Our paper describing the evolutionary effects of shifts in mutation bias is now published! We started out by asking if mutation spectrum could alter the fitness effects of new mutations in E. coli. To our surprise, we found a consistent effect across many environments, but could not attribute the difference to any particular properties of the mutations. The only exception was that transversion mutations seemed to be more beneficial/less deleterious than transitions. But why? Mathematical simulations helped us answer this: it is because transversions are relatively rare in the evolutionary history of E. coli, which has a transition biased mutation spectrum. So, we’ve discovered a very general effect – sampling new types of mutations (of any mutational class) should provide access to unexplored beneficial mutations. This leads us to several exciting predictions, which we are now testing in the lab.
This was a lot of fun to work on, and really tested and pushed us to think differently. Enormous effort from Mrudula Sane, Gaurav Diwan, Bhoomika Bhat, and a great new collaboration with Lindi Wahl (Western University). Do read the paper, and also this great summary by Nivedita Mukherjee (graduate student at NCBS). [Graphic: Pranjal Gupta]
AdaptationLab 