Scientists question one of the paradigms of evolution

Scientists at the Max Planck Society have discovered non-random mutations in Arabidopsis DNA. Scientists at the Max Planck Society Institute for Biology in Germany have found that mutations in the plant genome are non-random and less likely to affect the function of important genes. As the authors of the study, the results of which are published in the journal Nature, their discovery challenges one of the central paradigms in evolutionary biology, according to which mutations occur randomly throughout the genome regardless of their consequences.

It was originally thought that genetic variations in important gene regions in organisms were less common because such mutations were more likely to cause negative consequences and were ruled out by natural selection. Those organisms survive whose important genes remain intact, and the likelihood of mutations occurring is the same in all regions of the genome. However, new evidence demonstrates that there are molecular mechanisms underlying mutation 'bias'.

The researchers analysed new mutations in cells of the germline plant Arabidopsis thaliana. This allowed them to determine the frequency of mutations in different regions of the genome before they start affecting the developing organism. It turned out that mutations are less frequent in functionally important regions of the genome: within genes, their frequency decreases by half, and in particularly important genes by two-thirds.

This bias is explained by epigenomic mechanisms that do not change the DNA sequence itself but affect gene activity and possible variation. For example, genes can be enriched in G and C nucleotides, which reduces the likelihood of DNA damage. Some molecules bind to DNA and increase gene stability or repair efficiency. Overall, this reduces the occurrence of deleterious mutations in key regions of the Arabidopsis genome. Such mechanisms may have arisen during evolution as an adaptation that enhances the survival of the species.