A biodiversity hotspot is a biogeographic region with significant levels of biodiversity that is threatened by human habitation.

Norman Myers wrote about the concept in two articles in “The Environmentalist” (1988), and 1990 revised after thorough analysis by Myers and others “Hotspots: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions” and a paper published in the journal Nature.

To qualify as a biodiversity hotspot on Myers 2000 edition of the hotspot-map, a region must meet two strict criteria: it must contain at least 0.5% or 1,500 species of vascular plants as endemics, and it has to have lost at least 75% of its primary vegetation. Around the world, 36 areas qualify under this definition. These sites support nearly 60% of the world's plant, bird, mammal, reptile, and amphibian species, with a very high share of those species as endemics. Some of these hotspots support up to 15,000 endemic plant species and some have lost up to 95% of their natural habitat.

Biodiversity hotspots host their diverse ecosystems on just 2.4% of the planet's surface, however, the area defined as hotspots covers a much larger proportion of the land. The original 25 hotspots covered 11.8% of the land surface area of the Earth. Overall, the current hotspots cover more than 15.7% of the land surface area, but have lost around 85% of their habitat. This loss of habitat explains why approximately 60% of the world's terrestrial life lives on only 2.4% of the land surface area.

 

Note:   The above text is excerpted from the Wikipedia article Biodiversity hotspot, which has been released under the GNU Free Documentation License.