Abstracts (first author)
The rate of adaptation Escherichia coli to the mouse gut
The process of adaptation in bacterial populations is often studied in simple and well-defined laboratory environments, mainly involving abiotic interactions. On the other hand, adaptation to complex environments, within ecological communities, involving biotic interactions, is only rarely studied. A medically important and extremely diverse community is the gut microbiome. Here, we study the process of adaptation of Escherichia coli to the mouse gut. We combine methodologies from evolutionary genetics and molecular biology to understand the rate of adaptation and the number and selective strength of newly arising mutations. Previous work from our lab has shown that, in contrary to what is theoretically predicted and normally observed in-vitro, the rate of adaptation does not decrease through time, during two consecutive colonizations of the mouse gut (~900 generations). We now isolated three genetically distinct clones (from the second colonization), which represent three independent evolutionary paths and test whether the evolutionary process proceeds at the same pace (both in terms of rate of adaptation and selective strength of new mutations). To better understand the adaptive process, we use genome re-sequencing of the evolved clones and measure their fitness across a variety of environments that mimic different components of the gut environment. Our results, will allow us to further test the relevance of the following theoretical predictions: 1) as populations adapt to a given environment, the rate of adaptation decreases; 2) in the absence of recombination, clonal interference dominates the adaptive process. Moreover, we will be able to infer what are the main forces shaping the adaptation of an important commensal to the mouse gut.