What the skull and scapular morphology of the dugong (Dugong dugon) can tell us: sex, habitat and body length?

Nganvongpanit, Korakot; Buddhachat, Kittisak; Kaewmong, Patcharaporn; Cherdsukjai, Phaothep; Kittiwatanawong, Kongkiat

doi:10.1038/s41598-017-01899-7

Cited by 10 publications

(8 citation statements)

References 34 publications

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“…The finding of some regional genetic differences agrees with data on other biological parameters. In 2017, Nganvongpanit and colleagues found skull morphometric analyses were 100% accurate in identifying dugongs in the Andaman Sea versus the Gulf of Thailand, and that dugongs living in the Andaman Sea were larger, based on skull size, than those in the Gulf of Thailand 58 . In addition, mineral elements in dugong teeth were significantly different between dugongs in the two habitats 59 .…”

Section: Discussionmentioning

confidence: 99%

Genetic diversity in a unique population of dugong (Dugong dugon) along the sea coasts of Thailand

Poommouang

Kriangwanich

Buddhachat

et al. 2021

Sci Rep

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Dugong (Dugong dugon) populations have been shrinking globally, due in large part to habitat fragmentation, degradation and ocean pollution, and today are listed as Vulnerable by the IUCN. Thus, determining genetic diversity in the remaining populations is essential for conservation planning and protection. In this study, measures of inter-simple sequence repeat (ISSR) markers and mtDNA D-loop typing were used to evaluate the genetic diversity of 118 dugongs from skin samples of deceased dugongs collected in Thai waters over a 29-year period. Thirteen ISSR primers revealed that dugongs from the Andaman Sea and Gulf of Thailand exhibited more genetic variation in the first 12 years of the study (1990–2002) compared to the last decade (2009–2019). Dugongs from the Andaman Sea, Trang, Satun and some areas of Krabi province exhibited greater diversity compared to other coastal regions of Thailand. Eleven haplotypes were identified, and when compared to other parts of the world (235 sequences obtained from NCBI), five clades were apparent from a total 353 sequences. Moreover, dugongs from the Andaman Sea were genetically distinct, with a separate haplotype belonging to two clades found only in Thai waters that separated from other groups around 1.2 million years ago. Genetic diversity of dugongs in present times was less than that of past decades, likely due to increased population fragmentation. Because dugongs are difficult to keep and breed in captivity, improved in situ conservation actions are needed to sustain genetically healthy wild populations, and in particular, the specific genetic group found only in the Andaman Sea.

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Section: Discussionmentioning

confidence: 99%

Genetic diversity in a unique population of dugong (Dugong dugon) along the sea coasts of Thailand

Poommouang

Kriangwanich

Buddhachat

et al. 2021

Sci Rep

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“…Our study used 6 parameters of the pelvic bone to achieve the highest rate of accuracy for sex identification at up to 92.10%. A previous study involving other bones of the dugong reported an accuracy rate of up to 96.7% for the skull, 81.8% for the cranium, 78.4% for the mandible, and 68.1% for the scapula 19 . A study involving bottlenose dolphins using morphometric data acquired from pelvic bones reported a high accuracy rate of up to 97% 29 .…”

Section: Discussionmentioning

confidence: 89%

“…However, we could not find any significant hallmark for the pelvic bone that could be used for sex identification. Previous studies involving the scapula of the dugong reported a hallmark for sex identification by scapular morphology using the caudal border tubercle and coracoid process at 91.30% and 96.15% accuracy rates for identifying males and females 19 . The morphology of the dugong pelvic bone indicated a high variation in male and female subjects.…”

Section: Discussionmentioning

confidence: 99%

“…In general, there is limited available information on not only the pelvic bone, but also on other bones of this sea mammal. One study conducted in the year 2017 reported that the skull and scapular morphology and morphometric measurements of dugongs could be used as tools for sex identification, determination of habitat and estimation of body length 19 . Due to the fact that the dugong is an endangered species, a limited number of samples that can be collected by responsible institutes.…”

Section: Introductionmentioning

confidence: 99%

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Pelvic bone morphometric analysis in the dugong (Dugong dugon)

Nganvongpanit

Cherdsukjai

Boonsri

et al. 2020

Sci Rep

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The dugong (Dugong dugon Müller) is recognized as an endangered marine mammal. There is limited available anatomical data on the dugong’s skeletal system, while what is available has not been well established due to the limited number of archived samples and limited access to them. Importantly, there are certain key questions that should be answered when examining the bones and/or remains of animals such as; what kind of bone is it?; what species does it belong to?; what sex was the animal?; how old was the animal? or how big was it?, etc. In this study, we have focused on the pelvic bone of the dugong by asserting the hypothesis that pelvic bone morphology is related to age, sex, and body size. Here, we have established certain morphometric data encompassing 8 parameters and 5 indexes to analyze the morphology of the pelvic bones obtained from 88 specimens (45 dugongs). We will present three main findings: (1) the pelvic bone in mature male subjects is larger than it is in female subjects, (2) a high rate of accuracy can be established for sex identification using morphometric data obtained from the pelvic bone, and (3) the pelvic bone has the highest degree of correlation with body length, followed by body weight and age. Notably, the important data on the pelvic bone of the dugong acquired in this study can be reliable and extremely useful in sex identification and body size estimation.

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“…In nature, wild dugongs may not have access to as much seagrass or quantities of food available to captive dugongs. Density of dugongs in the habitat also may affect growth rates due to influences on food availability and habitat quality ( Marsh, 1980 ; Nganvongpanit et al, 2017a , 2017b ), which in turn could affect age of sexual maturity. Population differences in age at sexual maturity have been observed in wild dugongs.…”

Section: Discussionmentioning

confidence: 99%

Age relationships with telomere length, body weight and body length in wild dugong (Dugong dugon)

Cherdsukjai

Buddhachat

Brown

et al. 2020

PeerJ

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The ability to estimate age and determine the growth status of free-ranging dugongs (Dugong dugon) is vital to providing insight into the basic biology of this endangered species. Currently, age estimation in dugong carcasses relies on counting dentin growth layer groups (GLGs) in tusks, but a disadvantage is they need to be intact. We explored whether measures of telomere length could be used as an alternative approach to age estimation in dugongs given that in other species, telomere length and age are inversely related. In this study, relative telomere length (rTL) was measured by qPCR in skin samples from 24 dugongs of varying ages determined by counts of GLGs. In addition, relationships between age by GLG counts and body weight and length and were examined. Our findings indicate that age estimated by GLGs was negatively correlated with telomere length using the logistic formula with a rate of telomere attrition of approximately 0.036 rTL/year between the ages of 5–20 years. By comparison, both body weight and length were positively correlated with GLG-based age, with growth rates of ~8.8 kg/year for weight and ~3.58 cm/year for length, respectively. After that, growth rates slowed substantially and then plateaued. The results suggest that physical maturity in dugongs occurs at 20 years of age and that measures of rTL might serve as a tool for age estimation in dugongs, living and deceased.

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What the skull and scapular morphology of the dugong (Dugong dugon) can tell us: sex, habitat and body length?

Cited by 10 publications

References 34 publications

Genetic diversity in a unique population of dugong (Dugong dugon) along the sea coasts of Thailand

Genetic diversity in a unique population of dugong (Dugong dugon) along the sea coasts of Thailand

Pelvic bone morphometric analysis in the dugong (Dugong dugon)

Age relationships with telomere length, body weight and body length in wild dugong (Dugong dugon)

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