Goats were domesticated in the Fertile Crescent about 10,000 years before present (YBP) and subsequently spread across Eurasia and Africa. This dispersal is expected to generate a gradient of declining genetic diversity with increasing distance from the areas of early livestock management. Previous studies have reported the existence of such genetic cline in European goat populations, but they were based on a limited number of microsatellite markers. Here, we have analyzed data generated by the AdaptMap project and other studies. More specifically, we have used the geographic coordinates and estimates of the observed (Ho) and expected (He) heterozygosities of 1077 European, 1187 African and 617 Asian goats belonging to 38, 43 and 22 different breeds, respectively, to find out whether genetic diversity and distance to Ganj Dareh, a Neolithic settlement in western Iran for which evidence of an early management of domestic goats has been obtained, are significantly correlated. Principal component and ADMIXTURE analyses revealed an incomplete regional differentiation of European breeds, but two genetic clusters representing Northern Europe and the British-Irish Isles were remarkably differentiated from the remaining European populations. In African breeds, we observed five main clusters: (1) North Africa, (2) West Africa, (3) East Africa, (4) South Africa, and (5) Madagascar. Regarding Asian breeds, three well differentiated West Asian, South Asian and East Asian groups were observed. For European and Asian goats, no strong evidence of significant correlations between Ho and He and distance to Ganj Dareh was found. In contrast, in African breeds we detected a significant gradient of diversity, which decreased with distance to Ganj Dareh. The detection of a genetic cline associated with distance to the Ganj Dareh in African but not in European or Asian goat breeds might reflect differences in the post-domestication dispersal process and subsequent migratory movements associated with the management of caprine populations from these three continents.

中文翻译：

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调查驯化后扩散对现代欧洲、非洲和亚洲山羊多样性的影响


大约一万年前，山羊在新月沃地 (YBP) 被驯化，随后传播到欧亚大陆和非洲。随着与早期牲畜管理地区距离的增加，这种分散预计将产生遗传多样性下降的梯度。先前的研究报道了欧洲山羊种群中存在这种遗传谱系，但它们基于数量有限的微卫星标记。在这里，我们分析了 AdaptMap 项目和其他研究生成的数据。更具体地说，我们使用了分别属于 38 个、43 个和 22 个不同品种的 1077 只欧洲山羊、1187 只非洲山羊和 617 只亚洲山羊的观测杂合性 (Ho) 和预期杂合性 (He) 的地理坐标和估计值，以查明基因是否存在遗传性。多样性和距甘吉达雷 (Ganj Dareh) 的距离显着相关。甘吉达雷是伊朗西部的一个新石器时代定居点，已获得早期管理家山羊的证据。主成分和混合分析揭示了欧洲品种的不完全区域分化，但代表北欧和不列颠-爱尔兰群岛的两个遗传簇与其余欧洲种群显着不同。在非洲品种中，我们观察到五个主要集群：（1）北非，（2）西非，（3）东非，（4）南非和（5）马达加斯加。关于亚洲品种，观察到三个分化良好的西亚、南亚和东亚群体。对于欧洲和亚洲山羊，没有发现强有力的证据表明 Ho 和 He 与到 Ganj Dareh 的距离之间存在显着相关性。相比之下，在非洲品种中，我们发现了显着的多样性梯度，随着距 Ganj Dareh 的距离而减小。 在非洲山羊品种中检测到与甘吉达雷距离有关的遗传谱系，但在欧洲或亚洲山羊品种中却没有检测到，这可能反映了驯化后扩散过程以及随后与来自这三个大陆的山羊种群管理相关的迁徙运动的差异。