Salinity fluctuations constitute a well-known high stress factor strongly shaping global biological distributions and abundances. However, there is a knowledge gap regarding how increasing saline stress affects microbial biological interactions. We applied the combination of a probabilistic method for estimating significant co-occurrences/exclusions and a conceptual framework for filtering out associations potentially linked to environmental and/or spatial factors, in a series of connected ephemeral (hyper) saline lakes. We carried out a network analysis over the full aquatic microbiome—bacteria, eukarya, and archaea—under severe salinity fluctuations. Most of the observed co-occurrences/exclusions were potentially explained by environmental niche and/or dispersal limitation. Co-occurrences assigned to potential biological interactions remained stable, suggesting that the salt gradient was not promoting interspecific facilitation processes. Conversely, co-exclusions assigned to potential biological interactions decreased along the gradient both in number and network complexity, pointing to a decrease of interspecies competition as salinity increased. Overall, higher saline stress reduced microbial co-exclusions while co-occurrences remained stable suggesting decreasing competition coupled with lack of stress-gradient promoted facilitation in the microbiome of ephemeral saline lakes.

中文翻译：

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缺乏压力促进的便利化以及短暂盐湖微生物组的竞争减少

盐度波动构成了一个众所周知的高压力因素，强烈影响全球生物分布和丰度。然而，关于增加盐分胁迫如何影响微生物生物相互作用存在知识空白。在一系列相连的短暂（超）盐湖中，我们应用了一种概率方法的组合来估计重要的共现/排除和过滤掉可能与环境和/或空间因素相关的关联的概念框架。我们在严重的盐度波动下对整个水生微生物组——细菌、真核生物和古细菌——进行了网络分析。大多数观察到的共现/排除可能是由环境利基和/或扩散限制解释的。分配给潜在生物相互作用的共现保持稳定，表明盐梯度不会促进种间促进过程。相反，分配给潜在生物相互作用的共同排除在数量和网络复杂性方面都沿着梯度下降，表明随着盐度增加，种间竞争减少。总的来说，较高的盐度胁迫减少了微生物的共排斥，而共现保持稳定，这表明竞争减少加上缺乏胁迫梯度促进了短暂盐湖微生物群落的促进。表明随着盐度增加，种间竞争减少。总的来说，较高的盐度胁迫减少了微生物的共排斥，而共现保持稳定，这表明竞争减少加上缺乏胁迫梯度促进了短暂盐湖微生物群落的促进。表明随着盐度增加，种间竞争减少。总的来说，较高的盐度胁迫减少了微生物的共排斥，而共现保持稳定，这表明竞争减少加上缺乏胁迫梯度促进了短暂盐湖微生物群落的促进。