Andean Populations Research Articles

Native American gene continuity to the modern admixed population from the Colombian Andes: Implication for biomedical, population and forensic studies

Andean populations have variable degrees of Native American and European ancestry, representing an opportunity to study admixture dynamics in the populations from Latin America (also known as Hispanics). We characterized the genetic structure of two indigenous (Nasa and Pijao) and three admixed (Ibagué, Ortega and Planadas) groups from Tolima, in the Colombian Andes. DNA samples from 348 individuals were genotyped for six mitochondrial DNA (mtDNA), seven non-recombining Y-chromosome (NRY) region and 100 autosomal ancestry informative markers. Nasa and Pijao had a predominant Native American ancestry at the autosomal (92%), maternal (97%) and paternal (70%) level. The admixed groups had a predominant Native American mtDNA ancestry (90%), a substantial frequency of European NRY haplotypes (72%) and similar autosomal contributions from Europeans (51%) and Amerindians (45%). Pijao and nearby Ortega were indistinguishable at the mtDNA and autosomal level, suggesting a genetic continuity between them. Comparisons with multiple Native American populations throughout the Americas revealed that Pijao, had close similarities with Carib-speakers from distant parts of the continent, suggesting an ancient correlation between language and genes. In summary, our study aimed to understand Hispanic patterns of migration, settlement and admixture, supporting an extensive contribution of local Amerindian women to the gene pool of admixed groups and consistent with previous reports of European-male driven admixture in Colombia.

Pasantías Formativas del Instituto de Montaña: Generación de Información y Capacidades

La región andina se enfrenta al reto inminente que supone la generación de acciones que favorezcan la adaptación y mitigación de los efectos originados por el cambio climático. Los ecosistemas andinos y las poblaciones humanas que de ellos forman parte son altamente vulnerables a la variabilidad climática que estamos enfrentando. Para desarrollar estas herramientas de adaptación, es crucial el impulso de la investigación científica de calidad, así como la recuperación y puesta en práctica de los conocimientos ancestrales desarrollados a lo largo de miles de años por las poblaciones humanas que habitan este territorio cambiante. A fin de llevar a cabo estos propósitos a escala local en el entorno de la Cordillera Blanca, se detectaron una serie de brechas de información a ser cerradas, priorizando la falta y la dispersión de información de base ambiental a escala local que sirva para la realización de estudios e investigaciones que redunden en una mejora de las condiciones de vida de las poblaciones altoandinas. Asimismo, desde el Instituto de Montaña (TMI) se detectó la necesidad de poner en alza y apoyar el talento y motivación de los jóvenes egresados de la Universidad Nacional Santiago Antúnez de Mayolo (UNASAM). Estas pasantías universitarias tienen una duración de entre seis y ocho meses, y constituyen un primer acercamiento laboral, una experiencia de trabajo junto a las comunidades rurales, la posibilidad de formar parte de un equipo interdisciplinario, así como la oportunidad de recibir capacitación especializada en los temas de trabajo desarrollados. En el marco del programa, los y las pasantes han realizado hasta la fecha estudios base a nivel ecológico e hidrológico, tratamiento y sistematización de información hidrometeorológica recogida por el Centro de Investigación Ambiental para el Desarrollo (CIAD) de la UNASAM, levantamientos y tratamiento de información socioeconómica y modelamientos y evaluación del peligro proveniente de avalanchas glaciares. Los resultados y la información recabada han servido de base para estudios más específicos en torno a la implementación de Mecanismos de Retribución por Servicios Ecosistémicos (MRSE) y para la redacción de varios perfiles de proyectos de desarrollo como los Proyectos de Inversión Pública (PIP), entre otros.

Health beliefs, healing practices and medico-ritual frameworks in the Ecuadorian Andes: the continuity of an ancient tradition

ABSTRACT This paper introduces the European Commission-funded project ‘MEDICINE: Indigenous Concepts of Health and Healing in Andean Populations’, which takes a time-depth perspective to its subject, and uses a framework of interdisciplinary methods which integrates archaeological-historical, ethnographic and modern health sciences approaches. The long-term study objective is ultimately to offer novel perspectives and methods in the global agenda to develop policies sensitive to indigenous, refugee and migrant people’s social, economic and health needs, as well as culturally sensitive approaches to the conservation of their ‘intangible cultural heritage’. This paper focuses on the project’s first phase, the critical examination of archaeological and ethnohistorical evidence and accounts from contemporary indigenous practitioners of Andean Traditional Medicine. These sources then shape the development of health beliefs and practices models which have informed the development of questionnaires for the second ‘survey’ phase of three indigenous Andean populations in the Central Sierra region of Ecuador.

6.1-O3Indigenous concepts of health and healing in Andean populations. How to model health beliefs and practices for the development of equitable health policies relevant to refugee, migrant and First Nations peoples

6.1-O3Indigenous concepts of health and healing in Andean populations. How to model health beliefs and practices for the development of equitable health policies relevant to refugee, migrant and First Nations peoples

Cultural practices linked to health care and perception on the attention health facilities in residents of highandean settlements in Huancavelica, Peru

Inequalities in terms of access and quality of healthcare persist, especially among Andean populations, such as the community of Chopcca. Here, we describe the perception of healthcare provided in medical facilities as well as the practices linked to health care in residents of settlements in the Huancavelica region. We carried out a cross-sectional study by means of a structured questionnaire administered to 775 residents of urban and rural towns of the Yauli and Paucará districts. 68.7% refer always using medicinal plants to cure themselves; 86.7% never made a "payment" to Mother Earth; 81.4% has not practiced coca qaway or sara qaway. 88.5% of respondents visit the medical facility when they fall ill. 57.4% refer that the healthcare staff always transmits confidence and security, this proportion is higher in rural vs. urban areas (64.6% versus 28.8%). The communities under study demand the healthcare services offered by the formal system; nevertheless, traditional cultural practices persist, being the most important one the use of medicinal plants.

Genetic Missense Variants at the EGLN1 Locus Associated with High‐Altitude Adaptation in Tibetans are Rare in Andeans

High‐altitude populations have been challenged by chronic hypoxia for many generations and demonstrate some of the most rapid evolution observed in humans. Genome‐wide scans have brought to light numerous hypoxic‐response candidate genes that are associated with distinct traits in these populations. One example is EGLN1, which shows signals of selection in Tibetan and Andean populations and has been linked to hemoglobin concentration in Tibetans living at high altitude. EGLN1 encodes the hypoxia‐inducible factor (HIF) prolyl hydroxylase 2 (PHD2) protein, which serves as an oxygen‐sensitive regulator of HIF transcription factor activity. We examined the frequencies of two single nucleotide polymorphisms (SNPs) (rs186996510, rs12097901) in the first exon of EGLN1, previously identified at high frequencies and having a gain‐of‐function effect in Tibetans, in a cohort of Quechua Andeans resident at high altitude and individuals of Himalayan (Tibetan, Nepali) ancestry resident at sea level. The minor C allele of rs186996510 is rare among Andeans (0.95%; 1/105) and Nepalese (5.9%; 1/17) but present in 50% (3/6) of Tibetans (X2=36.6, p<0.0001). The minor G allele of rs12097901 was found at 6.6% (7/106) in Andeans, 11.8% (2/17) in Nepalese, and 50% (3/6) in Tibetans (X2=12.8, p<0.002). Two female sea‐level, Tibetan participants with the minor C allele rs186996510 both had significantly lower hematocrit values than the other sea‐level women (F(1,7)=8.8, p=0.025). These genomic differences suggest that despite the identification of an adaptive genetic signal at this locus in both Andean and Tibetan populations, the EGLN1 variants previously reported in Tibetans are very rare in Andeans.Support or Funding InformationThis study was supported by an NIH NRSA Individual Postdoctoral Fellowship (Parent F32) to ECH (F32HL131218), NIH TL1TR001443 to LW, a University of California, San Diego Ledell Family Undergraduate Research Scholarship award for Science and Engineering to ESL, and NIH R00HL118215 and American Physiological Society Giles F. Filley Memorial Award to TSS. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. The UPCH team was supported by a Wellcome Trust PHTM grant (107544/Z/15/Z) to FCV.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Long‐Period Biorhythm Variation in Enamel Microstructure of Pre‐Columbian South Americans

It has been argued that the periodicity (in days) between dental enamel growth lines known as striae of Retzius reflects an autonomic biorhythm regulating metabolism and life history. Therefore, quantifying variation in Retzius periodicity (RP) has been recently used as a tool to provide life history and metabolic information among humans, primates, and other mammals. For example, body size is a major driving factor in life history evolution, and correlates strongly with RP in anthropoid primates but not lemurs.Varying datasets disagree as to whether this particular relationship among anthropoid species extends within species, particularly within modern humans. Moreover, little is known regarding the impact that geography has had on life history evolution among modern human populations. Altitude is one unexamined factor that may have influenced this evolution, as high‐altitude human populations exhibit multiple adaptations to their relatively hypoxic environment, and low oxygen availability has obvious consequences for overall metabolic output. Therefore, this study uses RP variation to compare a coastal (low altitude) and Andean (high altitude) sample of Pre‐Columbian South Americans. We have two major objectives: 1) determine if RP is correlated with body mass within this previously unsampled group, and more importantly; 2) determine if RP differs between coastal and Andean populations, a possible consequence of life history adaptations to altitude.To answer our questions, we gathered teeth from 10 individuals, 5 each from low and high altitude archaeological sites of Peru, all part of the anthropology collection at the American Museum of Natural History. Teeth were cleaned, embedded in acrylic resin, thin‐sectioned, and polished according to standard dental histology protocols. They were imaged in circularly polarized light using a Zeiss Axioskop II microscope. Photomicrographs of dental enamel were used to count the number of 24‐hour growth lines (cross‐striations) between striae of Retzius, indicating the number of days taken to form each successive stria (RP). An average of cross‐striation breadths was also divided into an average of striae of Retzius breadths in the same region of each tooth to verify the counted value. For each individual, orbital height and foramen magnum length were used as proxy variables to assess body size. Individuals were sexed based on standard cranial characteristics.Regressions of RP against body size proxies demonstrate a statistically significant negative correlation in the total combined sample. There is no significant difference in RP variation between the sexes, nor in body size between low and high altitude populations. However, the higher altitude population has significantly longer RP values. In conclusion, our analysis suggests that as predicted, an intraspecific relationship exists for RP and body size among our sample, and that altitude elicits as yet unidentified life history/metabolic differences expressed in RP, warranting further study. The high vs. low altitude pattern appears to be independent of the relationship we find between body size and RP in studies of other human populations.Support or Funding InformationFGCU Professional Development GrantThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Heme‐oxygenase 2 (HMOX2) variants associated with evolutionary adaptation and hemoglobin concentration in Tibetans are common in Andean Highlanders

Andean and Tibetan populations have developed distinct adaptations to high altitude. The heme oxygenase 2 gene (HMOX2) is under selection in Tibetans and is associated with hemoglobin concentration in Tibetan men. Putatively adaptive variants within this gene are also prevalent in lowland population but have not been examined in Andean highlanders and could influence variation in hypoxia responses in this population. We genotyped ten variants within the HMOX2 gene region (rs2058812, rs2270363, rs6500606, rs3747584, rs4786509, rs860891, rs8129, rs11639998, rs9934267, and rs17761816) in 128 Quechua Andean highlanders in Cerro de Pasco, Peru (4,350 m) (female = 61; male = 67). We found that the frequencies in Andean highlanders are not as elevated as Tibetans' but similar to those observed in Han Chinese. After controlling for sex and age, there was no significant association between these SNPs and hematocrit (Hct), mean arterial pressure (MAP), oxygen saturation (SpO2), nor hypoxic ventilatory response (HVR). These results suggest that the putatively adaptive high‐altitude HMOX2 variants identified in Tibetans are found at intermediate frequencies in Andeans, although they may not be regulators of hemoglobin concentration in this population.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

MALOCLUSIONES ASOCIADAS A LA CALIDAD DE VIDA EN POBLACIÓN ANDINA

La Organización Mundial de la Salud (OMS) constató que la salud bucal esta íntegramente relacionada con la calidad devida de los pacientes (CVRSB), está puede estar íntimamente ligada con su bienestar y salud en general; mientras que lasmaloclusiones son variaciones anatómicas dentofaciales que afectan la salud del aparato estomatognático especialmente enla parte morfológica, funcional y estética, ya que estas varían según los grupos étnicos, zonas geográficas y método declasificación, afectando así en las acciones cotidianas de los individuos particularmente en su calidad de vida y bienestaren general. La presente revisión de la literatura está dirigida a la población andina, ya que se ha revisado que clínicamenteque dicha población ha sido afectada por diversos tipos de anomalías dentomaxilofaciales. Por tal motivo el objetivo de esteartículo es realizar una revisión bibliográfica y verificar como puede afectar las maloclusiones con la calidad de vida de lospacientes; con el fin de demostrar la necesidad de implementar en el Ministerio de sector público los tratamientos ortodónticosen adolescentes de la zona andina afectados de manera psicológica y social.

Genetic ancestry of families of putative Inka descent

This study focuses on the descendants of the royal Inka family. The Inkas ruled Tawantinsuyu, the largest pre-Columbian empire in South America, which extended from southern Colombia to central Chile. The origin of the royal Inkas is currently unknown. While the mummies of the Inka rulers could have been informative, most were destroyed by Spaniards and the few remaining disappeared without a trace. Moreover, no genetic studies have been conducted on present-day descendants of the Inka rulers. In the present study, we analysed uniparental DNA markers in 18 individuals predominantly from the districts of San Sebastian and San Jerónimo in Cusco (Peru), who belong to 12 families of putative patrilineal descent of Inka rulers, according to documented registries. We used single-nucleotide polymorphisms and short tandem repeat (STR) markers of the Y chromosome (Y-STRs), as well as mitochondrial DNA D-loop sequences, to investigate the paternal and maternal descent of the 18 alleged Inka descendants. Two Q-M3* Y-STR clusters descending from different male founders were identified. The first cluster, named AWKI-1, was associated with five families (eight individuals). By contrast, the second cluster, named AWKI-2, was represented by a single individual; AWKI-2 was part of the Q-Z19483 sub-lineage that was likely associated with a recent male expansion in the Andes, which probably occurred during the Late Intermediate Period (1000–1450 AD), overlapping the Inka period. Concerning the maternal descent, different mtDNA lineages associated with each family were identified, suggesting a high maternal gene flow among Andean populations, probably due to changes in the last 1000 years.

Landscape connectivity among remnant populations of guanaco (Lama guanicoe Müller, 1776) in an arid region of Chile impacted by global change.

Connectivity between populations plays a key role in the long-term persistence of species in fragmented habitats. This is of particular concern for biodiversity preservation in drylands, since water limited landscapes are typically characterized by little suitable habitat cover, high habitat fragmentation, harsh matrices, and are being rapidly degraded at a global scale. In this study, we modelled landscape connectivity between 11 guanaco Lama guanicoe populations in Chile’s arid Norte Chico, a region that supports the last remnant coastal populations of this emblematic herbivore indigenous to South America. We produced a habitat suitability model to derive a regional surface resistance map, and used circuit theory to map functional connectivity, investigate the relative isolation between populations, and identify those that contribute most to the patch connectivity network. Predicted suitable habitat for L. guanicoe represented about 25% of the study region (i.e., 29,173 km2) and was heterogeneously distributed along a continuous stretch along the Andes, and discontinuous patches along the coast. As a result, we found that high connectivity current flows in the mid and high Andes formed a wide, continuous connectivity corridor, enabling connectivity between all high Andean populations. Coastal populations, in contrast, were more isolated. These groups demonstrate no inter-population connectivity between themselves, only with higher altitude populations, and for two of them, animal movement was linked to the effectiveness of wildlife crossings along the Pan-American highway. Our results indicate that functional connectivity is an issue of concern for L. guanicoe in Chile’s Norte Chico, implying that future conservation and management plans should emphasize strategies aimed at conserving functional connectivity between coastal and Andean populations, as well as the protection of habitat patches likely to act as stepping stones within the connectivity network.

Species limits in the Rusty-breasted Antpitta (Grallaricula ferrugineipectus) complex

The Rusty-breasted Antpitta (Grallaricula ferrugineipectus) is widely distributed within the tropical Andes of South America. We analyzed 73 study specimens, 25 vouchered tissue samples, and 123 audio recordings to assess geographic variation in genetics, vocalizations, and morphology and evaluate species limits. We found that Grallaricula ferrugineipectus as currently defined is polyphyletic because populations from Colombia and Venezuela form a clade closely related to Andean populations of G. nana, whereas populations from Peru and Bolivia are recovered as sister to G. lineifrons. Birds in Colombia and Venezuela (the northern group) last shared a common ancestor with birds from Peru and Bolivia (the southern group) more than 10 million years ago. Northern and southern groups additionally differ in song, suggesting they may have evolved substantial premating reproductive isolation. Discriminant function analysis reliably distinguished songs from northern and southern groups in multivariate acoustic space, but univariate analyses found non-overlapping acoustic variation between northern and southern groups in only one trait: mean note maximum frequency (and other correlated measures of song pitch). This finding suggests that the ‘three-trait' threshold for using vocalizations to inform species limits, which was developed for another suboscine group, the antbirds (Thamnophilidae), may be conservative when applied to antpittas (Grallariidae). In addition, we document apparent clinal variation in song pace within the southern group, a rare example of a suboscine with geographic clinal variation in a vocal trait. Finally, we show that northern and southern groups differ markedly in morphology. In summary, northern and southern groups of Rusty-breasted Antpittas are divergent in genetics, vocalizations, and morphology, demonstrating that these taxa are best classified as 2 monophyletic, biological species with allopatric distributions.

Morphometric and molecular differences among Calvertius tuberosus (Coleoptera: Curculionidae) populations associated with Andean and coastal populations of Araucaria araucana in the La Araucanía Region, Chile

Calvertius tuberosus (Curculionidae) lives exclusively on Araucaria araucana trees (commonly known as pehuen) in southern Chile. In this study, morphometric and molecular genetic analyses of Andean and coastal populations of C. tuberosus were performed to evaluate evolutionary divergence associated with the discontinuity of the Araucaria forest between the coastal and Andean regions. Specimens of C. tuberosus were collected in Nahuelbuta National Park, Villa Las Araucarias, and Malalcahuello National Reserve and were classified and stored at the Animal Biotechnology Researching Laboratory (LINBA), University of La Frontera, Temuco, Chile. Thirteen morphometric parameters and the expression patterns of ISSR (inter-simple sequence repeat) markers were analyzed. Morphometric data revealed high phenotypic similarity between coastal populations. The genetic analysis revealed a high similarity between coastal populations (genetic identity, 93%), which were differentiated from the Andean population (genetic identity, 84%). This study contributes new genotypic and phenotypic data for the C. tuberosus populations in forest ecosystems of A. araucana, and clarifies the associations between these characteristics and the geographic distributions of populations.

Complementariedad de métodos y fuentes en el estudio histórico de familias indígenas (Belén, Altos de Arica, 1750-1820)

The reconstitution of families of Belen gave me access not only to demographic aspectsscarcely studied in Andean populations, but also to other qualitative phenomena, that allowa historical analysis related to marriage and kinship. The use of different kind of files andsources has strengthened the methodology development, which allows the comparison ofdifferent documents, fomenting a critical review of each of the sources as well as the resultsobtained using the various methods. Complementarity between them provides a comprehensiveunderstanding of the various aspects involved in the formation of families. In the case ofBelen, the integration of parish registers, revisitas and one padron, church reports and marriagecertificate have led me to distinguish phenomena such as the presence of compound families,two possible cases of polygyny, the male tendency towards endogamy within the village, possiblepreferences regulating marriages, especially concerning first marriage, as well as to observedemographic and social problems that lead me to hypothesize about the role those factors playedin favor of ritual kinship and against extended family.

Spatial prediction of soil water retention in a Páramo landscape: Methodological insight into machine learning using random forest

Soils of Páramo ecosystems regulate the water supply to many Andean populations. In spite of being a necessary input to distributed hydrological models, regionalized soil water retention data from these areas are currently not available. The investigated catchment of the Quinuas River has a size of about 90km2 and comprises parts of the Cajas National Park in southern Ecuador. It is dominated by soils with high organic carbon contents, which display characteristics of volcanic influence. Besides providing spatial predictions of soil water retention at the catchment scale, the study presents a detailed methodological insight to model setup and validation of the underlying machine learning approach with random forest. The developed models performed well predicting volumetric water contents between 0.55 and 0.9cm3cm−3. Among the predictors derived from a digital elevation model and a Landsat image, altitude and several vegetation indices provided the most information content. The regionalized maps show particularly low water retention values in the lower Quinuas valley, which go along with high prediction uncertainties. Due to the small size of the dataset, mineral soils could not be separated from organic soils, leading to a high prediction uncertainty in the lower part of the valley, where the soils are influenced by anthropogenic land use.

A revision of species limits in Neotropical pipits Anthus based on multilocus genetic and vocal data

Previous investigations of the systematics of Neotropical pipits Anthus revealed multiple cases of paraphyly. We revised the species limits of this group based on sequence data of mitochondrial (ND2) and nuclear genes (ACOI9, MB, FGB5) from 39 tissue samples of all 22 subspecies‐level taxa in the New World Anthus clade, as well as analysis of display song. We found that Anthus lutescens peruvianus is not part of Yellowish Pipit Anthus lutescens genetically or vocally; thus, we elevate peruvianus to species rank (Peruvian Pipit). Anthus lutescens abariensis Chubb (Bull. Br. Orn. Club., 41, 1921a, 79) should be placed in synonymy with Anthus lutescens parvus (instead of A. l. lutescens), at least until further morphological or vocal data become available. Paramo Pipit Anthus bogotensis is likewise paraphyletic, with Anthus meridae sister to all other bogotensis subspecies and also to Hellmayr's Pipit Anthus hellmayri. However, placement of the taxon is based on a relatively short stretch of mitochondrial DNA, and further data are needed. Andean populations of Short‐billed Pipit Anthus furcatus are split as Puna Pipit Anthus brevirostris, based on genetic and vocal data. South Georgia Pipit Anthus antarcticus is, at least genetically, part of Correndera Pipit Anthus correndera, and we recommend considering it a subspecies of Correndera Pipit, in line with the taxonomy of other morphologically distinct but genetically little‐differentiated insular bird taxa.

Between the acclimatization to high altitude, the medical anthropology and the civilizing utopia. Mapping of the evolution of thought of Carlos Monge Medrano on the health-illness process of andean populations

The main objective of this study is to describe how the ideas of Carlos Monge respect to high altitude sickness developed and how these were being deployed in the framework of the discussions on the living conditions of indigenous populations in the period 1928-1963. I postulate that the form how the Monge's paradigm was proposed, the tensions produced by various alternative movements and the way these contradictions were resolved were central, both for the subsequent development of different scientific disciplines and for their different institutional expressions in Peru. In addition, this article describes the evolutionary trajectory of Monge's ideas about the adaptation of indigenous populations to high altitude and the discussions that emerged with other research groups around the consumption of coca leaf. It also presents an analysis of the limitations of the biomedical view regarding the health of the Andean populations, a view that was progressively influenced by the changing social and political scenario in the context of the Cold War.

Commercial opportunities for productive development of the quinua. A reflection from the security, sovereignty and food justice

Aim: Food security is one of the most pressing issues of our century because of its implications for the future. To that extent, this article is a preliminary attempt to shed light on the opportunities stemming from the commercialization of quinoa. Description: We undertook this study to try and grasp why the Cosmovision of Andean populations consider quinoa as an alternative for development. We first go through some aspects of food security, sovereignty and justice, which will eventually lead us to take a closer look at quinoa’s proper characteristics and production process. We will complement our study by an analysis of data on the commercialization of quinoa in order to evaluate its opportunities internationally. Conclusions: Quinoa presents very interesting nutritive characteristics, offers a variety of seeds, is relatively easy to grow virtually anywhere and can be used in a number of byproducts. To that extent, it should be seriously considered as palatable solution to the global food crisis.

On the importance of geographic and taxonomic sampling in phylogeography: A reevaluation of diversification and species limits in a Neotropical thrush (Aves, Turdidae)

Phylogeographic studies seeking to describe biogeographic patterns, infer evolutionary processes, and revise species-level classification should properly characterize the distribution ranges of study species, and thoroughly sample genetic variation across taxa and geography. This is particularly necessary for widely distributed organisms occurring in complex landscapes, such as the Neotropical region. Here, we clarify the geographic range and revisit the phylogeography of the Black-billed Thrush (Turdus ignobilis), a common passerine bird from lowland tropical South America, whose evolutionary relationships and species limits were recently evaluated employing phylogeographic analyses based on partial knowledge of its distribution and incomplete sampling of populations. Our work employing mitochondrial and nuclear DNA sequences sampled all named subspecies and multiple populations across northern South America, and uncovered patterns not apparent in earlier work, including a biogeographic interplay between the Amazon and Orinoco basins and the occurrence of distinct lineages with seemingly different habitat affinities in regional sympatry in the Colombian Amazon. In addition, we found that previous inferences about the affinities and taxonomic status of Andean populations assumed to be allied to populations from the Pantepui region were incorrect, implying that inferred biogeographic and taxonomic scenarios need re-evaluation. We propose a new taxonomic treatment, which recognizes two distinct biological species in the group. Our findings illustrate the importance of sufficient taxon and geographic sampling to reconstruct evolutionary history and to evaluate species limits among Neotropical organisms. Considering the scope of the questions asked, advances in Neotropical phylogeography will often require substantial cross-country scientific collaboration.

Human adaptation to arsenic in Andean populations of the Atacama Desert.

Quebrada Camarones, in the Atacama Desert, has the highest arsenic levels in the Americas (>1,000 µg/L). However, the Camarones people have subsisted in this adverse environment during the last 7,000 years and have not presented any epidemiological emergencies. Therefore, to solve this conundrum we compared the frequencies of four protective genetic variants of the AS3MT gene associated with efficient arsenic metabolization, between the living populations of Camarones and two other populations historically exposed to lower levels of arsenic. The Chilean selected population samples come from Quebrada Camarones (n = 50) and the Azapa Valley (n = 47) in the north and San Juan de la Costa (n = 45) in southern Chile. The genotyping was conducted using PCR-RFLP. We compared the genotypic and allelic frequencies, and estimated the haplotype frequencies in the AS3MT gene. We found higher frequencies of the protective variants in those people from Camarones than in the other two populations. The haplotype estimation showed that the combination of protective variants of CTTA is very frequent in Camarones (68%) and Azapa (48%), but extremely low in San Juan de la Costa (8%). Also, the C variant associated with toxicity risks in the SNP Met287Thr had a lower frequency in Camarones (1%) and is higher in the other populations. The higher frequency of protective variants in both northern Chilean populations indicates a long exposure to naturally arsenic-contaminated water sources. Our data suggest that a high arsenic metabolization capacity has been selected as an adaptive mechanism in these populations in order to survive in an arsenic-laden environment.