title: Detection of convergent genome-wide signals of adaptation to tropical forests in humans.
abstract: Tropical forests are believed to be very harsh environments for human life. It is unclear whether human beings would have ever subsisted in those environments without external resources. It is therefore possible that humans have developed recent biological adaptations in response to specific selective pressures to cope with this challenge. To understand such biological adaptations we analyzed genome-wide SNP data under a Bayesian statistics framework, looking for outlier markers with an overly large extent of differentiation between populations living in a tropical forest, as compared to genetically related populations living outside the forest in Africa and the Americas. The most significant positive selection signals were found in genes related to lipid metabolism, the immune system, body development, and RNA Polymerase III transcription initiation. The results are discussed in the light of putative tropical forest selective pressures, namely food scarcity, high prevalence of pathogens, difficulty to move, and inefficient thermoregulation. Agreement between our results and previous studies on the pygmy phenotype, a putative prototype of forest adaptation, were found, suggesting that a few genetic regions previously described as associated with short stature may be evolving under similar positive selection in Africa and the Americas. In general, convergent evolution was less pervasive than local adaptation in one single continent, suggesting that Africans and Amerindians may have followed different routes to adapt to similar environmental selective pressures.
authors: Computational and Molecular Population Genetics Laboratory, Institute of Ecology and Evolution, Berne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland; Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; CAPES Foundation, Ministry of Education of Brazil, Brasília, Distrito Federal, Brazil.
authors: Carlos Eduardo G
authors: CE
authors: Amorim
authors: Computational and Molecular Population Genetics Laboratory, Institute of Ecology and Evolution, Berne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland.
authors: Josephine T
authors: JT
authors: Daub
authors: Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil.
authors: Francisco M
authors: FM
authors: Salzano
authors: Swiss Institute of Bioinformatics, Lausanne, Switzerland; School of Life Science, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Genetic Cancer Susceptibility Group, International Agency for Research on Cancer, Lyon, France.
authors: Matthieu
authors: M
authors: Foll
authors: Computational and Molecular Population Genetics Laboratory, Institute of Ecology and Evolution, Berne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland.
authors: Laurent
authors: L
authors: Excoffier
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D005260:Female; D015894:Genome, Human; D055106:Genome-Wide Association Study; D006801:Humans; D008297:Male; D020641:Polymorphism, Single Nucleotide; D065947:Rainforest