An extension

As you may recall,² Slatkin [3] pointed out that there is a relationship between coalescence time and $F_{st}$. Namely, if mutation is rare then

$$F_{ST} = \frac{\bar t - \bar t_0}{\bar t} \quad ,$$

where $\bar t$ is the average time to coalescence for two genes drawn at random without respect to population and $\bar t_0$ is the average time to coalescence for two genes drawn at random from the same populations. Results in [2] show that when $\delta_{ij}$ is linearly proportional to the time since two sequences have diverged, $\Phi_{ST}$ is a good estimator of $F_{ST}$ when $F_{ST}$ is thought of as a measure of the relative excess of coalescence time resulting from dividing a species into several population. This observation suggests that the combination of haplotype frequency differences and evolutionary distances among haplotypes may provide insight into the evolutionary relationships among populations of the same species.