Abstract
Simple SummaryFor this study, skin samples were analyzed from 77 individual stranded dugongs collected in Thai waters from 1994–2019 using six microsatellite markers to assess the genetic diversity and population structure. Dugongs in the Andaman Sea had higher genetic variation than those in the Gulf of Thailand. Populations in Trang, Satun and some areas of Krabi had highest diversity compared to other regions of Thailand. The analysis of Bayesian genetic clustering showed that dugongs in Thailand consist of five genetic groups. Furthermore, dugongs in the middle and lower Andaman Sea presented the greatest gene flow compared to other regions. Based on calculation of inbreeding coefficients, dugong populations in the Sea of Thailand are experiencing some levels of inbreeding, and so may warrant special protections. Results of this study provide important information on genetic diversity and genetic population structuring of dugongs in Thailand and for understanding the genetic status of dugongs that can lead to improved management and conservation of this endangered species.The dugong (Dugong dugon) is an endangered species of marine mammals, so knowledge of genetic diversity of these populations is important for conservation planning within different habitats. In this study, six microsatellite markers were used to assess the genetic diversity and population structure of 77 dugongs from skin samples of stranded animals collected from 1994–2019 (69 from Andaman Sea and 8 from the Gulf of Thailand). Our results found that dugongs in the Andaman Sea had higher genetic variation than those in the Gulf of Thailand. Populations in Trang, Satun, and some areas of Krabi had highest diversity compared to other regions of Thailand. Bayesian genetic clustering analysis revealed that dugongs in Thailand consist of five genetic groups. Moreover, dugongs in the middle and lower Andaman Sea presented the greatest gene flow compared to other regions. However, based on calculation of inbreeding coefficients (Fis value = 0.239), dugong populations in the Sea of Thailand are experiencing some levels of inbreeding, and so may warrant special protections. These results provide important information for understanding the genetic status of dugongs that can lead to improved management and conservation of this endangered species.
Highlights
The dugong (Dugong dugon), order Sirenia, family Dugongidae, is the only herbivorous marine mammal in the world, with a diet consisting of seagrass [1]
To visualize relationships among the Shannon’s information index, observed heterozygosity, and expected heterozygosity population, a principal component analysis (PCA) plot was constructed from a distance for each locus are shown in Table
The PCA of microsatellite loci of the five zones plotted on two axes cumulatively explained 35.41% of the variation (12.70% and 23.17%, respectively)
Summary
The dugong (Dugong dugon), order Sirenia, family Dugongidae, is the only herbivorous marine mammal in the world, with a diet consisting of seagrass [1]. Seagrass is the main food source of dugongs [5,6,7,8], so degradation and disappearance of these meadows are major reasons for declining dugong populations. Most of seagrass degradation is due to coastal construction, pollution, and illegal fishing [9]. It is affected by seasonal changes in some areas [10]. In high density areas like Australia, dugongs exhibit a large range of individualistic movement behaviors, with some being relatively sedentary, while others migrate over hundreds of kilometers, sequentially grazing seagrass meadows to prevent overgrazing [14]. Largescale movements in Sirenians occur in response to seasonal changes in environmental variables, such as temperature, water levels, salinity, and variability of forage [15]
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