Question

6. “Synonymous” and “nonsynonymous” sites Explain why synonymous sites typically evolve faster than nonsynonymous sites.

Answer 1

In synonymous substitutions , the produced amino acid does not change, hence also called as silent mutation. Whereas in non synonymous substitutions , the amino acid produced gets changed .

Thus synonymous mutations are considered to be neutral as the change does not affect the fitness of individual. But sometimes these are not neutral , certain codons are translated faster and more accurately than the others. These changes also affect the mRNA stability and splicing. Hence these aites evolve three times faster as they are subjected to weak constraints.