Abstract
Q ST is a commonly used metric of the degree of genetic differentiation among populations displayed by quantitative traits. Typically, Q ST is compared to F ST measured on putatively neutral loci; if Q ST = F ST , this is taken as evidence of spatially heterogeneous and diversifying selection. This paper reviews the uses, assumptions and statistics of Q ST and F ST comparisons. Unfortunately, Q ST / F ST comparisons are statistically challenging. For a single trait, Q ST must be compared not to the mean F ST but to the distribution of F ST values. The sources of biases and sampling error for Q ST are reviewed, and a new method for comparing Q ST and F ST is suggested. Simulation results suggest that the distribution of neutral F ST and Q ST values are little affected by various deviations from the island model. Consequently, the distributions of Q ST and F ST are well approximated by the Lewontin–Krakauer prediction, even with realistic deviations from the island‐model assumptions.