Latitudinal variation in the symbiotic dinoflagellateSymbiodiniumof the common reef zoantharianPalythoa tuberculosaon the Saudi Arabian coast of the Red Sea

Abstract
Aim

The Red Sea presents an ideal setting to explore the variability of Symbiodinium over environmental, latitudinal and geographical gradients. We used sequences from two molecular markers to examine genetic diversity of Symbiodinium associated with the widely distributed zoantharian Palythoa tuberculosa in the northern and central Red Sea. Location

Northern and central Red Sea. Methods

Specimens (n = 329) were collected from 15 locations. Sequence data from nuclear ribosomal ITS2 (n = 269) and chloroplast minicircle psbAncr (n = 173) were phylogenetically analysed (maximum likelihood, neighbour joining), and Symbiodinium types identified for each P. tuberculosa colony. To establish whether environment was a strong predictor of Symbiodinium psbAncr lineage, SST, chlorophyll-a, salinity, and depth data were fit into a multinomial logistic regression using the package VGAM in the R statistical environment. Results

Based on ITS2 and psbAncr results, P. tuberculosa colonies were shown to be in symbioses with Symbiodinium clade C (n = 172) and clade D (n = 1). Within clade C, four psbAncr lineages were observed; closely related lineages designated Pt-1-a and Pt-1-b, and closely related lineages Pt-3-a and Pt-3-b. By location, Pt-1-a dominated the sites within the Gulf of Aqaba (c. 86%, 37/43 colonies). At the entrance to the Gulf of Aqaba, Pt-3-a dominated (c. 88%, 15/17), while the more southern remaining sites in the Red Sea were dominated by Pt-3-b (c. 78%, 89/113). Main conclusions

Multinomial logistic regression analyses established that predictions based on the combination of temperature, chlorophyll-a and salinity accurately reflected symbiont distributions in the central and northern Red Sea. Palythoa tuberculosa host Pt-1-a in the coldest region, the Gulf of Aqaba (annual average SST = 24.5–25.0 °C), while immediately to the south Pt-3-a dominates (SST = 26.0–26.5 °C), with warmest southern sites dominated by Pt-3-b (SST > 26.5 °C). The Gulf of Aqaba is a unique environment, and more research on Symbiodinium outside the Gulf is required to understand symbiont diversity patterns within the Red Sea.

Citation
Reimer JD, Herrera M, Gatins R, Roberts MB, Parkinson JE, et al. (2016) Latitudinal variation in the symbiotic dinoflagellateSymbiodiniumof the common reef zoantharianPalythoa tuberculosaon the Saudi Arabian coast of the Red Sea. Journal of Biogeography. Available: http://dx.doi.org/10.1111/jbi.12795.

Acknowledgements
This research was supported by award No. 1389-CRG1 and baseline funding from the King Abdullah University of Science and Technology (KAUST) to M.L.B. The following people are thanked for logistical support: A. Magnum Kattan, J. Bouwmeester, L. Chen, J. DiBattista, A. Gusti, A. Macauley, C. Nelson, M. Priest, and T. Sinclair-Taylor of KAUST, and the crew of the MY ‘Dream Master’. J.P. Hobbs and D. Uyeno are thanked for sampling help. The first author was additionally supported in part by the International Research Hub Project for Climate Change and Coral Reef/Island Dynamics at the University of the Ryukyus. S. Guindon is thanked for advice with PhyML, K. Takishita for phylogenetic analyses and T. Soliman for help with PopART. Seven referees’ comments greatly improved the manuscript.

Publisher
Wiley

Journal
Journal of Biogeography

DOI
10.1111/jbi.12795

Additional Links
http://onlinelibrary.wiley.com/doi/10.1111/jbi.12795/full

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