Local adaptation of host-species specific gut microbiota

Abstract

Mammalian species harbor compositionally distinct gut microbial communities, but the mechanisms that maintain specificity of symbionts to host species remain unclear. Here we show that natural selection within house mice (Mus musculus domesticus) drives deterministic assembly of the house-mouse gut microbiota from mixtures of native and non-native microbiotas. Competing microbiotas from wild-derived lines of house mice and other mouse species (Mus and Peromyscus spp.) within germ-free wildtype (WT) and Rag1-knockout (Rag1-/-) house mice revealed widespread fitness advantages for native gut bacteria. Certain native Bacteriodetes and Firmicutes favored by selection in WT hosts were not favored or disfavored in Rag1-/- hosts, which lack adaptive immunity, indicating that Rag1 mediates fitness advantages of these strains. This study demonstrates local adaptation of gut microbiota to a mammalian species. One-Sentence SummaryAdaptive advantages for native bacteria underlie the assembly of the mouse gut microbiota.