University of Bath study challenges evolution gene protection theory

Analysis of bacterial and fungal DNA

Dr Sofia Radrizzani and Professor Laurence D Hurst analyzed spontaneous mutations in Escherichia coli and baker's yeast. Their team examined the largest collection of such data ever gathered for these two microorganisms. The study concludes that natural selection does not reduce mutation rates for vital genes as previously suggested. This research debunks a theory first proposed in 1972 which has resurfaced repeatedly since then.

The problem of hidden ghost mutations

Professor Hurst explained that natural selection removes harmful mutations quickly from important genes before scientists can detect them. This process creates an illusion that these genes mutate less frequently than others actually do. The researchers call these undetected changes ghost mutations which earlier studies failed to account for properly. Consequently, previous evidence supporting the protection theory was flawed because it missed these hidden events.

Mutation accumulation experiments reveal truth

To overcome these issues the team used mutation accumulation experiments involving E coli and Saccharomyces cerevisiae. They found that reducing mutation rates further for individual genes would bring very little benefit to organisms. Theoretical problems suggest gene mutation rates are already so low that additional reduction is difficult to favor. Random mutation generates genetic variation while natural selection acts like a sieve on those traits.