Research Summary

Bacterial evolution in host-associated communities

Bacteria typically live within complex communities composed of many species, that are in turn associated with other organisms. For instance, recent research suggests that most animals harbour (and depend upon) the millions of bacteria that they carry. What is the impact of this complexity on bacterial evolution? Specifically, if the host changes its diet, how does the gut bacterial community change? Such scenarios of dietary change are likely to be very common in many animals, including humans. If some gut bacteria cannot live in the new nutritional environment in the host’s gut, they might go extinct, or they might acquire mutations that turn out to be beneficial. Ultimately, some of these changes in the bacterial community may also improve the host’s ability to survive on the new food. We plan to test these ideas using flour beetles, which are common pests of cereal flours and derive a survival advantage from their gut microbes. In the laboratory, we will allow beetles to adapt to new flours on which they typically have high mortality, and then analyse how their gut bacterial communities change across evolutionary time. Our work will thus help understand how dietary shifts in animals affect the evolution of their gut bacteria.

Figure Legend: Possible effects of host diet shift on the gut microbiome. The host has low initial fitness on the new diet. As it adapts to the new diet, the microbiome may show (A) Immediate ecological change in composition (B) Longer term evolutionary change or (C) Both ecological and evolutionary changes