AIM: Biotic homogenization (BH), a reduction in the distinctness of species composition between geographically separated ecological communities in a region, is an important but underappreciated potential consequence of biological invasions. While BH theory has always considered invasions, it has generally been in a relatively narrow context that the cosmopolitan nature of invasive species increases BH because of their shared presence across many locations. We sought to evaluate this component of BH as well as broader effects of invasive species on BH through changes in native communities, including overall reductions in species richness or shifts in species composition. LOCATION: Minnesota, USA. TIME PERIOD: 2002–2014. MAJOR TAXA STUDIED: Aquatic macrophytes, including both vascular plants and attached macroalgae. METHODS: We used surveys of aquatic macrophyte communities from 1,102 shallow lakes in Minnesota, USA (including 248 lakes with repeated surveys) to evaluate relationships between invasion, native species and BH. RESULTS: We found that the presence of invasive species was associated with BH and that this pattern was reflected in both the total community (i.e., with invasive species included) and in the composition of the native species community alone. We found that invaded lakes were more compositionally similar to each other than uninvaded lakes, but that both groups were becoming more similar over time—despite neither group exhibiting declines in species richness. This pattern was largely driven by shifts in the native community itself, with common species becoming more widespread and rare species becoming rarer. MAIN CONCLUSIONS: Invasive species increase measures of community similarity through their own presence in multiple locations, and also by influencing the composition of native species. These patterns have important implications for conservation and management and suggest that BH should be considered more widely in evaluating the impacts of biological invasions and developing response strategies.

中文翻译：

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温带水生植物群落的入侵物种和生物同质化

目的：生物同质化 (BH)，即一个地区地理上分离的生态群落之间物种组成差异性的降低，是生物入侵的一个重要但未被充分认识的潜在后果。虽然 BH 理论一直考虑入侵，但通常在相对狭窄的背景下，入侵物种的世界性性质增加了 BH，因为它们在许多地方共享。我们试图通过本地群落的变化来评估 BH 的这一组成部分以及入侵物种对 BH 的更广泛影响，包括物种丰富度的整体减少或物种组成的变化。地点：美国明尼苏达州。时间段：2002-2014。研究的主要类群：水生大型植物，包括维管植物和附着的大型藻类。方法：我们使用美国明尼苏达州 1,102 个浅湖（包括重复调查的 248 个湖泊）的水生大型植物群落调查来评估入侵、本地物种和 BH 之间的关系。结果：我们发现入侵物种的存在与 BH 相关，这种模式反映在总群落（即包括入侵物种）和仅本地物种群落的组成中。我们发现被入侵的湖泊在成分上比未入侵的湖泊更相似，但随着时间的推移，这两个群体变得更加相似——尽管这两个群体都没有表现出物种丰富度的下降。这种模式主要是由本地社区本身的变化驱动的，常见物种变得越来越普遍，稀有物种变得越来越稀有。主要结论：入侵物种通过它们自己在多个地点的存在，以及通过影响本地物种的组成来增加群落相似性的度量。这些模式对保护和管理具有重要意义，并表明在评估生物入侵的影响和制定应对策略时应更广泛地考虑 BH。