Talk Title: Experimental evolution of evolvability
Abstract: Evolvability—the capacity to generate adaptive variation—is a trait that can itself evolve through natural selection. However, the idea that mutation can become biased toward adaptive outcomes remains controversial. In this work, we report the evolution of enhanced evolvability through localized hypermutation in experimental populations of bacteria. The evolved mechanism is analogous to the mutation-prone sequences of contingency loci observed in pathogenic bacteria. Central to this outcome was a lineage-level selection process, where success depended on the capacity to repeatedly evolve between two phenotypes that were optimal for growth under alternating conditions. Subsequent evolution showed that the hypermutable locus is itself highly evolvable with respect to alterations in the frequency of environmental change. Moreover, we reveal an unanticipated benefit to localized hypermutation, finding that lineages possessing this ability are more likely to acquire additional adaptive mutations. Our study demonstrates how evolvability can itself evolve adaptively and highlights the importance of this process for microbial pathogens.
