An allometry study of Caspian pond turtle (Mauremys caspica) in Golestan province, Iran

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.