Endemism as a Surrogate for Biodiversity

Although work casting doubt on the link between endemism and biodiversity has made recent headlines, new research shows that the two do overlap considerably at the local level. “This is good news,” says Richard Cowling of the University of Port Elizabeth in South Africa. “It justifies conservation strategies that have focused on endemism hotspots.”

To clarify whether endemism reflects diversity, John Lamoreux of the University of Virginia in Charlottesville and six coauthors identified the presence of more than 26,000 terrestrial vertebrate species in the nearly 800 ecoregions used for planning by major international conservation groups. Next, the researchers compared the richness of endemics with overall species richness for each of the four classes of terrestrial vertebrates (amphibians, reptiles, birds, and mammals) in each ecoregion. The richness of endemics was defined as the number of endemic species in a class divided by the total number of species in that class in a given ecoregion; likewise, the overall species richness was defined as the total number of species in a class divided by the total number of species in a given ecoregion.

The results showed that, collectively, ecoregions rich in endemics are also rich in overall species. For example, the 10 percent of the world’s land area with the most endemics also has more than 60 percent of all terrestrial vertebrate species. Better yet, the 10 percent of land with the greatest number of endemic amphibians and reptiles also contains more than 70 percent of all terrestrial vertebrate species. In addition, ecoregions rich in endemics of any one vertebrate class are also rich in endemics of the other three classes.

The researchers caution that their findings may not apply to nonvertebrates and that endemism is only one criterion for planning. “Using endemism along with other factors to identify global priorities focuses conservation in critical regions, where on-the-ground efforts will yield the greatest payoffs for biodiversity,” they say.

By Robin Meadows

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