Robustness promotes evolvability to thermotolerance in an RNA virus.

BMC Evolutionary Biology 8:231.
Year of Publication: 
McBride, R.C., C.B. Ogbunugafor, P.E. Turner.

The ability for an evolving population to adapt to a novel environment is achieved through a balance of robustness and evolvability. Robustness is the invariance of phenotype in the face of perturbation and evolvability is the capacity to adapt in response to selection. Genetic robustness has been posited, depending on the underlying mechanism, to either decrease the efficacy of selection, or increase the possibility of future adaptation. However, the true effect of genetic robustness on evolvability in biological systems remains uncertain. Here we demonstrate that genetic robustness increases evolvability in laboratory populations of the RNA virus phi-6. We observed that populations founded by robust clones evolved greater resistance to heat shock, relative to populations founded by brittle (less-robust) clones. Thus, we provide empirical evidence for the idea that robustness can promote evolvability, and further suggest that evolvability can arise indirectly via selection for robustness, rather than through direct selective action. Our data imply that greater tolerance of mutational change is associated with virus adaptability in a new niche, a finding generally relevant to evolutionary biology, and informative for elucidating how viruses might evolve to emerge in new habitats and/or overcome novel therapies.