Phylogenetic analyses of potentially free-living Symbiodinium spp. isolated from coral reef sand in Okinawa, Japan
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The existence of “free-living” Symbiodinium that can form symbioses with hosts is implied by the presence of hosts that produce Symbiodinium-free gametes and expulsion and/or expelled symbiotic algae from host. However, it is still unclear if potentially symbiotic Symbiodinium are found “free-living” in the coral reef environment. Sixteen Symbiodinium strains were established from samples taken from three sampling locations of coral reef sand in Okinawa, Japan. Phylogenetic analyses of the partial large subunit ribosomal DNA (28S-rDNA) and the internal transcribed spacer of ribosomal DNA (ITS-rDNA) conclusively showed that all 16 isolates belonged to Symbiodinium clade A sensu Rowan and Powers (1991). The lack of other Symbiodinium clades besides clade A in this study may be due to other clades not being readily culturable under culture conditions used here. The new isolates could be phylogenetically divided into four groups, though no sequences were identical to previously reported Symbiodinium. Two of the four groups were closely related to symbiotic Symbiodinium clade A isolated from a variety of host species. One isolate group formed a highly supported monophyly with Symbiodinium types that have previously been characterized as “free-living”. The remaining isolate group, although within clade A, was quite divergent from other clade A Symbiodinium. These results indicate that novel diversity of free-living Symbiodinium exists in coral sand.
KeywordsCoral Reef Markov Chain Monte Carlo Sand Sample Giant Clam Coral Sand
This study was partly supported by the twenty-first Century COE Program of the University of the Ryukyus. The authors thank Dr. Kiyotaka Takishita (JAMSTEC) for his critical comments that greatly improved the manuscript.
- Baker AC, Rowan R (1997) Diversity of symbiotic dinoflagellates (zooxanthellae) in screlactinian corals of the Caribbean and eastern Pacific. Proceeding 8th International Coral Reef Symposium 2:1301–1306Google Scholar
- Carlos AA, Baillie BK, Kawachi M, Maruyama T (1999) Phylogenetic position of Symbiodinium (Dinophyceae) isolates from tridacnids (Bivalvia), cardiids (Bivalvia), a sponge (Porifera), a soft coral (Anthozoa), and a free-living strain. J Phycol 35:1054–1062. doi: 10.1046/j.1529-8817.1999.3551054.x CrossRefGoogle Scholar
- Ishikura M, Hagiwara K, Takishita K, Haga M, Iwai K, Maruyama T (2004) Isolation of new Symbiodinium strains from Tridacnid giant clam (Tridacna crocea) and sea slug (Pteraeolidia ianthina) using culture medium containing giant clam tissue homogenate. Mar Biotechnol 6:378–385. doi: 10.1007/s10126-004-1800-7 CrossRefGoogle Scholar
- LaJeunesse TC (2001) Investigating the biodiversity, ecology, and phylogeny of endosymbiotic dinoflagellates in the genus Symbiodinium using the internal transcribed spacer region: in search of a “species” level maker. J Phycol 37:866–880. doi: 10.1046/j.1529-8817.2001.01031.x CrossRefGoogle Scholar
- LaJeunesse TC, Thornhill DJ, Cox E, Stanton F, Fitt WK, Schmidt GW (2004a) High diversity and host specificity observed among symbiotic dinoflagellates in reef coral communities from Hawaii. Coral Reefs 23:596–603Google Scholar
- LaJeunesse TC, Bhagooli R, Hidaka M, de Vantier L, Done T, Schmidt GW et al (2004b) Closely related Symbiodinium spp. differ in relative dominance in coral reef host communities across environmental, latitudinal and biogeographic gradients. Mar Ecol Prog Ser 284:147–161. doi: 10.3354/meps284147 CrossRefGoogle Scholar
- Moore RB (2006) Molecular ecology and phylogeny of protistan algal symbionts from corals. Ph.D. thesis, University of Sydney, p 390Google Scholar
- van Oppen MJH, Palstra FP, Piquet AMT, Miller DJ (2001) Patterns of coral-dinoflagellate associations in Acropora: significance of local availability and physiology of Symbiodinium strains and host-symbiont selectivity. Proc R Soc Lond B Biol Sci 268:1759–1767. doi: 10.1098/rspb.2001.1733 CrossRefGoogle Scholar
- Swofford D (2000) PAUP* 4.0b7a, Phylogenetic analysis using parsimony (*and other methods). Sinauer Associates, Sunderland, MAGoogle Scholar
- Taylor DL (1974) Symbiotic marine algae: taxonomy and biological fitness. In: Vernberg WE (ed) Symbiosis in the sea. University of Carolina Press, Columbia, pp 245–262Google Scholar
- Trench RK (1987) Dinoflagellates in non parasitic symbioses. In: Taylor FJD (ed) The biology of dinoflagellates. Blackwell Scientific Publications, Oxford, pp 530–570Google Scholar