Document Type : Original Article


Department of Biology, Faculty of Sciences, Golestan province, Gorgan


Caspian pond turtle, Mauremys caspica shows allometric growth and sexual dimorphism in the shell. Differences in allometric growth produce sexually dimorphic adults. Our results revealed that females are smaller than males that may be related to the risk of the predation, desiccation, and thermal stress. Allometric changes in shape of the shells are different between males and females. In females shape related characters such as plastral length (Pl1) and plastral fore and hind lobe width (PFLW, PHLW), gular, pectoral, abdominal and anal seam length (GSL, PSL, AbSL, AnSL) which represent width of  plastron and plastral length proportionally change with size (related to SCL2 as  index of size). The most remarkable changes related to size are right and left bridge length (RBr, LBr) in females but these changes have not effect on shell shape. For males character TL2 changes dramatically related to size (SCL2). Sexual dimorphism of the shell was also evident. ANCOVA indicated that the regression slopes of males and females differed significantly (p> 0.000) in 15 of the 24 characters examined.


Andersson M. 1994. Sexual selection. Princeton: Princeton University Press.
Berry J.F., Shine R. 1980. Sexual size dimorphism and sexual selection in turtles (order Testudines). Oecologia 44(2):185–191.
Benítez H., Vidal M., Briones R., Jerez V. 2010. Sexual dimorphism and population morphological variation of Ceroglossus chilensis (Eschscholtz) (Coleoptera, Carabidae). Journal of the Entomological Research Society 12(2): 87–95. 
Brophy T.R. 2006. Allometry and sexual dimorphism in the snail-eating turtle Malayemys macrocephala from the Chao Phraya River Basin of Central Thailand. Chelonian Conservation and Biology 5(1): 159-165.‏
Brown, W.C., Wilson, E.O. 1956. Character displacement. Systematic Zoology 5:49–64.
Cardillo M., Mace G.M, Jones K.E. Bielby J., Bininda-Edmonds O.R.P., Sechrest W.,Orme C.D.L., Purvis A. 2005. Multiple causes of high extinction risk in large mammal species. Science 309:1239–1241.
Ceballos, C.P., Hernández O.E., Valenzuela N. 2014. Divergent sex-specific plasticity in long-lived vertebrates with contrasting sexual dimorphism.  Evolutionary Biology 41(1):81–98.
Cox R.M., Butler M.A., John-Adler H.B. 2007. Chapter4: the evolution of sexual size dimorphism in reptiles. In: Fairbairn DJ, Blanckenhorn WU, Székely T, eds. Sex, size and gender roles: evolutionary studies of sexual size dimorphism. Oxford: Oxford University Press, 39–49.
Dunham A.E., Smith G.R., Taylor J.N. 1979. Evidence of ecological character displacement in western American catastomid fishes. Evolution 33:877–896.
Feldman A, Meiri S. 2013. Length mass allometry in snakes. Biological Journal of the Linnaean Society 108(1):161–172.
Gibbons, J.W. Lovich, J.E. 1990. Sexual dimorphism in turtles with emphasis on the slider turtle (Trachemys scripta). Herpetological Monographs, 4:1–29.
Gidaszewski N, Baylac M, Klingenberg C. 2009. Evolution of sexual dimorphism of wing shape in the Drosophila melanogaster subgroup. BMC Evolutionary Biology 9: 110.
Halámková L., Schulte J.A., Langen T.A. 2013. Patterns of sexual size dimorphism in Chelonia. Biological Journal of the Linnean Society, 108(2):396–413
Lovich J.E., Ernst C.H., McBreen J.F. 1990. Growth, maturity, and sexual dimorphism in the wood turtle, Clemmys insculpta. Canadian Journal of Zoology 68:672–677.
Lynch M. 2007. The origins of genome architecture. 1stedition.Sunderland: Sinauer Associates.
Pough F.H. 1980. The advantages of ect other my for tetrapods. American Naturalist 115:92–112.
Regis K.W., Meik J.M. 2017. Allometry of sexual size dimorphism in turtles: a comparison of mass and length data. PeerJ, 5: e2914.‏
Shreeves G., Field J. 2008. Parental care and sexual size dimorphism in wasps and bees. Behavioral Ecology and Sociobiology 62: 843–852.
Stephens P.R., Wiens J.T. 2009. Evolution of sexual size dimorphisms in Emydid turtles: ecological dimorphism, Rensch’srule, and sympatric divergence. Evolution 63:910–925
Székely T., Lislevand T., Figuerola J. 2007. Sexual size dimorphism in birds. Sex, sizeand genderroles:evolutionary studes of sexual size dimorphism. Oxford: Oxford University Press, 27–37.
Werner YL., Korolker  N., Sion G., Gö¸cmen B. 2016. Bermann’s and Rensch’s rules and the spur-thighed tortoise (Testudo graeca). Biological Journal of the Linnean Society 117:798–811
Yadollahvand R, Kami H.G. 2014. Habitat changes and its Impacts on the Caspian Pond Turtle (Mauremys caspica) Population in the Golestan and Mazandaran Provinces of Iran. Journal of Aquaculture Research & Development, 5: 232.
Yazarloo M., Kami  H.G. 2017. Sexual dimorphism and morphometric study of Caspian pond turtle, Mauremys caspica, (Testudines: Geoemydidae) in Golestan Province, southeast of the Caspian Sea. Caspian Journal of Environmental Sciences, 15(4): 321-334.