion seems to be related to patrilocality, as suggested by comparison of uniparental markers genetic differentiation. this genetic model of dispersion dynamics may have an important impact in the interpretation of archeological and linguistic data, allowing to test if female associated technologies, like ceramic, are more extensively shared between dispersed populations than those which are not female-exclusive.Keywords: tupí homeland. demographic. tupí expansion. Patrilocality. Genetic markers.Resumo: Grupos linguísticos tupí exibem uma grande dispersão geográfica na América do sul, provavelmente originadas, conforme apontada pela linguistica, na região Madeira-Guaporé (MGr), Brasil. o presente estudo revisou dados geneticos de populacoes tupí para marcadores autossomicos e uniparentais (Y-cromossomo and mtdnA), delineando abordagens para avaliar origem geográfica, bem como a dinâmica demográfica de sua dispersão, de um ponto de vista genético. Comparação da variabilidade genetica e das frequencias do haplogrupo d do mtdnA sugere um cenário onde MGr é o local de origem tupí. A relação entre cinco estimadores de variabilidade genetica thetas-s, -Pi, -m2, -H e -k) mostram que grupos tupí da MGr não MGr experienciaram diferentes padrões de dinâmica demográfica, com uma antiga expansão tupí em MGr, seguida de dispersão para outras regiões da América do sul, provavelmente associada a eventos de depopulação/efeito fundador. Além disso, outros eventos recentes de depopulação também puderam ser detectados em ambas as regiões. finalmente, a dispersão parece estar relacionada com práticas de patrilocalidade, como sugerido pela comparação de marcadores uniparentais. Este modelo genético de dinâmica de dispersão tupí pode ter um impacto importante na interpretação dos dados arqueológicos e linguísticos, permitindo testar se tecnologias associadas ao sexo feminino, como a cerâmica, são mais amplamente compartilhadas entre populações dispersas do que tecnologias não exclusivas do sexo feminino.
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