Differences in deep-sea corals
After sequencing a particular region of the DNA extracted from different corals, it is possible to assess their similarity. This raw information can be used to draw a phylogenetic tree retracing the hypothetical evolutionary history of the different corals. Such an approach was applied on a wide range of DNA sequences from coral species, including cold-water corals. It revealed that morphological characters used to define the family into which Lophelia is classified might not provide sufficient resolution to describe evolutionary relationships within that family. At the level of the species, Lophelia showed a high genetic variability across the Atlantic Ocean, as sequences obtained from samples of Lophelia from the NE Atlantic were very different from those obtained from samples collected in the SW Atlantic.
Surprisingly, another widespread cold-water coral species, Madrepora oculata did not group with other species from its morphological family. Such results show that molecular approaches can be a useful alternative approach to traditional morphological taxonomy to understand how deep-sea corals relate to each other and with their tropical counterparts.