Ice cores from the Tibetan Plateau reveal bacterial community convergence related to climate and anthropogenic activity Yongqin Liu, Tandong Yao, Baiqing Xu Institute of Tibetan Plateau Research, CAS 1

Glaciers on the Tibetan Plateau Number ： 46298, Area ： km 2, Volume ： 5590 km 3 Account for ~50% of glacier area in the non-polar region 2

Microbe in the Glaciers Rhodopseudomonas sp.Massilia sp. 3 Glacier OCEAN

4 Average precipitation:279, 392 m, and 797 mm, Temperature: -4.1,2.8 and and 12.1 °C GLDD, NJKS, and ZQP: are surrounded by steppe, meadow, and forests land

Ice core drill decontaminate 5 Bacterial abundance Extract DNA PCR 454 Pyrasequence Bacterial community Chemical analysis Methods

6 Bacterial abundance increased in the past 60 years in all three ice cores 4.3×10 4 ± 4.7×10 4 cells mL ×10 4 ± 2.3×10 4 cells mL ×10 4 ± 0.4×10 4 cells mL -1

7 Summary of bacterial time-series GAM Regression Model

8 Bacterial community composition in different years in three ice cores GLDD NJKS ZQP

9 Bacterial phylogenetic diversity (Shannon) in different years in three ice cores

10 Abundance Diversity Bacterial abundance and diversity in three ice cores

Year distance-decay relationship of bacterial communities dissimilarity

12 Nonmetric multidimensional scaling of Bray-Curtis dissimilarities at the OTU level in three ice cores over the past 60 years. Note the converging trend after 1990

GLDD ZQP 13 Actinobacteria (%) Bacteroidetes (%) Major group variation at different years in GLDD and ZQP

14 SourceTracker algorithm showing the percentage of the tracked community associated with sequences from regional soils, lake sediments, lake water, and marine water

Soil associated bacterial in GLDD decreased response to the increase of westerly precipitation (年)(年) 15 Soil associated bacterial (%) Accumulation (mm)

16 Ocean source bacteria decreased with the South Asian Monsoon, and soil assosiated bacteria increased in ZQP Soil associated bacterial (%) Marine associated bacterial (%) SAM index

17 Factors influence bacterial Communities Mantel test results show the significant factors: GLDD: Year (r=0.72,p=0.001); Westerly (r=0.22, p=0.05) ZQP: Year (r=0.59, p=0.001) ;Temperature ( r=0.68,p=0.001); Black Carbon ( r=0.62, p=0.001); SST (( r=0.44,p=0.003)

18 Atmospheric circulation Precipitation Glaciers Habitat homogenization Human activity homogenization Bacterial converage

Conclusion  we report the first high-resolution bacterial records from the last half-century in ice cores collected from three Tibetan Plateau glaciers.  Bacterial abundance, diversity, and community composition among the ice cores was related to geographical location and annual climatic events specific to each glacier.  Despite the broad environmental differences among the three ice cores studied, bacterial community composition in the ice cores converged through time while overall bacterial diversity decreased. Bacterial abundance also increased with the anthropogenic production of black carbon.  These biotic changes are related to increasing air temperature, atmosphere cycle impacts, and anthropogenic activities that have occurred on and around the Plateau during the last half-century.

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