Diversity Patterns Of Microbiota Associated With Snow-Active Collembola At Mid-High Latitude In Northeastern China

The pattern of biodiversity is an important research topic in the field of ecology.In the northern hemisphere about 50%regions are covered by snow in winter.Snow-cover affects biodiversity,freshwater resources and climate change.As an important component of biodiversity in the snowy environments,it is necessary to study biodiversity pattern of snow-adapted soil animals to understand the global biodiversity patterns.Gut microbiota co-evolve with animals and are critical for host health and adaptation.Studies on the gut microbiota of soil animals have attracted much attention in recent years.Previous studies have focused on the microbial diversity and composition in the guts of soil animals during the growing season,while studies on the gut microbiota and its drivers of soil animals living in the winter are scarce.Studying the gut microbial diversity pattern of snow-active soil animals and analyzing the driving factor of gut microbiota are of great importance for understanding the gut microbiota assembly and cold adaptation of soil animals.In this study,we selected Collembola,the dominant arthropod group of snow-active soil animals.The 16S r RNA high-throughput sequencing method was used to investigate the effects of host（feeding habits and active state）and environmental factors（different seasons,land-use changes and different spatial locations）on the microbiota of snow-active Collembola in the middle and high latitudes of northeastern China,to determine the extent of influence of host and environment on Collembola associated microbiota,and to analyze the driving factors of microbiota and to explore the relationship between microbiota and nutrient turnover and adaptation of the hosts.The main research results were as follows:（1）Food manipulation experiments showed that snow-active Collembola feeding on different food resources harbored different microbiota.The bacterial community of Collembola feeding on maize litter had the highest richness,dominated by Microbacteriaceae.Collembola feeding on yeast had the lowest bacterial richness,colonized by a large number of Pseudomonas.Collembola feeding on Quercus mongolica litter were dominated by Wolbachia.The microbial community of Collembola was distinct from that of their food.Stable isotope accumulation in Collembola tissues was significantly different between treatments after consuming different food sources.The relative abundance of Arthrobacter was significantly positively correlated withΔ¹³C of the hosts.Shannon index and the relative abundance of Devosia,Rathayibacter,Microbacteriaceae,Micrococcaceae and TM7a were significantly positively correlated withΔ¹⁵N of the hosts.The results of this study indicate that feeding habits are an important driver of the microbial community of snow-active Collembola,and that microbes may be involved in the nutrient utilization of the Collembola host.（2）Active and inactive Collembola in snowy environments showed differences in microbial diversity and composition.The Chao 1 richness of the microbiota associated with active Collembola was significantly higher than that of inactive Collembola.Wolbachia,Ralstonia,Burkholderia-Caballeronia-Paraburkholderia,Nocardioides,Bacillus,Microbacteriaceae and Micrococcaceae were enriched in active Collembola.Escherichia-Shigella,Delftia,Acinetobacter,Acidovorax,Phyllobacterium and Enterobacteriaceae were enriched in inactive Collembola.The bacterial composition among different species of snow-active Collembola varied,whereas the bacterial composition among different species of inactive Collembola was stable.The relative abundance of microbes involved in energy metabolism was significantly higher in active Collembola than in inactive Collembola,while lipid metabolism was higher in the microbiota of inactive Collembola.The results of this study suggest that the microbiota of Collembola living in snowy environments is influenced by the active state of the host and in some cases also by the identity of the host.The changes in gut microbiota may be related to energy acquisition of the Collembola in cold conditions.（3）Microbial diversity and composition in snow-active Collembola varied seasonally.Bacterial diversity and community structure of Collembola differed between summer and winter,bacterial diversity was lower in summer than in winter,and more Ralstonia colonized Collembola in summer.Bacterial diversity showed an increasing trend from early winter,mid-winter to late winter,and the relative abundance of Rhodoblastus in early winter Collembola was significantly higher than that in mid-winter and late winter Collembola.Micrococcaceae were enriched in mid-winter Collembola.Ambient temperature was significantly negatively correlated with bacterial Chao 1 richness and Shannon diversity,as well as the relative abundance of Sphingomonas,Mycobacterium and Micrococcaceae.The results of this study indicate that the microbial communities of snow-active Collembola are affected by different seasons and different periods of winter,and that microbes can adapt to changes in environmental temperature.（4）Microbial diversity and composition of snow-active Collembola were affected by land-use change.Conversion of wetlands to plantations significantly reduced the diversity of the bacterial communities of Tomocerus cf.jilinensis,but had no significant effect on the bacterial diversity of Desoria sp.1 and Desoria sp.3,indicating that land use change had different effects on the gut microbial diversity of Collembola in different microhabitats.The bacterial diversity of D.sp.1 and D.sp.3was significantly higher in the farmland habitat than in wetlands and plantations,and farmland had a greater effect on the gut bacterial community composition of the D.sp.1 and D.sp.3 than that in plantation and wetland,indicating that the habitat with more human activity had a greater change in the gut microbial community.The host was a determinant of the microbiota of snow-active Collembola compared to the environment.（5）The microbiota of snow-active Collembola,Desoria ruseki populations showed spatial variation,and there was no geographical distance-decay pattern in the Collembola associated microbial community.Compared to litter,snow microhabitats shared more microbes with Collembola.The amount and proportion of shared microbes shared between Collembola and the environment varied between sites,and environmental microbiota at different sites influenced the microbial community of Collembola.Total carbon of the snow microhabitat drove the food bacteria of Collembola,while total nitrogen,ammonium nitrogen and nitrate nitrogen of the snow microhabitat,and total carbon of the litter microhabitat together drove the symbiotic bacteria of Collembola.Bacteria were significantly correlated with environmental physicochemical factors,and these microbes may respond to changes in the environment.The results of this study suggest that variation in the microbiota of snow-active Collembola among different geographical populations is mainly influenced by environmental heterogeneity,and that snow and litter microhabitats together drive the microbiota of Collembola.In conclusion,the microbiota of snow-active Collembola shows certain changes due to differences in feeding habits and activity status of the host,as well as habitat and spatiotemporal changes.The microbiota is influenced by host and environmental factors,while the host is the dominant factor in shaping the microbial community of snow-active Collembola.The microbiota is closely related to the nutrient turnover and fitness of the host,and the host-associated microbiota could be as an important functional trait of soil animals to comprehensively study community assembly of soil animals in future studies.The results of this study will provide insight into the diversity maintenance of microbiota in soil animals and the interaction between hosts and their microbes in non-growing seasons,and will also help to further reflect on the effects of reduced winter snow-cover on the microbiota of soil fauna,and the implications of microbiota and host interaction mechanisms on soil biodiversity and ecosystem functioning in cold environments under global warming scenarios.