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Paleoendemism on Islands
Islands offer classic examples of paleoendemism. For this purpose, an island is an area of habitat that is suitable for an organism surrounded on all sides by habitat that is unsuitable. Islands as harbors for endemic species are explained by the Theory of Island Biogeography. However, in order to be considered a paleoendemic on an island, the species must have had a widespread distribution previously, thus eliminating newly formed islands as potential refuges of paleo-endemics.

Geographical Islands
For example, on the Canary Islands, there are a large number of relict plant species that were formerly distributed in Europe and North Africa. Of the 88 critically endangered species on the Canary Islands, many are the result of range reductions on the islands. The island of New Caledonia is also a prime example as many of the species on the island are paleoendemics. The palm species on New Caledonia grow in areas that are likely former Pleistocene refugia of lowland rainforests. Islands are also a refuge for relic t lineages of animals. Bermuda has a high diversity of species and home to one species of terrestrial vertebrate, the skink Plestiodon longirostris, which is the only extant lineage of mainland North American Plestiodon lineages.

Soil (edapphic) Islands
Many soil types harbor diverse and endemic plant species. Specific soil types act as “islands” of fertility and the distribution of these soils leads to high rates of paleo- and neoendemism. The primary example of this is serpentine soils. These soils are found in Balkan Peninsula, Turkey, Alps, Cuba, New Caledonia, the North American Appalachians, and a scattered distribution in California, Oregon, and Washington and elsewhere For example in the serpentine soil patches in the Pacific Northwest, Steptanthus glandulosus subsp. glandulosus is a paleoendemic, though the closely related members of the species complex are widely distributed.

Mountain Islands


Mountains can also be “islands” and harbors of paleoendemism because species that live on mountain peaks are geographically isolated. For example, in the Maritime Alps, Saxifraga florulenta, is an endemic plant that evolved in the Late Miocene and was once widespread across the Mediterranean Basin. Additionally, Piper’s bellflower (Campanula piperi) in the Olympic Mountains in Northern Washington is suspected to be a paleoendemic because the closest related species is located over 1,000 km away. Another example is Stroganowia tiehmii which is endemic to a single mountain range in Nevada and all other members of the genus are in Central Asia.