Sexual dimorphism in hormone–gut microbiome associations across reproductive states in wild giant pandas

Gut microbiota–host endocrine interactions in wild mammals remain poorly understood. Giant pandas experience seasonal dietary shifts and constrained annual reproduction, offering an ideal model to investigate microbiome–endocrine coupling. We integrated fecal hormone profiling, microsatellite-based individual identification, and gut microbiome sequencing in wild giant pandas. Microbial diversity and composition varied seasonally, with α diversity peaking during bamboo shoot-feeding. Hormonal dynamics followed predictable patterns: elevated estrogen during estrus, sustained progesterone post-estrus, and higher cortisol during leaf/stem-feeding periods. Hormone levels significantly correlated with microbial taxa and diversity, indicating coordinated microbiome–endocrine dynamics. Notably, microbiome–hormone coupling was significant in males but not in females, and males exhibited greater hormonal and microbial variability. Our findings demonstrate seasonal restructuring of gut microbiome and endocrine profiles in wild giant pandas with sex-dependent coupling, providing an integrated framework for non-invasive conservation monitoring.