Zoological Studies

Vol. 49 No. 4, 2010

Population Genetics of the Spotted Seahorse (Hippocampus kuda) in Thai Waters: Implications for Conservation

Thadsin Panithanarak1,*, Ratima Karuwancharoen1, Uthairat Na-Nakorn2, and Thuy Thi Thu Nguyen3

1Institute of Marine Science, Burapha University, Chonburi 20131, Thailand
2Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok 10900, Thailand
3Network of Aquaculture Centers in Asia-Pacific, Kasetsart University, Bangkok 10900, Thailand

Thadsin Panithanarak, Ratima Karuwancharoen, Uthairat Na-Nakorn, and Thuy Thi Thu Nguyen (2010) A population genetics approach was used to investigate the genetic diversity of the spotted seahorse (Hippocampus kuda) in Thai waters; specifically, the degree of genetic differentiation and species evolution was inferred from sequence analysis of 353 bp of the mitochondrial (mt)DNA control region.  The data were then used to identify discrete populations in Thai waters for effective conservation and management.  Spotted seahorses were collected from 4 regions on the east and west coasts of the Gulf of Thailand and a geographically separated region in the Andaman Sea.  Of the 101 mtDNA sequences analyzed, 7 haplotypes were identified, 5 of which were shared among individuals from the east and west coasts of the Gulf of Thailand.  The remaining haplotypes were restricted to individuals from the Andaman Sea.  Nucleotide and haplotype diversities were similar within the Gulf of Thailand samples, whereas diversity was lower in the Andaman Sea sample.  Genetic differentiation appeared between pairs of samples from the Gulf of Thailand and Andaman Sea (FST, p < 0.0001).  A large genetic variance appeared among the 2 population groups (94.46%, ΦCT = 0.94464, p < 0.01).  A Neighbor-joining tree indicated that individuals from the Gulf of Thailand and Andaman Sea formed 2 phylogenetically distinct groups, which were segregated into different population-based clades.  While results reported here indicate that populations from the Gulf of Thailand and Andaman Sea should be treated as separate conservation units, a larger sample size from the Andaman Sea is required to confirm this genetic partitioning and low level of diversity observed in the present study.

Key words: Hippocampus kuda, Mitochondrial DNA (mtDNA) control region, Spotted seahorses, Population genetics, Thailand.

*Correspondence: Tel: 66-38-391671 ext. 140.  Fax: 66-38-391674.   E-mail:thadsin@hotmail.com