Figure 8.

Medea: Comparisons between the single-age introductions and two-age introduction. In panels (A) and (B), both males and females are introduced, while in panels (C) and (D), only males are introduced. In panels (A) and (C), the reproductive pattern is I, while in panels (C) and (D), the reproductive pattern is II. In each panel, the dashed line and the dot-dashed line illustrate the thresholds for the single-age introductions, while the solid line gives the thresholds for the two-age introduction. In all panels, mating is assumed to be slightly assortative by age (i.e., MP₂ illustrated in Fig. 2).