PT  - JOURNAL ARTICLE
AU  - Sane, Mrudula
AU  - Diwan, Gaurav D
AU  - Bhat, Bhoomika A
AU  - Wahl, Lindi M
AU  - Agashe, Deepa
TI  - Shifts in mutation spectra enhance access to beneficial mutations
AID  - 10.1101/2020.09.05.284158
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.09.05.284158
4099  - http://biorxiv.org/content/early/2020/09/20/2020.09.05.284158.short
4100  - http://biorxiv.org/content/early/2020/09/20/2020.09.05.284158.full
AB  - Biased mutation spectra are pervasive, with widely varying direction and magnitude of mutational bias. Why are unbiased spectra rare, and how do such diverse biases evolve? We find that experimentally changing the mutation spectrum increases the beneficial mutation supply, because populations sample mutational classes that were poorly explored by the ancestor. Simulations show that selection does not oppose the evolution of a mutational bias in an unbiased ancestor; but it favours changing the direction of a long-term bias. Indeed, spectrum changes in the bacterial phylogeny are frequent, typically involving reversals of ancestral bias. Thus, shifts in mutation spectra evolve under selection, and may directly alter outcomes of adaptive evolution by facilitating access to beneficial mutations.One Sentence Summary Altered mutational biases allow populations to sample poorly explored mutational space, with wide-ranging evolutionary consequences.Competing Interest StatementThe authors have declared no competing interest.