Gut Microbiome Functional Reprogramming Reflects Divergent Social Strategies in a Wild Primate

The gut microbiome is a critical interface between host physiology and environmental challenges, yet its role in mediating behavioral strategies in socially complex mammals remains unclear. Using metagenomic sequencing of wild golden snub-nosed monkeys (Rhinopithecus roxellana), we investigated how social status (one-male unit [OMU] leaders vs. all-male unit [AMU] individuals) and seasonal variation (winter-spring [WS] and summer-autumn [SA]) shape gut microbial structure and function. We found that seasonal shifts drive primary microbial restructuring, but social status exerts a strong influence, particularly during the SA mating season. OMU leaders maintained stable microbial communities enriched in energy conservation and cellular maintenance pathways including methane metabolism and peptidoglycan biosynthesis. In contrast, AMU individuals exhibited highly plastic microbiomes potentially suited for competition, with enhanced functions in environmental sensing (e.g., flagellar assembly and two-component systems) and nitrogen metabolism. AMU gut microbiomes also showed reduced diversity in SA, indicating specialization for competitive readiness. These results demonstrate that the gut microbiome is functionally compartmentalized by social status, providing distinct metabolic toolkits that align with divergent behavioral strategies-investment in unit fitness for OMU leaders versus risk-taking for AMU individuals. Our study reveals the gut microbiome is closely associated with social adaptation in primate societies, serving as a dynamic indicator of divergent behavioral strategies.