In an archipelagic system, species diversity is maintained and determined by the balance among speciation, extinction, and migration. As the number of species increases, the average population size of each species decreases, and the extinction likelihood of any given species grows. In contrast, the role of reduced population size in geographic speciation has received comparatively less research attention. Here, to study the rate of recurrent speciation, we adopted a simple multi-species two-island model and considered...