Original Article Mitochondrial DNA Diversity of the Asian Moon Scallop, Amusium pleuronectes (Pectinidae), in Thailand Chulabhorn Mahidol, 1,2 Uthairat Na-Nakorn, 2 Srijanya Sukmanomon, 2 Nobuhiko Taniguchi, 3 Thuy T. T. Nguyen 4 1 Chulabhorn Research Institute, Vibhavadee-Rangsit Highway, Bangkok, 10210, Thailand 2 Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok, 10900, Thailand 3 Department of Population Genetic Bioinformatics, Tohoku University, Sendai, Japan 4 Network of Aquaculture Centres in Asia-Pacific, PO Box 1040, Kasetsart Post Office, Bangkok, 10903, Thailand Received: 19 September 2006 / Accepted: 12 December 2006 / Published online: 15 February 2007 Abstract Sequence variation of the mitochondrial DNA 16S rRNA region of the Asian moon scallop, Amusium pleuronectes, was surveyed in seven populations along the coast of Thailand. A total of 16 unique haplotypes were detected among 174 individuals with a total 27 variable sites out of 534 bp sequenced. The mitochon- drial haplotypes grouped into two distinct arrays (estimated to differ by about 2.62% to 2.99% nucleo- tide divergence) that characterized samples collected from the Gulf of Thailand versus the Andaman Sea. Low levels of intrapopulation variation were observed, while in contrast, significant divergence was observed between populations from the Gulf of Thailand and Andaman Sea. Results of AMOVA reveal a high F ST value (0.765) and showed that the majority of the total genetic variance (76.03%) occurred among groups (i.e., Andaman Sea and the Gulf of Thailand) and little among populations within the group (0.52%) and within populations (23.45%). The genetic differentia- tion between the populations recorded in the present study is similar to that observed in a variety of marine species in the Indo-Pacific. The implications of the findings for management of A. pleuronectes genetic resources in Thailand are discussed. Keywords: 16S rRNA —genetic diversity — mtDNA — Amusium pleuronectes — the Gulf of Thailand — Andaman Sea Introduction Amusium pleuronectes, commonly referred to as Asian moon scallop, is present over much of Indo- Pacific coastal areas. The species has been recorded from the Indian Ocean, South China Sea, Indo- China, Japan, the Philippines, New Guinea, Indo- nesia, Java, and Australia (Morton, 1980) and at a depth of 18 to 40 m (Minchin, 2003). In Thailand, the species is of significant commercial value, with about 500 to 1100 metric tonnes/year harvested during 1994–1999. However, the recent catch sta- tistics showed that production declined to 100 to 300 metric tonnes/year between 2000 and 2003 (FAO, 2006). An effort has been made to reduce pressure on wild-caught fisheries, through aquacul- ture development of this species although this is at an early stage. An understanding of genetic variability and population structure are critical for management and conservation of exploited aquatic species. It is now widely recognized that this information could be achieved through the recently developed molec- ular genetic techniques. Molecular genetic data provide fishery managers with essential information regarding the existence and distribution of discrete populations and/or management units (Ward and Grewe, 1995). In addition, for newly emerging aquaculture species such as the Asian moon scallop, genetic information would provide useful insight into the establishment of baseline stocks for selec- tive breeding and development of broodstock man- agement strategies (Carvalho and Pitcher, 1995). Molecular genetic studies using allozyme and DNA markers have provided useful insights into a number of areas of biology of many scallop species, including evolution, taxonomy, and fishery man- agement. For example, the identification of genetical- ly distinct populations of Pecten maximus (Wilding et al., 1997; Heipel et al., 1999) and Patinopecten yessoensis (Dolganov and Pudovkin, 1998) are of Correspondence to: Uthairat Na-Nakorn; E-mail: uthairatn@ yahoo.com 352 DOI: 10.1007/s10126-006-6137-y & Volume 9, 352–359 (2007) & * Springer Science + Business Media, Inc. 2007