11th ICRS Abstract book - Nova Southeastern University

14-45
Range-Wide Population Genetics Of The gorgonia Ventalina/symbiodinium
Octocoral Holobiont
Jason ANDRAS* 1 , Nathan KIRK 2 , C. Drew HARVELL 1
1 2
Ecology & Evolutionary Biology, Cornell University, Ithaca, NY, Biology, Auburn
University, Auburn, AL
The conspicuous and ecologically dominant Caribbean seafan coral, Gorgonia ventalina,
exists in an obligate mutualistic relationship with photosynthetic dinoflagellates of the
genus Symbiodinium, ITS type B1. Here we describe the population genetic structure of
the G. ventalina/Symbiodinium coral holobiont at 40 localities spanning more than 3,000
km throughout its range, using a total of 22 polymorphic microsatellite loci (13 loci from
the Symbiodinium genome; 9 loci from the G. ventalina genome). The large majority of
Symbiodinium populations within a single seafan colony were clonal, and seasonal
sampling of marked colonies showed within-host symbiont populations to be temporally
stable. Significant structure was detected between Symbiodinium populations among
different coral hosts separated by as little as 5km, and overall divergence in symbiont
populations followed a pattern of isolation by distance. Differentiation was also detected
between Symbiodinium populations hosted by corals in different size/age classes at the
same locality. A small fraction of seafan colonies sampled were found to host multiple
symbiont genotypes. The relative proportions of these genotypes were dynamic and
reversible in response to experimentally induced light and temperature stress, suggesting
that the fine-scale Symbiodinium genetic diversity described in this study may have
functional significance. Significant structure was also detected among populations of G.
ventalina, though at a broader scale of hundreds to thousands of kilometers. The
observed patterns of connectivity in populations of the coral host are consistent with data
from biogeographic studies of other Caribbean marine organisms with broadly dispersing
pelagic larvae. This is the first study we are aware of that considers the population
genetics of both members of the obligate coral/algal holobiont. These results will have
significance for our understanding of basic coral population biology, the establishment
and maintenance of the coral/algal symbiosis, and conservation genetics and management
of corals and other Caribbean reef creatures.
14-46
Genetic Variability Of Acropora Cervicornis And A .palmata in Puerto Rico
Garcia Reyes JOSELYD* 1 , Nikolaos SCHIZAS 1
1 Department of Marine Sciences, University of Puerto Rico-Mayaguez, Lajas, Puerto
Rico
Genetic variation of natural populations may be used as a proxy for the long-term
survival of populations or species. Effective conservation and management planning for
the rapidly declining scleractinian species Acropora cervicornis and A. palmata require
an understanding of the standing genetic variability. Over 100 colonies of Acropora
cervicornis and A. palmata have been sampled from several reefs around Puerto Rico to
assess levels of genetic variability. We used partial DNA sequences of the mitochondrial
control region to estimate levels of genetic connectivity in adjacent and geographically
distant reefs. Preliminary analysis shows that many of the reefs share haplotypes
indicating historical genetic exchange between reefs. Genetic diversity is significantly
different among reefs. Analysis of molecular variance suggests that most of the
variability is observed within reefs than among reefs. FST values were also significant for
both species suggesting that there is fine scale population structure, as previous studies
have indicated. Therefore, larval dispersal could be limited over long and even small
distances restricting larval supply, which could influence recuperation between reefs.
Populations that are considerably connected will not have a significant amount of
restriction on gene flow, allowing the exchange of genes between populations. Presence
of multiple mitochondrial haplotypes in a reef suggests that sexual reproduction may be
contributing to the observed levels of genetic variation in Puerto Rico. The awareness of
connectivity between large spatial and small spatial scales is important especially when
dealing with a threatened species in order to set the degree of conservation and
management strategies.
Oral Mini-Symposium 14: Reef Connectivity
14-47
Larval Retention And Population Connectivity in Two Coral-Reef Fishes
Mark CHRISTIE* 1 , Christopher STALLINGS 2 , Darren JOHNSON 1 , Mark ALBINS 1 , Jim
BEETS 3 , Brian TISSOT 4 , Stephen THOMPSON 5 , Mark HIXON 1
1 Department of Zoology, Oregon State University, Corvallis, OR, 2 Florida State University
Coastal and Marine Laboratory, St. Teresa, FL, 3 Department of Marine Science, University of
Hawaii at Hilo, Hilo, HI, 4 Washington State University, Vancouver, Vancouver, WA, 5 Cascadia
Conservation Trust, Sisters, OR
Patterns of demographic connectivity among and retention within local populations of marine
fish are poorly understood due to the difficulty of directly tracking pelagic larvae. To address
this issue, we conducted population genetic analyses of two species of coral reef fishes. In
2005, bicolor damselfish (Stegastes partitus) were collected from 5 islands within the Exuma
Sound, Bahamas, bordering an area of 100 by 175 km. Fifty adults and fifty recruits from each
site were genotyped at 7 polymorphic microsatellite loci. In 2006, 500 adult and 500 recruit
yellow tang (Zebrasoma flavescens) were collected from 9 sites distributed around the Big
Island of Hawai'i and subsequently genotyped at 15 microsatellite loci. Overall levels of
genetic differentiation (e.g., FST) were low for both systems, such that there were no significant
patterns of isolation by distance when Euclidean or along-shore distances were employed.
However, significant differences between populations of bicolor damselfish located on the
eastern and western sides of the Exuma Sound were detected. This pattern suggests that there is
limited dispersal across the eastern and western sides of the Exuma Sound and higher levels of
connectivity among sites located north and south of one another, coinciding with prevailing
northerly currents. Additionally, the high levels of polymorphism found within the genetic
markers allowed for the detection of parent-offspring pairs in both species using novel
statistical methods. The existence of parent-offspring pairs of fish in the same region provides
unequivocal documentation of larval retention and self-recruitment. Given that the overall
levels of genetic differentiation in both systems are low, parentage analysis in marine systems
may prove to be a powerful tool for informing population-level genetic analyses as well as for
providing insights into gene flow and dispersal at ecological timescales.
14-48
Levels Of Population Genetic Structure Of Table Top Acropora Corals At Village, Island
And Pacific-Wide Scales And The Value Of Local Marine Protected Areas.
Steve PALUMBI* 1 , Jason LADNER 2
1 Department of Biology, Stanford University, Pacific Grove, CA, 2 Stanford University, Pacific
Grove, CA
To estimate the movement of coral larvae among populations and to estimate the connectivity
of coral populations at various geographic scales, we measured mtDNA variation in populations
of the table top corals Acropora hyacinthus and A. cytherea from 20 populations from the
Philippines to Palmyra atoll. The same thirteen mtDNA haplotypes are seen across the Pacific,
indicating that long distance gene flow is possible. Between archipelagos (Philippines,
Micronesia, Fiji, American Samoa, Palmyra), coral populations always showed strong genetic
differentiation, suggesting such long distance gene flow is rare. Within archipelagos, coral
populations on separate islands usually showed strong genetic differences. Populations on
different reefs on the same islands showed strong differentiation in about half of the
comparisons. The two coral species showed little mtDNA genetic differentiation from one
another when sampled from the same reefs, but additional data from nuclear genes showed
higher levels of genetic distinction. Results suggest that, over ecologically relevant time scales,
coral larvae generally travel short distances along reef complexes on an island, and have low
dispersal abilities among islands. Use of coral protected areas to house healthy stands of corals
to reseed damaged reefs would require these coral gardens to be placed at short distances from
one another.
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