Paternal heritage in Jujuy province (Northwest Argentina): Evidence for sex-biased gene flow and genetic drift effects.

OBJECTIVES: This study aimed to explore the diversity of paternal lineages in Jujuy province (Argentina) by analyzing Y chromosome markers. Furthermore, we examined among-population genetic variability based both on paternally (NRY haplotypes) and maternally (mtDNA haplogroups) inherited markers. We sought to evaluate the impact of sex-biased gene flow on genetic background in Jujuy, and contribute data on the microevolutionary forces acting in this zone. METHODS: DNA from 149 males from five Jujuy regions were analyzed for 12 non-recombining Y (NRY) markers. Genetic heterogeneity among Jujuy regions was evaluated through population differentiation tests. To identify potential genetic boundaries in Jujuy, analysis of molecular variance (AMOVA) and the Monmonier's algorithm implemented in the Barrier v2.2 software were employed. RESULTS: A clear divergence between Jujuy highlands and lowlands for NRY haplotypes was found. A marked discrepancy between genetic structuring for paternal lineages and the lack of geographical pattern for mitogenomes was confirmed by all statistical analyses. CONCLUSIONS: Genetic structuring of paternal lineages is most likely caused by admixture processes that have occurred since colonial times in the Jujuy lowlands. Immigrants were predominantly male that settled in the lower altitude zones, due to the steep orography of the region. Input of allochthonous male lineages because of gene flow toward the lowlands would have increased diversity of NRY markers, thus compensating for drift effects. Likewise, limited input of allochthonous mitogenomes would have promoted genetic drift, a key factor in the shaping of diversity of maternal lineages across Jujuy subpopulations, irrespective of altitude.

Taino and African maternal heritage in the Greater Antilles.

Notwithstanding the general interest and the geopolitical importance of the island countries in the Greater Antilles, little is known about the specific ancestral Native American and African populations that settled them. In an effort to alleviate this lacuna of information on the genetic constituents of the Greater Antilles, we comprehensively compared the mtDNA compositions of Cuba, Dominican Republic, Haiti, Jamaica and Puerto Rico. To accomplish this, the mtDNA HVRI and HVRII regions, as well as coding diagnostic sites, were assessed in the Haitian general population and compared to data from reference populations. The Taino maternal DNA is prominent in the ex-Spanish colonies (61.3%-22.0%) while it is basically non-existent in the ex-French and ex-English colonies of Haiti (0.0%) and Jamaica (0.5%), respectively. The most abundant Native American mtDNA haplogroups in the Greater Antilles are A2, B2 and C1. The African mtDNA component is almost fixed in Haiti (98.2%) and Jamaica (98.5%), and the frequencies of specific African haplogroups vary considerably among the five island nations. The strong persistence of Taino mtDNA in the ex-Spanish colonies (and especially in Puerto Rico), and its absence in the French and English excolonies is likely the result of different social norms regarding mixed marriages with Taino women during the early years after the first contact with Europeans. In addition, this article reports on the results of an integrative approach based on mtDNA analysis and demographic data that tests the hypothesis of a southward shift in raiding zones along the African west coast during the period encompassing the Transatlantic Slave Trade.

STR Markers Unveil Microgeographic Differentiation over the Steep Mountainous Landscape of Jujuy Province, Northwest Argentina.

This study explores potential signals of microdifferentiation in the gene pool of three high-altitude populations from Jujuy province in northwest Argentina using highly polymorphic markers. These human communities are characterized by extreme living conditions and very low population densities owing to considerable height above sea level and steep orography. A set of autosomal short tandem repeats (STRs) located at chromosome 6 (6p21.3) was typed in samples from Quebrada Baja (∼2,500 m), Quebrada Alta (∼3,300 m), and Puna (> 3,500 m). Genetic diversity was estimated through the observed and expected heterozygosities and the haplotype diversity. Analyses of the molecular variance (AMOVAs) and population differentiation tests based on allele and haplotype frequencies were performed to assess genetic heterogeneity among subgroups. No deviation from Hardy-Weinberg equilibrium was detected in any subpopulation, yet significant departures were detected in the analysis considering the whole area (D6S2792 and D6S105 loci). Overall, genetic diversity showed a decreasing trend as the altitude increased. Thus, allele and haplotype frequencies showed the most significant differences between Puna and Quebrada Baja, the populations sited at the edges of the altitude range. The trend toward reduction of heterozygosity with altitude is compatible with historical patterns of colonization, interregional migration trends, population density, and genetic admixture. The main consequence of the complex mountainous landscape of Jujuy would be an imbalance in the interplay of gene flow and genetic drift, favoring the latter. The combined effect of restricted gene flow and intense genetic drift would have promoted local genetic differentiation between the Jujuy highland subpopulations, leading to spatial patterning of the allele frequencies not entirely attributable to geographic distance. Our findings corroborate the effectiveness of STRs to identify microevolutionary changes.

Young Alu insertions within the MHC class I region in native American populations: insights into the origin of the MHC-Alu repeats.

OBJECTIVES: Genetic heterogeneity of two Amerindian populations (Jujuy province, Argentina, and Waorani tribe, Ecuador) was characterized by analyzing data on polymorphic Alu insertions within the human major histocompatibility complex (MHC) class I region (6p21.31), which are completely nonexistent in Native Americans. We further evaluated the haplotype distribution and genetic diversity among continental ancestry groups and their potential implications for the dating of the origin of MHC-Alus. METHODS: Five MHC-Alu elements (AluMicB, AluTF, AluHJ, AluHG, and AluHF) were typed in samples from Jujuy (N = 108) and Waorani (N = 36). Allele and haplotype frequency data on worldwide populations were compiled to explore spatial structuring of the MHC-Alu diversity through AMOVA tests. We utilized the median-joining network approach to illustrate the continental distribution of the MHC-Alu haplotypes and their phylogenetic relationships. RESULTS: Allele and haplotype distributions differed significantly between Jujuy and Waorani. The Waorani featured a low average heterozygosity attributable to strong population isolation. Overall, Alu markers showed great genetic heterogeneity both within and among populations. The haplotype distribution was distinctive of each continental ancestry group. Contrary to expectations, Africans showed the lowest MHC-Alu diversity. CONCLUSIONS: Genetic drift mainly associated to population bottlenecks seems to be reflected in the low MHC-Alu diversity of the Amerindians, mainly in Waorani. Geographical structuring of the haplotype distribution supports the efficiency of the MHC-Alu loci as lineage (ancestry) markers. The markedly low Alu diversity of African populations relative to other continental clusters suggests that these MHC-Alus might have arisen after the anatomically modern humans expanded out of Africa.

Mitochondrial DNA control region data reveal high prevalence of Native American lineages in Jujuy province, NW Argentina.

Mitochondrial control region (16024-576) sequences were generated from 180 individuals of four population nuclei from the province of Jujuy (NW Argentina), located at different altitudes above sea level. The frequency at which a randomly selected mtDNA profile would be expected to occur in the general population (random match probability) was estimated at 0.011, indicating a relatively high diversity. Analysis of the haplogroup distribution revealed that Native American lineages A2 (13.9%), B (56.7%), C1 (17.8%), D1 (8.9%) and D4h3a (1.1%) accounted for more than 98% of the total mtDNA haplogroup diversity in the sample examined. We detected a certain degree of genetic heterogeneity between two subpopulations located at different points along the altitudinal gradient (Valles and Puna), suggesting that altitude above sea level cannot be ruled out as a factor promoting divergences in mtDNA haplogroup frequencies, since altitude is closely associated with human living conditions, and consequently, with low demographic sizes and the occurrence of genetic drift processes in human communities. In all, mitochondrial DNA database obtained for Jujuy province strongly points to the need for creating local mtDNA databases, to avoid bias in forensic estimations caused by genetic substructuring of the populations.

Alu polymorphisms in the Waorani tribe from the Ecuadorian Amazon reflect the effects of isolation and genetic drift.

OBJECTIVES: The Amazon basin is inhabited by some of the most isolated human groups worldwide. Among them, the Waorani tribe is one of the most interesting Native American populations from the anthropological perspective. This study reports a genetic characterization of the Waorani based on autosomal genetic loci. METHODS: We analyzed 12 polymorphic Alu insertions in 36 Waorani individuals from different communal longhouses settled in the Yasuní National Park. RESULTS: The most notable finding was the strikingly reduced genetic diversity detected in the Waorani, corroborated by the existence of four monomorphic loci (ACE, APO, FXIIIB, and HS4.65), and of other four Alu markers that were very close to the fixation for the presence (PV92 and D1) or the absence (A25 and HS4.32) of the insertion. Furthermore, results of the centroid analysis supported the notion of the Waorani being one of the Amerindian groups less impacted by gene flow processes. CONCLUSIONS: The prolonged isolation of the Waorani community, in conjunction with a historically low effective population size and high inbreeding levels, have resulted in the drastic reduction of their genetic diversity, because of the effects of severe genetic drift. Recurrent population bottlenecks most likely determined by certain deep-rooted sociocultural practices of the Waorani (characterized by violence, internal quarrels, and revenge killings until recent times) are likely responsible for this pattern of diversity. The findings of this study illustrate how sociocultural factors can shape the gene pool of human populations.

Microevolutionary processes due to landscape features in the province of Jujuy (Argentina).

OBJECTIVES: We seek to evaluate the influence of a diverse and rugged physical environment on the genetic background of human populations. METHODS: We analyzed eight polymorphic Alu insertions in 226 individuals from Jujuy province (Argentina), which is composed of several regions with well-defined geographical features and marked contrasts between them associated with differences in altitude (range: 700-3300 m). This regional division was used to assess the spatial variation of the Alu diversity. RESULTS: Deviations from Hardy-Weinberg Equilibrium expectations resulting from heterozygous deficit were found for FXIIIB and PV92 in the highest subpopulations. Several Alu elements showed genetic heterogeneity between the highest region (La Puna) and the lowest regions (Valle and Selva). Similarly, a decreasing trend of the average heterozygosity according to altitude was found. Both the centroid method and the admixture analysis unveiled a gene flow above the average in lowland populations, indicating a higher proportion of foreign genes introduced by immigrants of European and African ancestry. Furthermore, several Alu frequency clines fitting the orientation of the altitude gradient were detected. CONCLUSIONS: Our study reveals a spatial patterning of the Alu diversity in Jujuy, most likely determined by disparities in landscape and environmental features between the different subregions. Differences in the physical environment would have drastically reduced the homogenizing effects of the gene flow and would have promoted genetic drift episodes in the highest subpopulations. Microevolutionary processes detected in Jujuy have played an important role in the shaping of the gene pool of the populations from this sub-Andean zone from Argentina.

Mitochondrial DNA diversity in a population from Santa Catarina (Brazil): predominance of the European input.

The state of Santa Catarina (Brazil) is known to have represented a cultural crossroads in South America due to several historic migrations mainly from Europe and Africa. We set out to scrutinize whether the genetic imprint of these migrations could be traced through analysis of the matrilineal gene pool of the Catarinenses. The entire control region of the mitochondrial DNA was studied in 80 healthy and maternally unrelated individuals. The analysis of haplogroup distribution revealed that this population is extremely heterogeneous, showing the coexistence of matrilineal lineages with three different phylogeographic origins. European lineages are the most frequent due mainly to the impact of relatively recent migratory waves from Europe. In spite of this, Native American lineages and African lineages incorporated with the slave trade are also present in noticeable proportions. The strikingly high variability generated by intense gene flow is mirrored in a high sequence diversity (0.9930) and power of discrimination (0.9806). Thus, analysis of the entire mitochondrial DNA control region emerges as a valuable tool for forensic genetic purposes in this highly admixed population, an attribute common to several present-day Latin American populations.

Genetic admixture estimates by Alu elements in Afro-Colombian and Mestizo populations from Antioquia, Colombia.

AIM: This work was intended to gain insights into the admixture processes occurring in Latin American populations by examining the genetic profiles of two ethnic groups from Antioquia (Colombia). SUBJECTS AND METHODS: To analyse the genetic variability, eight Alu insertions were typed in 64 Afro-Colombians and a reference group of 34 Hispanics (Mestizos). Admixture proportions were estimated using the Weighted Least Squares and the Gene Identity methods. The usefulness of the Alu elements as Ancestry Informative Markers (AIMs) was evaluated through differences in weighted allelic frequencies (delta values) and by hierarchical analysis of the molecular variance (AMOVA). RESULTS: The Afro-Colombian gene pool was largely determined by the African component (88.5-88.8%), but the most prominent feature was the null contribution of European genes. Mestizos were characterized by a major European component (60.0-63.8%) and a comparatively low proportion of Amerindian (19.2-20.7%) and African (17.0-19.3%) genes. Five of the Alu loci examined (ACE, APO, FXIIIB, PV92 and TPA25) showed an adequate resolving power to differentiate between continental groups, as indicated by delta values and AMOVA results. CONCLUSIONS: The peculiarity of the Afro-Colombian gene pool seems to be associated with intense genetic drift episodes that occurred in isolated communities founded by small groups of runaway slaves. ACE, APO, FXIIIB, PV92 and TPA25 could be efficiently utilized in studies dealing with demographic history and biogeographical ancestry in human populations.

Genetic polymorphisms at four STR loci from the HLA region in a Venezuelan population.

POPULATIONS: Whole blood samples from 74 unrelated healthy individuals were collected. The donors' sample included Venezuelan mestizos from various regions of the country, but mostly from the resident population of Caracas City. A Venezuelan mestizo is the offspring of a mating between a native Venezuelan and a person born in Europe, mainly in Spain.

Evaluación de una tarea de discriminación visuo-espacial en monos de cola corta (Macaca arctoides) / Evaluation of visuo-spatial discriminatory task on stumptalied monkeys

Se evaluaron las capacidades discriminativas de color y posición en monos pardos de cola corta (Macaca arctoides), machos, adultos, de entre 12 y 15 kg de peso; se registró simultáneamente el tiempo de reacción y la mano utilizada preferencialmente por cada animal. La prueba se efectuó en un Wisconsin General Apparatus Test (WGTA) y consistió en 30 ensayos diarios de 60 s cada uno, con intervalo interensayos de 15 s. En cada ensayo, se utilizó una bandeja con tres recipientes de colores diferentes (rojo-azul-blanco) cuya posición central o lateral se modificaba aleatoriamente en cada presentación. El mono debía seleccionar y levantar el estímulo positivo (rojo-izquierdo) para obtener la recompensa colocada debajo de l. Como criterio de aprendizaje se consideró la obtención de un 90 por ciento o más de aciertos durante 5 días consecutivos. A partir de este diseño, y considerando que la ejecución de la tarea requiere utilizar ambas manos, asumimos como mano preferencial la asociada al acto motor más complejo y con menos posibilidades de estar vinculada al fenómeno de habituación. Sobre esta base, nuestros resultados indican una especialización izquierda para este tipo de actividad, lo cual coincide con lo obtenido por otros autores para tareas de complejidad similar a la nuestra utilizadas en la evaluación de otros primates no humanos (AU)

Evaluación de una tarea de discriminación visuo-espacial en monos de cola corta (Macaca arctoides) / Evaluation of visuo-spatial discriminatory task on stumptalied monkeys

Se evaluaron las capacidades discriminativas de color y posición en monos pardos de cola corta (Macaca arctoides), machos, adultos, de entre 12 y 15 kg de peso; se registró simultáneamente el tiempo de reacción y la mano utilizada preferencialmente por cada animal. La prueba se efectuó en un Wisconsin General Apparatus Test (WGTA) y consistió en 30 ensayos diarios de 60 s cada uno, con intervalo interensayos de 15 s. En cada ensayo, se utilizó una bandeja con tres recipientes de colores diferentes (rojo-azul-blanco) cuya posición central o lateral se modificaba aleatoriamente en cada presentación. El mono debía seleccionar y levantar el estímulo positivo (rojo-izquierdo) para obtener la recompensa colocada debajo de l. Como criterio de aprendizaje se consideró la obtención de un 90 por ciento o más de aciertos durante 5 días consecutivos. A partir de este diseño, y considerando que la ejecución de la tarea requiere utilizar ambas manos, asumimos como mano preferencial la asociada al acto motor más complejo y con menos posibilidades de estar vinculada al fenómeno de habituación. Sobre esta base, nuestros resultados indican una especialización izquierda para este tipo de actividad, lo cual coincide con lo obtenido por otros autores para tareas de complejidad similar a la nuestra utilizadas en la evaluación de otros primates no humanos