Center for Marine and Environmental Studies #2 John Brewer’s Bay, St. Thomas, USVI 00802 Tel: (340) 693-1380 Fax: (340) 693-1385

Phylogenetic Relationships among

Reef-building corals are the framework builders for reefs and a key player in the ecosystem. They are the that form the foundation of Virgin Islands coral reefs which provide protection from the open ocean, are an economic resource in terms of tourism and fisheries, are the source of chemical compounds of biomedical importance, and provide great natural beauty. Due to both natural and anthropogenic factors, coral reefs throughout the world are in peril. In order to better protect and conserve these important natural resources we must be able to recognize the animals that live in them and understand the relationships among them.

Reef-building corals belong to the order in the phylum , animals with stinging cells. Traditionally, scleractinian coral systematics have been based on skeletal characters. However, these characters are highly variable and in many cases their homologies are not well understood resulting in taxonomic uncertainties (Romano and Stake 2007). Consequently identifications can be problematic and understanding of relationships between genera and families has been confused. Molecular phylogenetic studies have provided a new perspective on relationships between genera and families, one that is in striking contrast to hypotheses based on morphology. Molecular phylogenetic studies at the species level have provided new insights into species formation in corals and connectivity between populations.

Weʼre using molecular tools to investigate the systematics of scleractinian corals. The two main areas of investigation are: 1) higher level phylogenetic relationships in the order Scleractinia, and 2) species level differences of morphologically similar corals that live sympatrically.

Molecular phylogenetic analyses of the order Scleractinia have resulted in a very different hypothesis for relationships of genera and families than has been proposed based on morphology (Romano and Palumbi 1996; Romano and Cairns 2000; Chen et al. 2002; Cuif et al. 2003; Fukami et al. 2004; Le Goff-Vitry et al. 2004; Barbeitos 2007; Fukami et al. 2008; Barbeitos et al. In prep). While morphological hypotheses divide the order into seven suborders (Fig. 1), molecular analyses suggest the order consists of two large clades, the Complex and Fig.1. Phylogenetic hypothesis for the Scleractinia based on morphology following Veron (2000). Robust corals, that diverged very early Colors represent suborders. on in the evolutionary history of the

1 Updated: March 2009 group (Fig. 2). Molecular analyses do not recover traditional orders and suggest that many families are polyphyletic. Although the most recent analysis by Fukami et al. (2008) provides Complex some resolution for relationships within the Complex and Robust corals, their analysis did not include any azooxanthellate (generally non reef-building) Robust taxa which represent about half the species in the order. Our analyses are designed to refine understanding of relationships within the two large clades while including azooxanthellate taxa in our sampling. We are Fig. 2. Molecular phylogenetic analysis of Scleractinia based on 566 bp collecting DNA sequences of the mitochondrial 16S rRNA gene from 68 species of scleractinians. from nuclear gene regions Only family names are shown. Colors represent suborders as in Fig. 1. Only branches supported by bootstrap proportions of greater than 70 and mitochondrial gene are shown. (Romano and Cairns 2000). regions from both reef- building and non-reef- building scleractinian corals. Undergraduates Cherissre Boateng and Elisha Jno- Baptiste who have been working on this project since June 2007 have conducted a good deal of this work.

While molecular techniques have been very useful for improving our understanding of higher level systematics in the Scleractinia, they have proved more difficult to use in examining species level differences. Markers routinely used to study species level differences in other groups of invertebrates are not as informative in anthozoans primarily due to slower rates of molecular evolution in this group (Shearer et al. 2002). In addition, interspecific hybridization events may complicate interpretation of molecular analyses (van Oppen et al. 2001; Van Oppen et al. 2002; Vollmer and Palumbi 2002). Despite these difficulties, molecular techniques are providing new insights into scleractinian species formation and relationships.

We are conducting a molecular phylogenetic analysis of Carribean Porites species. The genus is distributed circumglobally and Porites species are common, important inhabitants of Caribbean reefs. Our molecular analyses are designed to test the morphological hypothesis (Fig. 3) concerning relationships among the Caribbean

2 species as well as their relationship to Indo-Pacific species. There are two distinct morphologies, the finger corals (branching forms; Fig. 4) and the divaricata massive mustard hill corals (Fig. 5). P. branneri has a distinct porites blue coloration with an encrusting growth form that may also have finger-like projections. Its relationship furcata to other Caribbean species has been debated. branneri

Fig. 3. Phylogenetic hypothesis for asteroides relationships among Caribbean Porites species. Outgroups include the Indo- Pacific species P. compressa and the compressa confamilial genus Goniopora. Goniopora

The finger corals have been classified as either one variable species or three separate species based on morphological differences and electrophoretic data. Recent molecular analyses of a limited number of samples based on single copy nuclear genes (Stake 2007) do not support the hypothesis that the three species are genetically distinct. We are extending this analysis by using sequences from the nuclear ITS and three mitochondrial noncoding regions. We Fig. 4. Finger corals in the genus Porites. have collected ten samples of each species. Species differ morphologically in thickness of fingers and branching Analyses to date including 4-10 samples from each patterns. Some differences in allozymes species do not demonstrate genetic differences also exist. Left to right: divaricata, among the species (Lucas 2008). furcata, porites.

The mustard hill coral, P. astreoides, has two different co-occurring color forms which also have physiological differences (Gleason 1993). Morphometric and electrophoretic data demonstrate no significant differences between the color forms (Weil 1992; Potts et al. 1993). Preliminary molecular green phylogenetic analyses based on three mitochondrial brown non-coding gene regions do not demonstrate genetic differences between samples of the two different forms. Fig. 5. Color morphs of the mustard hill coral P. astreoides. Data from continuing work on these species will be The color morphs exhibit used to determine relationships among the different differences in microsporine-like species in this group and their relationship to Indo- amino acids. The green morph is shown on the left and the brown Pacific corals. Matthew Lucas did the molecular morph on the right. analyses of the finger corals for his Masterʼs Thesis

3 at Southeastern Missouri State University. He is now working on his PhD at the University of Puerto Rico, Mayaguez. UVI undergraduate Semoya Phillips collected morphological data on the finger corals. She is now in a Masterʼs program in Ecology and Evolutionary Biology at the University of Michigan. The majority of the data concerning P. asteroides was collected by undergraduate Tryphena Cuffy who is now working on her PhD in the Dept. of Genetics at the University of Iowa.

Partners The Cnidarian Tree of Life Project (funded by the National Science Foundation) coordinated by Paulyn Cartwright and Marymegan Daly.

Funding The National Science Foundation Assembling the Tree of Life Program. The National Science Foundation VI-EPSCoR Program. University of Puerto Rico Sea Grant Seed Money program. The National Institutes of Health MBRS-RISE and MARC programs.

Contact: Dr. Sandra L. Romano [email protected] +1-340-693-1389

Literature Cited

Barbeitos MS (2007) Phylogenetics and morphological evolution of Scleractinian corals Ph.D. dissertation. Biological Sciences, Buffalo Barbeitos MS, Lasker HR, Romano SL (In prep) Avoiding the devil in the deep blue sea: repeated loss of coloniality in Scleractinia may have allowed reef corals to overcome extinction Chen CA, Wallace CC, Wolstenholme JK (2002) Analysis of the mitochondrial 12S rRNA gene supports a two-clade hypothesis of the evolutionary history of scleractinian corals. Molecular Phylogenetics and Evolution 23: 137-149 Cuif J-P, Lecointre G, Perrin C, Tillier A, Tillier S (2003) Patterns of septal biomineralization in Scleractinia compared with their 28S rRNA phylogeny: a dual approach for a new taxonomic framework. Zoologica Scripta 32: 459-473 Fukami H, Budd AF, Paulay G, Sole-Cava AM, Chen CA, Iwao K, Knowlton N (2004) Conventional obscures deep divergence between Pacific and Atlantic corals. Nature 427: 832-835 Fukami H, Chen CA, Budd AF, Collins AG, Wallace CC, Chuang Y-Y, Chen C, Dai C-F, Iwao K, Sheppard C, Knowlton N (2008) Mitochondrial and Nuclear Genes Suggest that Stony Corals are Monophyletic but Most Families of Stony Corals are not (Order Scleractinia, Class , Phylum Cnidaria). PLoS One 3: e3222 Gleason DF (1993) Differential effects of ultraviolet radiation on green and brown morphs of the Caribbean coral . Limnology and Oceanography 38: 1452-1463

4 Le Goff-Vitry MC, Rogers AD, Baglow D (2004) A deep-sea slant on the molecular phylogeny of the Scleractinia. Molecular Phylogenetics and Evolution 30: 167- 177 Lucas MQ (2008) Molecular Phylogenetic Analyses Show No Genetic Divergence Between P. porites, P. furcata, P. divaricata (Cnidaria:Scleractinia: ). Dept. of Biology, Cape Girardeau Potts DC, Budd AF, Garthwaite RL (1993) Soft tissue vs. skeletal approaches to species recognition and phylogeny reconstruction in corals. Cour. Forsch.-Inst. Senckenberg 164: 221-231 Romano SL, Cairns SD (2000) Molecular phylogenetic hypotheses for the evolution of scleractinian corals. Bull. Mar. Sci. 67: 1043-1068 Romano SL, Palumbi SR (1996) Evolution of scleractinian corals inferred from molecular systematics. Science 271: 640-642 Romano SL, Stake JL (2007) Scleractinia. In: Daly M et al. Phylum Cnidaria: A review of phylogenetic patterns and diversity 300 years after Linnaeus, Zootaxa 1668:127- 182 Shearer TL, van Oppen MJH, Romano SL, Wörheide G (2002) Slow mitochondria DNA sequence evolution in the Anthozoa (Cnidaria). Molecular Ecology 11: 2495-2489 Stake JL (2007) Novel molecular markers for phylogenetic studies of scleractinian corals. PhD Dissertation. Dept. of Biology, Lafayette van Oppen MJH, McDonald BJ, Willis B, Miller DJ (2001) The evolutionary history of the coral genus (Scleractinia, Cnidaria) based on a mitochondrial and a nuclear marker: Reticulation, incomplete lineage sorting, or morphological convergence? MBE 18: 1315-1329 Van Oppen MJH, Willis BL, Van Rheede T, Miller DJ (2002) Spawning times, reproductive compatibilities and genetic structuring in the Acropora aspera group: evidence for natural hybridization and semi-permeable species boundaries in corals. Molecular Ecology 11: 1363-1376 Vollmer SV, Palumbi SR (2002) Hybridization and the Evolution of Reef Coral Diversity. Science: 2023-2025 Weil E (1992) Genetic and morphological variation in Caribbean and Eastern Pacific Porites (Anthozoa, Scleractinia). Preliminary results. In: Richmond RH (ed) Proceedings of the Seventh International Coral Reef Symposium. University of Guam Press, Guam, pp 643-655

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