Accelerated evolution in networked metapopulations of Pseudomonas aeruginosa

Natural populations are often spatially structured, meaning they exist as metapopulations composed of subpopulations connected by migration. Little is known about the impact of spatial structure, in particular the topology of connections among subpopulations, on adaptive evolution. Typically, spatial structure slows adaptation, although some models suggest topologies that concentrate dispersing individuals through a central hub can accelerate adaptation above that of a well-mixed system. We provide evidence to support this claim and show acceleration is accompanied by high rates of parallel evolution. Our results suggest metapopulation topology can be a potent force driving evolutionary dynamics and patterns of genomic repeatability in structured landscapes such as those involving the spread of pathogens or invasive species.