Variation in body size, age and growth in the Omei treefrog (Rhacophorus omeimontis) along an altitudinal gradient in western China

Abstract

Identifying variations in morphology and age across geographical gradients may help us to understand the evolution of life-history of animals. In view of this, we studied variation in body size, age and growth of the Omei treefrog (Rhacophorus omeimontis) along altitudinal gradients in Baoxing County of Sichuan province in western China. The results showed that adult females had larger body size than males for all populations. Body size differed significantly among populations in males, but not in females. In three populations, the average age from the 760 m and 1690 m sites differed significantly between males and females, but not at the 1000 m site. Individuals from the 1690 m site exhibited delayed sexual maturity as well as having greater average age than those from the 1000 m and 760 m sites. For males, the growth rates declined with increasing altitudes, while females from the 1690 m site exhibited higher growth rates than their conspecifics from the 1000 m and 760 m sites. Variation in body size in males did not change consistently with altitudes when removing the effect of age, not agreeing with Bergmann's rule.