Host phylogeny and diet shape gut microbiome and virome in wild small mammals of Gongga Mountain, China

Gut microbiotas play pivotal roles in host adaptation, yet their composition and function in high-altitude small mammals remain poorly characterized. This study investigated how host phylogeny (order-level) and dietary habits shape the gut microbiome and virome of three mammalian orders (Eulipotyphla, Rodentia, Lagomorpha) in Gongga Mountain, a biodiversity hotspot on the Qinghai-Xizang Plateau. Metagenomic sequencing of 219 samples from 22 species revealed order-specific microbial signatures: Eulipotyphla (carnivorous) harbored higher abundances of potential pathogens (e.g., Helicobacter, Hafnia) and Retroviridae; Lagomorpha (herbivorous) was enriched in cellulolytic bacteria (e.g., Lachnospiraceae, Prevotella) and carbohydrate-active enzymes (CAZymes); Rodentia (omnivorous) showed intermediate traits. We reconstructed 1 385 high-quality metagenome-assembled genomes (MAGs), 1 328 representing novel species, and identified 749 viral operational taxonomic units (vOTUs), >80% being Caudoviricetes. Crucially, Retroviridae abundance in Eulipotyphla suggests zoonotic risk. Phage-host network analysis indicated Caudoviricetes regulates cellulolytic bacteria in Lagomorpha. Host phylogeny and diet jointly drive gut microbiome divergence in small mammals. We establish the first gut microbiome and virome resource of small mammals in the high-altitude area of Gongga Mountain, highlighting Eulipotyphla as a potential vector for zoonotic pathogens.