title: The molecular diversity of adaptive convergence.
abstract: To estimate the number and diversity of beneficial mutations, we experimentally evolved 115 populations of Escherichia coli to 42.2°C for 2000 generations and sequenced one genome from each population. We identified 1331 total mutations, affecting more than 600 different sites. Few mutations were shared among replicates, but a strong pattern of convergence emerged at the level of genes, operons, and functional complexes. Our experiment uncovered a set of primary functional targets of high temperature, but we estimate that many other beneficial mutations could contribute to similar adaptive outcomes. We inferred the pervasive presence of epistasis among beneficial mutations, which shaped adaptive trajectories into at least two distinct pathways involving mutations either in the RNA polymerase complex or the termination factor rho.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of California-Irvine, CA 92697, USA. olivier.tenaillon@inserm.fr
authors.forename: Olivier
authors.initials: O
authors.lastname: Tenaillon
authors.forename: Alejandra
authors.initials: A
authors.lastname: Rodríguez-Verdugo
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Gaut
authors.forename: Pamela
authors.initials: P
authors.lastname: McDonald
authors.forename: Albert F
authors.initials: AF
authors.lastname: Bennett
authors.forename: Anthony D
authors.initials: AD
authors.lastname: Long
authors.forename: Brandon S
authors.initials: BS
authors.lastname: Gaut
mesh_terms: D000222:Adaptation, Physiological; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D004843:Epistasis, Genetic; D004926:Escherichia coli / Q000235:genetics* / Q000502:physiology*; D019143:Evolution, Molecular; D005798:Genes, Bacterial; D056084:Genetic Fitness; D016680:Genome, Bacterial; D008957:Models, Genetic; D009154:Mutation; D009876:Operon; D017354:Point Mutation; D012234:Rho Factor / Q000235:genetics; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion; D013696:Temperature
chemical_list: D012234:Rho Factor; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit