Arlington, Va. -- An international research team has identified a family of corals found only in the Atlantic Ocean-a first for such classifications in that ocean-in a study that could transform how corals are viewed and classified. The scientists, who will publish their results in the Feb. 26 issue of the journal Nature, say the findings are also important for future decisions about coral conservation and the preservation of threatened biodiversity regions.
Led by Nancy Knowlton of the Scripps Institution of Oceanography of the University of California, San Diego, the study revealed significant flaws in the widely accepted taxonomy of Pacific and Atlantic corals. The team, which included researchers from the Smithsonian Tropical Research Institute in Panama, used DNA analysis to uncover a significant and previously undetected divergence between Pacific and Atlantic corals. Unexpectedly, the researchers found that about one-third of Atlantic corals, which had been conventionally classified in two distinct families found around the tropics, are in fact very closely related. But, the report says, the Atlantic corals are very different from Pacific corals assumed to be their close relatives. The two corals are so distinct, the scientists suggest the Atlantic variety constitutes its own family, making them the first such grouping unique to the Atlantic Ocean.
"If genetic sequencing of two families of corals can produce a major revision in our understanding," said H. Richard Lane, director of the National Science Foundation's geology and paleontology program, which funded the research, "one can only imagine what kinds of changes will happen once sequencing is accomplished across the entire spectrum of the biotic world." NSF is an independent federal agency that supports fundamental research and education across all fields of science and engineering.
The DNA results contradict accepted classifications based on the evolutionary form and structure, or morphology, of corals. Calculating when the Atlantic lineage originated is difficult, the scientists say, because the results now call into question the identity of many fossilized corals. The best records indicate that the dominant Atlantic and Pacific lineages probably separated more than 34 million years ago. Indeed, the team's further analysis of corals from the Caribbean, Brazil, Japan, Taiwan and Palau found entire lineages misclassified.
While the results carry implications beyond the upheaval and realignment of coral classification systems, the study also suggests current Atlantic coral conservation efforts should be reconsidered.
"Corals are important organisms because of the reefs they build, which support the most diverse marine ecosystems on the planet. But these new results are not simply that the coral taxonomy is completely wrong," said Knowlton, director of the Center for Marine Biodiversity and Conservation at Scripps. "These results require us to think about conservation priorities in a really different way."
Conservation priorities have been heavily focused on the Pacific Ocean because more coral species live there. Biodiversity "hot- spot" analyses, however, have ignored deeper-level diversity because Atlantic corals were assumed not to be particularly distinctive, say the scientists.
The Smithsonian Institution, the Scripps Institution of Oceanography, and the Conselho Nacional de Pesquisas also funded the research.
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