An approach on the migratory processes in the north of Chile based on Y chromosome analysis.

Objectives: Northern Chile is an area characterized by a complex cultural and demographic trajectory. During the last few centuries, this complex trajectory has become the destination of intra- and intercontinental migratory waves. In this study, we analyzed the Y chromosome to evaluate how migratory and admixture patterns have affected the genetic composition of the populations in northern Chile compared with other populations of the country.

Recent population genomic insights into the genetic basis of arsenic tolerance in humans: the difficulties of identifying positively selected loci in strongly bottlenecked populations.

Recent advances in genomics have enabled researchers to shed light on the evolutionary processes driving human adaptation, by revealing the genetic architectures underlying traits ranging from lactase persistence, to skin pigmentation, to hypoxic response, to arsenic tolerance. Complicating the identification of targets of positive selection in modern human populations is their complex demographic history, characterized by population bottlenecks and expansions, population structure, migration, and admixture. In particular, founder effects and recent strong population size reductions, such as those experienced by the indigenous peoples of the Americas, have severe impacts on genetic variation that can lead to the accumulation of large allele frequency differences between populations due to genetic drift rather than natural selection.

The genetic prehistory of the Andean highlands 7000 years BP though European contact.

The peopling of the Andean highlands above 2500 m in elevation was a complex process that included cultural, biological, and genetic adaptations. Here, we present a time series of ancient whole genomes from the Andes of Peru, dating back to 7000 calendar years before the present (BP), and compare them to 42 new genome-wide genetic variation datasets from both highland and lowland populations. We infer three significant features: a split between low- and high-elevation populations that occurred between 9200 and 8200 BP; a population collapse after European contact that is significantly more severe in South American lowlanders than in highland populations; and evidence for positive selection at genetic loci related to starch digestion and plausibly pathogen resistance after European contact.

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

Objectives: 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.