Question

Choose all that apply: Which of the following are methods of detecting that there has been selection for a particular allele?

	a.	There is a higher number of nonsynonymous mutations compared to synonymous mutations in the sequence of interest.
	b.	Changes in the DNA sequence occur in accordance to expectations from the molecular clock.
	c.	A selective sweep occurred. Neutral variation that is nearby an allele that is under strong positive selection is eliminated.
	d.	The proportion of synonymous changes in a sequence among species is greater than the proportion of substitutions within a species.

Answer 1

Synonymous mutations will not alter the sequence of amino acids in a polypeptide chain whereas non synonymous mutations alter the sequence of amino acids in a polypeptide chain. Therefore, higher number of non synonymous mutations will not lead to selection for a particular allele. On the other hand, higher proportion of synonymous changes signifies selection of a particular allele.

Changes in DNA sequences in accordance with molecular clock signifies selection for a particular allele. When neutral variation nearby an allele is eliminated, it also signifies selection of a particular allele. So, the answers for this question are options b, c and d.