Gut microbiota contribute to cold adaptation in mammals-primates and ungulates.

Gut microbiota play an influential role in how animals adapt to extreme environments. Two phylogenetically distant mammals, Yunnan snub-nosed monkey and reindeer both adapted to frigid environments. Metagenomic analyses revealed they developed similar cold adaptation strategies in response to food scarcity (enhanced fiber degradation and nitrogen balance maintenance), energy shortages (increased short-chain fatty acid [SCFA] synthesis), and a constant body temperature sustainment (stimulation of non-shivering thermogenesis [NST]). Moreover, they evolved distinct adaptation strategies to cope with different cold ecosystems. Yunnan snub-nosed monkey adapt to high-altitude hypoxia environment through enhancing ability to synthesize lactate and metabolize purine, while reindeer adapt to extreme cold environment through increasing blood flow, strengthening urea cycling, and enriching fat storage associated bacteria. Notably, reindeer microbiota uniquely enriched cholesterol-degrading bacteria, potentially mitigating cardiovascular risks from lipid storage. Our study expands the knowledge of how gut microbiome promotes cold adaptation through shared and specialized mechanisms shaped by different phylogenetic and ecological contexts.