Adaptive dynamics of genetic assimilation

My postdoctoral work at the University of British Columbia focused on the adaptive dynamics of asexual populations. With Michael Doebeli, I investigated the molecular basis of convergence in Escherichia coli bacteria. We explored the genetic basis and the evolutionary dynamics of adaptive diversification in replicate populations of the bacterium Escherichia coli that diversified from a single ancestral strain into two distinct ecotypes due to competition for resources. Moreover, using the “fossil” (frozen) record of the evolving populations, we established time series of allele frequencies of these mutations, showing evolutionary dynamics of alternating invasions of mutations associated with the two derived ecotypes in a co-evolutionary process of reciprocal niche creation.

In order to explore the role of phenotypic plasticity in sympatric diversification, we modeled the ecological and evolutionary dynamics of E. coli in batch cultures. Our results describe an evolutionary pathway leading to metabolic diversification in a sympatric environment without spatial structure. In an environment that fluctuates widely and predictably, evolutionary branching leads to diversification and stable coexistence of generalist and specialist ecotypes for some combinations of parameters.

 

Relevant publications:

Herron, M. D. and M. Doebeli. 2013. Parallel evolutionary dynamics of adaptive diversification in Escherichia coli. PLoS Biology 11(2):e1001490. (pdf)

Herron, M. D. and M. Doebeli. 2011. Adaptive diversification of a plastic trait in a predictably fluctuating environment. Journal of Theoretical Biology 285:58-68. (pdf)