They lie 3200 km from North America and 5500 km from Japan. The most obvious result of this extreme isolation is that many groups are completely absent. The present-day bird fauna suggests only 15 different colonizations , attesting to the difficulty of migration to the islands. No terrestrial vertebrates occur here, and 21 orders of insect are completely absent. For example, ants are ubiquitous around the world, but were completely absent until humans brought them to the islands.
Adaptive radiation can be excessive here.
In general, the islands contain relatively few different families of plants and animals, but rather contains an unusual variety of species, nearly all unique to the islands. An excellent example of adaptive radiation concerns the honey-creepers of Hawaii. The ancestor to at least 16 different and endemic species of this bird was likely a single finch-like immigrant from Asia. Most of these are nectar-eaters, but some have adapted the ability to feed also on insects, fruits, and seeds. All rights reserved.