11th ICRS Abstract book - Nova Southeastern University

14-33
Temporal Patterns in Genetic Structure Within And Among Cohorts Of Settlement-
Stage Larvae And New Recruits Of A Coral Reef Fish
Tauna RANKIN* 1 , Su SPONAUGLE 1 , Dean WILLIAMS 2
1 Marine Biology and Fisheries, RSMAS/University of Miami, Miami, FL, 2 Biology,
Texas Christian University, Fort Worth, TX
High fecundity coupled with extensive and often variable mortality of early life stages
leads to highly variable recruitment dynamics of many marine organisms, including coral
reef fishes. Sources of variation in recruitment strength can be the result of random (e.g.
temperature, current trajectories) and selective (e.g. starvation, predation) processes.
Identifying sources of variation in and mechanisms important to early survival may
provide a means of predicting population structure and connectivity among populations.
Most population genetic studies have concentrated on spatial patterns of genetic structure.
The goal of this study was to identify temporal genetic variation within and among
cohorts of settlement-stage larvae and newly recruited juveniles and to determine 1)
whether allelic frequencies vary among monthly cohorts of settling larvae due to
fluctuating larval transport or chance reproductive success of a small proportion of adults,
and 2) whether temporal variation within monthly cohorts is indicative of selective or
random loss of alleles (i.e. genetic drift). To investigate the presence and mechanism of
temporal shifts in a population’s genetic composition, six monthly cohorts of newly
settled bicolor damselfish Stegastes partitus were sampled in the upper Florida Keys,
USA over four years. Late-stage larvae were collected in light traps and newly recruited
juveniles were collected a few days later on the reef. Exon-primed intron-crossing
polymerase chain reaction amplifiable introns (EPIC-PCR) and a 400 base pair region of
the mitochondrial control region I were compared within cohorts and among different
months and years. When differences in allelic frequencies among monthly cohorts were
detected, calculations of relatedness were used to test for a Hedgecock effect. We also
determined whether allele frequencies within cohorts resulted from selective processes
acting on certain loci or over all loci equally, suggesting random genetic drift.
14-34
Genetic Connectivity Of The Shallow And Deep Reef: Intra-Reef Genetic Structure
Of seriatopora Hystrix On The Northern Great Barrier Reef
Pim BONGAERTS* 1 , Norbert ENGLEBERT 1,2 , Tyrone RIDGWAY 1 , Cynthia
RIGINOS 3 , Ove HOEGH-GULDBERG 1
1 Centre for Marine Studies, University of Queensland, Brisbane, Australia, 2 IBED,
University of Amsterdam, Amsterdam, Netherlands, 3 School of Integrative Biology,
University of Queensland, Brisbane, Australia
Whilst many reef communities in the Great Barrier Reef Lagoon are limited to shallow
waters, there are a large number of reefs that extend beyond 25m depth (especially along
the Great Barrier Reef margin). These deeper reefs appear to be less prone to disturbance
than their shallow counterparts as the effects of several major stressors on coral reefs (e.g.
elevated sea surface temperatures and storm-induced waves) are largely confined to
shallow depths. As such, the relatively undisturbed deep reef has the potential to function
as a refugium and subsequently as a “re-seeding” reproductive source for the shallow,
aiding in recovery after a disturbance. Coral species that transcend the distinct shallow
and deep reef habitats (i.e. depth-generalist species) and thrive under a large range of
environmental conditions have the highest potential to provide a viable recruitment
resource for the shallow. However, due to the lack of appropriate markers, very little is
known about local recruitment processes and the extent of recruitment occurring between
shallow and deep reef habitats. In this study we explore the extent of gene flow in the
brooding coral Seriatopora hystrix between the deep reef slope (27m), the reef crest
(6m), and back reef (2-3m) on two outer-reefs of the northern Great Barrier Reef. Nine
microsatellite loci, specifically developed for Seriatopora hystrix were amplified and
their variation assessed. Preliminary results indicate that populations are largely self
seeding, which challenges the idea that reef systems may be rapidly repopulated from
external larval sources after a disturbance and rather highlights the importance of local
recruitment processes for shallow coral reef recovery.
Oral Mini-Symposium 14: Reef Connectivity
14-35
Low Genetic Diversity And Gene Flow Suggests Vulnerable Atlantic Coral Outposts
Flavia NUNES* 1 , Richard D. NORRIS 1 , Nancy KNOWLTON 1
1 Scripps Institution of Oceanography, La Jolla, CA
Coral species diversity in the Atlantic Ocean is concentrated in the Caribbean Sea, but coral
populations are also found along the coasts of Brazil and West Africa, and on mid-Atlantic
islands. These coral “outposts” are typically rocky reefs harboring a low number of coral
species, often rich in endemics. In order to study the levels of genetic diversity and gene flow
among these low-diversity outposts and the Caribbean, 130 individuals of Montastraea
cavernosa sampled from 6 Atlantic populations in the Caribbean (Panamá, Belize and Puerto
Rico), North Atlantic (Bermuda), Western South Atlantic (Brazil) and Eastern Tropical Atlantic
(São Tomé, West Africa) were genotyped at two nuclear and one mitochondrial loci. For the
two nuclear loci, Caribbean and North Atlantic populations displayed high levels of genetic
diversity and similar allele frequencies, whereas the Brazilian and West African populations
each had markedly lower levels of genetic diversity and distinct allele frequencies relative to
other populations. The mitochondrial locus had much lower diversity than the nuclear loci,
with one fixed allele in the South Atlantic populations (Brazil and São Tomé), and one very
common allele being nearly fixed in the Caribbean and North Atlantic populations.
Surprisingly, no population differentiation was observed among Caribbean and North Atlantic
populations of M. cavernosa over all loci, suggesting these populations are well-connected over
evolutionary time scales. Populations from Brazil and West Africa, however, were significantly
differentiated from all other populations over all loci, including each other, except for the
mitochondrial locus, where they display the same genotype. Genetic diversity and connectivity
may be important factors that contribute to the resilience of a coral population to disturbance.
Low genetic diversity and low levels of gene flow in Brazil and West Africa suggest that
isolated outposts may be more vulnerable to degradation and loss relative to Caribbean
populations.
14-36
Genetic Parental Analysis Reveals Both Local Retention And Large Scale Connectivity Of
Clownfish in Kimbe Bay
Serge PLANES* 1 , Geoffrey JONES 2 , THORROLD SIMON 3
1 UMR 5244 - Laboratoire Écosystèmes Aquatiques Tropicaux et Méditerranéens, CNRS -
EPHE - UPVD, Perpignan, France, 2 School of Marine and Tropical Biology, and ARC Centre
of Excellence for Coral Reef Studies, James Cook University, TOWNSVILLE, Australia,
3 Biology Department MS # 50, Woods Hole Oceanographic Institution, Woods Hole, MA
Many marine species produce larvae that can be pelagic for weeks or months and the potential
for long distance dispersal by prevailing currents is extremely high. Marine populations have, in
turn, been assumed to be demographically “open”, consisting of many sub-populations that are
connected by larval dispersal. However recent work has consistently demonstrated high levels
of self-recruitment in reef fish populations. Because of the technical difficulty of tracking
larvae, direct measures of dispersal have not previously been obtained. We report on the
potential of genetic parental analysis to estimate local self-recruitment and connectivity among
distant areas by identifying the parent (and their location) of a new recruit settling at a certain
location. We sampled (fin-clip) the entire adult population of clown fish (Amphiprion percula)
from the reef around a small island, Kimbe Island, Papua New Guinea, together with new
recruits from Kimbe Island and several other locations throughout Kimbe Bay. Parental analysis
demonstrated significant self-recruitment (about 50%) to the Kimbe Island sub-population, but
also significant connectivity among three distant locations within Kimbe Bay. As many as 10%
of new recruits at these distant locations - up to 50km from Kimbe Island - were spawned by
Kimbe Island adults. At small spatial scale, we observe strong retention (up to 50%) within
small lagoon around Kimbe island that question about the ability of the species to achieve the
pelagic larval phase within these lagoon. Finally, we demonstrate that some parents at specific
sites within Kimbe Island were more efficient in producing self-recruitmenting juveniles than
adults at other sites. Genetic parental analysis opens the possibility for new perspectives in
understanding success of the larval phase and investigating process determining connectivity in
the perspective of better management of marine populations.
Financial support provided by: CRISP
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