Long-distance dispersal (LDD) is a pivotal process for plants determining their range of distribution and promoting gene flow among distant populations. Most fleshy-fruited species rely on frugivorous vertebrates to disperse their seeds across the landscape. While LDD events are difficult to record, a few ecological studies have shown that birds move a sizeable number of ingested seeds across geographic barriers, such as sea straits. The foraging movements of migrant frugivores across distant populations, including those separated by geographic barriers, creates a constant flow of propagules that in turn shapes the spatial distributions of the genetic variation in populations. Here, we have analysed the genetic diversity and structure of 74 populations of Pistacia lentiscus, a fleshy-fruited shrub widely distributed in the Mediterranean Basin, to elucidate whether the Mediterranean Sea acts as a geographic barrier or alternatively whether migratory frugivorous birds promote gene flow among populations located on both sides of the sea. Our results show reduced genetic distances among populations, including intercontinental populations, and they show a significant genetic structure across an eastern-western axis. These findings are consistent with known bird migratory routes that connect the European and African continents following a north-southwards direction during the fruiting season of many fleshy-fruited plants. Further, approximate Bayesian analysis failed to explain the observed patterns as a result of historical population migrations at the end of Last Glacial Maximum. Therefore, anthropic and/or climatic changes that would disrupt the migratory routes of frugivorous birds might have genetic consequences for the plant species they feed upon.

中文翻译：

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跨地中海盆地的洲际长距离种子传播解释了鸟类分散灌木的种群遗传结构。

远程分散（LDD）是植物确定其分布范围并促进远距离种群间基因流动的关键过程。大多数果肉类物种依靠肉食性脊椎动物在整个景观中散布种子。尽管很难记录LDD事件，但一些生态学研究表明，鸟类将大量摄入的种子移过地理障碍，例如海峡。迁徙果蝇在遥远人群中的觅食运动，包括那些被地理障碍隔开的种群，产生了不断繁殖的繁殖体，进而塑造了种群遗传变异的空间分布。在这里，我们分析了74种分布在地中海盆地的肉果灌木黄连木（Pistacia lentiscus）的遗传多样性和结构，阐明地中海是地理障碍还是迁徙的食肉类鸟类是否促进了位于海两侧的种群之间的基因流动。我们的结果表明，包括洲际种群在内的种群之间的遗传距离减小，并且它们在东西轴之间显示出重要的遗传结构。这些发现与已知的鸟类迁徙路线相吻合，在许多肉质植物的结实季节，它们沿着南北方向连接欧洲和非洲大陆。此外，近似贝叶斯分析未能解释观察到的模式，这是由于最后一次冰川最大值结束时的历史人口迁移所致。因此，