Biodiversity hotspots are defined as areas featuring exceptional concentrations of endemic species and experiencing exceptional loss of habitat. Species are described as endemic if they are unique to a specific area or region, and don't naturally occur anywhere else. Due to their limited ranges, endemic species are particularly vulnerable to extinction.

The biodiversity hotspots concept was first proposed by Norman Myers in 1988. Since then, the hotspots have been reassessed and updated, and there are currently 25 hotspots. Because of the large number of species under threat and lack of conservation funding it is economically unfeasible to protect them all; areas must be given priority for conservation. The hotspots concept aims to protect the greatest number of species at the least cost. The 25 hotspots contain 44% of all vascular plant species and 35% of terrestrial vertebrates and encompass only 1.4% of the earths surface. However, collectively they have lost 88% of their original primary vegetation. Species in these areas are at risk from extinction if further habitat loss occurs.

Where are the hotspots?

1. It contains endemic vascular plant species comprising at least 0.5% of all the worlds' plant species. It must therefore include at least 1500 endemic plant species out of the worldwide total of 300 000.
2. It has lost at least 70% of its primary vegetation

Plants are used as an indicator of species endemism as their numbers and distribution are well known, and also because they support nearly all animal life. In several hotspots, there is a correlation between number of endemic plant species and number of endemic vertebrate species, which further justifies their hotspot status. Although areas are designated as hotspots based on number of endemic species and degree of habitat threat, areas of high endemism also tend to be areas of high species richness overall. The boundaries of hotspots are determined by 'biological commonalities'. Each hotspot contains separate biological communities which make up a biogeographic unit.

Targeting conservation efforts towards biodiversity hotspots may be crucial in preventing the mass extinctions predicted in the next 50 years; Over half of the worlds threatened species live in the hotspots. Between a half and two-thirds of all threatened plants and 57% of all threatened terrestrial vertebrates are endemic to the biodiversity hotspots. Mass extinctions are therefore predicted in the hotspots if current trends of habitat loss continue.

It has been estimated that 1.1 billion people (nearly 20% of the worlds population) live in the biodiversity hotspots. The population growth rate in the hotspots is 1.8% per year, which is higher than the world average population growth rate (1.3% per year). Humans therefore play significant roles in these areas, and are likely to cause further environmental damage as human populations expand.