CRC 1182 Talk – Prof. Dr. Brendan Bohannan (University of Oregon) 15.08.2018

Invited guest speaker at the Biology Center of the Christian-Albrechts-University Kiel

Wednesday, August 15th 2018, 16:15

Conference room 4th floor
Am Botanischen Garten 11

As guest of the CRC 1182

Prof. Dr. Brendan Bohannan

University of Oregon, USA

Talks about:

“Moving beyond metaphors in the study of host-associated microbiomes”


Recent research has resulted in a new appreciation for the fact that animals (including humans) have a rich assemblage of associated microorganisms, collectively known as their microbiome, which can contribute important physiological functions.  This has resulted in a call for a re-conceptualization of the individual animal, one that explicitly includes both animal and microbial cells.  Several conceptual frameworks have been proposed, including conceiving of individuals as organ systems in which the microbiome is an additional organ, holobionts in which the microbiome acts as a symbiont, and ecosystems with the microbiome an ecological community.   Each of these metaphors contains specific assumptions about how animals and their microbiomes interact, most notably regarding the relative importance of host selection and dispersal to microbiome assembly, and by extension to microbiome heritability and the potential for host-microbiome coevolution.  These metaphors have generated intense debate but have rarely been challenged by data. We experimentally determined the importance of host selection and dispersal to the assembly of the gut microbiome in an animal model, the zebrafish.  We observed that dispersal had a significant impact on assembly in larval zebrafish, sufficient to overwhelm differences in innate immunity.   We also observed that mathematical models that assume only dispersal and drift could explain substantial inter-individual variation in the composition of both zebrafish and human microbiomes.  However the fit of these models declined with host age, and some microbial taxa were more “neutrally” distributed than others. These results suggest that no one metaphor can fully describe the animal-microbe system, and that it is time to move beyond metaphors to robust theory that can incorporate variation in fundamental eco-evolutionary processes.  Much of this theory already exists within the field of quantitative genetics, but has been rarely applied to host-microbe systems.  Such an application could lead to new approaches for managing microbiomes.