Data from: Biological invasion modifies the co-occurrence patterns of insects along a stress gradient

1. Biological invasions have become one of the most important drivers of biodiversity loss and ecosystem change worldwide. However, it is still unclear how invasions may interact with local abiotic stressors, which are expected to increase as global change intensifies. Furthermore, we know little about the response to biological invasions of insects, despite their disproportionate contribution to global animal biodiversity.
2. The aim of the present work is to investigate the impact of an invasive aquatic insect on the co-occurrence patterns of native species of insects along a salinity gradient, and determine which assembly rules are driving these patterns.
3. First, we characterised the habitat specialisation and functional niches of each species from physiological and biological traits, respectively, and their degree of overlap. Second, we used field data to compare the co-occurrence patterns of native and invasive species in invaded and non-invaded areas of southern Iberia and northern Morocco. Finally, we tested if habitat filtering or niche differentiation assembly rules mediate their co-occurrence.
4. In non-invaded areas habitat filtering drives habitat segregation of species along the salinity gradient, with a lower contribution of niche differentiation. The presence of the invasive insect modifies the distribution and co-occurrence patterns of native species. In invaded areas, niche differentiation seems to be the main mechanism to avoid competition among the invasive and native species, enabling coexistence and resource partitioning.
5. The combined study of functional niche similarity and abiotic stressor tolerance of invasive and native species can improve our understanding of the effects of invasive species along abiotic stress gradients. This approach may increase our capacity to predict the outcomes of biological invasion in a global change context.

1. 生物入侵（Biological invasions）已成为全球范围内驱动生物多样性丧失与生态系统改变的核心驱动因素之一。然而，目前仍未明确生物入侵会如何与本地非生物胁迫因子（local abiotic stressors）发生交互作用——而随着全球变化加剧，这类胁迫因子的影响预计将持续增强。此外，尽管昆虫在全球动物生物多样性中所占比例极高，对全球动物生物多样性的贡献不成比例地显著，但我们对昆虫群落对生物入侵的响应机制仍知之甚少。
2. 本研究旨在探究入侵性水生昆虫沿盐度梯度对本土昆虫物种共存格局的影响，并明确驱动该格局的群落构建规则（assembly rules）。
3. 首先，我们分别基于生理性状与生物学性状，表征了各物种的生境特化水平与功能生态位（functional niches），并分析了它们之间的生态位重叠程度。其次，我们利用野外调查数据，对比了伊比利亚半岛南部与摩洛哥北部的入侵区域与非入侵区域内，本土物种与入侵物种的共存格局。最后，我们检验了生境过滤（habitat filtering）与生态位分化（niche differentiation）这两类群落构建规则是否介导了物种共存过程。
4. 在非入侵区域，生境过滤主导了物种沿盐度梯度的生境分隔，生态位分化的贡献相对较低。入侵性昆虫的存在会改变本土物种的分布与共存格局。在入侵区域，生态位分化似乎是避免入侵物种与本土物种间竞争、实现物种共存与资源划分的核心机制。
5. 结合功能生态位相似性与入侵、本土物种的非生物胁迫耐受能力开展研究，能够加深我们对入侵物种沿非生物胁迫梯度产生的生态效应的理解。该研究方法有助于提升我们在全球变化背景下预测生物入侵后果的能力。