HLA haplotypes and differential regional mortality caused by COVID-19 in Brazil: an ecological study based on a large bone marrow donor bank dataset.

The coronavirus disease 2019 (COVID-19) mortality rates varied among the states of Brazil during the course of the pandemics. The human leukocyte antigen (HLA) is a critical component of the antigen presentation pathway. Individuals with different HLA genotypes may trigger different immune responses against pathogens, which could culminate in different COVID-19 responses. HLA genotypes are variable, especially in the highly admixed Brazilian population. In this ecological study, we aimed to investigate the correlation between HLA haplotypes and the different regional distribution of COVID-19 mortality in Brazil. HLA data was obtained from 4,148,713 individuals registered in The Brazilian Voluntary Bone Marrow Donors Registry. COVID-19 data was retrieved from epidemiological bulletins issued by State Health Secretariats via Brazil's Ministry of Health from February/2020 to July/2022. We found a positive significant correlation between the HLA-A*01~B*08~DRB1*03 haplotype and COVID-19 mortality rates when we analyzed data from 26 states and the Federal District. This result indicates that the HLA-A*01~B*08~DRB1*03 haplotype may represent an additional risk factor for dying due to COVID-19. This haplotype should be further studied in other populations for a better understanding of the variation in COVID-19 outcomes across the world.

The record and threats of the invasion of palometa Serrasalmus maculatus (Characiformes: Serrasalmidae) in the Patos lagoon drainage, southern Brazil.

We report the occurrence of an invasive alien species, palometa Serrasalmus maculatus, in the Patos Lagoon drainage. Primary occurrence data were based on three specimens captured and preserved as vouchers in scientific collections. Additionally, we searched for secondary records from unpublished scientific sources, public agencies reports and media news to find additional reports. We discussed the possible pathways of invasion, suggesting as the vector of introduction transpositions from the Uruguay River basin. Ecological implications for ichthyofauna, environmental impacts and risk of other events of invasion in the adjoining basins are discussed.

What We Talk About When We Talk About "Junk DNA".

"Junk DNA" is a popular yet controversial concept that states that organisms carry in their genomes DNA that has no positive impact on their fitness. Nonetheless, biochemical functions have been identified for an increasing fraction of DNA elements traditionally seen as "Junk DNA". These findings have been interpreted as fundamentally undermining the "Junk DNA" concept. Here, we reinforce previous arguments that this interpretation relies on an inadequate concept of biological function that does not consider the selected effect of a given genomic structure, which is central to the "Junk DNA" concept. Next, we suggest that another (though ignored) confounding factor is that the discussion about biological functions includes two different dimensions: a horizontal, ecological dimension that reflects how a given genomic element affects fitness in a specific time, and a vertical, temporal dimension that reflects how a given genomic element persisted along time. We suggest that "Junk DNA" should be used exclusively relative to the horizontal dimension, while for the vertical dimension, we propose a new term, "Spam DNA", that reflects the fact that a given genomic element may persist in the genome even if not selected for on their origin. Importantly, these concepts are complementary. An element can be both "Spam DNA" and "Junk DNA", and "Spam DNA" can also be recruited to perform evolved biological functions, as illustrated in processes of exaptation or constructive neutral evolution.

Genetic differentiation in East African ethnicities and its relationship with endurance running success.

Since the 1960s, East African athletes, mainly from Kenya and Ethiopia, have dominated long-distance running events in both the male and female categories. Further demographic studies have shown that two ethnic groups are overrepresented among elite endurance runners in each of these countries: the Kalenjin, from Kenya, and the Oromo, from Ethiopia, raising the possibility that this dominance results from genetic or/and cultural factors. However, looking at the life history of these athletes or at loci previously associated with endurance athletic performance, no compelling explanation has emerged. Here, we used a population approach to identify peaks of genetic differentiation for these two ethnicities and compared the list of genes close to these regions with a list, manually curated by us, of genes that have been associated with traits possibly relevant to endurance running in GWAS studies, and found a significant enrichment in both populations (Kalenjin, P = 0.048, and Oromo, P = 1.6x10-5). Those traits are mainly related to anthropometry, circulatory and respiratory systems, energy metabolism, and calcium homeostasis. Our results reinforce the notion that endurance running is a systemic activity with a complex genetic architecture, and indicate new candidate genes for future studies. Finally, we argue that a deterministic relationship between genetics and sports must be avoided, as it is both scientifically incorrect and prone to reinforcing population (racial) stereotyping.

A Preliminary Assessment of the Potential Health and Genetic Impacts of Releasing Confiscated Passerines Into the Wild: A Reduced-Risk Approach.

The illegal capture and trade of wild birds have long been threats to biodiversity. The rehabilitation and release of confiscated animals may be a useful conservation tool in species management. However, differences between populations regarding health (e.g., different pathogens) and adaptation (e.g., local adaptation) must be taken into account, since both can negatively impact the recipient population. In this pilot study, we used two of the most illegally trafficked Brazilian wild passerine species, namely the red-crested cardinal (Paroaria coronata) and green-winged saltator (Saltator similis) as case studies and assessed some of the health threats that the release of confiscated passerines may pose to free-living birds. We also investigated the level of difference in mitochondrial genetic structure among populations living in different ecoregions. Blood, feces, and oropharyngeal swabs from confiscated (n = 115) and free-living (n = 120) passerines from the release sites were tested for the Newcastle disease virus, Salmonella spp., and Mycoplasma gallisepticum. These are considered major avian diseases by the Brazilian National Avian Health Program. We analyzed mtDNA to study the difference in genetic structure between populations using samples from 127 free-living passerines. We found no evidence of the Newcastle disease virus or Salmonella spp. in confiscated or free-living passerines from either species. However, the levels of infection with M. galissepticum detected in our study for red-crested cardinals and green-winged saltators calls for a high degree of caution in captive release programs. The difference in genetic structure between populations occurring in different regions was low, and was not significant between those from the Pampa/Subtropical Grasslands region. These results suggest that it may be possible to establish a cost-effective and sensitive protocol for releasing confiscated songbirds, provided that further genome-wide studies indicate that the functional genetic diversity among (at least some of the) populations is also low.

Seascape Genetics of the Atlantic Spotted Dolphin (Stenella frontalis) Based on Mitochondrial DNA.

The Atlantic spotted dolphin (Stenella frontalis) is endemic to tropical, subtropical, and warm temperate waters of the Atlantic Ocean. Throughout its distribution, both geographic distance and environmental variation may contribute to population structure of the species. In this study, we follow a seascape genetics approach to investigate population differentiation of Atlantic spotted dolphins based on a large worldwide dataset and the relationship with marine environmental variables. The results revealed that the Atlantic spotted dolphin exhibits population genetic structure across its distribution based on mitochondrial DNA control region (mtDNA-CR) data. Analyses based on the contemporary landscape suggested, at both the individual and population level, that the population genetic structure is consistent with the isolation-by-distance model. However, because geography and environmental matrices were correlated, and because in some, but not all analyses, we found a significant effect for the environment, we cannot rule out the addition contribution of environmental factors in structuring genetic variation. Future analyses based on nuclear data are needed to evaluate whether local processes, such as social structure and some level of philopatry within populations, may be contributing to the associations among genetic structure, geographic, and environmental distance.

Uniparental genetic markers in Native Americans: A summary of all available data from ancient and contemporary populations.

OBJECTIVES: The aim of this study was to create a comprehensive summary of available mtDNA and Y-chromosome data for Native Americans from North, Central, and South America, including both modern and ancient DNA. To illustrate the usefulness of this dataset we present a broad picture of the genetic variation for both markers across the Americas. METHODS: We searched PubMed, ResearchGate, Google Scholar for studies about mtDNA or Y-chromosome variation in Native American populations, including geographic, linguistic, ecological (ecoregion), archeological and chronological information. We used AMOVA to estimate the genetic structure associated with language and ecoregion grouping and Mantel tests to evaluate the correlation between genetic and geographic distances. RESULTS: Genetic data were obtained from 321 primary sources, including 22,569 individuals from 298 contemporary populations, and 3628 individuals from 202 archeological populations. MtDNA lineages of probable non-Amerindian origin were rare, in contrast with Y-chromosome lineages. Mantel tests showed a statistically significant correlation for the whole continent considering mtDNA but not the Y-chromosome. Genetic structure between groups was always stronger for mtDNA than for the Y-chromosome. CONCLUSIONS: This study summarizes decades of research conducted in Native American populations for both mtDNA and the Y-chromosome. Continental or sub-continental patterns of variation reveal that most of the genetic variation occurs within populations rather than among linguistic or ecoregional groups, and that isolation by distance is barely detectable in most population sets. The genetic structure among groups was always larger for mtDNA than for the Y-chromosome, suggesting between-sex differences in gene flow.

Hydrography rather than lip morphology better explains the evolutionary relationship between Gymnogeophagus labiatus and G. lacustris in Southern Brazil (Cichlidae: Geophagini)

Gymnogeophagus labiatus and G. lacustris have been long recognized as sister species exhibiting different ecological requirements. Gymnogeophagus labiatus occurs in rock bottom rivers in the hydrographic basins of Patos Lagoon (HBP) and Tramandaí River (HBT), while G. lacustris is exclusive from sand bottom coastal lagoons of the HBT. In this study, we used molecular markers, morphological measurements and data from nuptial male coloration to investigate the evolutionary relationship between these species in each hydrographic basin. We found, for all data sets, a closer relationship between G. labiatus and G. lacustris from the HBT than between G. labiatus populations from HBT and HBP. In particular, lip area had a large intraspecific plasticity, being uninformative to diagnose G. lacustris from G. labiatus. Molecular clock-based estimates suggest a recent divergence between species in the HBT (17,000 years ago), but not between G. labiatus from HBP and HBT (3.6 millions of years ago). Finally, we also found a divergent G. labiatus genetic lineage from the Camaquã River, in the HBP. These results show that the current taxonomy of G. labiatus and G. lacustris does not properly represent evolutionary lineages in these species.(AU)

Gymnogeophagus labiatus e G. lacustris vêm sendo consideradas espécies irmãs que possuem diferentes exigências ecológicas. Gymnogeophagus labiatus ocorre em rios de fundo de pedra nas bacias hidrográficas da Laguna dos Patos (HBP) e do rio Tramandaí (HBT), enquanto G. lacustris é exclusivo da HBT, ocorrendo em lagoas costeiras de fundo de arenoso. Nesse estudo, foram usados marcadores moleculares, medidas morfológicas e dados sobre a coloração nupcial em machos para investigar a relação evolutiva entre estas espécies em cada bacia hidrográfica. Para todos os conjuntos de dados foi observada uma relação mais próxima entre G. labiatus e G. lacustris da HBT do que entre as populações de G. labiatus da HBP e HBT. Em particular, a área do lábio teve uma grande plasticidade intraespecífica, não sendo informativa para diagnosticar G. lacustris de G. labiatus. Estimativas baseadas no relógio molecular sugeriram uma divergência recente entre as espécies da HBT (17.000 anos atrás), mas não entre as populações de G. labiatus da HBP e HBT (3,6 milhões de anos atrás). Finalmente, também foi encontrada uma linhagem genética de G. labiatus divergente no rio Camaquã, na HBP. Esses resultados mostram que a taxonomia atual de G. labiatus e G. lacustris não representa adequadamente as linhagens evolutivas nessas espécies.(AU)

HLA diversity in Brazil.

Brazil is the fifth largest country in the world in area and the fifth most populous. The Brazilian voluntary Bone Marrow Donor Registry is the third largest in terms of number of donors in the world, being a valuable source of HLA genetics to characterize the donor population of Brazil as well. The genetic background of the Brazilian population is quite heterogeneous, resulting from 5 centuries of admixture among Native Americans, Europeans and Africans, making the Brazilian population unique in terms of genetic ancestry. The unique characteristics of populations in different Brazilian regions make them an exciting focus for genetic diversity studies. Studies on HLA genetic diversity of Brazilian populations have been conducted since the late 1980s and, in this review, we highlight the main findings from studies carried out in Brazil based on classical HLA. In addition, we calculated the genetic distance from the molecular data of the studies included in this review in order to have a broader view of the HLA diversity in Brazilian populations. We emphasize that characterization of HLA diversity is not only important for transplantation programs, but can shed a light on ancestry, history and other demographic patterns with or without association with autoimmune disease.

Hepatitis B Virus: Alternative phylogenetic hypotheses and its impact on molecular evolution inferences.

Characterizing molecular evolution patterns of the Hepatitis B Virus (HBV) is important for a better understanding of the natural history of this infection. However, several molecular evolution estimates are conditioned on tree topology. There is no consensus about the phylogenetic relationships of HBV genotypes, and different studies often find alternative topologies. While most studies consider HBV genotypes F and H as sister to all other human genotypes, a recent study suggested an alternative HBV phylogeny that indicates an accelerated substitution rate for HBV-F/H partially driven by positive selection. In this study, we evaluate the impact of alternative HBV topologies on inferences of HBV phylogeny, rate acceleration, and positive selection on the HBV-F/H branch. Our results indicate that under certain methodological approaches alternative HBV topologies are equally likely. Considering phylogenetic uncertainty, there is no evidence that HBV-F/H had an accelerated substitution rate, even though inferences of positive selection are robust to alternative background topologies. Our results further suggest that, under reasonable assumptions, HBV-F/H most likely represents the sister lineage to all other human/ape HBV genotypes. Understanding the full range of likely topologies will be crucial for elaborating, testing, and refining hypothesis about the evolutionary HBV origins in our species.

Measuring the impact of European colonization on Native American populations in Southern Brazil and Uruguay: Evidence from mtDNA.

OBJECTIVES: The major aim of this article was to estimate the demographic impact of European arrival and colonization over Native American populations from southern Brazil and Uruguay. We also compared the mitochondrial DNA (mtDNA) genetic diversity, structure, and demography of Native American lineages present in current indigenous (Natives) and nonindigenous admixed (Admixed) populations to estimate the effective population size (Ne ) of contemporary and ancestral (pre-Columbian) Native American populations. METHODS: We retrieved published mtDNA sequences from Native (n = 396) and Admixed (n = 309) populations from southern Brazil, Uruguay, and surrounding areas. We conducted genetic diversity, structure, and demographic analyses. Finally, we used Approximate Bayesian Computation to estimate the Ne for current Native, Admixed, and pre-Columbian Native American populations. RESULTS: We found higher Native American mtDNA genetic diversity in admixed rather than in indigenous populations (131/309 vs 27/396 different haplotypes, respectively). Only Admixed populations maintained ancient signals of the Native American population expansion approximately 14 to 17 kya, which have decayed in Natives. Our Ne estimates suggest that Natives represent only 0.33% (0.18%-1.19%) of the Ne for ancestral pre-Columbian indigenous populations. CONCLUSIONS: Admixed populations represent an important genetic reservoir of Native American lineages, many of which are extinct in contemporary indigenous populations. In addition, the Native American lineages present in Admixed populations retain part of the past demographic history of Native Americans. The intensity of the reduction is congruent with historical accounts of strong indigenous depopulation during the colonization process.

Molecular Identification of Shark Meat From Local Markets in Southern Brazil Based on DNA Barcoding: Evidence for Mislabeling and Trade of Endangered Species.

Elasmobranchs, the group of cartilaginous fishes that include sharks and rays, are especially vulnerable to overfishing due to low fecundity and late sexual maturation. A significant number of elasmobranch species are currently overexploited or threatened by fisheries activities. Additionally, several recent reports have indicated that there has been a reduction in regional elasmobranch population sizes. Brazil is an important player in elasmobranch fisheries and one of the largest importers of shark meat. However, carcasses entering the shark meat market have usually had their fins and head removed, which poses a challenge to reliable species identification based on the morphology of captured individuals. This is further complicated by the fact that the internal Brazilian market trades several different elasmobranch species under a common popular name: "cação." The use of such imprecise nomenclature, even among governmental agencies, is problematic for both controlling the negative effects of shark consumption and informing the consumer about the origins of the product. In this study, we used DNA barcoding (mtDNA, COI gene) to identify, at the species level, "cação" samples available in local markets from Southern Brazil. We collected 63 samples traded as "cação," which we found to correspond to 20 different species. These included two teleost species: Xiphias gladius (n = 1) and Genidens barbus (n = 6), and 18 species from seven elasmobranch orders (Carcharhiniformes, n = 42; Squaliformes, n = 3; Squatiniformes, n = 2; Rhinopristiformes, n = 4; Myliobatiformes, n = 3; Rajiformes, n = 1; and Torpediniformes, n = 1). The most common species in our sample were Prionace glauca (n = 15) and Sphyrna lewini (n = 14), while all other species were represented by four samples or less. Considering IUCN criteria, 47% of the elasmobranch species found are threatened at the global level, while 53% are threatened and 47% are critically endangered in Brazil. These results underline that labeling the meat of any shark species as "cação" is problematic for monitoring catch allocations from the fishing industry and discourages consumer engagement in conservationist practices through informed decision-making.

How strong was the bottleneck associated to the peopling of the Americas? New insights from multilocus sequence data.

In spite of many genetic studies that contributed for a deep knowledge about the peopling of the Americas, no consensus has emerged about important parameters such as the effective size of the Native Americans founder population. Previous estimates based on genomic datasets may have been biased by the use of admixed individuals from Latino populations, while other recent studies using samples from Native American individuals relied on approximated analytical approaches. In this study we use resequencing data for nine independent regions in a set of Native American and Siberian individuals and a full-likelihood approach based on isolation-with-migration scenarios accounting for recent flow between Asian and Native American populations. Our results suggest that, in agreement with previous studies, the effective size of the Native American population was small, most likely in the order of a few hundred individuals, with point estimates close to 250 individuals, even though credible intervals include a number as large as ~4,000 individuals. Recognizing the size of the genetic bottleneck during the peopling of the Americas is important for determining the extent of genetic markers needed to characterize Native American populations in genome-wide studies and to evaluate the adaptive potential of genetic variants in this population.

How strong was the bottleneck associated to the peopling of the Americas? New insights from multilocus sequence data

Abstract In spite of many genetic studies that contributed for a deep knowledge about the peopling of the Americas, no consensus has emerged about important parameters such as the effective size of the Native Americans founder population. Previous estimates based on genomic datasets may have been biased by the use of admixed individuals from Latino populations, while other recent studies using samples from Native American individuals relied on approximated analytical approaches. In this study we use resequencing data for nine independent regions in a set of Native American and Siberian individuals and a full-likelihood approach based on isolation-with-migration scenarios accounting for recent flow between Asian and Native American populations. Our results suggest that, in agreement with previous studies, the effective size of the Native American population was small, most likely in the order of a few hundred individuals, with point estimates close to 250 individuals, even though credible intervals include a number as large as ~4,000 individuals. Recognizing the size of the genetic bottleneck during the peopling of the Americas is important for determining the extent of genetic markers needed to characterize Native American populations in genome-wide studies and to evaluate the adaptive potential of genetic variants in this population.

Genetic variation of the bronze locus (MC1R) in turkeys from Southern Brazil.

Domestic turkeys present several color phenotypes controlled by at least five genetic loci, but only one of these has been identified precisely: the bronze locus, which turned out to be the melanocortin-1 receptor (MC1R) gene. MC1R variation is important for breeders interested in maintaining or developing different color varieties. In this study, we sequenced most of the MC1R gene from 16 White Holland (the main commercial turkey variety) and 19 pigmented turkeys from southern Brazil with two purposes. The first was to describe the MC1R diversity in White Holland turkeys, which may serve as reservoirs of genetic diversity at this locus. The second was to test whether the traditional color classification used by Brazilian breeders is related to previously known MC1R alleles. White Holland turkeys had four different haplotypes corresponding to the bronze (b+) and black-winged bronze (b1) alleles. Pigmented turkeys also had four haplotypes corresponding to the b+ and b1 alleles, but different haplotypes represent the most common b+ allele in these two groups. The black (B) allele was absent from our samples. Overall, our results suggest that white and pigmented individuals form two different populations, and that the traditional color classification used by Brazilian breeders cannot accurately predict the genotypes at the bronze locus.

Genetic variation of the bronze locus (MC1R) in turkeys from Southern Brazil

Abstract Domestic turkeys present several color phenotypes controlled by at least five genetic loci, but only one of these has been identified precisely: the bronze locus, which turned out to be the melanocortin-1 receptor (MC1R) gene. MC1R variation is important for breeders interested in maintaining or developing different color varieties. In this study, we sequenced most of the MC1R gene from 16 White Holland (the main commercial turkey variety) and 19 pigmented turkeys from southern Brazil with two purposes. The first was to describe the MC1R diversity in White Holland turkeys, which may serve as reservoirs of genetic diversity at this locus. The second was to test whether the traditional color classification used by Brazilian breeders is related to previously known MC1R alleles. White Holland turkeys had four different haplotypes corresponding to the bronze (b+) and black-winged bronze (b1) alleles. Pigmented turkeys also had four haplotypes corresponding to the b+ and b1 alleles, but different haplotypes represent the most common b+ allele in these two groups. The black (B) allele was absent from our samples. Overall, our results suggest that white and pigmented individuals form two different populations, and that the traditional color classification used by Brazilian breeders cannot accurately predict the genotypes at the bronze locus.

Population Genetic Structure of Cnesterodon decemmaculatus (Poeciliidae): A Freshwater Look at the Pampa Biome in Southern South America.

The Pampas is a Neotropical biome formed primarily by low altitude grasslands and encompasses the southernmost portion of Brazil, Uruguay, and part of Argentina. Despite the high level of endemism, and its significant environmental heterogeneity, Pampean species are underrepresented in phylogeographic studies, especially aquatic organisms. The Pampean hydrological system resulted from a long history of tectonism, climate, and sea level changes since the Neogene. In this study, we examined the population genetic structure of Cnesterodon decemmaculatus, a freshwater fish species that occurs throughout most of the Pampa biome. We characterized mitochondrial and autosomal genetic lineages in populations sampled from Southern Brazil and Uruguay to investigate (1) the correspondence between current drainage systems and evolutionary lineages, (2) the demographic history for each genetic lineage, and (3) the temporal depth of these lineages. Overall, we found that the major evolutionary lineages in this species are strongly related to the main Pampean drainage systems, even though stream capture events may have affected the distribution of genetic lineages among drainages. There was evidence for recent population growth in the lineages occupying drainages closest to the shore, which may indicate the effect of quaternary sea-level changes. In general, divergence time estimates among evolutionary lineages were shallow, ranging from 20,000 to 800,000 years before present, indicating a geologically recent history for this group, as previously reported in other Pampean species. A Bayesian phylogeographical reconstruction suggested that an ancestral lineage probably colonized the Uruguay River Basin, and then expanded throughout the Pampas. This evolutionary scenario may represent useful starting models for other freshwater species having a similar distribution.

Ontogenetic changes in mouth morphology triggers conflicting hypotheses of relationships in characid fishes (Ostariophysi: Characiformes)

Bryconamericus lethostigmus is the type-species of the monotypic genus Odontostoechus, diagnosed in part based on the presence of a unique tooth series in the premaxilla. Recently a new proposal of classification of the Stevardiinae placed Odontostoechus as a junior synonym of a monophyletic genus Bryconamericus sensu stricto, a genus characterized by the presence of two tooth series. Bryconamericus lethostigmus is redescribed herein and the single tooth series in the premaxilla is demonstrated to originate from merging of the external tooth row with the inner row during ontogeny refuting primary hypothesis of homology between the mouth morphology of B. lethostigmus and the genera Bryconacidnus, Ceratobranchia, Monotocheirodon, Othonocheirodus, Rhinopetitia and Rhinobrycon. A phylogeographic analysis indicated that the pattern described for the sympatric species Diapoma itaimbe is not mirrored by B. lethostigmus. The results also do not support the hypothesis of a new species in the rio Araranguá drainage.(AU)

Bryconamericus lethostigmus é a espécie tipo do gênero monotípico Odontostoechus, diagnosticado em parte pela presença de uma única série de dentes na pré-maxila. Recentemente uma nova proposta de classificação de Stevardiinae considerou Odontostoechus como sinônimo júnior do gênero monofilético Bryconamericus sensu stricto caracterizado pela presença de duas séries de dentes. Bryconamericus lethostigmus é redescrito e demonstra-se que a única série de dentes no premaxilar se origina pela junção da série externa de dentes com a série interna durante a ontogenia, refutando a hipótese de homologia primária entre a morfologia da boca de B. lethostigmus e os gêneros Bryconacidnus, Ceratobranchia, Monotocheirodon, Othonocheirodus, Rhinopetitia e Rhinobrycon. A análise filogeográfica indica que o padrão descrito para a espécie simpátrica Diapoma itaimbe não se repete em B. lethostigmus. Os resultados também não suportam a hipótese de uma nova espécie para a bacia do rio Araranguá.(AU)

High prevalence of HBV/A1 subgenotype in native south Americans may be explained by recent economic developments in the Amazon.

Native American populations present the highest prevalence of Hepatitis B Virus (HBV) infection in the Americas, which may be associated to severe disease outcomes. Ten HBV genotypes (A­J) have been described, displaying a remarkable geographic structure, which most likely reflects historic patterns of human migrations. In this study, we characterize the HBV strains circulating in a historical sample of Native South Americans to characterize the historical viral dynamics in this population. The sample consisted of 1070 individuals belonging to 38 populations collected between 1965 and 1997. Presence of HBV DNA was checked by quantitative real-time PCR, and determination of HBV genotypes and subgenotypes was performed through sequencing and phylogenetic analysis of a fragment including part of HBsAg and Pol coding regions (S/Pol). A Bayesian Skyline Plot analysis was performed to compare the viral population dynamics of HBV/A1 strains found in Native Americans and in the general Brazilian population. A total of 109 individuals were positive for HBV DNA (~ 10%), and 70 samples were successfully sequenced and genotyped. Subgenotype A1 (HBV/A1), related to African populations and the African slave trade, was the most prevalent (66­94%). The Skyline Plot analysis showed a marked population expansion of HBV/A1 in Native Americans occurring more recently (1945­1965) than in the general Brazilian population. Our results suggest that historic processes that contributed to formation of HBV/A1 circulating in Native American are related with more recent migratory waves towards the Amazon basin, which generated a different viral dynamics in this region.