Animal hosts often exhibit phylosymbiosis, but signals can be attenuated in birds. We profiled gut microbiota from 110 individuals across 26 passerine species (15 families) breeding at Maoershan, China, using 16S rRNA sequencing. Communities were dominated by Proteobacteria and Bacteroidota, with clear shifts across feeding guilds. Across Bray–Curtis, Jaccard and UniFrac distances, PERMANOVA and constrained ordination (CAP) identified host family as the strongest predictor of β‐diversity (PERMANOVA R 2 up to ≈0. 18; P < 0. 05), followed by feeding guild (typical R 2 ≈ 0. 01–0. 03) ; foraging height had modest effects, whereas nesting strategy and sex were negligible. A Mantel test revealed a significant association between host relatedness and gut microbiome composition, such that closely related hosts harboured more similar microbiota, with correlograms indicating that the signal peaks at intermediate evolutionary scales. Mechanistic inference using a βNTI–RCbray framework showed that within‐family comparisons were dominated by homogenizing dispersal, consistent with frequent horizontal transmission and shared environments, with pockets of heterogeneous selection (notably in Phylloscopidae) and mixed heterogeneous selection/limited dispersal in Sittidae and Fringillidae. Together, these lines of evidence support a hybrid assembly model in which host family provides a baseline template, diet imposes primary ecological filtering, and phylogeny leaves a weaker, scale‐dependent imprint—explaining strong family‐ and diet‐associated structure despite attenuated phylosymbiosis in passerines.
Li et al. (Wed,) studied this question.