Evolutionary forecasting of phenotypic and genetic outcomes of experimental evolution in Pseudomonas

Experimental evolution is often highly repeatable, but the underlying causes are generally unknown, which prevents extension of evolutionary forecasts to related species. Data on adaptive phenotypes, mutation rates and targets from the Pseudomonas fluorescens SBW25 Wrinkly Spreader system combined with mathematical models of the genotype-to-phenotype map allowed evolutionary forecasts to be made for several related Pseudomonas species. Predicted outcomes of experimental evolution in terms of phenotype, types of mutations, relative rates of pathways and mutational targets were then tested in Pseudomonas protegens Pf-5. As predicted, most mutations were found in three specific regulatory pathways resulting in increased production of Pel exopolysaccharide. Mutations were, as predicted, mainly found to disrupt negative regulation with a smaller number in upstream promoter regions. Mutated regions in proteins could also be predicted, but most mutations were not identical to those previously found. This study demonstrates the potential of short-term evolutionary forecasting in experimental populations.