Tequila bats (Phyllostomidae: <i>Leptonycteris yerbabuenae</i> ) and their associated bat flies: disentangling the effects of physical proximity and organism source as predictors of microbiota dissimilarities

Abstract The biosphere is dominated by bacteria, and cohabiting taxa are to each other either a viable substrate or a competitor for space and other resources. Animal bodies are no exception to this rule. For the vertebrate microbiota, it is a crucial question where all these bacteria came from and how they got there, including the relative contributions of the surrounding environment and of ecological interactions with other organisms such as parasites. In this article, we explore the relations between the microbiota compositions of the inner (gastrointestinal) and the outer (fur) body of the flower-visiting Tequila Bat (Leptonycteris yerbabuenae), of their ectoparasites (bat flies: Streblidae; Trichobius sphaeronotus and Nycterophilia coxata), and of the immediate roosting environment (cave wall). We established 4 different predictions on how these compositions might be related to each other. Similarity could come from: (i) provenance (each sample type harbors a dissimilar microbiota); (ii) phylogenetic association (bat microbiotas vs. bat fly microbiotas); or (iii) physical proximity (outer microbiotas, i.e., bat fly, bat fur, cave walls, vs inner microbiotas such as the bat gastrointestinal tract). From each individual bat, we collected a fecal sample, a fur swab, all ectoparasites—we also collected 5 swabs of the cave wall from the place where the bats were commonly roosting. Using 16S rRNA amplicon sequencing, we characterized the bacterial microbiomes of these samples. Our results show that although the type of sample was the strongest predictor of group clustering, the dissimilarity between different bacterial communities closely matched our “physical proximity association” prediction, i.e., the fur and gastrointestinal tract of bats supported distinct bacterial communities, but the microbiota of the bat fur was more similar to the microbiota of the bat flies and the cave wall in terms of dissimilarity.