Examination of species boundaries in the Acropora cervicornis group (Scleractinia, Cnidaria) using nuclear DNA sequence analyses
Van Oppen, M.J.H., Willis, B.L., Van Vugt, H.W.J., and Miller, D.J. (2000) Examination of species boundaries in the Acropora cervicornis group (Scleractinia, Cnidaria) using nuclear DNA sequence analyses. Molecular Ecology, 9 (9). pp. 1363-1373.
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Although Acropora is the most species-rich genus of the scleractinian (stony) corals, only three species occur in the Caribbean: A. cervicornis, A. palmata and A. prolifera. Based on overall coral morphology, abundance and distribution patterns, it has been suggested that A. prolifera may be a hybrid between A. cervicornis and A. palmata. The species boundaries among these three morphospecies were examined using DNA sequence analyses of the nuclear Pax-C 46/47 intron and the ribosomal DNA Internal Transcribed Spacer (ITS1 and ITS2) and 5.8S regions. Moderate levels of sequence variability were observed in the ITS and 5.8S sequences (up to 5.2% overall sequence difference), but variability within species was as large as between species and all three species carried similar sequences. Since this is unlikely to represent a shared ancestral polymorphism, the data suggest that introgressive hybridization occurs among the three species. For the Pax-C intron, A. cervicornis and A. palmata had very distinct allele frequencies and A. cervicornis carried a unique allele at a frequency of 0.769 (although sequence differences between alleles were small). All A. prolifera colonies examined were heterozygous for the Pax-C intron, whereas heterozygosity was only 0.286 and 0.333 for A. cervicornis and A. palmata, respectively. These data support the hypothesis that A. prolifera is the product of hybridization between two species that have a different allelic composition for the Pax-C intron, i.e. A. cervicornis and A. palmata. We therefore suggest that A. prolifera is a hybrid between A. cervicornis and A. palmata, which backcrosses with the parental species at low frequency.
|Item Type:||Article (Refereed Research - C1)|
|Keywords:||Acropora; Caribbean; coral; hybridization; nuclear intron; rDNA ITS|
|FoR Codes:||06 BIOLOGICAL SCIENCES > 0699 Other Biological Sciences > 069999 Biological Sciences not elsewhere classified @ 100%|
|SEO Codes:||97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%|
|Deposited On:||31 Aug 2012 12:17|
|Last Modified:||15 Mar 2013 11:59|
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