Karimi Karim, Strucken Eva M, Moghaddar Nasir, Ferdosi Mohammad H, Esmailizadeh Ali, Gondro Cedric
Department of Animal Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, PB, 76169-133, Iran.
School of Environmental and Rural Science, University of New England, Armidale, 2351, NSW, Australia.
BMC Genet. 2016 Jul 15;17(1):108. doi: 10.1186/s12863-016-0416-z.
Two separate domestication events gave rise to humped zebu cattle in India and humpless taurine cattle in the Fertile Crescent of the Near and Middle East. Iran covers the Eastern side of the Fertile Crescent and exhibits a variety of native cattle breeds, however, only little is known about the admixture patterns of Iranian cattle and their contribution to the formation of modern cattle breeds.
Genome-wide data (700 k chip) of eight Iranian cattle breeds (Sarabi N = 19, Kurdi N = 7, Taleshi N = 7, Mazandarani N = 10, Najdi N = 7, Pars N = 7, Kermani N = 9, and Sistani N = 9) were collected from across Iran. For a local assessment, taurine (Holstein and Jersey) and indicine (Brahman) outgroup samples were used. For the global perspective, 134 world-wide cattle breeds were included. Between breed variation amongst Iranian cattle explained 60 % (p < 0.001) of the total molecular variation and 82.88 % (p < 0.001) when outgroups were included. Several migration edges were observed within the Iranian cattle breeds. The highest indicine proportion was found in Sistani. All Iranian breeds with higher indicine ancestry were more admixed with a complex migration pattern. Nineteen founder populations most accurately explained the admixture of 44 selected representative cattle breeds (standard error 0.4617). Low levels of African ancestry were identified in Iranian cattle breeds (on average 7.5 %); however, the signal did not persist through all analyses. Admixture and migration analyses revealed minimal introgression from Iranian cattle into other taurine cattle (Holstein, Hanwoo, Anatolian breeds).
The eight Iranian cattle breeds feature a discrete genetic composition which should be considered in conservation programs aimed at preserving unique species and genetic diversity. Despite a complex admixture pattern among Iranian cattle breeds, there was no strong introgression from other world-wide cattle breeds into Iranian cattle and vice versa. Considering Iran's central location of cattle domestication, Iranian cattle might represent a local domestication event that remained contained and did not contribute to the formation of modern breeds, or genetics of the ancestral population that gave rise to modern cattle is too diluted to be linked directly to any current cattle breeds.
两次独立的驯化事件分别产生了印度的瘤牛和近东及中东新月沃地的无瘤原牛。伊朗位于新月沃地的东部，拥有多种本土牛品种，然而，对于伊朗牛的混合模式及其对现代牛品种形成的贡献却知之甚少。
从伊朗各地收集了八个伊朗牛品种（萨拉比牛N = 19头、库尔德牛N = 7头、塔勒希牛N = 7头、马赞德兰牛N = 10头、纳吉迪牛N = 7头、帕尔西牛N = 7头、克尔曼牛N = 9头、锡斯坦牛N = 9头）的全基因组数据（700k芯片）。为进行本地评估，使用了原牛（荷斯坦牛和泽西牛）和瘤牛（婆罗门牛）的外群样本。从全球角度看，纳入了134个世界范围内的牛品种。伊朗牛品种之间的品种差异解释了总分子变异的60%（p < 0.001），纳入外群后这一比例为82.88%（p < 0.001）。在伊朗牛品种中观察到了几条迁移边缘。锡斯坦牛的瘤牛比例最高。所有具有较高瘤牛血统的伊朗品种混合程度更高，且迁移模式复杂。19个奠基群体最准确地解释了44个选定代表性牛品种的混合情况（标准误差0.4617）。在伊朗牛品种中发现了低水平的非洲血统（平均7.5%）；然而，该信号在所有分析中并不持续。混合和迁移分析显示，伊朗牛向其他原牛（荷斯坦牛、韩牛、安纳托利亚品种）的基因渗入极少。
八个伊朗牛品种具有独特的遗传组成，在旨在保护独特物种和遗传多样性的保护计划中应予以考虑。尽管伊朗牛品种之间存在复杂的混合模式，但其他世界范围内的牛品种向伊朗牛的基因渗入并不强烈，反之亦然。考虑到伊朗在牛驯化中的中心位置，伊朗牛可能代表了一次局限于本地的驯化事件，没有对现代品种的形成做出贡献，或者说产生现代牛的祖先群体的基因过于稀释，无法直接与任何当前的牛品种联系起来。
