Sex determination of green sea turtle (Chelonia mydas) hatchlings on the bases of morphological characters
Bektaş Sönmez, Cemal Turan, Şükran Yalçın Özdilek, Funda Turan
Cumhuriyet University, Koyulhisar Vocational Training School, 58140, Koyulhisar, Sivas, TURKEY
Molecular Ecology and Fisheries Genetics Laboratory, Faculty of Marine Sciences and Technology, İskenderun Technical University, 31200, Iskenderun, Hatay, TURKEY
Department of Biology, Faculty of Science and Arts, Canakkale Onsekiz Mart University, Terzioglu Campus 17100 Çanakkale, TURKEY
Morphological differences between female and male hatchlings of green sea turtle (Chelonia mydas) were investigated to identify key morphological characters for sex determination. A total of 152 dead hatchlings of green sea turtles were examined for 14 morphometric and seven meristic characters in the 2008 and 2009 nesting seasons on Samandag Beach in the north-eastern Mediterranean Sea, Turkey. The sex of dead hatchlings was determined with gonad histology. Multivariate statistics revealed significant differences in three morphometric characters between females and males. The males had a longer curved carapace width (CCW), hind limb length (HLL) and plastron–cloaca length (PCL) than the females. Principal component analysis also supported the detected differences between sexes.
Keywords: Green Turtle, sex determination, gonad histology, morphology
Ackerman, R.A. (1981) Growth and gas exchange of embryonic sea turtles. Copeia 4: 757-765.
Berry, J.F., Shine, R. (1980) Sexual size dimorphism and sexual selection in turtles (Order: Testudines). Oecologia 44: 185-191.
Bjorndal, K.A., Bolten, A.B., Chaloupka, M.Y. (2000) Green turtle somatic growth model: evidence for density dependence. Ecological Applications 10: 269-282.
Bull, J.J. (1980) Sex determination in reptiles. Q. Rev. Bid. 55: 3-21.
Bulmer, M. (1994) Theoretical Evolutionary Ecology. Sinauer Associates, Inc., Sunderland, MA.
Casale, P., Freggi, D., Basso, R., Argano, R. (2005) Size at male maturity, sexing methods and adult sex ratio in loggerhead turtles (Caretta caretta) from Italian waters investigated through tail measurements. Herpetological Journal
15:145 – 148.
Glen, F., Broderick, A.C., Godley, B.J., Hays, G.C. (2003) Incubation environment affects phenotype of naturally incubated green turtle hatchlings. J. Mar. Biol. Ass. U.K. 83: 1183-1186.
Godfrey, M.H., Mrosovsky, N. (2006) Pivotal temperature for green sea turtles, Chelonia mydas, nesting in Suriname. Herpetological Journal 16: 55-61.
Gross, T.S., Crain, D.A., Bjorndal, K.A., Bolten, A.B., Carthy, R.R. (1995) Identification of sex in hatchling loggerhead turtles (Caretta caretta) by analysis of steroid concentrations in chorioallantoic/amniotic fluid. Gen. Comp. Endocrin. 99: 204-210.
Hendrickson, J.R. (1958) The green turtle Chelonia mydas in Malaya and Sarawak. Proc. Zool. Soc. Lond. 130: 455-535.
Ikonomopoulou, M.P., Aland, R.C., Ibrahim, K., Gosden, E., Whittier, J.M. (2012) Quantitative sex identification of hatchling green sea turtles. J. Herpetology 46 (3):331-332.
Janzen, F.J. (1994) Climate change and temperature-dependent sex determination in reptiles. Proc. Nat. Acad. Sci. USA. 91: 7487-7490.
Limpus, C., Chaloupka. M. (1997) Nonparametric regression modelling of green sea turtle growth rates (southern Great Barrier Reef). Marine Ecology Progress Series 149: 23-34.
McCoy, C.J., Vogt, R.C., Censky, E.J. (1983) Temperature-controlled sex determination in the sea turtle Lepidochelys olivacea. Journal of Herpetology17: 404-406.
Merchant-Larios, H., Villalpando-Fierro, I., Centeno-Urruiza, B. (1989) Gonadal morpho-genesis under controlled temperature in the sea turtle. Herpetological Monographs 3: 43-61.
Michel-Morfin, J.E., Gomez Munoz, V., Navarro Rodriguez, C. (2001) Morphometric model for sex assessment in hatchling olive ridley sea turtles. Chel. Conserv. Biol. 4: 53-58.
Mrosovsky, N. (1994) Sex ratios of sea turtles. J. Exp. Zool. 270:16–27.
Owens, D.W., Hendrickson, J.R., Lance, V.A., Callard, I.P. (1978) A technique for determining sex of immature Chelonia mydas using radioimmunoassay.
Herpetologica 34: 270-273.
Packard, G.C., Packard, M.J. (1988) The physiological ecology of reptilian eggs and embryos. In: Biology of the Reptilia Vo. 16, (eds., Gans, C., Huey, R. B.), Alan R. Liss. New York, pp. 524-605.
Valenzuela, N., Adams, D.C., Bowden, R.M., Gauger, A.C. (2004) Geometric morphometric sex estimation for hatchling turtles: a powerful alternative for detecting subtle sexual shape dimorphism. Copeia 4: 735-742.
Van der Heiden, A. M., Briseno, R., Rios-Olmeda, D. (1985) A simplified method for determining sex in hatchling sea turtles. Copeia 1985: 779-782.
Wibbles, T., Owens, D.W., Morris, Y.A., Amos, M.S. (1987) Sexing techniques and sex ratios for immature loggerhead sea turtles captured along the Atlantic coast of the United States. In: Proceedings of the Cape Canaveral, Florida Sea Turtle Workshop (ed., Witzell, W.N.) NOAA Technical Report NMFS 53.
Wyneken, J., Balazs, G.H., Murakawa, S.K.K., Anderson, Y. (1999) Size differences in hind limbs and carapaces of hatchling green turtles (Chelonia mydas) from Hawaii and Florida, USA. Chelonian Conservation and Biology 3: 491-495.
Wyneken, J., Epperly, S.P., Crowder, L.B., Vaughan, J., Esper, K.B. (2007) Determining sex in posthatchling loggerhead sea turtles using multiple gonadal and accessory duct characteristics. Herpetologica 63: 19-30.
Yntema, C.L. Mrosovsky, N. (1980) Sexual differentiation in hatching loggerheads (Caretta caretta) incubated at different controlled temperatures. Herpetologica 36: 33-36.