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Vol. 49 No. 5, 2010
Comparative Study of Genetic Variability of AAT and CT/GT Microsatellites in Staghorn Coral, Acropora (Scleractinia: Acroporidae)
Pei-Ciao Tang1,2, Nuwei Vivian Wei1, Chein-Wei Chen1,4, Carden C. Wallace3, and Chaolun Allen Chen1,4,5,*
1Biodiversity Research Center, Academia Sinica, Nankang, Taipei 115, Taiwan
2Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70504, USA
3Museum of Tropical Queensland, Townsville Q4810, Australia
4Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan
5Institute of Life Science, National Taitung University, Taitung 950, Taiwan
Pei-Ciao Tang, Nuwei Vivian Wei, Chein-Wei Chen, Carden C. Wallace, and Chaolun Allen Chen (2010) Acropora
is the most speciose genus of scleractinian corals. However,
phylogenies among closely related species and population genetics of Acropora remain equivocal. In this study, 7 AAT-repeat loci developed from the Caribbean species, A. palamta, and 5 dinucleotide (CT/GT)-repeat microsatellites newly developed from the Indo-West-Pacific (IWP) species, A. muricata, were examined to determine their utility for revealing the mutation rate and genetic diversity of Acropora
species. Five of the 8 AAT-repeat loci were successfully
amplified in IWP species, with DNA sequences in the flanking region
showing over 97% similarity to those of the Caribbean species,
suggesting homology of these AAT loci among these cross-oceanic Acropora.
In contrast, amplifications of all GT-repeat loci failed in the
Caribbean species. Eight loci (5 AAT and 3 CT/GT ones) showed
Mendelian inheritance based on crossing experiments of A. muricata
larvae. When the mutation rate ( ɵ ) was estimated, AAT-repeat loci showed relatively higher mutation rates ( ɵ = 39.94-112.82) compared to GT-repeat loci ( ɵ
= 2.44-53.33). Analysis of molecular variance indicated a
relatively higher within-population variation at AAT-repeat loci
(98.6%) than at GT-repeat loci (78.7%). The FST statistic of 2 sympatric Acropora species (A. muricata and A. digitifera) indicated that the value for AAT loci (FST = 0.014) was about 15 times lower than that for GT loci (FST
= 0.213), although both microsatellite motifs showed statistically
significant differentiation of species. Our study highlights that
AAT-repeat loci might have functional constraints and result in
underestimating the genetic variability of species and populations;
thus, their application to revealing genetic variations within Acropora should be utilized with caution.
Key words: Microsatellite, Acropora, Trinucleotide, Dinucleotide, Mutation rate.
*Correspondence: Tel: 886-2-27899549. Fax: 886-2-27858059. E-mail:cac@gate.sinica.edu.tw
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