Genetic diversity and connectivity of the Irrawaddy dolphin in Southern Thailand: Emphasizing the last fourteen of the Songkhla dolphin status from a microsatellite perspective

TRIFAN BUDI (Animal Genomics and Bioresource Research Unit (AGB Research Unit), Faculty of Science, Kasetsart University. 50 Ngamwongwan, Chatuchak, Bangkok 10900, Thailand)
SANTI NINWAT (Marine and Coastal Resources Research Center, the Lower Andaman Sea, Department of Marine and Coastal Resources. Trang 92150, Thailand)
WATCHARA SAKORNWIMON (Marine and Coastal Resources Research Center, the Central Gulf of Thailand, Department of Marine and Coastal Resources. Chumphon 86000, Thailand)
KHUNANONT THONGCHAM (Marine and Coastal Resources Research Center, the Lower Gulf of Thailand, Department of Marine and Coastal Resources. Songkhla 90100, Thailand)
RATTANAKORN PHAKPHIEN (Marine and Coastal Resources Research Center, the Lower Gulf of Thailand, Department of Marine and Coastal Resources. Songkhla 90100, Thailand)
CHAWANON KALAYA (Marine and Coastal Resources Research Center, the Lower Gulf of Thailand, Department of Marine and Coastal Resources. Songkhla 90100, Thailand)
JANJIRA PHAVAPHUTANON (Department of Companion Animal Clinical Sciences, Faculty of Veterinary Medicine, Kasetsart University Kamphaeng Saen Campus. Nakhon Pathom 73140, Thailand)

Biodiversitas Journal of Biological Diversity
Vol. 25 No. 4 (2024)

Abstract. Budi T, Ninwat S, Sakornwimon W, Thongcham K, Phakphien R, Kalaya C, Phavaphutanon J. 2024. Genetic diversity and connectivity of the Irrawaddy dolphin in Southern Thailand: Emphasizing the last fourteen of the Songkhla dolphin status from a microsatellite perspective. Biodiversitas 25: 1729-1735. Irrawaddy dolphin (Orcaella brevirostris Gray, 1866) can be found in diverse aquatic environments, ranging from coastal to brackish water, stretching from the West of Bengal in India to the central part of the Indonesian archipelago. Despite its widespread distribution and flexible habitat tolerance, Irrawaddy dolphins in Songkhla Lake, Southern Thailand, are hypothesized to be isolated and exhibit concerningly low population numbers, threatening their long-term survival. Limited knowledge exists regarding their population genetics status. This study analyzed 30 samples from Songkhla Lake (SKL) and the Lower Gulf of Thailand (LGT) to assess their genetic diversity, structure, and connectivity using 16 microsatellite loci. Extremely low genetic diversity was observed in SKL (Ho = 0.039±0.039; AR = 1.122±0.489) and LGT (Ho = 0.033±0.033; AR = 1.141±0.566) populations. Population differentiation (FST = 0.033, p>0.05) and clustering analyses based on both Principal Coordinate Analysis (PCoA) and Discriminant Analysis of Principal Component (DAPC) suggest limited genetic divergence and potential panmixia (single genetic pool) between both populations. These findings highlight critical conservation concerns due to low diversity despite the lack of isolation, emphasizing the need for immediate and targeted efforts to ensure the long-term viability of this iconic yet vulnerable population.