Seasonal Adaptation of the Gut Microbiome in Japanese Macaques: Linking Gut Microbiome Shifts With Fermentative Function

Seasonal fluctuations in food availability strongly influence the ecology of wild mammals, yet the role of the gut microbiome in mediating these challenges remains insufficiently explored. In this study, we examined how seasonal dietary shifts influence gut microbial composition and fermentative function in wild Japanese macaques (<i>Macaca fuscata</i>). Integrating meta-16S rRNA sequencing and in vitro fermentation assays, we investigated how the gut microbiome and the associated fermentative ability of Japanese macaques vary with seasonal dietary shifts. Although alpha diversity remained relatively stable throughout the year, significant changes in microbial composition revealed a flexible, seasonally responsive microbiome. Importantly, in vitro fermentation assays indicated that fermentative ability was stable across seasons for leaf fermentation but flexible for fermenting easily fermentable monkey chow. This dual strategy may represent an essential adaptive feature of the macaque gut microbiome, balancing metabolic stability and plasticity to effectively cope with seasonal dietary fluctuations. By linking microbial dynamics with dietary variation, this study provides new insights into the feeding ecology of Japanese macaques and highlights the essential role of gut microbiomes in supporting the ecological success of temperate primates.