Isolation by distance promotes strain diversification in the wild mouse gut microbiota

Area of Science:

• Microbial Ecology
• Evolutionary Biology
• Genomics

Background:

• Mammalian gut microbiota display strain diversity linked to host geography and ancestry.
• Disentangling geographic and host ancestry effects on bacterial diversification is challenging due to confounding factors.

Purpose of the Study:

• To investigate the independent contributions of geographic isolation and host ancestry to gut bacterial strain diversification.
• To analyze the interplay between bacterial dispersal mechanisms and geographic structuring.

Main Methods:

• Joint profiling of gut bacterial and mitochondrial genomes from wild deer mice (Peromyscus maniculatus) across the United States.
• Analysis of isolation by distance (IBD) patterns in predominant gut bacterial species.
• Assessment of bacterial spore formation's impact on IBD.

Main Results:

• Significant isolation by distance (IBD) was observed in 27 predominant gut bacterial species, independent of host ancestry.
• Limited evidence for co-inheritance of bacterial and host mitochondrial genomes.
• Bacterial species forming spores showed reduced IBD, irrespective of their evolutionary history.

Conclusions:

• Geographic separation of host populations, rather than host genealogical divergence, primarily mediates gut bacterial strain diversification.
• Bacterial adaptations for dispersal can counteract geographic structuring of microbial strain diversity.