Co-evolution disrupts diversification in experimental populations of E. coli and P. fluorescens by weakening intraspecific selection

This study aimed to test the effects of growth with another species on the Pseudomonas fluorescens SBW25 adaptive radiation. In this study Escherichia coli and P. fluorescens were cultured in monoculture and co-culture for 8 weeks. In P. fluorescens monoculture, Wrinkly and Smooth Spreader types rapidly evolved and were maintained over 8 weeks, while E. coli monocultures evolved two colony types, a big and a small colony variant. We found that in co-culture, E. coli did not evolve small colony variants, and that Wrinkly and Smooth Spreader evolution was altered. Whole genome sequencing revealed the genetic basis of co-culture specific adaptation in E. coli and P. fluorescens.