11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 11: From Molecules to Moonbeams: How is Reproductive Timing Regulated in Coral Reef Organisms?
11-1
Sex Change In Fungiid Corals
Yossi LOYA* 1 , Kazuhiko SAKAI 2
1 Zoology, Tel Aviv University, Tel Aviv, Israel, 2 Sesoko Station, University of the
Ryukyus, Okinawa, Sesoko, Motobu-Cho, Japan
Sex change in animals has been the subject of a variety of theoretical and empirical
evolutionary studies. The direction of sex change in animals has been reported occurring
mainly from M to F (males to females; protandry) and visa versa (protogyny) and in
some cases as bidirectional. Our knowledge of the various modes of sexual reproduction
in scleractinian corals has increased greatly during the last two decades, but is far from
encompassing the wide plasticity of reproductive strategies exhibited by this group. Here
we report on novel observations of sex change in two coral species, where tagged
individuals have been monitored during 3 years in the field and experimental aquaria at
Sesoko, Okinawa: Fungia repanda (exhibiting protandry), and Ctenactis echinata,
revealing novel bidirectional mode of sex change: (M-F-M and F-M-F). Our study
exemplifies the view that models that can be applied on the scale of individuals may
provide important insights to the factors underlying the evolution of sex change in
animals.
11-2
Behavioural Endocrinology Of Bi-Directional Sex Change in Coral-Dwelling Gobies
Frederieke KROON* 1 , Philip MUNDAY 2 , David WESTCOTT 1 , Luke GARDNER 3 ,
Abigail ELIZUR 4,5
1 CSIRO Sustainable Ecosystems, Atherton, Australia, 2 James Cook University, School of
Marine and Tropical Biology, Townsville, Australia, 3 Queensland Department of Primary
Industries & Fisheries, Woorim, Bribie Island, Australia, 4 University of the Sunshine
Coast, School of Science and Education, Maroochydore DC, Australia, 5 Queensland
Department of Primary Industries & Fisheries, Woorim, Australia
The discovery of bi-directional sex change (i.e. the ability to change sex repeatedly in
both directions) in various fish species provides a unique opportunity to study the
endocrine mechanisms underlying female and male sex differentiation. We examined a
potential causal relationship between behaviour, endocrine pathways, and natural sex
change in coral-dwelling gobies of the genus Gobiodon. These species generally live in
heterosexual pairs and natural sex change occurs as a result of changes in social
conditions. If adult sex change in coral-dwelling gobies is a result of changes in
behavioural interactions perceived by an individual fish, then we predict the following:
that in heterosexual pairs males are behaviourally dominant;
that in heterosexual pairs cortisol levels are higher in females than in males;
that in heterosexual pairs aromatase expression is higher in females than in males;
that in heterosexual pairs estradiol levels are higher in females than in males;
that an increase in cortisol levels results in protandrous sex change, and a decrease in
cortisol levels results in protogynous sex change.
To test these predictions, we observed behavioural interactions in existing heterosexual
pairs in the laboratory, and conducted field experiments under natural social conditions.
The results suggest that, in coral dwelling gobies, behavioural interactions mediates sex
change in each direction via the aromatase pathway.
11-3
Light Sensing And The Coordination Of Coral Broadcast Spawning Behavior
Dan HILTON 1 , Peter VIZE* 2
1 Biological Sciences, University of Calgary, Calgary, AB, Canada, 2 Biological Sceinces,
University of Calgary, Calgary, AB, Canada
While lunar cycles establish the day of spawning in corals, sunlight driven systems control the
hour and minute of spawning. The two lines of evidence supporting this contention are: 1. coral
spawning times change from year to year corresponding to changes in sunset time 2. artificially
changing sunset time results in a corresponding change to spawn time. This later point also
indicates that the solar control is not an entrained circadian system or it would not respond in
this manner. Our research is exploring the cellular pathways by which solar light regulates
spawning behavior through a combination of proteomics and candidate pathway analysis. We
are mapping coral protein phosphorylation oscillations in response to different levels of
illumination. As most light transduction systems result in changes in such patterns this approach
will identify phosphoprotein signatures that can be used as markers of signal perception. Such
signatures can then be used to test the role of different signaling pathways in the response to
light, to compare responses in species with different spawning times, to measure the importance
of zooxanthellae in the response etc. A second approach is identifying coral orthologs of genes
involved in regulating either circadian cycles or light responses. These candidates are then
tested for responsiveness to lunar and solar light at both the transcriptional and posttranscriptional
level. Through a combination of these two approaches we hope to map the
pathways by which lunar and solar light independently regulate coral spawning behavior. We
are particularly interested in how these two different systems intersect to select the exact
moment of gamete release and how changes in the dynamics of the molecular sensing systems
generates distinct species-specific spawning windows.
11-4
Light-Responsive Cryptochromes From A Simple Multicellular Animal, The Coral
Acropora Millepora
Oren LEVY* 1 , Lior APPELBAUM 2 , William LEGGAT 3 , Yoav GOTHILF 4 , David
HAYWARD 5 , David MILLER 6 , Ove HOEGH-GULDBERG 7
1 Department of Environmental Sciences, The Weizmann Institute of Science, Rehovot, Israel,
2 Center For Narcolepsy, Stanford University, Palo Alto, CA, 3 Biochemistry and Molecular
Biology, James Cook University, Townsville, Australia, 4 Department of Neurobiochemistry,
Tel Aviv University, Tel Aviv, Israel, 5 Molecular Genetics and Evolution Group, Australian
National University, Canberra ACT, Australia, 6 Comparative Genomics Centre, James Cook
University, Townsville, Australia, 7 Centre for Marine Studies, The University of Queensland,
Brisbane, Australia
Hundreds of species of reef-building corals spawn synchronously over a few nights each year,
and moonlight regulates this spawning event. However, the molecular elements underpinning
the detection of moonlight remain unknown. Here we report the presence of an ancient family
of blue-light–sensing photoreceptors, cryptochromes, in the reef-building coral Acropora
millepora. In addition to being cryptochrome genes from one of the earliest-diverging
eumetazoan phyla, cry1 and cry2 were expressed preferentially in light. Consistent with
potential roles in the synchronization of fundamentally important behaviors such as mass
spawning, cry2 expression increased on full moon nights versus new moon nights. Our results
demonstrate phylogenetically broad roles of these ancient circadian clock–related molecules in
the animal kingdom.
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