GENETIC DIVERSITY AND SPECIES-DIAGNOSTIC MARKERS OF MUD CRABS (GENUS SCYLLA) IN EASTERN THAILAND DETERMINED BY RAPD ANALYSIS

S. Klinbunga, A. Boonyapakdee, B. Pratoomchat-2000

Marine Biotechnology, 2 (2): 180-187 (from Current Contents)

Abstract:

Genetic diversity of three mud crab species, Scylla serrata (Forskal), S. oceanica (Dana), and S. tranquebarica (Fabricius), collected from two locations in eastern Thailand (Chanthaburi and Trat) was examined by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). Ninety-one reproducible RAPD fragments, generated by UBC456, UBC457, and YNZ22, were polymorphic. The percentage of polymorphic bands within populations ranged from 47.92% to 77.59%. Species-specific RAPD markers were also observed and used to construct a molecular diagnostic key in these taxa. Large genetic differences between species were found ((D) over bar(ij) = 0.425 to 0.751), whereas those between populations within each species were much lower ((D) over bar(ij) = 0.171 to 0.199). The neighbor-joining tree based on genetic distances among pairs of individuals indicated three distinct groups, corresponding to S. serrata, S. oceanica, and S. tranquebarica icn. No genotypes were shared among these three species. This suggests the absence of genetic exchanges between sympatric mud crab species in eastern Thailand. Therefore, mud crabs in this area should be recognized as three different species rather than a single panmitic species exhibiting different morphs.

(Chulalongkorn Univ, Marine Biotechnol Res Unit, Bangkok 10330, Thailand, e-mail: sirawut@biotec.or.th)

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