11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 26: Biodiversity and Diversification of Reef Organisms
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Integrative Taxonomy And Phylogeny Of The Siderastreid Scleractinian Corals
Francesca BENZONI* 1 , Fabrizio STEFANI 2 , Jaroslaw STOLARSKI 3 , Michel
PICHON 4 , Paolo GALLI 2
1 Dept. of Biotechnologies and Biosciences, University of Milan-Bicocca, Milano, Italy,
2 Dept. of Biotechnologies and Biosciences, University of Milan-Bicocca, Milan, Italy,
3 Instytut Paleobiologii PAN, Warszawa, Poland, 4 Ecole Pratique des Hautes Etudes,
Perpignan, France
Integrative taxonomy is currently recognised by many as the solution to the “taxonomic
crisis”. However, the use of a multi-disciplinary approach to the study of species
boundaries in Scleractinia has been, so far, limited. Molecular techniques have provided
new opportunities to explore taxonomic boundaries and the phylogeny of taxa
traditionally identified according to incongruence of macro-morphological characters of
the skeleton and have shown that the traditional coral classification is frequently not
congruent with the molecular results. However, skeleton morphology remains the most
commonly used tool for the identification of coral taxonomy, is the only link between
extant corals and the fossil record, and thus indispensable for reconstruction of the
complete scleractinian phylogenetic tree.
The family Siderastreidae includes six genera (Siderastrea Blainville, 1830, Psammocora
Dana, 1846, Coscinaraea Milne Edwards and Haime, 1848, Anomastraea Marenzeller,
1901, Pseudosiderastrea Yabe and Sugiyama, 1935, and Horastrea Pichon, 1971)
grouped together based on frequent presence of synapticulae and the fusion of septa. We
re-assessed the taxonomy and phylogeny of the Siderastreidae through a multidisciplinary
approach including the morphologic study of the polyp, morphometric analysis of the
corallite structures, skeletal microstructures, and the molecular analysis of both a nuclear
and a mitochondrial markers. The morpho-molecular study of the Siderastreidae
confirmed the partial results previously obtained by other molecular studies indicating
that the genera, and some species, currently ascribed to the family belong to different
phylogenetic lineages and that commonly used skeletal macro-characters are not
necessarily the most informative ones. In particular, the deepest divergence detected
separates Pseudosiderastrea and Siderastrea from the remaining genera, and indicates
that the genera Psammocora and Coscinaraea are not monophyletic. The re-evaluation of
the polyp and skeleton characters and of previously disregarded macro and
microstructures have proved phylogenetically informative when combined with
molecular results.
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Mitochondrial And Nuclear Genes Suggest That Stony Corals Are Monophyletic
But Most Families Of Stony Corals Are Not
Nancy KNOWLTON* 1 , Hironobu FUKAMI 2 , Allen CHEN 3 , Ann BUDD 4
1 National Museum of Natural History, Smithsonian Institution, Washington, DC, 2 Seto
Marine Biological Laboratory, Kyoto University, Shirahama, Japan, 3 Research Centre for
Biodiversity, Academia Sinica, Taipei, Taiwan, 4 Department of Geoscience, University
of Iowa, Iowa City, IA
Modern hard corals (Class Hexacorallia; Order Scleractinia) are widely studied because
of their fundamental role in reef building and their superb fossil record extending back to
the Triassic. Nevertheless, interpretations of their evolutionary relationships have been in
flux for over a decade. Recent analyses undermine the legitimacy of traditional suborders,
families and genera, and suggest that a non-skeletal sister clade (Order Corallimorpharia)
might be imbedded within the stony corals. However, these studies either sampled a
relatively limited array of taxa or assembled trees from heterogeneous data sets. Here we
provide a more comprehensive analysis of Scleractinia (127 species, 75 genera, 17
families) and various outgroups, based on two mitochondrial genes (cytochrome oxidase
I, cytochrome b), with analyses of nuclear genes (beta-tubulin, ribosomal DNA) of a
subset of taxa to test unexpected relationships. Eleven of 16 families were found to be
polyphyletic. Strikingly, over one third of all families as conventionally defined contain
representatives from the highly divergent “robust” and “complex” clades. However, the
recent suggestion that corallimorpharians are true corals that have lost their skeletons was
not upheld. Relationships were supported not only by mitochondrial and nuclear genes,
but also often by morphological characters which had been ignored or never noted
previously. The concordance of molecular characters and more carefully examined
morphological characters suggests a future of greater taxonomic stability, as well as the
potential to trace the evolutionary history of this ecologically important group using
fossils.
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Phylogenetics And Morphological Evolution Of Scleractinian Corals.
Marcos BARBEITOS* 1,2 , Sandra ROMANO 3 , Howard LASKER 4
1 Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 2 Biological Sciences,
University at Buffalo, Buffalo, 3 Division of Science and Mathematics, University of the Virgin
Islands, St. Thomas, Virgin Islands (U.S.), 4 Department of Geology, University at Buffalo,
Buffalo, NY
Scleractinian corals are modular organisms of great ecological and economic importance which
grow in either solitary or colonial forms. Over recent years, molecular phylogenetic analyses
have repeatedly made it clear that Scleractinian taxonomy does not reflect phylogenetic
relationships within the order. Pervasive plasticity of skeletal characters and evolutionary
convergence make it very difficulty to infer homology when using traditional diagnostic
characters. Unlike the current classification schemes, molecular phylogenies suggest the
presence of separate lineages in different biogeographic provinces, and have even challenged
the monophyly of the order. Perhaps because they are easier to sample, the majority of recent
analyses have concentrated on symbiotic reef corals, but half of the extant Scleractinian species
are azooxanthellate and are uncommon on coral reefs. We conducted comprehensive
phylogenetic reconstructions of the group using partial sequences from a nuclear and a
mitochondrial marker (rRNA genes 28S and 12S, respectively). Bayesian and parsimony
analyses recovered a monophyletic Scleractinia clade, rejecting the “naked coral hypothesis”.
Additionally, our analyses recovered well supported clades containing both azooxanthellate taxa
that are not normally found in coral reefs and zooxanthellate, reef-dwelling, highly integrated
colonial species. The large morphological disparity between these two groups contrasts with
the small genetic distances. This pattern can be explained by loss of coloniality via
heterochronic processes, which allow for substantial morphological change with minimal
genetic reprogramming. Such losses may have been adaptive or exaptive in the context of
global change. This hypothesis was corroborated by Bayesian reconstruction of ancestral
character states. These results suggest that evolution of coloniality in corals may have been
much more dynamic than previously suspected. The link between reef and non-reef coral
species points towards the need for more extensive taxonomic sampling of the latter in future
phylogenetic reconstructions of the order.
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New Trends in Scleractinian Coral Phylogeny Interpretation: Towards A Solution To Old
Taxonomic Wrangles ?
Michel PICHON* 1 , Francesca BENZONI 2 , Jaroslav STOLARSKI 3
1 Biologie Ecologie tropicale et mediterraneene, Ecole Pratique des Hautes Etudes, Perpignan,
France, 2 Biotecnologie e Biocienze, University of Milano-Bicocca, Milano, Italy, 3 Instytut
Paleobiologii PAN Warsawa, Warszawa, Poland
The first scleractinian coral species were described by Linnaeus in his «t», which saw the birth
of the binomial zoological nomenclature. The supra-generic basis for scleractinian
classification was however very loose, and it is fair to say that it became better organized thanks
to the work of eminent palaeontologists, who took advantage of the long fossil record and the
fossilization potential of scleractinian corals. Thus, for over a century, scleractinian coral
phylogeny interpretation (and hence classification) was essentially morpho-taxonomic, and
exclusively based on skeletal structures. During that time,very few attempts have been made by
zoologists to utilize the characters of the living organism. In parallel, a growing awareness of
intraspecific variability became widespread and the shortcomings of the traditional purely
morpho-taxonomic approach more and more obvious. In the last few decades, new tools were
developed so as to improve on a situation deemed less than satisfactory. The usefulness of
skeletal microstructures (almost totally forgotten for a while) was re-emphasized, and other
avenues were also explored to provide more robust information on species boundaries, in
addition to that given by the traditional morpho-taxonomic approach: Physiological and
ecophysiological characters were introduced to help discriminating between species, and more
recently, molecular genetics. At the same time, characters of skeletal structures colony shape,
corallite parameters) were revisited with the help of powerful techniques such as
morphometrics, with a large array of statistical data processing methods, and fractal analysis of
colony surface characters. There is now a large spectrum of techniques available to the
scleractinian coral taxonomist, and if none of the approaches mentioned above can, in isolation,
give a satisfactory answer, their simultaneous implementation is, in most instances able to solve
taxonomic wrangles inherited from the past situation. Practical examples of the results obtained
by such a combined approach are given.
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