Outlining the Ancestry Landscape of Colombian Admixed Populations

The ancestry of the Colombian population comprises a large number of well differentiated Native communities belonging to diverse linguistic groups. In the late fifteenth century, a process of admixture was initiated with the arrival of the Europeans, and several years later, Africans also became part of the Colombian population. Therefore, the genepool of the current Colombian population results from the admixture of Native Americans, Europeans and Africans. This admixture occurred differently in each region of the country, producing a clearly stratified population. Considering the importance of population substructure in both clinical and forensic genetics, we sought to investigate and compare patterns of genetic ancestry in Colombia by studying samples from Native and non-Native populations living in its 5 continental regions: the Andes, Caribe, Amazonia, Orinoquía, and Pacific regions. For this purpose, 46 AIM-Indels were genotyped in 761 non-related individuals from current populations. Previously published genotype data from 214 Colombian Natives from five communities were used for population comparisons. Significant differences were observed between Native and non-Native populations, among non-Native populations from different regions and among Native populations from different ethnic groups. The Pacific was the region with the highest African ancestry, Amazonia harboured the highest Native ancestry and the Andean and Orinoquían regions showed the highest proportion of European ancestry. The Andean region was further sub-divided into 6 sub-regions: North East, Central West, Central East, West, South West and South East. Among these regions, the South West region showed a significantly lower European admixture than the other regions. Hardy-Weinberg equilibrium and variance values of ancestry among individuals within populations showed a potential stratification of the Pacific population.哥伦比亚人群的遗传祖源构成包含大量分化显著的原住民社群，这些社群隶属于多样的语言族群。15世纪晚期，随着欧洲殖民者的到来，人群血统混合进程正式启动；数年后，非洲人群也加入了哥伦比亚人群的基因库。因此，当前哥伦比亚人群的基因库源自美洲原住民、欧洲人与非洲人的血统混合。这种血统混合模式在该国各区域间存在显著差异，最终塑造了具有明显分层特征的哥伦比亚人群。鉴于群体亚结构在临床遗传学与法医遗传学领域均具有重要研究价值，本研究旨在通过分析分布于哥伦比亚5个大陆区域（安第斯、加勒比、亚马逊、奥里诺科河与太平洋区域）的原住民与非原住民样本，探究并比较哥伦比亚国内的遗传祖源模式。为此，我们对761名来自当代无关个体的样本进行了46个祖先信息插入缺失标记（AIM-Indels）的基因分型。同时采用此前已发表的、来自5个社群的214名哥伦比亚原住民的基因型数据用于群体比较分析。研究结果显示，原住民与非原住民群体间、不同区域的非原住民群体间，以及不同族群的原住民群体间均存在显著遗传差异。其中，太平洋区域的非洲祖源占比最高，亚马逊区域的原住民祖源占比最高，而安第斯与奥里诺科河地区的欧洲祖源占比最高。安第斯区域进一步被划分为6个子区域：东北、中西、中东、西部、西南与东南。在这些子区域中，西南子区域的欧洲血统混合比例显著低于其他子区域。哈迪-温伯格平衡（Hardy-Weinberg equilibrium）检验以及群体内个体间祖源方差分析结果显示，太平洋群体存在潜在的群体亚结构。