11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 26: Biodiversity and Diversification of Reef Organisms
26-21
Diversity And Diversification in The Southwest Indian Ocean (Program Anr Biotas)
J. Henrich BRUGGEMANN* 1 , Gustav PAULAY 2 , François MICHONNEAU 2 , Nicolas
HUBERT 1 , Mireille M.M. GUILLAUME 1,3
1 ECOMAR, Université de la Réunion, Saint-Denis, Reunion, 2 Florida Museum of Natural
History, University of Florida, Gainesville, FL, 3 Milieux et Peuplements Aquatiques,
UMR 5178 CNRS UPMC MNHN, Muséum National d'Histoire Naturelle, Paris, France
Biological diversity is unevenly distributed across the world. Both species richness and
endemism vary greatly across land and sea and often show localized peaks in
geographically restricted "hotspots". Eight of 10 marine hotspots lie adjacent to terrestrial
hotspots, suggesting that similar processes may be responsible for their origin and/or
maintenance. The Southwest Indian Ocean (SWIO) region is both a marine and terrestrial
biodiversity hotspot. It represents a varied terrain for evolutionary processes,
encompassing old as well as young island groups (e.g. Madagascar, the Mascarenes,
Seychelles and Comoros). We are examining patterns of diversity, differentiation, and
diversification in this region using integrative taxonomy and phylogenetic analysis of
rapidly evolving DNA markers in marine (invertebrates and fish) as well as terrestrial
organisms. Field work begun on Reunion Island, where new collections include ~400
species of molluscs, ~250 crustaceans, ~100 echinoderms, ~250 reef fishes, and ~100
species in other phyla. Approximately 30% of species collected are new records for
Reunion. An estimate based on echinoderms suggests that >5% represent new species.
About 60% of the species collected at Reunion are also represented by the same form or
sister species in recent collections from Pacific Oceania, allowing fauna-level
comparisons of differentiation on the scale of ocean basins. Species that show
differentiation on this scale will be subjected to detailed phylogeographic analysis within
the SWIO. Such a taxonomically-wide approach allows us to test what factors are
associated with different types and levels of differentiation.
26-22
Patterns Of Diversity, Endemism, Origination And Extinction On Coral Reefs:
Stomatopod Crustaceans
Marjorie REAKA* 1
1 Biology, University of Maryland, College Park, MD
Reef-dwelling stomatopods show roughly similar contours of Indo-Pacific diversity as
corals, reef fishes and cowries, having a very strongly accentuated peak in the Indonesian
area of the Indo-Australian Archipelago but also high diversity along the western Indian
Ocean shelf and especially Madagascar. The degree to which endemism corresponds to
this pattern depends upon the scale examined, with local endemics occurring everywhere
but regional endemics occurring disproportionately in the Indo-Australian Archipelago
and on the periphery of the wider Indian and Pacific Ocean realms. Like the greatest
proportion of coral reef organisms, the size frequency distribution of reef-dwelling
stomatopods is skewed toward small body sizes with restricted reproductive output,
dispersal and geographic range sizes. Small species, speciation and extinction are
concentrated in the central "hotspot" but also at the periphery of the regions, supporting a
"Merry Go Round" rather than a "Cradle" or a "Museum" hypothesis for the generation
and maintenance of Indo-Australian Archipelago diversity. However, the areas of high
diversity in the Indo-Australian Archipelago and in the western Indian Ocean also contain
species of large body size with greatly enhanced reproductive output, dispersal potential
and sizes of geographic ranges. The West to Central Pacific region appears to operate as
a "Sink", where extinction likely outpaces origination, leading to declining diversity but
considerable endemism.
26-23
Are Echinoderms From Mars? Insights Into Diversification And Biogeography From The
“most Bizarre” Animal Phylum.
Gustav PAULAY* 1
1 Florida Museum of Natural History, University of Florida, Gainesville, FL
While all animal phyla are defined and distinguished by the distinctiveness of their bioplans,
echinoderms are more distinct than most. Arguably echinoderms are the most apomorphic,
“bizarre” group of free-living animals. Their unusual morphological and physiological features
include major reorientations of body symmetry, loss of cephalisation, development of multiple,
complex, coelomic “plumbing” systems, mutable connective tissue, and a unique calcareous
endoskeleton. These apomorphies coexist with plesiomorphic metazoan features such as a
reliance on external fertilization and a diffuse, intra-epidermal nervous system. The resulting,
unusual bioplan has made echinoderms highly successful: they are among the largest, most
conspicuous, and ecologically important mobile invertebrates in a wide variety of marine
habitats, ranging from the abyss to coral reefs. Our knowledge as well as lack thereof of
echinoderms is striking, and has influenced thinking in other fields. For example echinoids
have served as model systems in molecular biology and marine speciation, yet like many
echinoderms, they have unusual diversification dynamics that do not generalize well to other
phyla. Most reef surveys focus in large part on echinoderms when attempting to document
“invertebrate diversity”, yet many if not most of the taxa enumerated in these represent cryptic
species complexes, making survey data not meaningful at the species level. Here I will explore
faunistic, taxonomic, and phylogenetic studies of echinoderms to ask whether and how these
animals differ in their evolutionary and distributional dynamics from other taxa on reefs.
Lessons learned from these bizarre animals improve our understanding of the biodiversity and
diversification of reef biota.
26-24
New Insights Into The Biodiversity And Evolution Of Aspidochirotid Holothurians
François MICHONNEAU* 1,2 , Kris NETCHY 3 , John STARMER 1,2 , Alexander KERR 3 ,
Gustav PAULAY 1
1 Florida Museum of Natural History, Gainesville, FL, 2 Department of Zoology, University of
Florida, Gainesville, FL, 3 Marine Laboratory, University of Guam, Mangilao, Guam
Understanding and management of coral reefs depend fundamentally on our ability to
distinguish and identify species, in conjunction with knowledge on their origin, distribution and
biological characteristics. Yet available information on reef biota remains often inadequate and
difficult to access. Aspidochirotid sea cucumbers are a case in point: they include the largest
and most conspicuous motile invertebrates on reefs, and are often severely overfished because
of their economical value. Identification of some harvested species, even though common, is
problematic. We are undertaking a revision of these organisms. Here we present results from a
molecular phylogeny on 200+ taxa, based on 2 mitochondrial gene regions. Results provide
insight into macroevolutionary transitions, diversification, and species limits. Holothurians
show substantial niche conservatism in latitudinal distribution, depth range, and feeding mode.
Heavy reliance on ossicles has led to a confused taxonomy: in some groups ossicles evolve
rapidly, possibly in response to variation in carbonate saturation levels, in others they are
conserved and mask substantial cryptic diversity. The latter is exemplified by the circumtropical
"species" Holothuria impatiens. This species complex revealed to consist of at least a dozen
reciprocally monophyletic, well-defined, evolutionary significant units (ESUs). Each major
tropical region has at least one endemic ESU, the East Pacific and Indo-West Pacific (IWP) host
multiple taxa. The latter include peripheral, archipelagic endemics as well as ESUs that range
across the entire IWP. Broad overlap in the range of some in combination with recent
divergence indicate the rapid evolution of reproductive isolation barriers among these ESUs.
Morphological distinctiveness of ESUs vary: some show differences in ossicle morphology,
others in live coloration, yet others show no morphological differences that we have been able
to discern to date. These results are leading to a better understanding of the varied diversity and
diversification mechanisms of reef organisms.
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