Oral Presentation Society for Molecular Biology and Evolution Conference 2016

Phenotypic changes in organismal adaptation to new environments: plasticity distorts while evolution restores (#175)

Wei-Chin Ho 1 , Jianzhi Zhang 1
  1. Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Ann Arbor, MI, United States

At the phenotypic level, adaption to a new environment involves plastic changes followed by evolutionary changes, but neither the relationship between the two changes nor the underlying reason for the relationship is well understood.  Here we address these questions by studying plastic and evolutionary changes of Escherichia coli metabolic fluxes upon switches of the nutritional environment.  We computationally mimic plastic changes using minimization of metabolic adjustment (MOMA) and mimic evolutionary changes using flux balance analysis (FBA), because these mathematical tools have been shown to respectively predict plastic and evolutionary responses to perturbations.  We find that an environmental alteration typically plastically distorts the fluxes of many reactions, a large fraction of which are then restored via evolutionary changes.  Rarely are reactions subject to plastic and evolutionary changes in the same direction or subject to evolutionary changes only.  This prominent pattern of distortion-restoration generally holds regardless of whether the new environment is richer or poorer than the original environment.  These findings echo recent transcriptome-based observation that evolutionary changes in gene expression level tend to reverse plastic changes.  Because the mechanisms of flux changes in MOMA and FBA are known, we are in the process of discerning the underlying cause of the plastic distortion followed by evolutionary restoration in environmental adaptations.