Bacterial microbiome and their assembly processing in two sympatric desert rodents ( and ) from different geographic sources.

The microbiome of mammals has profound effects on host fitness, but the process, which drives the assembly and shift of mammalian microbiome remains poorly understood. To explore the patterns of small mammal microbial communities across host species and geographical sites and measure the relative contributions of different processes in driving assembly patterns, 2 sympatric desert rodent species ( and ) were sampled from 2 geographically distant regions, which differed in the environment, followed by 16S rRNA gene sequencing. The microbiomes differed significantly between and , and linear mixed modeling (LMM) analysis revealed that microbial diversity was mostly affected by species rather than the environment. For each rodent species, the microbiome diversity and structure differed across geographical regions, with individuals from lower rainfall environments exhibiting greater diversity. The null modeling results suggested dispersal limitation and ecological drift rather than differential selective pressures acting on the microbiome. In addition, each group had a different core genus, suggesting that the taxonomic composition of the microbiome was shaped most strongly by stochastic processes. Our results suggest that variation in the microbiome between hosts, both within and among geographic rodent populations, is driven by bacterial dispersal and ecological drift rather than by differential selective pressures. These results elucidated the diversity patterns and assembly processes of bacterial microbiomes in small desert mammals. Deciphering the processes shaping the assembly of the microbial community is a premise for better understanding how the environment-host-microbe interactions of mammals are established and maintained, particularly in the context of increased environmental disturbances and global changes.