Study On Growth And Reproduction Of Rana Chensinensis

Growth and reproduction of Rana chensinensis were studied in Huozhou and Luya Mountain, in Shanxi. In Rana chensinensis, Age of frogs was assessed by skeletochronology. Age and body length were positively correlated. Body length increased with increasing age, but growth rate decreased with increasing age when frogs were sexual maturity, and growth rate became slow as increased age. Age distribution did differ significantly between both sexes. Mean body length was greater in females than males, and mean age showed the same trend within population. Female body length was larger than male body length presumably as a result of more energy being allocated to maturation, to reproduction, and to growth of ovary. Among populations, mean body length and age at higher altitude were significantly larger than those at lower altitude. In higher altitude where temperature was lower and food lacked, the frogs had a shorter period of activity. Because mean body length and physiological longevity increased with decreasing activity period, individuals exposed to a short activity period could have a delayed sexual maturity and thus attain a greater final length.We analyzed variation in clutch size, egg size and clutch mass in association with body size and age of Rana chensinensis from a population in Huozhou and from three-altitudinal widely separated populations in Luya Mountain. Within each population, female body size was a remarkable factor that affected individual reproductive output. Clutch size, egg size and clutch mass increased with increasing female body size, respectively. Female age was a remarkable factor that affected individual reproductiveoutput. Individual age was no significantly related to clutch size or egg size, but clutch mass was found to be positively correlated with age. Within a given range of body length, there was a trade-off between clutch size and egg size. Any increase in the production of egg numbers was accompanied by a corresponding decline in egg size, and vice versa. After accounting for differences in body size and age among populations, clutch size, egg size and clutch mass differed significantly among populations. Female body and age was no significantly related to reproductive output. Reproductive output was related to variation in environmental conditions. At 1900 m, relative larger clutch mass was associated with relatively larger eggs, whereas at lower altitudes it was associated with relatively larger clutch size.