title: What drives parallel evolution?: How population size and mutational variation contribute to repeated evolution.
abstract: Parallel evolution is the repeated evolution of the same phenotype or genotype in evolutionarily independent populations. Here, we use evolve-and-resequence experiments with bacteria and yeast to dissect the drivers of parallel evolution at the gene level. A meta-analysis shows that parallel evolution is often rare, but there is a positive relationship between population size and the probability of parallelism. We present a modeling approach to estimate the contributions of mutational and selective heterogeneity across a genome to parallel evolution. We show that, for two experiments, mutation contributes between ∼10 and 45%, respectively, of the variation associated with selection. Parallel evolution cannot, therefore, be interpreted as a phenomenon driven by selection alone; it must also incorporate information on heterogeneity in mutation rates along the genome. More broadly, the work discussed here helps lay the groundwork for a more sophisticated, empirically grounded theory of parallel evolution.
authors.affiliation: Bioinformatics Research Centre, University of Aarhus, Aarhus, Denmark.
authors.forename: Susan F
authors.initials: SF
authors.lastname: Bailey
authors.affiliation: Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
authors.forename: François
authors.initials: F
authors.lastname: Blanquart
authors.affiliation: Bioinformatics Research Centre, University of Aarhus, Aarhus, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bataillon
authors.affiliation: Department of Biology, University of Ottawa, Ottawa, Canada.
authors.forename: Rees
authors.initials: R
authors.lastname: Kassen
mesh_terms: D001419:Bacteria / Q000235:genetics; D019143:Evolution, Molecular; D008957:Models, Genetic; D009154:Mutation; D011156:Population Density; D011550:Pseudomonas aeruginosa / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*
keywords: bacteria; evolve and resequence experiment; experimental evolution; mutation; parallel evolution; selection yeast