Module 7 - Molecular Evolution Neutral Selection vs. Natural Selection Kimura argued that random "genetic drift" instead of natural selection is the main cause of evolution at the molecular level this is known as the theory of neutral evolution. Although initially, this theory was dependent on the cost of natural selection, it was later emphasized on the molecular clock which is the constancy of the rate of molecular evolution. The neutral theory also demonstrated the inverse relationship between the importance of a protein and its rate of evolution. Therefore, important proteins are more constrained and changes in their amino acids less likely to be neutral. Neutral drift is when non-synonymous and synonymous mutations are equal. Years later around the 1990s, DNA sequence data had increased leading to a comparison of patterns of substitutions. Nonsynonymous mutations are selectively important while synonymous mutation sites are selectively unimportant. [1] Can you gue...