In an iBiology Techniques expert lecture, Harmit Malik explains how sequence analysis identifies genes under diversifying (positive) selection. The core method compares the nonsynonymous substitution rate with the synonymous substitution rate of protein-coding genes; an elevated nonsynonymous rate at host-virus conflict interfaces suggests potentially beneficial mutations favored by natural selection. Diversifying (positive) selection, also called adaptive evolution, differs from purifying selection in that it increases amino acid diversity in protein-coding genes and raises the fixation rate of potentially beneficial variants in populations.
Why it matters
The clip uses nonsynonymous-to-synonymous rate comparison to explain positive selection and how beneficial amino acid variants fix at host-virus interfaces.
