Genome complexity: regions protected from mutations (Introduction)

by David Turell , Thursday, January 27, 2022, 15:18 (820 days ago) @ David Turell

Mutation rates vary in different regions of the genome:

https://www.the-scientist.com/news-opinion/essential-genes-protected-from-mutations-69643

"...a new study cements the countering idea that the process of mutation isn’t evenly distributed across genomes. The work, published in Nature on January 12, finds that there’s a discrepancy in the rates of mutations among genes in model plant Arabidopsis thaliana. Specifically, genes playing a crucial role in survival and reproduction mutate far less often than those that are less important. (my bold)

"Arabidopsis is a small flowering plant that has a comparatively small genome, making it a popular system for genetic research. The study, which began at the Max Planck Institute for Biology in Germany and was carried over to University of California, Davis, when lead author and plant scientist J. Grey Monroe got a job there, finds a 58 percent lower mutation rate within genes than in the areas of the genome around them. On top of that, genes considered essential had a 37 percent lower mutation rate than those in which modifications would be less likely to prove disastrous.

"Mutations are distributed in a way that seems to be beneficial to the plant, Monroe tells The Scientist. The finding is “part of an ongoing movement that’s been happening since we started being able to sequence DNA,” which challenges the idea that mutations are equally likely throughout the genome and clarifies how evolution occurs, Monroe says. He adds that his paper is the first comprehensive analysis in a eukaryotic species that connects the mechanisms driving the variability in mutation rate at the cellular level with the finding that more important genes seem protected from mutation.

"Monroe and his colleagues found evidence of specific epigenetic characteristics such as cytosine methylation that prevent mutations from occurring in those regions, not unlike protective barriers. These structures and the variability in mutation rates within a single organism’s genome, Monroe says, suggest that “evolution created mechanisms that changed how evolution works.”

"Scientists have been demonstrating that mutations don’t occur randomly for nearly a century. Monroe, then, isn’t the first to show a mutation bias—previous studies to do so include a Journal of Molecular Evolution paper from 2005 demonstrating an increased mutation rate out near chromosomes’ telomeres, a 2011 publication in Nature Reviews Genetics suggesting the existence of a mutation bias across the human genome, and a 2012 review in BioEssays that suggests organisms may develop higher mutation rates in areas of the genome where changes would be most advantageous. With methodological improvements and a thorough epigenetic analysis, Monroe’s team added another piece to the puzzle."

Comment: The article contains many guesses as to why these protections exist, with no clear answer. I have one. These protections stabilize the existence of species, and do not allow speciation, which would then require a very special set of events as if a designer stepped in.