Bacterial diversity and co‐occurrence patterns differ across a world‐wide spatial distribution of habitats in glacier ecosystems

Glaciers cover nearly 10% of the Earth's surface and are unique biomes dominated by microbial communities that support key ecosystem processes. The melting of glaciers is among the most conspicuous consequences of global climate change, with impacts on microbial ecology and associated biogeochemistry. However, we are still missing an integrative understanding of microbial biodiversity from divergent habitats associated with glaciers. Here, we compiled global microbiome metadata from 93 representative glaciers over 180 locations and used random forest, microbial ecological networks and structural equation modelling to evaluate the biodiversity and environmental factors associated with the glacier microbiomes of seven contrasting habitats: water, epilithic biofilm, cryoconite, mat, ice, sediment and permafrost soil. The results showed that microbial diversity largely changed across habitats, with the highest in permafrost soil, followed by sediment, ice, mat, cryoconite, water and epilithic biofilm. More importantly, we provided critical evidence that the environmental and climatic factors associated with the microbiomes of glaciers varied with glacier habitats. Microbial diversity in water was highly correlated with latitude, cryoconite microbial diversity was significantly (p = 0.01) correlated with pH, and permafrost soil and sediment microbial diversity were mainly explained by temperature (17.05% and 13.37% respectively). Using ecological association network analysis, we identified some tightly linked common microbial taxa (e.g. Proteobacteria and Bacteroidetes) that were present in all the habitats and were vulnerable to climatic factors, such as temperature and precipitation. This study demonstrated that microbial diversity, drivers and co‐occurrence patterns differ among glacier habitats globally, and diverse habitat‐dependent glacier microbiomes could serve as early warning sentinels for the study of life on glaciers and its potential future in a warming world. Read the free Plain Language Summary for this article on the Journal blog. 摘要 地球陆地表面大约有10%的面积被冰川覆盖。由于强烈的人为和自然因素，冰川正面临生物多样性的丧失。目前关于冰川微生物及其对气候因素的反馈主要与以下事实有关：大多数研究都集中在局部尺度和单一栖息地（例如冰或生物膜）。然而，冰川生态系统包含许多栖息地，包括水，生物膜，微生物席，沉积物和永久冻土等。纵观全球尺度，我们仍然缺乏对冰川微生物组的综合理解。据我们所知，目前尚未有研究在全球尺度上报道冰川微生物组的多样性、气候驱动因素和物种共现模式。 在这项研究中，我们汇编了来自全球范围内 93 个代表性冰川的全球微生物组的数据集，包括南极洲、北极洲、格陵兰岛、冰岛、西欧、北美以及青藏高原的冰川生态系统，以加强我们对冰川生态系统生物多样性的理解。对来自水、生物膜、冰尘、微生物席、冰、沉积物和永久冻土的微生物群落进行了全球调查。微生物多样性在多年冻土中最高，其次是沉积物、冰、微生物席、冰尘和水，而生物膜中细菌多样性最低。 使用随机森林模型分析，我