Fecal fungal communities of millipedes: host species as the dominant driver rather than habitat factors.

backgroundMillipedes are important decomposers in forest ecosystems, but their fecal fungal communities remain poorly understood. This study examined whether fecal fungal communities differ among millipede species and habitats, and clarified whether host species or habitat is the dominant factor shaping community structure. METHODS AND

resultsA total of 42 fecal samples were collected from three millipede species (Spirobolus bungii, Oxidus gracilis, and Paracortina sp.) across three mountains (Zijin, Fang, Mufu) in Nanjing, China; the ITS1 region was amplified and sequenced on the Illumina NovaSeq platform. At the phylum, family, and genus levels, Ascomycota, Aspergillaceae, and Aspergillus were consistently detected across all three host species. Fungal communities of sympatric species at Fang and Mufu differed significantly (Adonis: F = 3.185, P = 0.001 and F = 1.96, P = 0.001, respectively). Conspecific S. bungii populations from different mountains also differed in composition (Adonis: F = 1.533, P = 0.002), although alpha diversity remained similar. Clustering analysis consistently grouped conspecific populations together, whereas heterospecific populations from the same site formed separate clades. Most importantly, host species explained a greater proportion of community variation (R² = 0.135, P = 0.001) than did habitat (R² = 0.100, P = 0.001). These results indicate that both host species identity and habitat contribute to the assembly of fecal fungal communities, although the effect of host species is stronger than that of environmental variation.

conclusionsBoth host species and habitat influence fecal fungal community structure, but host species has a stronger effect than habitat. These findings provide new evidence for host-associated specificity in millipede fecal fungal communities and offer a foundation for future studies on their ecological roles in decomposition processes.