High genetic diversity of the symbiotic dinoflagellates in the coral Pocillopora meandrina from the South Pacific

Abstract

Symbioses between dinoflagellates in the genus Symbiodinium (commonly referred to as zooxanthellae) and scleractinian corals are an essential feature for the maintenance of coral reefs. The fine-scale diversity and population structure of the zooxanthellae inhabiting the coral Pocillopora meandrina, a major reef building species in Polynesia, was examined. We used two polymorphic microsatellites to study seven populations from the South Pacific, whose host structuring has been previously investigated. The symbionts of P. meandrina showed high levels of diversity, with more than one zooxanthella genotype being identified in most of the host individuals. Genetic differentiation between sym-biont populations was detected at a large scale (2,000 km) between the Tonga and the Society Archipelagos. Within the Society Archipelago, the two most remote populations (Tahiti and Bora-Bora; 200 km apart) were only weakly differentiated from each other. Statistical tests demonstrated that the symbiont genetic structure was not correlated with that of its host, suggesting that dispersal of the symbionts, whether they are transported within a host larva or free in the water, depends mainly on distance and water currents. In addition, the data suggests that hosts may acquire new symbionts after maternal transmission, possibly following a disturbance event. Lastly, the weak differentiation between symbiont populations of P. verrucosa and P. meandrina, both from Moorea, indicated that there was some host-symbiont fine-scale specificity detectable at the genetic resolution offered by microsatellites.

Novel algal symbiont (Symbiodinium spp.) diversity in reef corals of Western Australia

“…100s of km) of Symbiodinum by ocean currents has not been extensively studied. However, Howells et al (2009) suggest that currents are the primary dispersal mechanism for Symbiodinium in horizontally transmitting coral species which do not pass Symbiodinium to their larvae (see also Magalon et al 2006). Although ITS-2 Symbiodinium diversity has yet to be well described from the Indo-Malay region (but see Loh et al 2001), we hypothesize that reefs in Western Australia are potentially 'sinks' for Indo-Malay Symbiodinium diversity.…”

“…To test this hypothesis, a combination of phylogenetic and population genetic analyses of Symbiodinium (e.g. Santos et al 2004, Magalon et al 2006, Kirk et al 2009, Pettay & LaJeunesse 2009 in the same species of coral from the Indo-Malay region and Western Australia will be necessary to characterize symbiont population structure over this broad geographic area.…”

Worldwide biogeography of Symbiodinium in tropical octocorals

“…Studies of other DNA regions such as internal transcribed spacer (ITS) regions of nuclear DNA (Baillie et al 2000, LaJeunesse 2001, van Oppen et al 2001, the 23S rDNA of chloroplasts (Santos et al 2002, Pochon et al 2006, psbA minicircle (Barbrook et al 2006), mitochondrial sequences (Takabayashi et al 2004), and microsatellites , Magalon et al 2006 support the cladal relationships based on ssRNA and lsRNA and provide within-clade resolution. Most reports have identified Symbiodinium at the clade level.…”

“…Santos et al 2003b, Magalon et al 2006, the broad clade level, and all levels in between, with each level providing important information about the symbioses. Clade-level comparisons are informative.…”

One-year survey of a single Micronesian reef reveals extraordinarily rich diversity of Symbiodinium types in soritid foraminifera

“…Although SSU and LSU rDNA-based markers have been extensively applied to deciphering appreciable levels of ecological and physiological variations in the genus Symbiodinium (Rowan and Knowlton 1995;Baker et al 1997;Rowan et al 1997;Belda-Baillie et al 1999;Carlos et al 1999;Karako-Lampert et al 2004;Chen et al 2005), the recent use of highly variable markers such as polymorphic microsatellites (Santos et al 2004;Magalon et al 2006), the plastid-coding psbA minicircle (Barbrook et al 2006) and nrDNA Internal transcribed spacer regions (LaJeunesse 2001;Rodriguez-Lanetty 2003;van Oppen et al 2001van Oppen et al , 2005a have revealed additional phylogenetic structure within each Symbiodinium clade. General knowledge of Symbiodinium diversity, speciWcity and distribution has been greatly increased by several surveys of Symbiodinium ITS-2 diversity within entire reef invertebrate communities, comprising diverse species of hard corals, soft corals, gorgonians, anemones, zoanthids, corallimorphs, tridacnid clams and nudibranchs (LaJeunesse 2002(LaJeunesse , 2005LaJeunesse et al 2003LaJeunesse et al , 2004a.…”