Speaker
Description
Whether evolution is predictable has become an outstanding question in the field of evolutionary biology and requires knowledge of the complex genotype-fitness map. Experimental evolution studies have begun to shed light on this, but it has not yet been determined if predictions can be extended between different species. Here, we use the Pseudomonas fluorescens SBW25 wrinkly spreader (WS) system to predict the outcome of experimental evolution in the closely related P. protegens Pf-5. When cultured in static microcosms, populations of SBW25 rapidly evolve to form a biofilm at the air-liquid interface, with the most adaptive phenotype (the WS) overproducing a cellulosic polymer, ultimately promoting cell-cell adhesion, resulting in a wrinkly colony morphology. The genotype-to-phenotype map of this trait is well characterized, making this system ideal to test the efficacy of predictability in related species. Our results show that predictions based on previous experiments and models in SBW25 were sufficient to predict evolution in Pf-5 across several biological levels. Although Pf-5 lacks the main structural component of SBW25 biofilms, cellulose, we successfully predicted the four main pathways to the adaptive WS genotype, but the phenotypic basis of biofilm formation could only be partially predicted. Types of mutations were also successfully predicted, with loss-of-function mutations in negative regulators being the most common. Mutated regions in genes could also be predicted, but there was little parallelism at the nucleotide level. Finally, we will present novel results experimentally testing predictions of two additional species, P. savastanoi and P. syringae, that encode diverse biofilm genes.
