Chapter 17.3, Problem 1CSC

It is not surprising that the forests of New Guinea are home to a variety of distinctive species like the miniature frog Paedophryne amauensis. New Guinea is, after all, an island. It is likely that in the past, populations colonized the island and became genetically isolated from mainland populations, thereby initiating the process of speciation. But what about non-island species, such as the saola, the olinguito (FIG. 17-9), and the other unique species of the Annamite and Andes Mountains? How might populations inhabiting mainland forests in Vietnam or Ecuador have become isolated from other populations?