11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 26: Biodiversity and Diversification of Reef Organisms
26-25
Diversity And Speciation Of Coral-Dwelling Barnacles in The Genus trevathana
(Balanomorpha: Pyrgomatidae): A Case Of Host-Race Speciation?
Maria Celia MALAY* 1
1 Dept of Zoology & Florida Museum of Natural History, University of Florida,
Gainesville, FL
The Pyrgomatidae is a unique, understudied family of balanomorph barnacles that has
very successfully radiated as epizootic symbionts on living corals. Pyrgomatid barnacles
show remarkable morphological trends in specialization for symbiosis, including highly
derived and reduced skeletal elements and coral parasitism in at least one lineage. In this
study my goal is to elucidate species diversity and mechanisms of speciation in the Indo-
Pacific pyrgomatid genus Trevathana. Trevathana is morphologically apomorphic, has
the widest geographic range of all pyrgomatid genera, and lives exclusively on faviid
corals. In these respects it contradicts earlier hypotheses that proposed an inverse
relationship between pyrgomatid morphological apomorphy and geographical and host
ranges. Phylogenetic (DNA sequence) and morphological data from new collections of
pyrgomatids have uncovered at least 6 previously-undescribed evolutionarily significant
units (ESUs), effectively doubling species diversity in this genus. Moreover almost all
Trevathana ESUs are specific to a single coral host, and multiple ESUs are sympatrically
distributed. This talk will explore the possibility that Trevathana diversification has
proceeded through sympatric host-switching events.
26-26
Molecular Diversity And Specificity Of Waminoa Sp. Worms Associated With
Corals in The Gulf Of Eilat (Red Sea).
Orit BARNEAH* 1 , Eitan BEN-DOV 1 , Yehuda BENAYAHU 2 , Itzchak BRICKNER 2 ,
Ariel KUSHMARO 1
1 1Department of Biotechnology Engineering, Ben-Gurion University P. O. Box 653,
Be'er-Sheva 84105 Israel, Be'er-Sheva 84105, Israel, 2 Departmrnt of Zoology, Tel-Aviv
University Ramat Aviv, Tel Aviv 69978, Israel., Tel Aviv, Israel
Acoel worms belonging to the genus Waminoa are known to be epizoic on 14 coral
species in Eilat's reefs. A single species named Waminoa brickneri was identified from
this location according to morphological features of the sexual reproduction system.
Waminoa worms found on various coral hosts differed in size and possessed different
sub-clades of Symbiodinium symbionts, thus suggesting the existence of different species.
The main objectives of the present research were to study the diversity of Waminoa
worms and to reveal the specificity of the relationship with their coral hosts. We
constructed 9 DNA clone libraries, originating from worms that were removed from 5
different species of stony corals. 74 sequences of the 18S rRNA gene were obtained and a
phylogenetic tree was constructed. All the sequences displayed high similarity (≥97%) to
each other. The data shows 2 clusters of sequences: one containing 7 sequences from the
library originated from the coral Echinophyllia sp. and the second containing the rest of
the sequences which comprise a mixture of sequences from all other libraries. In addition,
algal 18S rRNA gene sequences retrieved from 3 DNA libraries were identified as
belonging to the genus Amphidinium, thus corroborating our previous morphological
findings regarding this algal symbiont.
Our results suggest that the 18S rRNA gene might not be sufficient for species-level
classification in the genus Waminoa and it is therefore suggested to use additional
sequences (e.g. ITS region) in order to obtain an improved resolution.
26-27
Host Specificity, Spatial Niche Diversity And Adaptations Of Coral-Associated Gobies in
The Northern Red Sea
Juergen HERLER* 1 , Markus DIRNWOEBER 1 , Lucie SCHIEMER 1 , Simone
NIEDERMUELLER 1
1 University of Vienna, Vienna, Austria
There are numerous specialized fishes that exploit a variety of spatially restricted habitats in
coral reefs, for example gobiids which live in association with live corals or coral rock. In the
Gulf of Aqaba (northern Red Sea), 21 species belonging to seven genera of tiny reef-associated
gobies were found, occupying a great range of spatial niches. Four genera (Gobiodon,
Paragobiodon, Bryaninops and Pleurosicya) are coral-associated among which
Gobiodon is the most prominent one. Coral growth forms constrain fish morphology and drive
adaptations. Differences in body shape and growth patterns were investigated in Gobiodon by
geometric morphometrics and related to interbranch width of preferred Acropora corals.
Restricted interbranch width provide fitness advantages for species that grow more compress,
because they attain larger body size in the same corals by being thinner. The swimming
performance, as tested in aquarium experiments by simulating different coral interbranch
spaces, was better in Gobiodon histrio than in G. rivulatus, two species which differ in
shape but overlap in habitat use and compete for host corals. Different shapes may even be
reflected in internal characters, such as the head skeleton. Specific microhabitat characteristics
may thus have driven adaptive radiation among these habitat specialists. Niche width (degree of
specialization) and different competitive abilities among species result in differential
consequences for species if coral colonies or entire communities become degraded. This was
shown by effects on the frequency of goby breeding pairs found in reefs of very different
conditions, where heavily damaged corals were up to 80% less frequently occupied. As postsettlement
movement experiments have revealed, breeding pairs build stable relationships and
prefer certain coral colonies and are thus extremely sensitive to coral degradation and habitat
loss.
26-28
Ribosomal Rna Reveals Phylogenetic Conservatism in The Evolution Of Host Associations
in Caribbean Symbiotic Zoanthids
Timothy SWAIN* 1
1 Department of Biological Science, Florida State University, Tallahassee, FL
Symbiotic zoanthids (Cnidaria, Anthozoa, Hexacorallia, Zoanthidea, Macrocnemina) form
associations with a diverse group of invertebrates (representing at least 5 phyla) in most major
benthic habitats with a bathymetric range from mangrove roots to the deep sea. The currently
accepted morphology-based taxonomy arranges zoanthid species with dissimilar host
associations into the same higher taxa, apparently challenging patterns of phylogenetic
conservatism often observed in the evolution of symbiotic associations. Shallow-water
Caribbean symbiotic zoanthids (10 species representing 2 families and 3 genera) form
associations with a single hydroid species and approximately 100 species of coral reef sponges
(representing 6 orders, 21 families, and 33 genera). The taxonomy of Caribbean symbiotic
zoanthids results in congeneric zoanthid species forming associations dissimilar hosts and
heterogeneric zoanthid species forming associations similar hosts.
The complete internal transcribed spacer region of the ribosomal RNA nuclear gene was PCR
amplified from multiple individuals representing each symbiotic zoanthid species collected
from 11 locations spanning the entire greater Caribbean region. Phylogenetic analyses resulted
in topologies that are paraphyletic for all zoanthid genera and families included in the analysis.
The clades of zoanthid species recovered by the phylogenies have similar host associations,
suggesting phylogenetic conservatism in zoanthid-host association evolution. A single example
of a zoanthid species switching hosts was detected within a clade where all other members
shared the same sponge hosts. The host switch was away from symbioses with sponges that
generally host photo-endosymbionts to symbioses with sponges that generally do not host
photo-endosymbionts and was accompanied by a loss of photosynthetic dinoflagellate
symbionts (Symbiodinium) of the zoanthid. The loss of Symbiodinium coinciding with a host
switch on the phylogeny maintains the match in photo-endosymbionts first detected by
examining the specificity of sponge hosts and zoanthid symbionts.
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