Diversity, Phylogeography, and Taxonomy of Hard-Corals in the Genus Porites from the Arabian Peninsula

Abstract

The genus Porites is one of the most important scleractinian genera in terms of species diversity and panmictic tropical distribution. However, Porites is notorious for challenging taxonomic identification based on colony gross morphology, micromorphology, and single gene analyses, suggesting that the current classification poorly represents real evolutionary relationships. This research integrates skeletal morphology data and single locus genetic evidence with genome-wide analyses and alternative line of evidence to taxonomy (i.e. symbiotic association data), with the aim of clarifying biodiversity, biogeography, and taxonomy of Porites from the Arabian Peninsula. In this dissertation, I evaluated the diversity of Porites in the Red Sea and the Gulf of Aden, providing a basic morpho-molecular background to the taxonomy of Porites in the region, and highlighting that a) the current taxonomic and phylogenetic position of 15 Porites morphological species needs to be reassessed, and that b) coral biodiversity in the Arabian region needs to be re-evaluated. To address this, I reconstructed the complete mitochondrial genomes of two endemic Red Sea species, contributing a solid framework for clarifying the phylogeny and taxonomy of Porites in future molecular studies. I implemented the morpho-molecular results with high-throughput sequencing data, generating a comprehensive hypothesis of species boundaries and biogeography of Porites in the seas surrounding the Arabian Peninsula. These results suggested that 15 morphological species from this region, were clustered into eight molecular lineages, two of which previously unknown. Finally, using the nuclear Internal Transcribed Spacer II (ITS2) marker in a high-throughput sequencing framework, I presented evidence derived from symbiotic association of Porites with dinoflagellates in the family Symbiodiniaceae. Symbiont diversity showed patterns of geographic-specific association at multiple levels, including at the level of Symbiodiniaceae genera, majority ITS2 sequences, and ITS2 type profile levels. Specific associations with host genotypes were also recovered, providing a further line of evidence that the current taxonomy of Porites is in need for revision. This dissertation highlights the utility of an integrated approach to taxonomy in elucidating species boundaries and phylogenetic relationships in Scleractinia and represents a framework that could be applied to other taxa awaiting revision.