Centre d'Ecologie Fonctionnelle et Evolutive, UMR 5175, 1919 Route de Mende, 34293 Montpellier Cedex 5, France.
Mol Ecol. 2013 Feb;22(4):1092-104. doi: 10.1111/mec.12129. Epub 2012 Nov 27.
Genetic diversity of contemporary domesticated species is shaped by both natural and human-driven processes. However, until now, little is known about how domestication has imprinted the variation of fruit tree species. In this study, we reconstruct the recent evolutionary history of the domesticated almond tree, Prunus dulcis, around the Mediterranean basin, using a combination of nuclear and chloroplast microsatellites [i.e. simple sequence repeat (SSRs)] to investigate patterns of genetic diversity. Whereas conservative chloroplast SSRs show a widespread haplotype and rare locally distributed variants, nuclear SSRs show a pattern of isolation by distance with clines of diversity from the East to the West of the Mediterranean basin, while Bayesian genetic clustering reveals a substantial longitudinal genetic structure. Both kinds of markers thus support a single domestication event, in the eastern side of the Mediterranean basin. In addition, model-based estimation of the timing of genetic divergence among those clusters is estimated sometime during the Holocene, a result that is compatible with human-mediated dispersal of almond tree out of its centre of origin. Still, the detection of region-specific alleles suggests that gene flow from relictual wild preglacial populations (in North Africa) or from wild counterparts (in the Near East) could account for a fraction of the diversity observed.
当代驯化物种的遗传多样性是由自然和人为驱动的过程共同塑造的。然而，直到现在，人们对于驯化过程如何影响果树物种的变异知之甚少。在这项研究中，我们使用核和叶绿体微卫星[即简单序列重复（SSR）]组合，重建了地中海盆地周边驯化扁桃树（Prunus dulcis）的近期进化历史，以调查遗传多样性模式。保守的叶绿体 SSR 显示出广泛的单倍型和罕见的局部分布变体，而核 SSR 则显示出距离隔离的模式，多样性从地中海盆地的东部到西部呈梯度分布，而贝叶斯遗传聚类则显示出显著的纵向遗传结构。这两种标记都支持在地中海盆地东部发生的单一驯化事件。此外，基于模型的遗传分化时间估计表明，这些聚类之间的遗传分化发生在全新世期间，这一结果与人类介导的扁桃树从起源中心向外扩散是一致的。尽管如此，特定区域等位基因的检测表明，来自残余的冰川前野生种群（北非）或野生对应物（近东）的基因流可能解释了观察到的多样性的一部分。
