Hotspots are regions that harbor a great diversity of endemic species* and, at the same time, have been significantly impacted and altered by human activities.
To qualify as a hotspot, a region must
support 1,500 endemic plant** species, 0.5% of the global total;
have lost more than 70% of its original habitat.
There are 34 hotspots areas worldwide where 75% of the planet’s most threatened mammals, birds, and amphibians survive within habitat covering just 2.3% of the Earth’s surface (roughly equivalent to the combined areas of the five largest US states).
* Some plants and animals, like humans and grey rats, are widespread and inhabit most regions, while others have very restricted distributions and may be found only on a single island or mountaintop, in a single river or lake. We refer to these highly restricted organisms as endemic species because they are unique to a specific region.
** Plants have been used as qualifiers because they are the basis for diversity in other taxonomic groups and are well-known to researchers. Typically, the diversity of endemic vertebrates in hotspot regions is also extraordinarily high.