Dipartimento di Genetica e Microbiologia, Università di Pavia, Pavia, Italy.
PLoS One. 2010 Dec 28;5(12):e15760. doi: 10.1371/journal.pone.0015760.
When domestic taurine cattle diffused from the Fertile Crescent, local wild aurochsen (Bos primigenius) were still numerous. Moreover, aurochsen and introduced cattle often coexisted for millennia, thus providing potential conditions not only for spontaneous interbreeding, but also for pastoralists to create secondary domestication centers involving local aurochs populations. Recent mitochondrial genomes analyses revealed that not all modern taurine mtDNAs belong to the shallow macro-haplogroup T of Near Eastern origin, as demonstrated by the detection of three branches (P, Q and R) radiating prior to the T node in the bovine phylogeny. These uncommon haplogroups represent excellent tools to evaluate if sporadic interbreeding or even additional events of cattle domestication occurred.
The survey of the mitochondrial DNA (mtDNA) control-region variation of 1,747 bovine samples (1,128 new and 619 from previous studies) belonging to 37 European breeds allowed the identification of 16 novel non-T mtDNAs, which after complete genome sequencing were confirmed as members of haplogroups Q and R. These mtDNAs were then integrated in a phylogenetic tree encompassing all available P, Q and R complete mtDNA sequences.
Phylogenetic analyses of 28 mitochondrial genomes belonging to haplogroups P (N = 2), Q (N = 16) and R (N = 10) together with an extensive survey of all previously published mtDNA datasets revealed major similarities between haplogroups Q and T. Therefore, Q most likely represents an additional minor lineage domesticated in the Near East together with the founders of the T subhaplogroups. Whereas, haplogroup R is found, at least for the moment, only in Italy and nowhere else, either in modern or ancient samples, thus supporting an origin from European aurochsen. Haplogroup R could have been acquired through sporadic interbreeding of wild and domestic animals, but our data do not rule out the possibility of a local and secondary event of B. primigenius domestication in Italy.
当国内的黄牛从新月沃地扩散开来时，当地的野生原牛（Bos primigenius）仍然很多。此外，原牛和引入的牛经常共存了数千年，因此不仅为自然杂交提供了潜在条件，也为牧民创造了涉及当地原牛种群的二次驯化中心提供了潜在条件。最近的线粒体基因组分析表明，并非所有现代黄牛的 mtDNA 都属于起源于近东的浅宏单倍群 T，因为在牛的系统发育中，在 T 节点之前就已经检测到了三个分支（P、Q 和 R）放射状分支。这些不常见的单倍群是评估是否发生了零星杂交甚至是牛的额外驯化事件的绝佳工具。
对 37 个欧洲品种的 1747 个牛样本（1128 个新样本和 619 个来自先前研究的样本）的线粒体 DNA（mtDNA）控制区变异进行了调查，鉴定出 16 个新的非 T 线粒体 DNA，这些 DNA 经完整基因组测序后被确认为单倍群 Q 和 R 的成员。然后，这些 mtDNA 被整合到一个包含所有可用的 P、Q 和 R 完整 mtDNA 序列的系统发育树中。
对属于单倍群 P（N=2）、Q（N=16）和 R（N=10）的 28 个线粒体基因组的系统发育分析以及对所有先前发表的 mtDNA 数据集的广泛调查表明，单倍群 Q 和 T 之间存在主要相似性。因此，Q 很可能是与 T 亚单倍群的祖先一起在近东地区驯化的另一个次要谱系。而单倍群 R 至少目前仅在意大利发现，无论是在现代还是古代样本中，都没有在其他地方发现，因此支持它来自欧洲原牛。单倍群 R 可能是通过野生动物和家养动物的偶然杂交而获得的，但我们的数据并不能排除意大利发生欧洲原牛局部和二次驯化的可能性。
