for National Geographic News
Until now, all Atlantic coral families were believed to be close relatives to distinct coral families in the Pacific Ocean. But a new study for the first time identifies a family of corals found only in the Atlantic.
According to the study, at least one third of the corals that thrive in the Atlantic Ocean are free of any family ties to corals in the Pacific Ocean. The study could transform how the marine organisms are viewed, classified, and conserved.
Using modern DNA analysis techniques, an international team of scientists found that at least a third of the corals in the Atlantic are more closely related to each other than to their supposed Pacific Ocean mates.
Moreover, the analysis shows that some Pacific corals thought to belong to distinct family groups are in fact quite similar to each other and are likely all members of the same family.
"The standard taxonomy has been established for a hundred years, and this turns it on its head," said Nancy Knowlton, a marine biologist with the Scripps Institution of Oceanography at the University of California, San Diego.
Knowlton, who is a member of the National Geographic Society's Committee for Research and Exploration, directed the study, which will be published in tomorrow's issue of the science journal Nature.
Calculating just when the Atlantic lineage originated is difficult, according to the researchers, because their study calls into question the identity of many fossil corals. However, the best records indicate that the dominant Atlantic and Pacific lineages probably separated more than 34 million years ago.
Isabelle Côté, a biologist at the University of East Anglia in Norwich, England, who has studied coral reefs in the Caribbean, said she is surprised and fascinated by the finding of a unique lineage in the Atlantic.
"Like most other people, I went along with the taxonomic classification which is based mainly on morphology," she said.
Knowlton said it is easy to understand how the differences between corals in the Pacific and Atlantic went undetected for more than a century: They all look about the same. And looksor morphologyis how the corals were traditionally classified.
"This study highlights how misleading it can be to rely only on morphology and appearance to make inferences about patterns of speciation and evolution," Côté said.
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