This could "at last enable ecology to estimate worldwide species diversity," say Michael Rosenzweig, Will Turner and Jonathan Cox of the University of Arizona, Tucson, and Taylor Ricketts of Stanford University in Stanford, California, and the World Wildlife Fund in Washington, DC, in the June issue of Conservation Biology.
While conservationists can predict how many species there are within a single habitat, the usefulness of this approach is limited because it's impossible to sample all the habitats in large areas. Knowing the number of species is critical to tracking and addressing -- declines in biodiversity. "Right now we can only guess that the correct answer for the total number of species worldwide lies between 2 and 100 million," says Rosenzweig.
To help find a way to assess biodiversity in large regions, Rosenzweig and his colleagues tested six methods for assessing biodiversity in a single habitat on a remarkably well-known group of species: butterflies in the U.S. and Canada. Because butterflies are so popular, we have an unusually complete set of data for which species live where. There are 561 known butterfly species and 110 ecoregions in the U.S. and Canada, and the researchers determined which of the six methods predicted the total number of species most accurately based on data from the smallest number of ecoregions.
Rosenzweig and his colleagues found that three of methods worked well even when limited to only a tenth of the ecoregions (11 out of 110). The best such estimate yielded nearly all of the known butterfly species (556 out of 561). While the researchers found that selecting ecoregions at random worked
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Contact: Michael Rosenzweig
scarab@u.arizona.edu
520-621-7296
Society for Conservation Biology
23-May-2003