Genes from many isolates of the influenza virus have been sequenced.In certain regions of the genome,nonsynonymous substitutions have been found to occur much more frequently than synonymous substitutions.From this pattern we can infer that
A) a great deal of genetic drift is taking place.
B) most of the amino acid changes are neutral.
C) strong stabilizing selection is acting on this gene.
D) strong positive selection is acting on this gene.
E) mutations that change the amino acid are disadvantageous.

Question

Quizplus · Accepted Answer

The fact that nonsynonymous substitutions are occurring much more frequently than synonymous substitutions suggests that there is strong positive selection acting on this gene. Positive selection often leads to the fixation of beneficial mutations, which can result in an increase in the frequency of nonsynonymous substitutions. This is consistent with the idea that the influenza virus is constantly evolving to avoid host immune responses.

Genes from Many Isolates of the Influenza Virus Have Been