But, says Lefcheck, "Just counting species is a really coarse way of understanding diversity. By gathering information on the animal's traitswhat they eat, how they move, where they livewe can understand more about how dissimilar they are. Dissimilarity is the essence of diversity."
Lefcheck illustrates the team's new approach to studying biodiversity by reference to a tide pool. "Consider a pool with a fish, a bird, and a crab," he says. "Now consider one with three fishes. Which is more diverse? Intuitively, we know it's the one with the fish, bird, and crab. But until recently, ecologists treated each of them as equally diverse, since they both have the same number of species."
"Most biodiversity censuses simply count species because it's relatively simple to do," says Duffy. "But to understand how species help ecosystems work, we need to know how abundant they are and what they're doing. That sounds obvious but such data are much harder to get. Ours is the first study to do this comprehensively, and we find that the extra knowledge paints a very different map of global diversity."
The team conducted their study by analyzing data from 4,357 standardized surveys conducted by volunteer RLS divers at 1,844 coral and rocky reef sites worldwide. The surveys spanned 133 degrees of latitude and found 2,473 different species of fish.
Moving beyond traditional species counts, the research team noted how the members of each of these species make a living, using a detailed matrix of "functional traits." These include what the fishes eat (plankton, invertebrates, algae, other fish, or a combination), how they eat it (browsing, scraping, or predation), where they live (in, on, or near the bo
|Contact: David Malmquist|
Virginia Institute of Marine Science