Symbiont Shuffling in Corals: Is it Rare or Widespread?
Silverstein, R.N., Correa, A.M.S. and Baker, A.C. 2012. Specificity is rarely absolute in coral-algal symbiosis: implications for coral response to climate change. Proceedings of the Royal Society B 279: 2609-2618.
To determine whether additional Symbiodinium clades might be present but undetected in various corals using conventional discovery and identification techniques, Silverstein et al. say they "applied a high-resolution, real-time PCR [polymerase chain reaction] assay to survey Symbiodinium (in clades A-D) from 39 species of phylogenetically and geographically diverse scleractinian corals," which survey, according to their report, "included 26 coral species thought to be restricted to hosting a single Symbiodinium clade," which latter corals they refer to as symbiotic specialists.
In doing so, the three U.S. scientists say they "detected at least two Symbiodinium clades (C and D) in at least one sample of all 39 coral species tested," while "all four Symbiodinium clades were detected in over half (54%) of the 26 symbiotic specialist coral species." And they report that, "on average, 68% of all sampled colonies within a given coral species hosted two or more symbiont clades."
In light of their several discoveries, Silverstein et al. conclude that "the ability to associate with multiple symbiont clades is common in scleractinian (stony) corals," and that in regard to coral-algal symbiosis, "specificity is rarely absolute." And on this basis they express their opinion that "the potential for reef corals to adapt or acclimatize to environmental change via symbiont community shifts may therefore be more phylogenetically widespread than has previously been assumed."