Figure 2.

Geographic distribution of Porites/Symbiodinium associations. (a) Proportion of Symbiodinium rDNA ITS2-type C3 and C3-Gulf ITS2 variant marker sequences detected in Porites spp. corals from within eight locations in the PAG and the Gulf of Oman (Dalma to Muscat, Figure 1a; Supplementary Table S4) and in corals from reference regions. All available reference C3 sequences were retrieved from GeoSymbio (https://sites.google.com/site/geosymbio/database) and GenBank (https://www.ncbi.nlm.nih.gov/genbank/) and included independent of the taxonomic background of the host corals. The number of analysed sequences/number of analysed colonies are shown in brackets next to the bars. (b) Phylogenetic tree produced by Bayesian inference analysis of psbA^ncr sequences from C3-type zooxanthellae samples from the PAG, Musandam and the Gulf of Oman (colour coded as indicated in the legend) and from zooxanthellae of the C3-type and closely related variants from elsewhere (regions detailed in the figure). psbA^ncr sequences of S. thermophilum from the PAG (Hume et al., 2015) were included for reference (open circles). Branches are drawn to scale as indicated by the bar. The separation of the S. thermophilum group in the PAG and the Gulf of Oman from the group containing the available sequences from elsewhere in the world is supported with a posterior probability value of 1.0. All accession numbers of the psbA^ncr sequences used in the analysis are given in Supplementary Tables S5 and S6.