Sky Island

Sky islands are isolated mountains surrounded by radically different lowland environments; the term originally described those found on the Mexican Plateau and has since extended to similarly isolated high-elevation forests elsewhere. Their isolation has significant consequences for the habitats they carry, producing endemism, altitudinal migration and relict populations, and the key defining feature of a sky island is separation by physical distance from other mountain ranges, creating a habitat island such as a forest surrounded by desert. The resulting patterns of species richness draw attention from biogeography, and the biodiversity they hold is a concern for conservation biology. Some sky islands serve as refugia for boreal species stranded by a warming climate since the last glacial period, while in other cases their isolated populations of plants and animals tend toward speciation, in a manner similar to oceanic islands such as the Galapagos Islands of Ecuador.