RESUMO
OBJECTIVE: Studies on population genetics have become highly relevant for understanding the evolutionary history of human settlement in southern South America. The eastern Pampa-Patagonia transition is an area that stands out due to its complex population dynamics, especially during the last about 1,000 years BP. The aim of this work is to characterize the maternal lineages of individuals buried in the Paso Alsina 1 archaeological site (ca. 500 years BP) through the analysis of mitochondrial genetic variability, in order to discuss the population models previously proposed for the southern cone of South America. METHODS: Mitochondrial HyperVariable Region I sequences were analyzed on teeth belonging to 20 adult individuals. Statistical analyses were carried out to compare the interpopulation and intrapopulation molecular variability between the results obtained in this work and those previously published data from pre-Hispanic human groups. D1 haplotype network was constructed drawing from data on ancient and extant population group samples. RESULTS: Thirteen sequences (65%) were obtained from the 20 analyzed samples. The maternal lineages or subhaplogroups identified were D1g (69.24%), C1 (15.38%), D1 (7.69%), and D1j (7.69%). There was low haplotype variability within the site; some individuals could be matrilineally related. DISCUSSION: The subhaplogroups registered in Paso Alsina 1 site are in accordance with those reported for ancient and contemporary Patagonian populations. The results suggest that an initial nucleus of individuals carrying mostly subhaplogroup D1g settled in northern Patagonia, from which local diversity of this matrilineage could have arisen. The existence of gene flow in the final late Holocene with groups from Northern Andean Patagonia, as well as from Central Argentina, is proposed. The D1j variant probably developed in the latter region.
Assuntos
DNA Mitocondrial/genética , Variação Genética , Indígenas Sul-Americanos/genética , Dinâmica Populacional , Arqueologia , Argentina , Feminino , Humanos , MasculinoRESUMO
The genetic composition of Amerindian descendants from Patagonia has long been a focus of interest, although the information available is still scarce for many geographic areas. Here, we report the first analysis of the variation in the mitochondrial DNA (mtDNA) control region for an area of northwestern Patagonia, the North of Neuquén, with the aim of studying the processes and historical events that modeled the evolutionary history of these human groups. We analyzed 113 individuals from two localities of northern Neuquén, along with 6 from southern Neuquén and 223 previously published mtDNA sequences from neighboring areas in Argentina and Chile. We estimated the haplotypic variation and spatial structure of molecular variability. Amerindian subhaplogroups predominate in the two samples from northern Neuquén (n = 70), with D1g and C1b13 the most represented, although in different proportions. These samples exhibit Amerindian mtDNA haplotypes similar to the variants from neighboring areas. Most of haplotype variability was within group; variation among groups was relatively low and scarcely associated with geographical space. The most frequent subhaplogroups in northern Neuquén are characteristic of native populations from Patagonia and Chilean Araucanía, and probably originated in the region during the Late Pleistocene or Early Holocene. However, the spatial variation of mtDNA haplotypes departs from a latitudinal pattern and suggests differential levels of gene flow among areas during the Late Holocene, with moderate levels across the North of Neuquén as well as between this area and neighboring populations from Chile, the South of Neuquén, and Río Negro.
RESUMO
OBJECTIVES: The early groups of hunter-gatherers who peopled South America faced significant ecological changes in their trophic niche for a relatively short period after the initial peopling. In particular, the incorporation of cultigens during the Holocene led to a wider trophic niche and probably to an increased carrying capacity of the environment. Here, we study the relationship between the incorporation of domestic resources during the Holocene and the demographic dynamics of human populations at a regional scale in South America. MATERIAL AND METHODS: We employ mitochondrial DNA (mtDNA), radiocarbon data and Bayesian methods to estimate differences in population size, human occupation and explore the demographic changes of human populations in three regions (i.e., South-Central Andes, Northwest, and South Patagonia). We also use archaeological evidence to infer the main diet changes in these regions. RESULTS: The absolute population size during the later Late Holocene was fifteen times larger in the South-Central Andes than in Northwest Patagonia, and two times larger in the latter region than in South Patagonia. The South-Central Andes display the earlier and more abrupt population growth, beginning about 9000 years BP, whereas Northwest Patagonia exhibits a more slow growth, beginning about 7000-7500 years BP. South Patagonia represents a later and slower population increase. DISCUSSION: In this work we uncovered a well-supported pattern of the demographic change in the populations from South-Central Andes and Patagonia, obtained on the basis of different data and quantitative approaches, which suggests that the incorporation of domestic resources was paramount for the demographic expansion of these populations during the Holocene.
Assuntos
Migração Humana , Indígenas Sul-Americanos , Crescimento Demográfico , Antropologia Física , Teorema de Bayes , DNA Mitocondrial/genética , Dieta , Ecologia , Feminino , História Antiga , Migração Humana/história , Migração Humana/estatística & dados numéricos , Humanos , Indígenas Sul-Americanos/genética , Indígenas Sul-Americanos/estatística & dados numéricos , América do SulRESUMO
Mitochondrial DNA (mtDNA) sequences are becoming increasingly important in the study of human population history. Here, we explore the differences in the amount of information of different mtDNA regions and their utility for the reconstruction of South American population history. We analyzed six data sets comprising 259 mtDNA sequences from South America: Complete mtDNA, Coding, Control, hypervariable region I (HVRI), Control plus cytochrome b (cytb), and cytb plus 12S plus 16S. The amount of information in each data set was estimated employing several site-by-site and haplotype-based statistics, distances among sequences, neighbor-joining trees, distances among the estimated trees, Bayesian skyline plots, and phylogenetic informativeness profiles. The different mtDNA data sets have different amounts of information to reconstruct demographic events and phylogenetic trees with confidence. Whereas HVRI is not suitable for phylogenetic reconstruction of ancient clades, this region, as well as the Control data set, displays information for the demographic reconstruction during the Holocene period, probably because of the high rate of mutation of these regions. As expected, the Complete mtDNA and Coding data sets, displaying slower rates of mutation, present suitable information to estimate the founding subhaplogroups that populated South America and for the reconstruction of ancient demographic events. Our results point out the importance of evaluating the utility of different DNA regions to respond to different questions and problems in the human population studies, mainly considering the time scale of the phenomenon and the informativeness of the molecular region in a particular geographical area.