AIM: Biological invasions are pervasive in freshwater ecosystems, often causing native species to contract into areas that remain largely free from invasive species impacts. Predicting the location of such ecological refuges is challenging, because they are shaped by the habitat requirements of native and invasive species, their biotic interactions, and the spatial and temporal invasion patterns. Here, we investigated the spatial distribution and environmental drivers of refuges from invasion in river systems, by considering biotic interactions in geostatistical models accounting for stream network topology. We focused on Mediterranean amphibians negatively impacted by the invasive crayfishes Procambarus clarkii and Pacifastacus leniusculus. LOCATION: River Sabor, NE Portugal. METHODS: We surveyed amphibians at 168 200‐m stream stretches in 2015. Geostatistical models were used to relate the probabilities of occurrence of each species to environmental and biotic variables, while controlling for linear (Euclidean) and hydrologic spatial dependencies. Biotic interactions were specified using crayfish probabilities of occurrence extracted from previously developed geostatistical models. Models were used to map the distribution of potential refuges for the most common amphibian species, under current conditions and future scenarios of crayfish expansion. RESULTS: Geostatistical models were produced for eight out of 10 species detected, of which five species were associated with lower stream orders and only one species with higher stream orders. Six species showed negative responses to one or both crayfish species, even after accounting for environmental effects and spatial dependencies. Most amphibian species were found to retain large expanses of potential habitat in stream headwaters, but current refuges will likely contract under plausible scenarios of crayfish expansion. MAIN CONCLUSIONS: Incorporating biotic interactions in geostatistical modelling provides a practical and relatively simple approach to predict present and future distributions of refuges from biological invasion in stream networks. Using this approach, our study shows that stream headwaters are key amphibian refuges under invasion by alien crayfish.

中文翻译：

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结合地质统计学和生物相互作用模型预测小龙虾入侵树突状溪流网络下的两栖动物避难所

目标：生物入侵在淡水生态系统中普遍存在，通常会导致本地物种收缩到基本不受入侵物种影响的地区。预测此类生态避难所的位置具有挑战性，因为它们受本地和入侵物种的栖息地要求、它们的生物相互作用以及时空入侵模式的影响。在这里，我们通过考虑考虑河流网络拓扑的地质统计模型中的生物相互作用，研究了河流系统中避难所的空间分布和环境驱动因素。我们专注于受侵入性小龙虾 Procambarus clarkii 和 Pacifastacus leniusculus 负面影响的地中海两栖动物。地点：葡萄牙东北部萨博尔河。方法：我们于 2015 年在 168 条 200 米的河流延伸处调查了两栖动物。地统计模型用于将每个物种的出现概率与环境和生物变量相关联，同时控制线性（欧几里得）和水文空间依赖性。使用从先前开发的地质统计模型中提取的小龙虾发生概率来指定生物相互作用。在小龙虾扩张的当前条件和未来情景下，模型被用来绘制最常见的两栖动物物种潜在避难所的分布图。结果：为检测到的 10 个物种中的 8 个生成了地统计模型，其中 5 个物种与较低的河流等级相关，只有 1 个物种与较高的河流等级相关。六个物种对一种或两种小龙虾物种表现出负面反应，即使在考虑了环境影响和空间依赖性之后也是如此。大多数两栖动物物种被发现在溪流源头保留了大片的潜在栖息地，但在小龙虾扩张的合理情景下，目前的避难所可能会收缩。主要结论：将生物相互作用纳入地质统计建模提供了一种实用且相对简单的方法来预测河流网络中生物入侵避难所的当前和未来分布。使用这种方法，我们的研究表明，河流源头是外来小龙虾入侵的关键两栖动物避难所。将生物相互作用纳入地质统计建模提供了一种实用且相对简单的方法来预测河流网络中生物入侵避难所的当前和未来分布。使用这种方法，我们的研究表明，河流源头是外来小龙虾入侵的关键两栖动物避难所。将生物相互作用纳入地质统计建模提供了一种实用且相对简单的方法来预测河流网络中生物入侵避难所的当前和未来分布。使用这种方法，我们的研究表明，河流源头是外来小龙虾入侵的关键两栖动物避难所。