Potamogeton crispus (curlyleaf pondweed) and Myriophyllum spicatum (Eurasian watermilfoil) are widely thought to competitively displace native macrophytes in North America. However, their perceived competitive superiority has not been comprehensively evaluated. Coexistence theory suggests that invader displacement of native species through competitive exclusion is most likely where high niche overlap results in competition for limiting resources. Thus, evaluation of niche similarity can serve as a starting point for predicting the likelihood of invaders having direct competitive impacts on resident species. Across two environmental gradients structuring macrophyte communities—water depth and light availability—both P. crispus and M. spicatum are thought to occupy broad niches. For a third dimension, phenology, the annual growth cycle of M. spicatum is typical of other species, whereas the winter-ephemeral phenology of P. crispus may impart greater niche differentiation and thus lower risk of native species being competitively excluded. Using an unprecedented dataset comprising 3404 plant surveys from Minnesota collected using a common protocol, we modeled niches of 34 species using a probabilistic niche framework. Across each niche dimension, P. crispus had lower overlap with native species than did M. spicatum; this was driven in particular by its distinct phenology. These results suggest that patterns of dominance seen in P. crispus and M. spicatum have likely arisen through different mechanisms, and that direct competition with native species is less likely for P. crispus than M. spicatum. This research highlights the utility of fine-scale, abundance-based niche models for predicting invader impacts.

中文翻译：

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生态位模型区分两种水生入侵植物物种对本地大型植物的潜在影响。

人们普遍认为，Potamogeton crispus（弯叶草）和Myriophyllum spicatum（欧亚水草）可以竞争性地取代北美的本地大型植物。但是，他们认为的竞争优势尚未得到全面评估。共存理论表明，通过竞争排斥排斥入侵者最有可能在高生态位重叠导致竞争限制资源的情况下发生。因此，对生态位相似性的评估可以作为预测入侵者对居民物种产生直接竞争影响的可能性的起点。跨越两个构造大型植物群落的环境梯度（水深和光利用率），P。crispus和M. spicatum被认为占据着广阔的位置。对于第三维，物候，年生长周期M.藻是典型其它物种的，而在冬季，短暂的物候菹可以赋予更大的位分化和本地物种被竞争性地排除风险因此降低。我们使用前所未有的数据集，其中包括使用通用协议收集的来自明尼苏达州的3404种植物调查，我们使用概率生态位框架对34种物种的生态位建模。在每个生态位维度上，P。crispus与本地物种的重叠率均低于sp。spicatum。这尤其是由其独特的物候学驱动的。这些结果表明，在P. crispus和P.狐尾藻有可能通过不同的机制出现，并与本地物种的直接竞争是不太可能的菹草比狐尾藻。这项研究强调了基于规模的，基于丰度的利基模型在预测入侵者影响方面的实用性。