435357.fig.002a
(a) Divergence at A locus
435357.fig.002b
(b) Divergence at B locus
435357.fig.002c
(c) Intrinsic Isolation (based on F 2 hybrids)
435357.fig.002d
(d) Barrier into Population 1
435357.fig.002e
(e) Barrier into Population 2
Figure 2: Numerical simulation results for the epistatic trade-off model (Case 1). Various properties are shown as a function of the migration rate, expressed relative to the strength of ecological selection on the A locus, s. The migration rates numbered 1–12 correspond to 𝑚 = 𝑠 { 1 / 1 0 0 , 1 / 8 0 , 1 / 6 0 , 1 / 4 0 , 1 / 2 0 , 1 / 1 0 , 1 / 8 , 1 / 6 , 1 / 4 , 1 / 2 , 1 , 2 } ; migration is symmetric, that is, 𝑚 1 = 𝑚 2 = 1 / 2 𝑚 ( 𝑐 = 1 / 2 ) . The points in black represent values prior to the evolution of the modifier (i.e., assuming both populations fixed for the B allele as shown in Time 1 in Figure 1). Colored points represent values after the evolution of the modifier; different colors correspond to modifiers of varying effects (see legend). Left column: moderate linkage 𝑟 = 0 . 1 ; right column: no linkage: 𝑟 = 0 . 5 . (a) Divergence at A locus. (b) Divergence at B locus. (c) Intrinsic isolation as measured by the average fitness individuals from Populations 1 and 2 compared to the average fitness of 𝐹 2 hybrids. (d) Strength of the barrier into Population 1. (e) Strength of barrier into Population 2. Parameter values used: 𝑠 = 𝑠 1 = 𝑠 2 = 0 . 1 ; 𝑡 1 = 𝑡 2 = 0 . See text for details.