Figure 6:

Example of the variance of ancestry under a constant-admixture scenario with assortative mating in producing g ≥ 2 when populations are allowed to differ in the direction of their mating preference. (A) Autosomes, $\mathbb{V}\left[H_{1,g,\delta }^A\right]$. (B) X chromosomes in a female, $\mathbb{V}\left[H_{1,g,f}^X\right]$. (C) X chromosomes in a male, $\mathbb{V}\left[H_{1,g,m}^X\right]$. In all scenarios, populations S₁ and H experience positive assortative mating, c₁₁,c_hh = 0.02. Green curves show a scenario in which S₂ also experiences positive assortative mating, c₂₂ = 0.06; purple curves show a scenario in which S₂ experiences negative assortative mating, c₂₂ = −0.04. The scenario of random mating with the same contribution parameters is the black dashed line. The plots use eqs. (20), (21), and (29)–(32). We set $s_1^f=s_1^m=s_2^f=s_2^m=0.2$, and use initial conditions $s_{1,0}^f=s_{1,0}^m=s_{2,0}^f=s_{2,0}^m=0.5$ and c_11,0 = 0. In this example, negative assortative mating in S₂ offsets the positive assortative mating in S₁ and H, producing lower variances of admixture in S₁, $\mathbb{V}\left[H_{1,g,\delta }^{\gamma }\right]$, in the assortatively mating population than in the randomly mating population.