Search

The brain is among the most energetically costly organs in the vertebrate body. The expensive-tissue hypothesis (ETH) predicts that increasing the size of another costly organ, such as the gut, should compensate for the cost of a small brain. To date, this hypothesis has mainly been tested in homoeothermic animals and in some ectothermic animals (e.g., fishes and anurans). Here, we undertake a test of the ETH by analyzing the relationship between brain size variation and length of the digestive tract in Hylarana guentheri. After controlling for geographical situation and body size, we did not find a correlation between brain mass and the length of the digestive tract in H. guentheri. Our findings suggest that the variation of brain size did not follow general patterns in this species and that the effect of diet quality cannot play a role in the variation of brain. [ABSTRACT FROM AUTHOR]

The compensation hypothesis predicts that one testis may grow more for compensating for a reduced function in the other testis, thus exhibiting a directional asymmetry in testis size. In this study, we tested the prediction of the compensation hypothesis in the Chinese endemic Tree Frog Hyla gongshanensis jingdongensis in a population in Kegong Reserve site of Yunan Province in western China. For fifty-three male samplings, we found that the left testis size was significantly bigger than the right testis, which exhibited a significantly directional testis asymmetry, consistent with the evidence that mainly the left testis is functional with the right testis having a compensatory role, i.e. the left testis would increase in size if the right testis became non-functional. However, the relative testes size and the degree of testes asymmetry were not correlated with body condition in this species, suggesting that the testes asymmetry can not reflect male quality: high-quality individuals would not have more asymmetric testes. [ABSTRACT FROM AUTHOR]

Increased brain size significantly contributes to the performance and fitness of organisms. The expensive-tissue hypothesis (ETH) based on studies of the correlation between brain size and size of the other energetically costly organs in mammals predicts that energy investment increased in one energetically costly tissue necessitates a decrease of investments in other costly tissues. Here, we test this hypothesis in an ectothermic species, the dark-spotted frog, Pelophylax nigromaculatus. We found that relative brain size was not correlated with relative sizes of testes, heart, liver, spleen, kidneys or limb muscles within each sex. Moreover, we also failed to find significantly negative correlation among the expensive organs (i.e., testes, heart, liver, spleen, kidneys or limb muscles) in this frog. However, we observed a significantly positive correlation between liver residuals and kidney residuals. Our finding suggests that energetic costs of one expensive tissue do not direct necessarily affect the investment in another expensive tissue, but rather may scatter its effect on all other expensive tissues. [ABSTRACT FROM AUTHOR]

Bergmann's rule states that, within species of endotherms, individuals tend to be larger in cooler environments, and has been reputed to apply to some ectotherms including amphibians. However, the validity of the rule has been debated, questioning whether Bergmann's dines are generally present in anurans. In the view, we studied altitudinal variation in body size in the rice frog (Rana limnocharis) among populations from Sichuan province located at three altitudes to find if there exist any differences in a relatively small altitudinal range (290-375 m). The results showed that individuals from higher altitudes tended to be larger in body size than lower altitudes, which was consistent with Bergmann's dine. Moreover, when the effect of age was removed, variation in body size of the frogs across altitudes still remained. Our findings suggested that age affected the pattern of variation in body size across the altitudinal dine, we also discussed that factors other than age also contributed to size differences among populations. [ABSTRACT FROM AUTHOR]

I used mark-recapture technique to estimate site fidelity in a subtropical high-elevation torrent frog (Amolops mantzorum) during the breeding season in Fengtongzhai National Nature Reserve in western China. I captured, measured, and individually marked 30 males and 15 females in 20 May 2007. I recorded each individual's initial positions using a Global Positioning System (GPS). For each night from 21 May to 10 June 2007, I recaptured the marked individuals and recorded capture points. The results showed that 16 males and 4 females were never recaptured in the field experiment. Most of the remaining individuals were recaptured only one time. Males and female were recaptured more than 2 and 8 times, respectively. Males and females were recaptured from subsequent positions as far apart as 55 m and 30 m, as close as 0,2 m and 0.1 m. Average neighbor distances on successive capture positions of males recaptured was 10.1 m, and that of females was 4.2 m, suggesting that there were significant difference in site fidelity between females and males. However, there was not significant average activity distance between the sexes. For females, small average activity areas were 10.9 ± 14.9 m2. [ABSTRACT FROM AUTHOR]

I used skeletochronology to estimate age structure of the Siberian Wood Frog, Rana amurensis, from northeastern China. Average age did not differ significantly between males and females. Age at sexual maturity in both males and females was 1 year. For both sexes the maximum age observed was 4 years. Average body size differed significantly between the sexes, with males being larger than females. A significantly and positively correlation between body size and age was found within each sex in the population. When the effect of age was controlled, males also had larger size than females, suggesting that sexual selection for larger males might improve male mating success. [ABSTRACT FROM AUTHOR]

Age determination in amphibians is crucial to investigation of life-history traits. In this context, we studied age structure of the Guenther's frog, Hylarana guentheri, population from southwestern China located at an altitude of 300 m using skeletochronological method. Our results showed that age in adult males ranged from 1 to 4 years, and from 2 to 6 years in adult females. Average age in females was significantly older than males in 2008 and 2009. Also, females had significantly larger average body size than males in both years. A significant relationship between age and body size within each sex was found in this species for both years. The ANCOVA analysis revealed that there was significant difference in body size between sexes when the effect of age was removed. The von Bertalanffy's model showed that females had larger [ABSTRACT FROM AUTHOR]