On Evolutionary Dynamics: Theory and Experiments

Abstract

After the first life forms emerged, the primitive organization of these protobiotic systems must have imposed severe constraints in the metabolic networks that they were able to encode. A solid hypothetical candidate for a primordial organization of life is the RNA ribocell or more commonly denominated the protocell. The protocell model encapsulates a set of replicating sequences that are both enzymes and genes, modelling a likely scenario given the RNA world theory in which RNA constituted both the catalytic and the informational component of living systems. The need to perform both functions in the context of the populations dynamics of the protocell establishes severe constraints that determine the metabolic networks that can be encapsulated. To address the effect of these constraints, we developed an intermediate complexity model of metabolism that captures enzyme saturation and evaluated how different network organizations evolve in the protocell model. Additionally, we considered the evolution of bacterial populations under fluctuating environments by performing a laboratory evolution experiment with Escherichia coli to determine the genetic adaptations under different types of environmental fluctuations and their effect in the overall phenotypic signature in each environment.