Scientists have determined in a new study that coral reefs of the same species display particular genetic and morphologic characteristics, which appear to be particular to their standard locations. In other words, same-species corals living at different depths are very different from each other as a result.
The investigation was conducted on Bird's nest coral (Seriatopora hystrix), a species of corals that is known to live at a wide variety of depths, in oceans around the world. Researchers patiently sampled numerous such populations, and then carried out genetic analysis on all of them.
They discovered that even the algal endosymbiont Symbiodinium – a microorganism that lives on the surface of corals and provides them with energy – is genetically different from versions of itself living at other depths. This finding was remarkable in itself.
What this research demonstrates is the efficiency of evolution and natural selection when it comes to forcing a species to adapt perfectly to its environment. The new investigation was carried out in the Indian and Pacific Oceans, where these particular types of corals abound.
Details of the research appear in the latest issue of the open-access journal BMC Evolutionary Biology, which is edited and published by BioMed Central. The study was carried out by experts at the University of Queensland and the ARC Center of Excellence for Coral Reef Studies.
“The different selective pressures across reef environments pose an ecological barrier to migration and further promote genetic divergence of these coral populations by limiting the extent of interbreeding,” explains the lead author of the BMC paper, Dr. Pim Bongaerts.
“This case study of S. hystrix clearly shows how ecological processes of selection can play an important role in the diversification of corals,” the team leader goes on to add. He is based at the Heron Island Research Station, in Australia.
The facility is operated by the Coral Reef Ecosystems Lab at the UQ School of Biological Sciences, Eurekalert
“The corals we looked at exhibited distinct physiological strategies – while normally corals are dependent on light for their energy requirements, the deep corals, appeared to have adapted to low light conditions by having an increased capacity to exploit nutrients and plankton,” Dr. Sophie Dove adds.
Until recently, it was believed that the amount of sunlight coral reefs received was paramount to their health and survival. The new data appear to indicate that this is not the case, since deep-sea corals appear to fare better without too much sunlight and associated photosynthesis.