The main force driving neutral molecular evolution is:
Molecular evolution studies changes in DNA, RNA and proteins over time. Neutral theory by Kimura proposes most molecular substitutions are neutral and fixed by drift at rate equal to mutation rate, explaining molecular clock constancy where synonymous mutations accumulate steadily. Mitochondrial DNA maternally inherited and pseudogenes evolving faster due to lack of constraint provide markers for phylogeny. Purifying selection removes deleterious variants. Therefore Genetic drift illustrates principle of molecular evolution and neutral processes. This concept integrates genetics, ecology and m
Ref: Li, Molecular Evolution, Neutral Theory and Molecular Clocks.