Assessing the Genetic Influence of Ancient Sociopolitical Structure: Micro-differentiation Patterns in the Population of Asturias (Northern Spain)

The human populations of the Iberian Peninsula are the varied result of a complex mixture of cultures throughout history, and are separated by clear social, cultural, linguistic or geographic barriers. The stronger genetic differences between closely related populations occur in the northern third of Spain, a phenomenon commonly known as “micro-differentiation”. It has been argued and discussed how this form of genetic structuring can be related to both the rugged landscape and the ancient societies of Northern Iberia, but this is difficult to test in most regions due to the intense human mobility of previous centuries. Nevertheless, the Spanish autonomous community of Asturias shows a complex history which hints of a certain isolation of its population. This, joined together with a difficult terrain full of deep valleys and steep mountains, makes it suitable for performing a study of genetic structure, based on mitochondrial DNA and Y-Chromosome markers. Our analyses do not only show that there are micro-differentiation patterns inside the Asturian territory, but that these patterns are strikingly similar between both uniparental markers. The inference of barriers to gene flow also indicates that Asturian populations from the coastal north and the mountainous south seem to be relatively isolated from the rest of the territory. These findings are discussed in light of historic and geographic data and, coupled with previous evidence, show that the origin of the current genetic patterning might indeed lie in Roman and Pre-Roman sociopolitical divisions.伊比利亚半岛的人类群体是历经历史演变的多元文化融合产物，且被清晰的社会、文化、语言或地理屏障所分隔。亲缘关系较近的群体间的显著遗传差异集中分布于西班牙北部三分之一区域，这一现象通常被称为“微分化（micro-differentiation）”。学界已围绕该遗传结构如何与伊比利亚北部崎岖地貌及古代社会产生关联展开论证与探讨，但由于此前数个世纪人类流动性极强，多数地区难以对该假说进行验证。不过，西班牙阿斯图里亚斯自治区拥有复杂的历史脉络，暗示其本土群体存在一定程度的隔离性。加之该区域拥有遍布深邃河谷与陡峭山峦的复杂地形，使其成为基于线粒体DNA（mitochondrial DNA）与Y染色体（Y-Chromosome）标记开展遗传结构研究的理想样本区域。我们的分析不仅揭示了阿斯图里亚斯区域内存在微分化模式，还发现这两类单亲遗传标记（uniparental markers）所呈现的模式具有极高的相似性。对基因流屏障的推断同样表明，阿斯图里亚斯北部沿海与南部山地的群体相对区域内其他群体处于隔离状态。我们结合历史与地理数据对上述发现展开探讨，并结合既往研究证据表明，当前阿斯图里亚斯群体遗传格局的起源，或许确实可追溯至罗马时代及前罗马时代的社会政治分化。