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Abstract

Animals harbor microbial communities (microbiome) that play an important role in normal development and health and provide opportunities for host-microbial coevolution. However, studying the shared evolutionary history and selection pressures involved between hosts and microbes remains a challenge, especially in mammalian hosts with a complex gut microbiota. Here, I show that multiple species of adult and child gut microbes codiversified within and between human populations. Analyses of paired human genotypes and bacterial strain genotypes from fecal metagenomes, obtained from five countries, indicate that strains of common gut bacteria have transmitted vertically for thousands of generations. In accord, strains are also shared between mothers and children. Patterns of strain transfer between populations are consistent with an African origin for common gut bacteria in humans. A second line of my work uses wild house mice as a model system and explored how the microbiome imposes selection pressure to the host and how the microbiome contributes to host adaptation to new environments by combing both field- and lab-based approaches. I will briefly describe an ongoing experimental evolution project on the wild mouse microbiome and how a selection on the microbiome alone is sufficient to shift host traits within five generations without host evolution. Together, I will discuss how the microbiome can affect host ecology and evolution with and without coevolution.