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Why mutation tales are key in the evolution story

BENGALURU: A new scientific paper published by a team of scientists from the National Centre for Biological Sciences (NCBS) in Bengaluru and Western University, Canada, has shown direct evidence for how mutations are key to understanding evolution.Any biology textbook will tell you mutation and natural selection drive evolutionary change in species. The role of mutations was thought to be relatively passive while they create the raw material for evolution, their fate is ultimately decided by selection. But evidence from the past few years is beginning to change this view, NCBS said.Scientists point out that mutation is inherently biassed in most species, such that some types of mutations occur more often than others. While several studies have suggested that this mutational bias could significantly shape the course of evolution, the new paper shows direct evidence for such important effects of mutation bias. On changing the existing mutation bias of Escherichia coli (type of bacteria), scientists found that the bacterium could access many more beneficial mutations, which are key for adaptation in new environments. Indeed, mathematical simulations showed that bias shifts promote faster adaptation. This effect arises because changing the mutational bias allows a population to explore different types of mutations that were previously rare, NCBS said.Based on these results, the scientists predicted that changing mutation bias is a good way to find new adaptive mutations. And, analysis of more than 1,000 bacterial genomes suggested that historically, bacteria may have often experienced such beneficial bias switches. Altogether, the study proposes a novel hypothesis for the importance of mutational biases, opening an exciting new angle of inquiry into the fundamental question of what drives evolutionary change, NCBS said.Explaining the significance, the researchers said in their paper: Mutations are important because they provide raw material for evolution. Some types of mutations occur more often than others, and the strength of such mutational bias varies across species. It is not clear how this variation arises. We experimentally measured the immediate effects of changing the mutation bias of Escherichiacoli and used simulations to understand the long-term effects.Altering mutational bias is beneficial whenever new bias increases sampling of mutational classes that were previously undersampled, they said, adding that theyve also shown that historically, bacteria have often experienced such beneficial bias switches. Our work thus demonstrates the importance of mutational biases in evolution. By allowing exploration of new mutational space, altered mutation biases could drive rapid adaptation, they argue.

Wednesday, May 31, 2023 at 7:09 am

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