Sky island

The American Southwest region began warming up between c. 20,000 and 10,000 years BP and atmospheric temperatures increased substantially, resulting in the formation of vast deserts that isolated the sky islands.

The complex dynamics of species richness on sky islands draws attention from the discipline of biogeography, and likewise the biodiversity is of concern to conservation biology.

Herpetologist Edward H. Taylor presented the concept of "Islands" on the Mexican Plateau in 1940 at the 8th American Scientific Congress in Washington, D. C. His abstract on the topic was published in 1942.

[3] In about the same era, the term was used to refer to high alpine, unglaciated, ancient topographic landform surfaces on the crest of the Sierra Nevada, California.

In his 1967 book, Sky Island, he demonstrated the concept by describing a drive from the town of Rodeo, New Mexico, in the western Chihuahuan desert, to a peak in the Chiricahua Mountains, 56 km (35 miles) away and 1,700 m (5,600 ft) higher in elevation, ascending from the hot, arid desert, to grasslands, then to oak-pine woodland, pine forest, and finally to spruce-fir-aspen forest.

His book mentions the concept of biome, but prefers the terminology of life zones, and makes reference to the work of Clinton Hart Merriam.

[12] Confusing the matter somewhat is the potential for an archipelago of sky islands or even the valleys between them to act not only as a barrier to biological dispersal, but also as a path for migration.