Sexual Dimorphism and morphological variation of three populations of Phrynocephalus helioscopus (Agamidae): Test of Bergmann’s rule, Allen’s rule and Rensch’s rule
Author of the article:LIANG Tao, SHI Lei
Author's Workplace：The college of Animal Science, Xinjiang Agricultural University
Key Words：Phrynocephalus helioscopus; Sexual dimorphism; geographical variation; Bergmann's rule; Allen's rule; Rensch's rule; Allometry
Abstract：Environmental impact of animal body size and exposed parts has been extensively studied, but its influence on sexual dimorphism is still rare. We studied sexual dimorphism and geographical variation of morphology in three populations of a toad-headed agama lizard (Phrynocephalus helioscopus), a combined analysis of Bergmann’s rule, Allen’s rule and Rensch’s rule on the variation of body, limbs and tail size. The results of t-test showed that juveniles are sexually dimorphic in body size (snout-vent length, SVL) of Beitun city (P < 0.05) with males having longer SVL but not from Yinning city or Tacheng city (P > 0.05). Adults from Yinning city and Beitun city are sexually dimorphic (P < 0.05) with females having longer SVL but not from Tacheng city (P > 0.05). Analysis of covariance (ANCOVA) showed that juveniles from Beitun and Yining city do not show a sexual dimorphism in fore-limb length (FLL), hind-limb length (HLL) and tail length (TL) (P > 0.05), while male juveniles having longer FLL from Tacheng city but not in HLL or TL. Among adults, male has larger HLL and TL (P < 0.01) from three populations, but female has larger FLL from Yining city (P < 0.05) except for Beitun and Tacheng city. Body size exhibits an anti-Bergmann phenomenon, while the size of the limbs and tail follows Allen’s rule. Body size, forelimb length, length of hind legs and tail length do not follow Rensch phenomenon from three populations. Pressure by diffused natural selection plays a stronger role than of the fecundity advantage selection and sexual selection in three populations of P. helioscopus.