Biologists investigated how corals specialize to particular environments in the ocean. (Credit: © vlad61_61 / Fotolia) Enlarge

Feb. 6, 2013 — Since the observations made by English naturalist Charles Darwin on the Galapagos Islands, researchers have been interested in how physical barriers, such as isolation on a particular island, can lead to the formation of new species through the process of natural selection. Natural selection is a process whereby heritable traits that enhance survival become more common in successive generations, while unfavorable heritable traits become less common. Over time, animals and plants that have morphologies or other attributes that enhance their suitability to a particular environment become more common and more adapted to that specific environment.

Researchers today are intimately familiar with how physical barriers and reproduction isolation can lead to the formation of new species on land, especially among plants and animals with short generation times such as insects and annual plants. Michael E. Hellberg, associate professor in the Department of Biological Sciences at LSU, however, is interested in a more obscure form of speciation: the speciation of animals in the ocean.

"Marine plants and animals can drift around in the ocean extremely long distances," Hellberg said. "So how do they specialize?"

In a recent publication in theProceedings of the National Academy of Sciences, or PNAS, Hellberg and his graduate student Carlos Prada investigate how corals specialize to particular environments in the ocean. Corals, animals that form coral reefs and some of the most diverse ecosystems in the world, start their lifecycle with a free floating larval stage. Coral larvae can disperse vast distances in open water. Different coral species share similar geographical locations, with different species often existing only yards apart. As Prada and Hellberg propose in their recent publication, the large dispersal potential of coral larvae in open water and the proximity of different species on the ocean floor creates a mystery for researchers who study speciation. Hellberg and Prada ask, "How can new marine species emerge without obvious geographic isolation?"

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