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Updated: Apr 23, 2026

Daily Transfers, Archiving Populations, and Measuring Fitness in the Long-Term Evolution Experiment with Escherichia coli
Published on: August 18, 2023
Reductive genome evolution at both ends of the bacterial population size spectrum
Bérénice Batut1, Carole Knibbe2, Gabriel Marais3
11] Université Lyon 1, Centre National de la Recherche Scientifique (CNRS), Laboratoire de Biomtrie et Biologie volutive (LBBE), UMR5558, F-69622, France. [2] Université de Lyon, CNRS, French Institute for Research in Computer Science and Automation (INRIA), Institut National des Sciences Appliquées (INSA) de Lyon, Laboratoire d'Informatique en Images et Systèmes d'Information (LIRIS), UMR5205, F-69621, France.
Abstract:
Bacterial genomes show substantial variations in size. The smallest bacterial genomes are those of endocellular symbionts of eukaryotic hosts, which have undergone massive genome reduction and show patterns that are consistent with the degenerative processes that are predicted to occur in species with small effective population sizes. However, similar genome reduction is found in some free-living marine cyanobacteria that are characterized by extremely large populations. In this Opinion article, we discuss the different hypotheses that have been proposed to account for this reductive genome evolution at both ends of the bacterial population size spectrum.
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