Research On The Relationship Of Leptin And Its Receptor Genes To Male Amplexus Position In The Omei Tree Frog, Rhacophorus Omeimontis

Energy is the essential factor in regulating animal reproduction. Its reservation or allocation and related genes expression level may limit individual difference in animal reproductive behavior. Therefore, investigating the relationship between energy reservation or allocation, energy-related genes expression level and individual difference in reproductive behaviors is especially important.There are obvious behavioral differences among individuals when they attend to reproductive process. And this phenomenon is common in amphibians. Omei tree frog (Rhacophorus omeimontis) is a typical species who displays polyandrous breeding pattern. During the breeding season, one or more males clasp a female and form a spawning group which forms different amplexus positions of males in a clutch with one amplexed males followed by several satellite males. Interestingly, the reproductive success and number of offspring of amplexed males are higher than those of satellite males. However the mechanism of shaping the differential amplexus positions of the Omei tree frog in one clutch is presently unknown. In this study, we have observed and recorded amplexus time of amplexed males and satellite males during two breeding seasons in 2013 and 2014, and then compared the relative expression level of energy-related genes LEP, LEPR and LEPROT between the amplexed males and the satellite males in the same clutch. We aimed to explore the relationship between reproductive behavior and the energy and related genes expression level, and then to further investigate the molecular basis of shaping different reproductive behavior of Omei tree frogs.Our results showed that 1) the amplexus time differed significantly between amplexd males and satellite males in the same clutch (P< 0.01); 2) there is no significant difference in the expression level of LEP, LEPR genes between amplexd males and satellite males in the same clutch; 3) the expression levels of LEPROT gene in brain (P< 0.01) and testis (P< 0.05) of amplexed males were significantly higher than those of satellite males. Our results suggested that difference of amplexus positions in one clutch is correlated with energy allocation. And this situation is related to different expression of energy-related genes. Amplexed males with high expression level of LEPROT gene may apportion more stored energy to reproduction than satellite males through inhibiting the leptin-leptin receptor signal pathway, and difference in gene expression level between amplexed males and satellite males is sure existence. Our results provide a new feasible approach to advance our understanding of the molecular mechanisms that underlie the individual difference in Omei tree frog reproductive behavior.