Genotypic diversity and spatial–temporal distribution of Symbiodinium clones in an abundant reef coral

Abstract

Genetic data are rapidly advancing our understanding of various biological systems including the ecology and evolution of coral-algal symbioses. The fine-scale interactions between individual genotypes of host and symbiont remain largely unstudied and constitute a major gap in knowledge. By applying microsatellite markers developed for both host and symbiont, we investigated the intra-colony diversity, prevalence and stability of Symbiodinium glynni (type D1) multilocus genotypes in association with dense populations of Pocillopora at two sites in the Gulf of California. The genetic diversity and allelic frequencies in reef populations of S. glynni remained stable over three years. Common clone genotypes persisted over this period and no temporal population subdivision (ΦPT = 0.021 & −0.003) was detected. Collections from circular plots showed no statistical correlation between related Pocillopora individuals and their associations with particular S. glynni genotypes, with no spatial structuring or clonal aggregation across a reef for the symbiont. From permanent linear transects, samples were analyzed from multiple locations within a colony and some were re-sampled ~one year later. Many of these multi-sampled colonies (~ 53%) were dominated by a single S. glynni genotype and tended to associate with the same symbiont genotype(s) over time, while colony ramets often possessed unrelated symbiont genotypes. In contrast to the species level, associations between genotypes of Pocillopora and S. glynni are apparently more flexible over space and time. The abundance of sexually recombinant genotypes of S. glynni combined with greater flexibility might provide adaptive mechanisms for these symbioses to evolve rapidly to changes in environmental conditions, and allow particular symbiont genotypes to spread through a host population.

Symbiodinium spp. in colonies of eastern Pacific Pocillopora spp. are highly stable despite the prevalence of low-abundance background populations

“…The haphazard pattern of background symbiont dynamics is possibly a sampling artifact due to the removal of coral tissue from different locations between the respective years. The relative abundance of each Symbiodinium sp., as well as distinct genotypes within a single symbiont species, can vary at different locations within some individual colonies (Pettay et al 2011).…”

Microbial invasion of the Caribbean by an Indo-Pacific coral zooxanthella

“…2 A and B) (24,25). Other members of this group, including Symbiodinium "glynni" (nomen nudum = type D1), also exhibit high allelic and genotypic diversity in the Indo-Pacific (20,22) (Fig. S2D).…”

“…Finally, as mentioned above, S. trenchii behaves opportunistically and can successfully invade the colonies of many coral species experiencing physiological stress (analogous in some ways to "disturbed habitats") (16,21). Therefore, we tested the hypothesis that populations of Atlantic S. trenchii represent a recent invasion by examining interindividual genotypic diversity and divergence across the IndoPacific and Greater Caribbean using high-resolution microsatellite loci (22,23).…”

Glucose-Induced Trophic Shift in an Endosymbiont Dinoflagellate with Physiological and Molecular Consequences

“…Cnidarian hosts often appear to be populated by just one or a very small number of Symbiodinium strains, with some symbiont-host associations appearing to be highly specific while others are more flexible and can change over developmental time and space (LaJeunesse, 2002;Goulet and Coffroth, 2003;Andras et al, 2011;Pettay et al, 2011). There may also be free-living Symbiodinium strains (Manning and Gates, 2008;Hansen and Daugbjerg, 2009;Pochon et al, 2010).…”