Figure 1.

F_st between a population and a hypothetical second population that is admixed between two other populations. log₁₀[G(γ)], seen as a function of γ, is plotted against γ, where G(γ) is $F_{\mathit{\text{st}}}[\underset{¯}{p_1},\gamma \underset{¯}{p_2}+(1-\gamma )\underset{¯}{p_3}]$, (eq. 3). Populations 1, 2, and 3 represent populations of Mestizo, European, and Native American descent, respectively, and $\underset{¯}{p_1},\underset{¯}{p_2}\text{ and }\underset{¯}{p_3}$ are based on allele frequencies estimated from Wang et al. (2008). Twenty randomly selected loci are considered, with each curve representing a different locus. The dots indicate the maxima for individual curves. In accordance with Lemma 1, for γ ∈ [0, 1], the maximal value of log₁₀[G(γ)], and therefore of G(γ), is always at γ = 0 or γ = 1.