A central tenet in evolutionary theory is that mutations occur randomly in the genome, now Luscombe and co-workers show that “neutral mutation rate varies by more than an order of magnitude across 2,659 genes” and surprisingly this variation is not random. Researchers detected a lower rate in highly expressed genes and in those undergoing stronger purifying selection. These findings suggest that the mutation rate has been evolutionarily optimized to reduce the risk of deleterious mutations. It seems like that bacteria have evolved a mechanism that protects important genes from random mutation, effectively reducing the risk of self-destruction.
Iñigo Martincorena, Aswin S. N. Seshasayee & Nicholas M. Luscombe
Evidence of non-random mutation rates suggests an evolutionary risk management strategy
Nature, 22 April 2012