Unique microbial communities and phylosymbiosis signals in herpetofauna

Microbial symbionts are closely related to the internal and external factors of their host. However, the prevalence of phylosymbiosis (the presence of host phylogenetic signal in microbial community composition) remains controversial, especially in animals collectively referred to as herpetofauna. To expand our understanding of host-microbiota interactions, we analysed 11 697 symbiotic microbiota samples from of 337 herpetofaunal species, covering skin, oral cavity, gut, cloaca, feces, and other body sites. The composition of the microbial communities gradually changes along the digestive tract, and is host-specific in each region. Overall, herpetofauna's dominant microbial taxa (Firmicutes, Proteobacteria, Bacteroidota) are more similar to mammals than fish (which are dominated by Proteobacteria, Firmicutes, and Fusobacteriota). However, phylosymbiosis in herpetofauna is weaker than in mammals and tends to occur at higher host taxonomic levels. The strength of the phylosymbiosis signal is influenced by body site, host genetic distance, and analytical method. It indicates that phylosymbiosis exists but is not universal. The intensity and significance of this signal are influenced by host taxonomic scale, the location of the microbial communities, and the assessment methods. These results advance our knowledge of host-microbe interactions across the Tree of Life.