Data from: Genetic footprints of Iberian cattle in America 500 years after the arrival of Columbus

BACKGROUND: American Creole cattle presumably descend from animals imported from the Iberian Peninsula during the period of colonization and settlement, through different migration routes, and may have also suffered the influence of cattle directly imported from Africa. The introduction of European cattle, which began in the 18th century, and later of Zebu from India, has threatened the survival of Creole populations, some of which have nearly disappeared or were admixed with exotic breeds. Assessment of the genetic status of Creole cattle is essential for the establishment of conservation programs of these historical resources. METHODOLOGY/PRINCIPAL FINDINGS: We sampled 27 Creole populations, 39 Iberian, 9 European and 6 Zebu breeds. We used microsatellite markers to assess the origins of Creole cattle, and to investigate the influence of different breeds on their genetic make-up. The major ancestral contributions are from breeds of southern Spain and Portugal, in agreement with the historical ports of departure of ships sailing towards the Western Hemisphere. This Iberian contribution to Creoles may also include some African influence, given the influential role that African cattle have had in the development of Iberian breeds, but the possibility of a direct influence on Creoles of African cattle imported to America can not be discarded. In addition to the Iberian influence, the admixture with other European breeds was minor. The Creoles from tropical areas, especially those from the Caribbean, show clear signs of admixture with Zebu. CONCLUSIONS/SIGNIFICANCE: Nearly five centuries since cattle were first brought to the Americas, Creoles still show a strong and predominant signature of their Iberian ancestors. Creole breeds differ widely from each other, both in genetic structure and influences from other breeds. Efforts are needed to avoid their extinction or further genetic erosion, which would compromise centuries of selective adaptation to a wide range of environmental conditions.

背景：美洲克里奥尔牛（American Creole cattle）一般被认为源自殖民定居时期从伊比利亚半岛引进的家畜，历经不同迁徙路径，同时可能还受到直接从非洲引进的牛只的影响。18世纪起欧洲牛的引入，以及后续印度瘤牛（Zebu）的引进，对克里奥尔牛种群的存续构成了威胁，部分种群几近灭绝或与外来品种发生了基因混合。对克里奥尔牛的遗传现状进行评估，是制定这类历史资源保护方案的必要前提。
方法/主要发现：本研究共采样了27个克里奥尔牛种群、39个伊比利亚牛品种、9个欧洲牛品种以及6个瘤牛品种。我们利用微卫星（microsatellite）标记技术，解析了克里奥尔牛的起源，并探究了不同品种对其遗传构成的影响。其主要的祖先血统贡献来自西班牙南部与葡萄牙的牛品种，这与历史上驶往西半球的船只的出发港口分布相一致。考虑到非洲牛在伊比利亚牛品种培育过程中发挥了重要影响，克里奥尔牛的伊比利亚血统中可能也包含部分非洲血统，但不能排除直接从非洲引进至美洲的牛只对克里奥尔牛产生直接影响的可能性。除伊比利亚血统的影响外，克里奥尔牛与其他欧洲牛品种的基因混合程度较低。来自热带地区（尤其是加勒比地区）的克里奥尔牛种群，展现出与瘤牛发生基因混合的明确信号。
结论与意义：在牛只首次被引进美洲近五个世纪后的今天，克里奥尔牛仍保留着其伊比利亚祖先的显著且主导的遗传特征。不同克里奥尔牛品种之间在遗传结构以及外来品种影响上均存在显著差异。亟需采取措施避免其灭绝或进一步的遗传侵蚀，否则将损害其历经数百年适应多样环境条件的适应性进化成果。