In a Sequence of DNA Taken from Various Species of Snails

question 185

Multiple Choice

In a sequence of DNA taken from various species of snails, researchers have found that the rates of nonsynonymous substitutions and synonymous substitutions are roughly the same.What can we infer from this pattern?

• A) Transversions are more common than transitions.
• B) Most of the amino acid changes are neutral.
• C) Strong purifying selection is acting on this gene.
• D) Strong positive selection is acting on this gene.
• E) This gene cannot be used as a molecular clock.