In recent years, major international conservation groups have focused their limited resources on protecting a small number of "biodiversity hotspots"-threatened habitats that are home to many of the world's rarest plants and animals.

But a handful of protected areas will not be sufficient to save the countless species of plants and animals facing extinction worldwide, according to a new study by scientists from Stanford University and the National Autonomous University of Mexico (UNAM). Writing in the Dec. 15 online edition of the Proceedings of the National Academy of Sciences (PNAS), the researchers say that it's time for ecologists to reconsider the hotspot approach to conservation.

"Hotspots, which have played a central role in the selection of sites for reserves, require careful re-thinking," wrote Gerardo Ceballos, professor of ecology at UNAM, and Paul R. Ehrlich, the Bing Professor of Population Studies at Stanford, co-authors of the PNAS study. "Assigning global conservation priorities based on hotspots is at best a limited strategy."

The idea of funneling resources into biodiversity hotspots was proposed in 1988 and quickly adopted by Conservation International and other leading environmental groups. "Few topics in conservation biology have received as much attention as hotspots of species diversity," Ceballos and Ehrlich wrote. "Hotspots have been widely used to determine priority areas for conservation at different geographic scales and in recommending concentrating resources in those regions to maximize the number of protected species."

Hotspot biodiversity is usually based on one of three factors-the number of total species (species richness), the number of unique or endemic species (endemism) or the number of species at risk.

According to Ceballos and Ehrlich, however, a critical assumption of hotspot ecology that has not been widely tested is the extent to which the thre
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-3062
Stanford University
11-Dec-2006