Which statement about QST is correct?

Which statement about QST is correct?

• A. QST measures genetic differentiation at neutral markers
• B. QST measures differentiation of quantitative traits
• C. QST measures geographic distribution of species
• D. QST measures mutation rates in populations

Answer: (B)

QST is a statistic designed to quantify how much additive genetic variation in a quantitative trait is distributed among populations compared with within populations. In practice, it captures differentiation of trait values that have a genetic basis, across populations, much like FST does for neutral genetic markers. This focus on quantitative traits—traits influenced by many genes—makes the statement that QST measures differentiation of quantitative traits the best description. It’s helpful to connect this to how QST is used: by comparing QST to FST, you can infer whether trait differences are due to selection or just drift. If QST is higher than FST, it suggests divergent selection on the trait; if QST is similar to FST, drift could explain the differences; if QST is lower, stabilizing selection or high gene flow may be at work. The other options don’t fit because QST isn’t about neutral markers (that’s FST), geographic distribution, or mutation rates.

QST is a statistic designed to quantify how much additive genetic variation in a quantitative trait is distributed among populations compared with within populations. In practice, it captures differentiation of trait values that have a genetic basis, across populations, much like FST does for neutral genetic markers. This focus on quantitative traits—traits influenced by many genes—makes the statement that QST measures differentiation of quantitative traits the best description.

It’s helpful to connect this to how QST is used: by comparing QST to FST, you can infer whether trait differences are due to selection or just drift. If QST is higher than FST, it suggests divergent selection on the trait; if QST is similar to FST, drift could explain the differences; if QST is lower, stabilizing selection or high gene flow may be at work.

The other options don’t fit because QST isn’t about neutral markers (that’s FST), geographic distribution, or mutation rates.