Researchers find unique genetic profiles in Thai dugongs

14 June 2021

Faculty of Veterinary Medicine

Dugongs are marine mammals whose population is declining at an alarming rate. Only around 200 are found in the Thai sea, mostly along Trang’s coast. Due to their endangered status, dugongs are protected by several laws, including the Fishery Act, B.E. 2490 (1947), the National Park Act, B.E. 2490 (1947), the Wildlife Conservation and Protection Act, B.E. 2535 (1992), and The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). A key obstacle in dugong population increase is the fact that breeding is impossible, and it is difficult for baby dugongs to survive in confined areas that are not the open sea, as can be seen from the famous Baby Mariam and Baby Yamil.

The Faculty of Veterinary Medicine, Chiang Mai University and the Phuket Marine Biological Centre, Department of Marine and Coastal Resources, Ministry of Natural Resource and Environment, found success in their study on ‘Genetic Diversity of Dugongs in Thailand and around the World’, which has intrigued scholars, both domestic and international, as a group of dugongs inhabiting the Andaman Sea had unique population characteristics, unlike dugongs anywhere else. This research was published in Scientific Reports, an international academic journal, in June 2021. (Poommouang A, Kriangwanich W, Buddhachat K, Brown JL, Piboon P, Chomdej S, Kampuansai J, Mekchay S, Kaewmong P, Kittiwattanawong K, Nganvongpanit K*. Genetic diversity in a unique population of dugong (Dugong dugon) along the sea coasts of Thailand. Scientific Reports. 2021. 11, 11624) This discovery is going to be of great significance to the planning of dugong conservation.

Assoc. Prof. Dr. Korakot Nganvongpanit, head of the research team, has explained that this research used tissue samples collected between 2009 and 2019 from 118 dugongs, 110 from the Andaman Sea and 8 from the Gulf of Thailand. It was found that during the last 10 years, dugong’s genetic diversity has declined and in Thailand, there are 11 different genetic patterns, of which 9 are found in the Andaman Sea and 2 in the Gulf of Thailand (Figure 1). When compared to the genetic characteristics of dugongs from other parts of the world, the group found in the Andaman Sea shows a unique distinction from all other groups in the world, while the other group belongs to the same group as the ones inhabiting the South China Sea, along Malaysia, Indonesia, Japan, and Australia (Figure 2). A genetic sequencing study revealed that the group unique to Thai waters separated from another group about 1.2 million years ago (Figure 3).

Figure 1 Genetics patterns of dugongs in Thailand
In Zone 1 of the Gulf of Thailand, there is one pattern found (b), in Zone 2, there are two patterns (c), and in Zone 3, two patterns (d). In Zone 4 and 5, eight and six patterns are found, respectively (Poommouang et al., 2021).

Figure 2 Distribution of genetic characteristics of dugongs across 26 regions around - Japan (1 clade), Palau (2), Philippines (3), Malaysia (4), Thailand-Gulf of Thailand (5), Thailand-Andaman Sea (6), Indonesia (7), Papua New Guinea (8), Australia (9), India (10), Sri Lanka (11), Indian Ocean (12), Bahrain (13), United Arab Emirates (14), Yemen (15), Egypt (16), Sudan (17), Djibouti (18), Kenya (19), Tanzania (20), Comoros (21), Mozambique (22), Madagascar (23), Mauritius (24), Indian Ocean in Africa (25) and Unknown (26).

Figure 3 Evolution of dugongs by genetic patterns (a) the time of separation from the common ancestors in Mya (million years ago) (b), and the separation into six clades, whereby Clade A separated from another group at about 1.2 million years ago (c).

Dr. Kongkiat Kittiwatanawong, director of the Phuket Marine Biological Centre, has added that throughout the years, there has been a question about whether dugongs in Thai seas share the same genetic profiles as those from other parts of the world, and these findings are exciting because we now know that the dugong population here is unique and has to be protected at all costs. We cannot afford to lose any more of these endangered creatures and there must be strict conservation measures that protect especially from human causes. As for the question about the number of dugong families in the Thai seas, the team is working on finding out the answer.