" Checks and Balances " in the identification of Symbiodinium genetic diversity

The identification of genetic diversity in dinoflagellates belonging to the genus Symbiodinium has been the subject of numerous studies over the last decade. During this time, a variety of molecules have been utilized. Some of these loci offer a "coarse" (i.e., 18S-rDNA) view while others provide a much "finer" (i.e., DNA fingerprinting) portrait of diversity within Symbiodinium. The use of sequences from the ribosomal internal transcribed spacer (ITS) region has become a standard in categorizing genetic diversity of these dinoflagellates and has revealed a plethora of ecological "types" within the genus. For some of these "types", data from microsatellite loci has uncovered additional, biologically relevant, diversity. However, one cannot help to ask if this diversity is truly "real" or results from artifacts of the molecules or techniques that are utilized. Here, I discuss ways in which Symbiodinium ITS and microsatellite data can be "checked" for methodological and interpretation errors. These processes not only lead to a “balance” in our quantification of Symbiodinium diversity, but also provide novel insight into the biology of these unique organisms.