11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 6: Ecological and Evolutionary Genomics of Coral Reef Organisms
6.160
Intracolonial Genotypic Variations And Heterozygosity Excess Of A Scleractinian
Coral Pocillopora Damicornis
Shang-Ru YEOH 1 , Chang-Feng DAI* 1
1 Institute of Oceanography, National Taiwan University, Taipei, Taiwan
The naturally occurring intraorganismal genetic heterogeneity (IGH) and heterozygosity
excess of Pocillopora damicornis populations were studied in southern Taiwan. Two
populations of P. damicornis were sampled exhaustively in a fine-scale and an additional
population was sampled randomly for index comparisons (n = 107). Identities of colonies
were characterized genotypically with seven microsatellite markers. Both genuine
clonemates (colonies with identical multilocus genotypes) and genotypic varieties that
differed only slightly from them were found. In order to discern whether these genotypic
varieties were the coincidental products of sexual reproductions, we redefined the clones
into clonal lineages (genuine clonemates and their closely-related clonal varieties) with a
threshold value determined from the frequency histogram of pairwise genotypic distances
between all multilocus genotype (MLG)-pairs under the infinite allele model (IAM). Ten
distinct clonal lineages (C1 to C10) were defined and intracolonial genetic variations
were observed in all but one clonal lineage, suggesting that autonomous genetic changes
such as somatic mutations and mitotic gene conversions might occur frequently in the
clonal population of P. damicornis. Moreover, allele-sharings among several clonal
lineages were also observed, implying that allogeneic fusions might occur between
individuals of newly settled larvae and young colonies, either intraclonally or
interclonally. In addition, heterozygosity excess, a phenomenon that was rarely observed
in the sessile marine invertebrates, was found to prevail in all three populations. This
observation was probably a result derived from an interplay between negative assortative
mating, selection for heterozygotes, and asexual reproductions.
6.161
Comparative Coral Mitogenomics And Its Application To Phylogenetic, Population
Genetic And Biodiversity Studies
Jean-François FLOT* 1 , Simon TILLIER 1
1 Département Systématique et Evolution, Muséum National d'Histoire Naturelle, Paris,
France
The mitochondrial genomes of scleractinian corals used to be considered uniform in
terms of gene content and order (Medina et al. 2006) as all corals sequenced had been
found to conform to the Acropora tenuis model (van Oppen et al. 2002). Moreover, the
apparently slow rate of evolution of coral mitochondrial DNA (Shearer et al. 2002) was
generally thought to preclude its use in population genetic studies (Hellberg 2006).
New data, however, have started to emerge that challenge this view: the mitochondrial
genome of Pocillopora contains two hypervariable regions, located respectively in an
intergenic region and in a novel open reading frame (ORF) (Flot and Tillier 2007). This
ORF is also present in Madracis, Seriatopora and Stylophora, and we have observed
other original gene arrangements involving for instance the duplication of a tRNA gene.
In Pocillopora, hypervariable regions appear variable enough for population genetic
studies: this shows that, in some groups of corals at least, mitochondrial sequence
markers can be much more useful than previously thought.
Flot J-F, Tillier S (2007) The mitochondrial genome of Pocillopora (Cnidaria:
Scleractinia) contains two variable regions: The putative D-loop and a novel ORF of
unknown function. Gene 401:80-87
Hellberg M (2006) No variation and low synonymous substitution rates in coral mtDNA
despite high nuclear variation. BMC Evol Biol 6:24
Medina M, Collins AG, Takaoka TL, Kuehl JV, Boore JL (2006) Naked corals: skeleton
loss in Scleractinia. Proc Natl Acad Sci U S A 103:9096-9100
Shearer TL, van Oppen MJH, Romano SL, Wörheide G (2002) Slow mitochondrial DNA
sequence evolution in the Anthozoa (Cnidaria). Mol Ecol 11:2475-2487
van Oppen MJ, Catmull J, McDonald BJ, Hislop NR, Hagerman PJ, Miller DJ (2002)
The mitochondrial genome of Acropora tenuis (Cnidaria; Scleractinia) contains a large
group I intron and a candidate control region. J Mol Evol 55:1-13
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