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

Biological invasions have become one of the most important drivers of biodiversity loss and ecosystem change world-wide. 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.
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.
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.
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.
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.

生物入侵（biological invasions）已成为全球范围内生物多样性丧失与生态系统改变的关键驱动因素之一。然而，目前仍不清楚生物入侵如何与当地非生物胁迫因子（abiotic stressors）相互作用，而随着全球变化加剧，非生物胁迫因子的影响预计会进一步增强。此外，尽管昆虫对全球动物生物多样性的贡献举足轻重，但我们对昆虫在生物入侵下的响应仍知之甚少。
本研究旨在探究入侵水生昆虫沿盐度梯度对本土昆虫物种共现模式的影响，并明确驱动该模式的群落构建规则（assembly rules）。
首先，我们分别基于生理性状与生物学性状，表征各物种的生境特化（habitat specialisation）程度与功能生态位（functional niches），并分析二者的重叠度。其次，我们利用野外调查数据，对比伊比利亚半岛南部与摩洛哥北部的入侵区与非入侵区内本土物种与入侵物种的共现模式。最后，我们检验生境过滤（habitat filtering）或是生态位分化（niche differentiation）这两类群落构建规则是否介导了二者的共现关系。
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。入侵昆虫的存在改变了本土物种的分布格局与共现模式。在入侵区域，生态位分化似乎是规避入侵物种与本土物种间竞争的核心机制，实现了二者的共存与资源划分（resource partitioning）。
对入侵物种与本土物种的功能生态位相似度及非生物胁迫因子耐受性开展联合研究，可加深我们对入侵物种沿非生物胁迫梯度产生的影响的认知。该方法可提升我们在全球变化背景下预测生物入侵后果的能力。