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Genetic distances of four Manila clam (Ruditapes philippinarum) populations identified by PCR analysis
The author has investigated four Manila clam populations of the family Veneridae, belonging to the order Veneroida. The clam is also indigenous to some parts of the sandy regions of the West Sea in the Korean Peninsula, as well as in several areas in China. Clams are the most popular marine products in Korea because of their taste and nutritional value, and Koreans consume them in large quantities. However, in spite of their economic and scientific consequences, a little information currently exist regarding the physiological and ecological levels only of clam species in Korea. This study attempt is to elucidate the genetic distances within and between clam populations from the West Sea. Four populations of Manila clam (R. philippinarum) were obtained in adjacent district to the West Sea in Korea. Four populations of clam muscle was collected in sterile tubes, placed on ice immediately, and stored under refrigeration until needed. Genomic DNA was extracted and purified under the conditions described previously (Yoon and Kim, 2004). The degree of variability was calculated by use of the Dice coefficient (F), which is given by the formula: F=2 nab / (na+nb), where nab is the number of bands shared between the samples a and b, na is the total number of bands for sample a and nb is the total number of bands for sample b (Jeffreys and Morton, 1987; Yoke-Kqueen and Radu, 2006). Euclidean genetic distances within- and between-species were also calculated by complete linkage method with the support of the hierarchical dendrogram program Systat version 10. The genomic DNA isolated from four Manila clams populations in the West Sea, were amplified several times by PCR reaction. The dendrogram obtained by the six oligonucleotides primers indicates three genetic clusters. The hierarchical dendrogram indicates four main branches: cluster 1 (GOCHANG 01, 02, 04 and 05), cluster 2 (SEOCHEON 06, 07, 08, 09 and 10), cluster 3 (TAEAN 11, 12, 13, 14 and 15) and cluster 4 (ANMYEON 16, 17, 18, 19, 20 and GOCHANG 03). Multiple comparisons of average bandsharing values among Manila clam populations from four sections were generated according to the bandsharing values and similarity matrix. Ultimately, individuals from SEOCHEON clam population (0.637±0.227) exhibited higher bandsharing values than did individuals from GOCHANG clam population (0.402±0.115) (P<0.05).
