Iguanas were not known to exist on this island before the hurricanes. The source region for these iguanas was likely the island of Guadeloupe , about 250 km away, and the journey probably took about six months. Two years later, the new population of iguanas was alive and well. Seeds and spores of some plants and ferns can be carried airborne hundreds of miles. Some fruits and seeds can adhere to animal skin, fur, and feathers.
Some seeds can germinate after up to two weeks inside digestive systems.
Some seeds and plants can be carried unharmed in the ocean for long distances. Thor Heyerdahl hypothesized Polynesians arrived by boats from lands to the east, and mounted the Kon Tiki series of voyages in the 1940s to prove it. Islands that are more isolated from the mainland will have a much lower biodiversity than islands near the mainland. The intervening sea between islands act as a barrier to dispersal. Think of a stepping-stone pattern of islands, with the farthest island having fewer species.