Spotlight on Environmental Buzzwords: Biodiversity Hotspot

Fourth installment in our series on environmental buzzwords

The world map of red-tinted biodiversity hotspots is by now a familiar sight to conservation students. It's a visually compelling filter through which to view worldwide environmental change, and a major determinant of conservation funding. It's also a controversial simplification that cuts to the heart of the debate over what makes biodiversity important.

"Hotspot" has been used to refer to areas of intense activity since the mid-19th century, and seems to have first been used in a biodiversity context by EO Wilson in 1985. The current list of hotspots, however, is the work of ecologist Norman Myers. Over a series of papers beginning in 1988 and culminating in a 2000 Nature paper, Myers identified 25 global hotspots as "areas featuring exceptional concentrations of endemic species and experiencing exceptional loss of habitat."

Although that number has since been updated to 34, the same basic criteria apply: hotspots must contain at least 0.5% of the earth's plant species as endemics (a species richness criterion), and must have lost 70% or more of its primary vegetation (a threat criterion). The concept's goal is to prioritize conservation funding, and it does this by saving the most possible species in the least possible land. The current list does this admirably, containing 42% of Earth's vertebrate species and 50% of its plant species in only 2.3% of its land surface.

A literature's worth of questions have been raised about how hotspots are best defined. But critics of the biodiversity hotspot concept raise a more fundamental issue: is conserving small areas of high species diversity a desirable conservation goal?

In a 2003 essay entitled "Conserving Biodiversity Coldspots," conservation biologists Peter Kareiva and Michelle Marvier point out that minimizing the amount of land that needs conserving may throw certain conservation objectives under the bus. Tropical ecosystems are disproportionately represented on the list, while even notably diverse temperate ecosystems like Yellowstone National Park don't make the cut. Species with few living relatives are not prioritized over species that come from well-represented taxa. Low-diversity landscapes that provide important ecosystem services, like wetlands, go unmentioned.

The hotspot, then, is an interesting case of a concept that's become the victim of its own success. Myers himself never claimed that it should be the only approach used to direct conservation funding. But as hotspots begin to draw the lion's share of conservation funding, the blind spots they leave need renewed attention.