Pisa S, Vanderpoorten A, Patiño J, Werner O, González-Mancebo J M, Ros R M
Departamento de Biología Vegetal, Universidad de Murcia, Murcia, Spain.
Institute of Botany, University of Liège, Liège, Belgium.
Plant Biol (Stuttg). 2015 Sep;17(5):1057-65. doi: 10.1111/plb.12348. Epub 2015 Jun 22.
The distinction between native and introduced biotas presents unique challenges that culminate in organisms with high long-distance dispersal capacities in a rapidly changing world. Bryophytes, in particular, exhibit large distribution ranges, and some species can truly be qualified as cosmopolitan. Cosmopolitan species, however, typically occur in disturbed environments, raising the question of their nativeness throughout their range. Here, we employ genetic data to address the question of the origin of the cosmopolitan, weedy moss Bryum argenteum on the island of Tenerife. The genetic diversity of B. argenteum on Tenerife was comparable to that found in continental areas due to recurrent colonisation events, erasing any signature of a bottleneck that would be expected in the case of a recent colonisation event. The molecular dating analyses indicated that the first colonisation of the island took place more than 100,000 years ago, i.e. well before the first human settlements. Furthermore, the significant signal for isolation-by-distance found in B. argenteum within Tenerife points to the substantial role of genetic drift in establishing the observed patterns of genetic variation. Together, the results support the hypothesis that B. argenteum is native on Tenerife; although the existence of haplotypes shared between Tenerife and continental areas suggests that more recent, potentially man-mediated introduction also took place. While defining nativeness in organisms that are not deliberately introduced, and wherein the fossil record is extremely scarce, is an exceedingly challenging task, our results suggest that population genetic analyses can represent a useful tool to help distinguish native from alien populations.
本地生物群和外来生物群之间的区别带来了独特的挑战，在一个快速变化的世界中，这些挑战最终体现在具有高远距离扩散能力的生物身上。特别是苔藓植物，分布范围很广，有些物种可以真正称得上是世界性的。然而，世界性物种通常出现在受干扰的环境中，这就引发了它们在整个分布范围内是否为本地物种的问题。在这里，我们利用遗传数据来解决特内里费岛上世界性杂草苔藓银叶真藓的起源问题。由于反复的定殖事件，特内里费岛上银叶真藓的遗传多样性与大陆地区的遗传多样性相当，消除了近期定殖事件中预期会出现的瓶颈迹象。分子年代分析表明，该岛的首次定殖发生在10万多年前，即远早于第一批人类定居点出现的时间。此外，在特内里费岛的银叶真藓中发现的显著的距离隔离信号表明，遗传漂变在建立观察到的遗传变异模式中起了重要作用。这些结果共同支持了银叶真藓在特内里费岛是本地物种的假设；尽管特内里费岛和大陆地区共享单倍型的存在表明，最近也可能有人为介导的引入。虽然在非人为引入且化石记录极其稀少的生物中定义本地性是一项极具挑战性的任务，但我们的结果表明，种群遗传分析可以成为帮助区分本地种群和外来种群的有用工具。
