Gómez-Pérez Luis, Alfonso-Sánchez Miguel A, Dipierri José E, Peña José A
1 Departamento de Genética y Antropología Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Bilbao, Spain.
2 Instituto de Biología de la Altura, Universidad Nacional de Jujuy, San Salvador de Jujuy, Argentina.
Hum Biol. 2016 Jul;88(3):210-218. doi: 10.13110/humanbiology.88.3.0210.
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.
本研究利用高度多态性标记，探索了来自阿根廷西北部胡胡伊省的三个高海拔人群基因库中的微分化潜在信号。这些人类群落的特点是生活条件极端，且由于海拔相当高以及地形陡峭，人口密度非常低。对来自下峡谷（约2500米）、上峡谷（约3300米）和普纳（>3500米）的样本进行了一组位于6号染色体（6p21.3）上的常染色体短串联重复序列（STR）分型。通过观察到的和预期的杂合度以及单倍型多样性来估计遗传多样性。基于等位基因和单倍型频率进行了分子方差分析（AMOVA）和群体分化测试，以评估亚组之间的遗传异质性。在任何亚群体中均未检测到偏离哈迪-温伯格平衡的情况，但在考虑整个区域的分析中（D6S2792和D6S105位点）检测到了显著偏离。总体而言，遗传多样性呈现出随着海拔升高而降低的趋势。因此，等位基因和单倍型频率在普纳和下峡谷这两个位于海拔范围边缘的群体之间表现出最显著的差异。杂合度随海拔降低的趋势与殖民历史模式、区域间迁移趋势、人口密度和基因混合相符合。胡胡伊复杂的山地景观的主要后果将是基因流动和遗传漂变相互作用的失衡，有利于后者。受限的基因流动和强烈的遗传漂变的综合作用将促进胡胡伊高地亚群体之间的局部遗传分化，导致等位基因频率的空间模式并非完全归因于地理距离。我们的研究结果证实了STR在识别微进化变化方面的有效性。
