Conley Andrew B, Rishishwar Lavanya, Norris Emily T, Valderrama-Aguirre Augusto, Mariño-Ramírez Leonardo, Medina-Rivas Miguel A, Jordan I King
Applied Bioinformatics Laboratory, Atlanta, Georgia.
PanAmerican Bioinformatics Institute, Cali, Valle del Cauca, Colombia.
G3 (Bethesda). 2017 Oct 5;7(10):3435-3447. doi: 10.1534/g3.117.1118.
At least 20% of Colombians identify as having African ancestry, yielding the second largest population of Afro-descendants in Latin America. To date, there have been relatively few studies focused on the genetic ancestry of Afro-Latino populations. We report a comparative analysis of the genetic ancestry of Chocó, a state located on Colombia's Pacific coast with a population that is >80% Afro-Colombian. We compared genome-wide patterns of genetic ancestry and admixture for Chocó to six other admixed American populations, with an emphasis on a Mestizo population from the nearby Colombian city of Medellín. One hundred sample donors from Chocó were genotyped across 610,545 genomic sites and compared with 94 publicly available whole genome sequences from Medellín. At the continental level, Chocó shows mostly African genetic ancestry (76%) with a nearly even split between European (13%) and Native American (11%) fractions, whereas Medellín has primarily European ancestry (75%), followed by Native American (18%) and African (7%). Sample donors from Chocó self-identify as having more African ancestry, and conversely less European and Native American ancestry, than can be genetically inferred, as opposed to what we previously found for Medellín, where individuals tend to overestimate levels of European ancestry. We developed a novel approach for subcontinental ancestry assignment, which allowed us to characterize subcontinental source populations for each of the three distinct continental ancestry fractions separately. Despite the clear differences between Chocó and Medellín at the level of continental ancestry, the two populations show overall patterns of subcontinental ancestry that are highly similar. Their African subcontinental ancestries are only slightly different, with Chocó showing more exclusive shared ancestry with the modern Yoruba (Nigerian) population, and Medellín having relatively more shared ancestry with West African populations in Sierra Leone and Gambia. Both populations show very similar Spanish ancestry within Europe and virtually identical patterns of Native American ancestry, with main contributions from the Embera and Waunana tribes. When the three subcontinental ancestry components are considered jointly, the populations of Chocó and Medellín are shown to be most closely related, to the exclusion of the other admixed American populations that we analyzed. We consider the implications of the existence of shared subcontinental ancestries for Colombian populations that appear, at first glance, to be clearly distinct with respect to competing notions of national identity that emphasize ethnic mixing () group-specific identities (multiculturalism).
至少20%的哥伦比亚人认为自己有非洲血统，这使哥伦比亚成为拉丁美洲第二大非洲裔人口国家。迄今为止，针对拉丁裔非洲人种群遗传血统的研究相对较少。我们报告了对乔科省遗传血统的比较分析，乔科省位于哥伦比亚太平洋沿岸，该省80%以上的人口为非洲裔哥伦比亚人。我们将乔科省遗传血统和混合情况的全基因组模式与其他六个美洲混合种群进行了比较，重点是来自附近哥伦比亚城市麦德林的混血种群。对来自乔科省的100名样本捐赠者在610545个基因组位点进行了基因分型，并与来自麦德林的94个公开的全基因组序列进行了比较。在大陆层面，乔科省主要显示非洲遗传血统（76%），欧洲血统（13%）和美洲原住民血统（11%）比例几乎均等，而麦德林主要是欧洲血统（75%），其次是美洲原住民血统（18%）和非洲血统（7%）。与基因推断相比，来自乔科省的样本捐赠者自我认定的非洲血统更多，相反，欧洲和美洲原住民血统更少，这与我们之前在麦德林发现的情况相反，在麦德林，个体往往高估欧洲血统水平。我们开发了一种新的次大陆血统分配方法，该方法使我们能够分别为三个不同的大陆血统部分确定次大陆来源种群的特征。尽管乔科省和麦德林在大陆血统层面存在明显差异，但这两个人口群体显示出高度相似的次大陆血统总体模式。它们的非洲次大陆血统仅有细微差异，乔科省与现代约鲁巴（尼日利亚）种群有更多独特的共同血统，而麦德林与塞拉利昂和冈比亚的西非种群有相对更多的共同血统。两个人口群体在欧洲都显示出非常相似的西班牙血统，美洲原住民血统模式几乎相同，主要来自恩贝拉和瓦纳纳部落。当综合考虑三个次大陆血统成分时，乔科省和麦德林的人口群体显示出关系最为密切，排除了我们分析的其他美洲混合种群。我们思考了次大陆共同血统的存在对于哥伦比亚人口的影响，这些人口乍一看在强调种族混合（）群体特定身份（多元文化主义）的国家认同竞争观念方面明显不同。
