Abstracts (first author)
Evolving in an unpredictable world - the E. coli storyPDF
Effects of temporally fluctuating environments on the fitness of populations are less explored compared to the effects of directional selection regimes. Existing studies on temporally fluctuating environments employ a narrow selection regime i.e. mostly one environmental parameter fluctuating predictably between two limit points and the fitness measurements happen in the environmental backgrounds similar to that of selection. Obviously such studies fail to predict the fitness outcomes in the complex and/or novel, unpredictable environments. We select replicate microbial populations under randomly fluctuating complex, stressful environmental regime. When fitness proxies of these selected lines are compared with the control populations grown in benign environments, under multiple novel environmental backgrounds, selected lines display ‘Generalist’ properties. We further characterize these Generalists by fitness proxy measurements at different time intervals during the growth in the novel environments. We see that acclimation is beneficial in both selected and control populations but consistently more advantageous in the populations with the history of randomly fluctuating environment. Characterization of the Generalists on the mechanistic level, shows that the commonly evoked explanations of evolution of hypermutators or modified permeability or carry over plasticity are not sufficient to explain observed Generalist phenomenon.