11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 26: Biodiversity and Diversification of Reef Organisms
26-46
Geographic Structure and Cryptic Species in Oculina Inferred from Nuclear Gene
Sequences
Michael HELLBERG* 1 , Ron EYTAN 2 , Marshall HAYES 3 , Margaret MILLER 4
1 Biological Sciences, Louisiana State University, Baton Rouge, LA, 2 Louisiana State
University, Baton Rouge, LA, 3 Duke University Marine Lab, Beaufort, NC, 4 NOAA
Fisheries, Miami, FL
Colony form is often highly plastic within coral species, leading to taxonomic confusion
that cripples efforts to understand the biology of species or to manage their populations.
This may be especially troublesome for species found in a variety of habitats. Species of
the genus Oculina occur along the southeastern coast of the United States and into the
Caribbean. Their forms range from small, shallow water colonies that tolerate turbid
conditions without bleaching, to deep water azooxanthellate colonies that form reefs
extending up to 10 m off the substrate. Our objective was to assess the history of genetic
connectivity among nominal species, populations found at different depths, and
populations from along ca. 2000 km of their range along the southeastern coast of the US.
Although sequence markers are best suited for drawing inferences about population
history, mtDNA in anthozoans has proven too slowly evolving for use within species. As
an alternative, we developed three nuclear sequence markers from expressed sequence
tags (EST's) drawn from a cDNA library. Comparisons with a confamilial species
(Solenastrea bournoni) shows the three nuclear gene regions evolve at rates ten times
faster than mitochondrial COI. Variation within these genes reveals no differentiation
between nominal species nor between shallow (1 m) and mid-depth (30 m) populations
from the same locale. However, populations did vary geographically, with a pronounced
attenuation of variation to the north of Cape Canaveral consistent with a historical range
expansion. Most notably, the population from the deep water Oculina Banks (> 80 m)
were more distinct than any other sampled, with two of three loci consisting solely of
alleles found nowhere else, a degree of differentiation suggesting long term genetic
isolation.
26-47
Using The Toolbox On Acroporidae
Carden WALLACE* 1
1 Museum of Tropical Queensland, Townsville, Australia
The scleractinian family Acroporidae has maintained a major role in the waxing and
waning of coral assemblages and evolution of species diversity, through time and
throughout the world, to become a dominant family on modern Indo-Pacific reefs, and its
type genus Acropora the most diverse coral genus. New information from molecular
studies has prompted neontologists and paleontologists to re-examine membership of this
family and re-assess the evolutionary and biogeographic consequences of various life
histories and morphologies. So far, we have elevated Isopora (a subgenus of Acropora)
to genus, and are considering combining Montipora and Anacropora, and changing the
family status of Alveopora, all changes indicated by molecular phylogenies and
supported by other evidence. In modern and paleontological distribution studies, it has
been found that the widespread Indo-Pacific genus Isopora was briefly present and
abundant in the southern Caribbean before becoming extinct there, and that Acropora
already exhibited much of its current structural diversity during its build-up on European
reefs, before post-Miocene Indo-Pacific diversification. Because Isopora and Acropora
have differing reproductive strategies (viviparity versus oviparity respectively),
clarification of their taxonomy, modern distribution and paleoecology are indicating the
extinction vulnerability incurred by the different strategies under differing environmental
scenarios. Dendracis, which occurred in western Indian Ocean, Mediterranean and
Caribbean, became extinct by the Miocene, possibly due to a poor potential for
morphological variation relative to Acropora, although the almost equally non-diverse
Astreopora has survived to the present day. This paper will present an update on the
research and researchers involved in the taxonomic renaissance of Acroporidae and the
application of the new findings to new issues in coral reef biology.
26-48
Need For A More Integrative Approach To Scleractinian Taxonomy
Vassil ZLATARSKI* 1
1 Independent Consultant, Bristol, RI
Different approaches have been used for scleractinian taxonomy. The original taxonomy was
typological and based on skeletal parts. Then, the variability of the coralla was recognized at
the end of the 19th century. In 1930’s very detailed skeletal studies of fossil and extant
scleractinians began. After 1960 scuba facilitated in situ observations and sampling and helped
reveal a global variability that challenged taxonomy. Beginning in the 1980’s the discoveries
of molecular genetics and life history offered new taxonomic tools. In the last years a
taxonomy based on the genetic method found some gross-morphology characters to be
homoplasious rather than represent common descent. These molecular data contradict the
conventional systematics, but appear to be compatible with detailed paleontological skeletal
studies.
Presently, there are four sources of scleractinian taxonomic information: morphology,
paleobiology, developmental biology, and molecular genetics. Only the efficient collaboration
of specialists using all existing lines of evidence can combine these data into an improved
integrative taxonomy.
It is therefore imperative to form an international body of taxonomists of extant and fossil
scleractinians, to develop and prioritize goals in global, regional and specific cases, and to
coordinate efforts to solve the fundamental and applied taxonomic tasks. These efforts should
gain from more complete sampling, field observations and experiments, application of digital
tools, usage of cyberinfrastructure, improved collection preservation, and virtual access to
collections, along with training of taxonomists to meet the tasks. The present state of the
fundamental taxonomy is reflected in the quality of the applied taxonomy and explains the
shortage of reliable coral-identification tools necessary for better understanding and
preservation of reef diversity.
26-49
Intragenomic Its2 Variation: Low Rates Of Concerted Evolution Are Concordant With
Recent Species Radiations in Reef Octocorals
Juan SANCHEZ* 1 , Camila GRANADOS 1 , Daniel DORADO 1 , Nestor ARDILA 1 , Nelson
MANRIQUE 1 , Luisa DUEÑAS 1 , Olga TORRES 1 , Martha CARDENAS 1 , Santiago
HERRERA 1 , Claudia AGUDELO 1
1 Biological Sciences, Universidad de los Andes, Bogota, Colombia
The internal transcribed spacer 2 is part of the nuclear ribosomal cistron, whose secondary
structure has an important function for the ribosome assembling. For a number of years,
contrasting results in terms of inter- and intra-specific ITS2 variation have been found in a
number of taxa including reef cnidarians. There are different results finding either single or
multiple intragenomic variants, even pseudogenes, which have brought a great deal of
confusion regarding the evolution and usefulness of ITS2 for phylogenetic reconstruction as
well as the generality of the nRNA concerted evolution process. We examined ITS2 copies in a
diverse number of Atlantic and Pacific octocorals (Octocorallia: Cnidaria) using Denaturing
Gradient Gel Electrophoresis (DGGE) coupled with DNA sequencing, phylogenetic
approaches, and prediction of RNA secondary structures. First we found that morphologically
diverse taxa exhibited high intragenomic variation. Candidate pseudogenes were seldom found
in a few octocorals but most of the multiple intragenomic ITS2 variants were functional
according to secondary structure predictions. These low rates of concerted evolution in ITS2,
i.e. multiple intragenomic functional ITS2 copies, were concordant with low substitution rates
in mitochondrial DNA within multiple-taxa and morphologically diverse octocoral clades. A
few intraspecific analyses revealed also that some of the ITS2 copies are shared among
populations and might follow gene flow patterns. Moreover, we suggest that low rates of
concerted evolution, such as multiple intragenomic ITS2 variants, are concordant with recent
species radiations in octocorals, as seen as diverse closely related species with high
morphologic diversity but low mitochondrial divergence. What process is driving such rapid
radiation and increased phylogenetic diversity is still unknown in reef octocorals.
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