Bacterial communities of blood, gut of pikas and their ectoparasites

Vector-borne microbmes influence the pathogen transmission and blood microbiome composition, thereby influencing the emergence of infectious diseases and host health. Thus it is important to understand the relationship between host and vector microbiomes. Here, we studied the bacterial community composition, diversity and assembly of the flea (Rhadinopsylla dahurica vicina), torsalo (Hypoderma curzonial), blood and gut of their shared pika host, Ochotona curzoniae. We found that Bartonella, Sphingomonas and Bradyrhizobium were enriched in pika's blood, while Wolbachia and Fusobacterium were more abundant in fleas and torsaloes. Most of potential pathogenic OTUs (belonging to Fusobacterium, Rickettsia, Kingella, Porphyromonas, Bartonella and Mycoplasma) were present in blood of pikas and their arthropod vectors. Blood microbiome of pikas showed a higher alpha diversity than their ectoparasites microbiomes, but had a lower diversity than gut microbiome. Sample types significantly influence the community membership and structure of bacterial communities. Microbial communities of the blood were more similar to those of flea than other sample types, and were independent of host factors or geographical sites. Notably, blood microbes originate mainly from fleas rather than gut or torsaloes, and selects for rare bacteria from fleas, gut or torsaloes. Interestingly, we found that the community assembly of blood, fleas and torsaloes was primarily governed by stochastic processes, while gut microbiomes were determined by deterministic processes. These results suggested that blood microbiomes in wild lagomorphs are more likely to be mainly influenced by flea-associated microbiomes, and ecological drift (not selection) may play dominant roles in the assembly of blood and vector microbiomes.