Understanding how environmental factors and short-term evolution affect the growth of invasive plants is a central issue in Invasion Biology. For macrophytes, salinity is one of the main factors determining distribution along estuarine environments. Urochola arrecta is a Poaceae with high invasive potential in several freshwater and estuarine ecosystems. In South Brazilian estuaries, this species is found sparsely in mangroves, and invades successfully freshwaters and areas with low salinity. We experimentally described the U. arrecta tolerance to salt. Furthermore, we tested if the response to the saline gradient depends on the population origin, through an experiment with populations inhabiting estuarine and freshwater ecosystems. We designed the experiment with three populations of this species, expecting that estuarine populations were more resistant to salinity. Plants grew in a salinity gradient and after 40 days we measured macrophytes biomass and length. Salinity was highly stressful for U. arrecta independently of its origin. Even so, plant growth differed significantly among populations. Despite higher growth, the population originated from freshwater habitats presented the fastest decrease in performance indicators with increasing salinity. This result indicates short-term evolutionary changes because all populations grew common-garden conditions in our experiment. Furthermore, salinity did not prevent the full establishment of this plant, since almost all propagules developed roots even in the saline treatments. Differences among populations suggest that invasion potential of this species can be higher than predicted by the environmental conditions of current invaded sites. Constant monitoring in estuarine invaded ecosystems is central to manage invasions in critical ecosystems, such as mangroves areas.

中文翻译：

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侵入性禾本科植物响应盐度快速进化的证据

了解环境因素和短期进化如何影响入侵植物的生长是入侵生物学的核心问题。对于大型植物，盐度是决定沿河口环境分布的主要因素之一。Urochola arrecta 是禾本科，在几个淡水和河口生态系统中具有很高的入侵潜力。在巴西南部的河口，该物种在红树林中稀疏地发现，并成功侵入淡水和低盐度地区。我们通过实验描述了 U. arrecta 对盐的耐受性。此外，我们通过对居住在河口和淡水生态系统中的种群进行的实验，测试了对盐度梯度的响应是否取决于种群起源。我们设计了这个物种的三个种群的实验，预计河口种群对盐度的抵抗力更强。植物在盐度梯度中生长，40 天后我们测量了大型植物的生物量和长度。盐度对 U. arrecta 的压力很大，与其起源无关。即便如此，不同种群的植物生长情况也存在显着差异。尽管增长率较高，但随着盐度的增加，来自淡水栖息地的种群表现出的性能指标下降最快。这个结果表明了短期的进化变化，因为在我们的实验中所有种群都在普通花园条件下生长。此外，盐度并没有阻止这种植物的完全建立，因为即使在盐水处理中，几乎所有的繁殖体都能生根。种群之间的差异表明，该物种的入侵潜力可能高于当前入侵地点的环境条件所预测的。对河口入侵生态系统的持续监测对于管理关键生态系统（如红树林地区）的入侵至关重要。