Diet and sexual dimorphism of Rana chaochiaoensis

Key words: 
• zoology /
• Rana chaochiaoensis /
• diet /
• sexual dimorphism /
• secondary sexual characters

Abstract: The 428 specimens of Rana chaochiaoensis collected from May 1998 to October 2003 were anatomized (♀202 , ♂184 , subadults 42)for diet analysis ;151 adult frogs whose body lengths were larger than 40 mm were measured (♂81 , ♀70)for sexual dimorphism study .The diet analysis showed that R .chaochiaoensis gave priority to animality food and there was no significant discrepancy in cliet between male and female frogs .The food habits didnt lead to their sexual dimorphism polarization .The results of t-test indicated that there was significant discrepancy in width and length of forearm between male and female adult R .chaochiaoensis .The results of univariate analysis of variance showed that there was significant discrepancy in head width , snout length , tympanum diameter , eye diameter , forearm length , forearm width , hand length , length of hindlimb , tibia length and foot length between male and female adult frogs .Sexual dimorphism was primarily determined by the ultimate sexual selection .There was no significant difference in body size between male and female R .chaochiaoensis .Forearm in adult male R .chaochiaoensis was stronger than females .The first finger base in adult male frog had nuptial pad with fine and dense cutin tubercles , which could increase embrace friction , strengthen embrace ability and avoid female frog escaping .Male R .chaochiaoensis had no vocal sac .However , its longer hindlimb andmore developed web than females were helpful to improve its capacity of chasing female , which could successfully increase mating rate .Developed hindlimb of female could enhance its ability to jump , which was useful for female keeping away rapidly from disturbance and threat .[ Ch , 2 tab .29 ref .]