We take for granted that island populations must have a continental origin, and not the other way around. The number of islands that acquire their biota [i.e., plant and animal life] from a larger source supports this notion. There is, however, no fundamental mechanism in the equilibrium theory of island biogeography to preclude island species from colonizing the mainland. The belief in one-way biogeographic traffic has only begun to erode as phylogenetic analyses have revealed island origins for continental rodents and lizards. Among plants, the genus Exostema has successfully diversified in the continental Neotropics, while two populations in the angiosperm genus Erithalis have colonized Florida. At least two Neotropical bat lineages can be added to the growing list of island-to-continent colonizers.