Instituto de Ecología y Biodiversidad, Departamento de Ecología, Facultad de Ciencias, Universidad de Chile, Ñuñoa, Santiago, Chile.
PLoS One. 2012;7(12):e51311. doi: 10.1371/journal.pone.0051311. Epub 2012 Dec 11.
With analyses of entire mitogenomes, studies of Native American mitochondrial DNA (MTDNA) variation have entered the final phase of phylogenetic refinement: the dissection of the founding haplogroups into clades that arose in America during and after human arrival and spread. Ages and geographic distributions of these clades could provide novel clues on the colonization processes of the different regions of the double continent. As for the Southern Cone of South America, this approach has recently allowed the identification of two local clades (D1g and D1j) whose age estimates agree with the dating of the earliest archaeological sites in South America, indicating that Paleo-Indians might have reached that region from Beringia in less than 2000 years. In this study, we sequenced 46 mitogenomes belonging to two additional clades, termed B2i2 (former B2l) and C1b13, which were recently identified on the basis of mtDNA control-region data and whose geographical distributions appear to be restricted to Chile and Argentina. We confirm that their mutational motifs most likely arose in the Southern Cone region. However, the age estimate for B2i2 and C1b13 (11-13,000 years) appears to be younger than those of other local clades. The difference could reflect the different evolutionary origins of the distinct South American-specific sub-haplogroups, with some being already present, at different times and locations, at the very front of the expansion wave in South America, and others originating later in situ, when the tribalization process had already begun. A delayed origin of a few thousand years in one of the locally derived populations, possibly in the central part of Chile, would have limited the geographical and ethnic diffusion of B2i2 and explain the present-day occurrence that appears to be mainly confined to the Tehuelche and Araucanian-speaking groups.
通过对整个线粒体基因组的分析,对美洲原住民线粒体 DNA(MTDNA)变异的研究已经进入了系统发育精细化的最后阶段:将起源于美洲的母系单倍群进一步划分为支系,这些支系出现在人类到达和扩散之后。这些支系的年龄和地理分布可以为不同地区的殖民过程提供新的线索。对于南美洲的南部锥体地区,这种方法最近已经确定了两个当地支系(D1g 和 D1j),它们的年龄估计与南美洲最早的考古遗址的年代相符,这表明古印第安人可能在不到 2000 年的时间内从白令海峡到达该地区。在这项研究中,我们对属于另外两个支系(称为 B2i2(前 B2l)和 C1b13)的 46 个线粒体基因组进行了测序,这些支系是基于 mtDNA 控制区数据最近确定的,其地理分布似乎仅限于智利和阿根廷。我们确认它们的突变模体很可能在南部锥体地区产生。然而,B2i2 和 C1b13 的年龄估计(11-13000 年前)似乎比其他当地支系年轻。这种差异可能反映了不同的进化起源,一些独特的、与南美洲相关的亚单倍群在不同的时间和地点,处于扩张波的最前沿,而另一些则是在部落化过程开始后在原地产生的。在南美洲扩张波的最前沿的不同时间和地点,一些独特的、与南美洲相关的亚单倍群已经存在,而在智利中部等地区的一个当地衍生种群中,这种起源可能会延迟几千年,这可能会限制 B2i2 的地理和种族扩散,并解释其目前似乎主要局限于特维切和阿拉乌干语群体的存在。