Temperature-driven shifts in bacterioplankton biodiversity: Implications for cold-preferred species in warming Tibetan proglacial lakes.

Recent climate warming and associated glacier retreat have dramatically changed the environmental conditions and microbial inhabitants of proglacial lakes. However, our understanding of the effects of climate warming and glacial influence on microbial biodiversity in these lakes remain relatively limited. Here, we studied bacterioplankton communities in 22 proglacial lakes on the Tibetan Plateau, spanning a range of nearly 7 °C in mean annual temperature (MAT), and examined the effects of climate and glaciers on their biodiversity by a space-to-time substitution. MAT emerged as the primary environmental driver of bacterioplankton biodiversity compared to glacial influence, increasing species richness and decreasing β-diversity. We identified 576 low-MAT (cold-preferred) species and 2,088 high-MAT (warm-preferred) species, and found that low-MAT species are less environmentally adapted, with their numbers declining as temperature increased. These results advance our understanding of temperature-driven bacterioplankton dynamics by disentangling the contrasting responses and adaptations of cold-preferred and warm-preferred species. Our findings highlight the vulnerability of cold-specialist taxa and the potential biodiversity losses associated with climate warming in the rapidly changing proglacial lakes.