Lorenz J G, Smith D G
Analytical Genetic Testing Center, Denver, CO 80231, USA.
Hum Biol. 1997 Dec;69(6):749-76.
The distributions of mtDNA diversity within and/or among North American haplogroups, language groups, and tribes were used to characterize the process of tribalization that followed the colonization of the New World. Approximately 400 bp from the mtDNA control region of 1 Na-Dene and 33 Amerind individuals representing a wide variety of languages and geographic origins were sequenced. With the inclusion of data from previous studies, 225 native North American (284 bp) sequences representing 85 distinct mtDNA lineages were analyzed. Mean pairwise sequence differences between (and within) tribes and language groups were primarily due to differences in the distribution of three of the four major haplogroups that evolved before settlement of the New World. Pairwise sequence differences within each of these three haplogroups were more similar than previous studies based on restriction enzyme analysis have indicated. The mean of pairwise sequence differences between Amerind members of haplogroup A, the most common of the four haplogroups in North America, was only slightly higher than that for the Eskimo, providing no evidence of separate ancestry, but was about two-thirds higher than that for the Na-Dene. However, analysis of pairwise sequence divergence between only tribal-specific lineages, unweighted for sample size, suggests that random evolutionary processes have reduced sequence diversity within the Na-Dene and that members of all three language groups possess approximately equally diverse mtDNA lineages. Comparisons of diversity within and between specific ethnic groups with the largest sample size were also consistent with this outcome. These data are not consistent with the hypothesis that the New World was settled by more than a single migration. Because lineages tended not to cluster by tribe and because lineage sharing among linguistically unrelated groups was restricted to geographically proximate groups, the tribalization process probably did not occur soon after settlement of the New World, and/or considerable admixture has occurred among daughter populations.
北美单倍群、语系和部落内部和/或之间的线粒体DNA（mtDNA）多样性分布，被用于描述新大陆殖民化之后的部落化过程。对1名纳-德内语族个体和33名代表多种语言和地理起源的美洲印第安个体的mtDNA控制区约400个碱基对进行了测序。纳入先前研究的数据后，对代表85个不同mtDNA谱系的225条北美原住民（284个碱基对）序列进行了分析。部落和语系之间（以及内部）的平均成对序列差异，主要是由于在新大陆定居之前进化的四个主要单倍群中三个的分布差异。这三个单倍群中每个单倍群内部的成对序列差异，比基于限制性内切酶分析的先前研究表明的更为相似。北美最常见的四个单倍群中，单倍群A的美洲印第安成员之间的成对序列差异平均值，仅略高于爱斯基摩人，没有提供单独祖先的证据，但比纳-德内语族高出约三分之二。然而，仅对部落特异性谱系之间的成对序列分歧进行分析（未对样本量加权）表明，随机进化过程降低了纳-德内语族内部的序列多样性，并且所有三个语系的成员拥有大致同等多样的mtDNA谱系。对样本量最大的特定族群内部和之间的多样性比较也与这一结果一致。这些数据与新大陆是由不止一次迁徙定居的假设不一致。由于谱系往往不会按部落聚类，并且由于语言不相关群体之间的谱系共享仅限于地理上相邻的群体，部落化过程可能在新大陆定居后不久并未发生，和/或在子群体之间发生了相当程度的混合。
