Abstract. Acacia longifolia is an aggressive invader worldwide. This species was brought to Portugal by the forestry services and is now found throughout the country with very strong ecological and social impacts. Although several ecological and physiological studies have been carried out, molecular studies in this species are sparse. Particularly, genetic variability evaluation in invasive ranges clearly deserves more attention. The aim of this study was to evaluate the genetic diversity and the genetic differentiation among populations of the alien invasive A. longifolia under different Mediterranean conditions. For that we studied three sandy dune populations along the Portuguese coast: Osso da Baleia (mesomediterranean), Pinheiro da Cruz and Vila Nova de Milfontes (termomediterranean). All sampled acacia plants were located underneath a pine forest, with the exception of the latter case study, where we also sampled in a diversified habitat conditions associated with the margins of agriculture fields. According to the historical records, it was also possible to compare acacia samples from original plantations and recently invaded areas. We have used two molecular markers – inter-simple sequence repeats (ISSR) and microsatellites (SSR). ISSR analysis showed that A. longifolia populations at all sampled locations have similar levels of diversity and a relatively low differentiation ( ΦPT=0.135 ). However, samples tended to cluster according to the regional (macro-scale) collection site. Microsatellites confirmed this low differentiation pattern. Our results indicate that differences in phenology and reproductive success observed during a previous study cannot be accounted for by genetic diversity and differentiation alone. Furthermore, our results taken together with historical information of A. longifolia suggest a single original introduction and a subsequent acclimation process.

中文翻译：

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葡萄牙入侵<i>长叶相思</i>的遗传多样性和分化

摘要。长叶金合欢是世界范围内的侵略性入侵者。该物种由林业部门带到葡萄牙，现在遍布全国，对生态和社会影响非常大。尽管已经进行了多项生态和生理研究，但对该物种的分子研究很少。特别是，侵入范围内的遗传变异性评估显然值得更多关注。本研究的目的是评估不同地中海条件下外来入侵的A. longifolia种群的遗传多样性和遗传分化。为此，我们研究了葡萄牙海岸沿线的三个沙丘种群：Osso da Baleia（中地中海）、Pinheiro da Cruz 和 Vila Nova de Milfontes（地中海）。所有采样的金合欢植物都位于松树林下，除了后一个案例研究，我们还在与农田边缘相关的多样化栖息地条件下采样。根据历史记载，还可以比较来自原始种植园和最近入侵地区的金合欢样本。我们使用了两种分子标记——简单序列间重复序列 (ISSR) 和微卫星 (SSR)。ISSR 分析表明，所有采样位置的长叶 A. longifolia 种群具有相似的多样性水平和相对较低的分化（ ΦPT=0.135 ）。然而，样本倾向于根据区域（宏观尺度）收集地点进行聚类。微卫星证实了这种低分化模式。我们的结果表明，在先前的研究中观察到的物候学和繁殖成功率的差异不能仅由遗传多样性和分化来解释。此外，我们的结果与 A. longifolia 的历史信息一起表明了一个单一的原始引入和随后的适应过程。