Evaluation of genetic markers for assessing sex-related differences in the hawksbill turtle (Eretmochelys imbricata)

Document Type : Research Paper

Authors

1 MSc Student, Animal Science Department, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.

2 Professor of Animal Science Department, Shahid Bahonar University of Kerman

3 Professor, Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran.

4 PhD Student, Animal Science Department, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.

Abstract

Objective
The hawksbill sea turtle (Eretmochelys imbricata) is a critically endangered species that has a temperature-dependent sex determination (TSD) system. Given the impact of climate change on the sex ratio of this species and the lack of information on genetic differences associated with sex, this study aimed to evaluate the utility of four genetic markers 6299, 6299-T, 14749, and 14749-T (introduced in previous genomic studies on the Chinese softshell sea turtle (Pelodiscus sinensis)) to investigate whether these markers can reveal potential genetic differences between males and females of E. imbricata.
Materials and methods
Sampling was conducted during the nesting season from three main nesting habitats of the hawksbill sea turtle in the Persian Gulf, including Nakhiloo, Ommolgorm Islands, and Naiband Coasts. The samples consisted of one adult female turtle and fifteen hatchlings. Genomic DNA was extracted from organ tissue and its quality and quantity were assessed by agarose gel electrophoresis and spectrophotometry. The PCR reaction was performed using four primer pairs introduced in the study of Zeng et al. (2024). The PCR products were electrophoresed on 2% agarose gel and the banding patterns between individuals, populations and sexes were compared qualitatively and semiquantitatively.
Results
The results showed that markers 6299 and 6299-T produced significant genetic variation between individuals and populations, but these differences were not uniformly associated with sex. Marker 14749 revealed differences at the population level, such that the banding patterns varied between islands but were uniform within each population. In contrast, marker 14749-T showed almost identical banding patterns in all samples, indicating low genetic diversity in this genomic region in E. imbricata. None of the markers showed a definitive and stable pattern of male-female segregation.
Conclusion
This study shows that genetic markers introduced for species with genetic sex determination cannot be used as definitive sex determination markers in a species with a temperature-dependent sex determination system such as Eretmochelys imbricata. However, some of these markers can be valuable tools for investigating genetic diversity, population structure, and conservation studies. The results emphasize the need to develop and validate species-specific markers and conduct genomic, epigenetic, and gene expression studies to better understand the molecular mechanisms associated with sex in sea turtles.

Keywords

References

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Agricultural Biotechnology Journal
Volume 18, Issue 1
January 2026
Pages 481-498

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