Novos resultados do experimento de Lenski: tempo e modo da evolução do genoma no experimento de 50.000 gerações de bactérias E. coli

sábado, janeiro 16, 2016

New Results

Tempo and mode of genome evolution in a 50,000-generation experiment

Olivier Tenaillon, Jeffrey E. Barrick, Noah Ribeck, Daniel E. Deatherage, Jeffrey L. Blanchard, Aurko Dasgupta, Gabriel C. Wu, Sebastien Wielgoss, Stephane Cruveiller, Claudine Medigue, Dominique Schneider, Richard E. Lenski

Source/Fonte: BEACON


Adaptation depends on the rates, effects, and interactions of many mutations. We analyzed 264 genomes from 12 Escherichia coli populations to characterize their dynamics over 50,000 generations. The trajectories for genome evolution in populations that retained the ancestral mutation rate fit a model where most fixed mutations are beneficial, the fraction of beneficial mutations declines as fitness rises, and neutral mutations accumulate at a constant rate. We also compared these populations to lines evolved under a mutation-accumulation regime that minimizes selection. Nonsynonymous mutations, intergenic mutations, insertions, and deletions are overrepresented in the long-term populations, supporting the inference that most fixed mutations are favored by selection. These results illuminate the shifting balance of forces that govern genome evolution in populations adapting to a new environment.


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