Amorim Carlos Eduardo G, Daub Josephine T, Salzano Francisco M, Foll Matthieu, Excoffier Laurent
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.
Computational and Molecular Population Genetics Laboratory, Institute of Ecology and Evolution, Berne, Switzerland; Swiss Institute of Bioinformatics, Lausanne, Switzerland.
PLoS One. 2015 Apr 7;10(4):e0121557. doi: 10.1371/journal.pone.0121557. eCollection 2015.
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.
热带森林被认为是对人类生活而言非常恶劣的环境。目前尚不清楚，如果没有外部资源，人类是否曾经在这些环境中生存过。因此，人类有可能为应对这一挑战，针对特定的选择压力发展出了近期的生物适应性。为了了解此类生物适应性，我们在贝叶斯统计框架下分析了全基因组单核苷酸多态性（SNP）数据，寻找在热带森林中生活的人群与非洲和美洲森林外的相关基因人群相比，具有过度分化程度的异常标记。在与脂质代谢、免疫系统、身体发育和RNA聚合酶III转录起始相关的基因中发现了最显著的正选择信号。我们根据假定的热带森林选择压力，即食物短缺、病原体高流行率、行动困难和体温调节效率低下，对结果进行了讨论。我们的结果与之前关于俾格米人表型（一种假定的森林适应原型）的研究结果一致，这表明一些先前被描述为与身材矮小相关的基因区域可能在非洲和美洲受到类似的正选择而进化。总体而言，趋同进化不如在一个大陆内的局部适应普遍，这表明非洲人和美洲印第安人可能遵循了不同的途径来适应类似的环境选择压力。
