Functional relevance of seasonal variations in the gut microbiota of the Critically Endangered Hangul (Cervus hanglu hanglu)

Background Understanding the role of gut microbiota in adapting to seasonal dietary and environmental fluctuations is essential for the conservation of endangered species. This study presents the first comprehensive analysis of seasonal variations in the gut microbiota of the critically endangered hangul ( Cervus hanglu hanglu ), endemic to Dachigam National Park, Jammu & Kashmir, India. Using high-throughput 16S rRNA gene sequencing, we analyzed 79 fecal samples collected in four distinct seasons. Results Our results revealed Firmicutes and Bacteroidota as the dominant phyla throughout the year, with significant seasonal shifts in microbial diversity and composition. Alpha diversity metrics indicated a marked reduction in microbial richness and evenness during autumn, potentially reflecting reduced dietary diversity and forage quality. Beta diversity analyses demonstrated distinct clustering of microbial communities across seasons (PERMANOVA, p < 0.001), highlighting dynamic microbial responses to seasonal dietary changes. Functional predictions inferred 429 functional pathways using PICRUSt2, and identified significant seasonal variation in metabolic pathways, with increased lactose and galactose degradation pathways in spring and enhanced methanogenesis in winter, reflecting adaptive microbial strategies to optimize host energy metabolism across changing seasons. Network analysis further revealed seasonal restructuring of microbial interactions, identifying key taxa that drive seasonal transitions. The decline in functional diversity during autumn underscores potential metabolic constraints faced by hangul during forage scarcity. Conclusions These findings provide critical insights into the ecological and physiological adaptability of hangul mediated by gut microbiota, and underscore the importance of integrating microbiome research into conservation strategies. Targeted habitat management and dietary interventions aligned with the natural microbiota dynamics could enhance the health and resilience of hangul populations facing environmental and anthropogenic pressures.