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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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6 October 2006 (All day)
In the tropics, which wrap around swaths of nearly every continent, animal and plant diversity is abundant, and it declines as one moves toward the North and South poles. Why this difference? Many evolutionary biologists favor one of two explanations: Either the tropics are where most new species originate, or species are less likely to go extinct there than elsewhere. New research suggests that both are true. The finding indicates that the tropics drive biodiversity and that extinctions there may have especially devastating effects.
University of Chicago evolutionary biologist David Jablonski and colleagues reached those conclusions after 10 years studying fossils of bivalves, marine and freshwater mollusks with two-part hinged shells. The researchers mapped the global geographic distribution and evolution of the shellfish over the past 11 million years. They broke the world into 10-degree bands they called "latitudinal bins" and then tracked how 147 lineages of bivalves deployed in each band over time. "We tracked back through geological time," Jablonski says, "looking at ... where they started and where they migrated to."
They found that the tropics are the source of most of the world's bivalve biodiversity. More than two-thirds made their first appearance there. Many then migrated to other regions. The tropics "are net exporters of biodiversity, so damaging biological diversity in the tropics cuts biological evolution off at its roots," Jablonski says. Their paper appears in the 6 October issue of Science.
The work "cuts to the very core of our knowledge about evolution," says Stuart Pimm, an evolutionary biologist at Duke University in Durham, North Carolina. The results of this study have practical as well as theoretical implications, Pimm says. "When you start hurting the tropics, you are cutting off the source of species for other places."