A higher rate of synonymous relative to nonsynonymous substitutions in a protein-coding gene is expected under
A) purifying selection.
B) positive selection.
C) neutral evolution.
D) concerted evolution.
E) None of the above

Question

Quizplus · Accepted Answer

A higher rate of synonymous relative to nonsynonymous substitutions in a protein-coding gene indicates that the protein is under purifying selection. This means that selection is favoring the preservation of the amino acid sequence and function of the protein, resulting in more synonymous (silent) mutations that do not affect the protein sequence. In contrast, positive selection would favor more nonsynonymous substitutions, leading to changes in the amino acid sequence of the protein. Neutral evolution would result in similar rates of synonymous and nonsynonymous substitutions, while concerted evolution refers to the coordinated evolution of gene families and is not relevant to a single protein-coding gene.

A Higher Rate of Synonymous Relative to Nonsynonymous Substitutions in a Protein-Coding