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The article discusses research which examined the possible mediation of the relationship between predation risk and crypsis by brain size. Topics explored include the cognitive abilities of well-camouflaged animals that help them evade predators, the use of reflectance measurements and visual modeling to assess the conspicuousness of anuran species from China, and observations relating to predation pressure, relative brain size, and hind leg muscle mass in the frogs studied.

Sexual size dimorphism (SSD), the difference in body size between males and females, is a widespread phenomenon and commonly attributed to variation in sex-specific patterns of selection. Using data from three populations of Polypedates megacephalus, we tested the hypotheses that sexual selection favoured large male body size and that fecundity selection favoured large female size. Females had a larger body size than males in all populations and thus exhibited a female-biased sexual size dimorphism. Standardized selection gradients showed that sexual selection for large male size was weak at best and hence unlikely to be an important driving force for SSD. As fecundity selection favouring large females was weak as well, it could not explain the female-biased SSD patterns found. However, a faster growth rate in females favoured a larger size, providing an explanation for female-biased SSD. Our findings suggest that female-biased SSD does not result from a phenotypic selection of female by size in P. megacephalus. [ABSTRACT FROM AUTHOR]

Competition for fertilization in multi-male group spawning can drive variation in male reproductive investment (i.e., testis mass and sperm size). Inter-population comparisons of variation in energetic availability and allocation along geographical gradients allow insights into the mechanisms shaping the reproductive investments of animals. Although inter-population differences in female reproductive investment (i.e., clutch size and egg size) have been studied extensively across a wide range of taxa, little information on variation in reproductive investment in males is available. Here, we studied altitudinal variation in testis mass and sperm length among three populations in the Jingdong tree frog (Hyla gongshanensis jingdongensis), a polyandrous species, in Yunnan Province in China. The results showed that individuals exhibited smaller testes at higher altitudes while testes mass was positively correlated with body size, body condition and age. Longer sperm length was observed in the middlealtitude population. Moreover, we found that sperm number was positively correlated with testes mass and sperm length. Our correlational findings suggest that environmental constraints at high altitude select for less investment in testes and offspring number. [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]

Background The degree of postcopulatory sexual selection, comprising variable degrees of sperm competition and cryptic female choice, is an important evolutionary force to influence sperm form and function. Here we investigated the effects of mating system and spawning location on the evolution of sperm morphology in 67 species of Chinese anurans. We also examined how relative testes size as an indicator of the level of sperm competition affected variation in sperm morphology across a subset of 29 species. Results We found a significant association of mating system and spawning location with sperm morphology. However, when removing the effects of body mass or just testes mass for species for which such data were available, this effect became non-significant. Consistent with predictions from sperm competition theory, we found a positive correlation between sperm morphology and relative testes size after taking phylogeny into account. Conclusions Our findings suggest that sexual selection in Chinese anurans favors longer sperm when the level of sperm competition is high. Pre-copulatory male-male competition and spawning location, on the other hand, do not affect the evolution of sperm morphology after taking body mass and just testes mass into account. [ABSTRACT FROM AUTHOR]

Rensch's rule describes that sexual size dimorphism (SSD) increases with body size (hyperallome-try) when males are larger, and decreases with body size (hypoallometry) when males are smaller. In this paper, on the basis of mean adult body size resulting from 18 populations of the common frog Rana temporaria and 24 populations of the Tibetan frog Nanorana parkeri, we tested the consistency of allometric relationships between males and females with Rensch's rule. Our results show that the variation in degree of female-biased SSD increased with increasing mean size at intraspecific levels in two species, which is consistent with the inverse of Rensch's rule. Furthermore, we tested the hypoth-esis that the degree of SSD decreased with increasing altitudes. Inconsistent with the predications of our hypothesis, we found no relationships between the degree of SSD and altitude for the two species investigated. These findings suggest that females living in adverse climates in high altitudes cannot adjust their body size as plastically as males. [ABSTRACT FROM AUTHOR]

The article discusses the study which determined the ages of 249 odorous frogs, Odorrana grahami, from four locations in Sichuan Province, China, with the use of skeletochronology. It found from excised toe bone for 242 individuals, distinct lines of arrested growth (LAGs), with each LAG assumed to represent one year of age. The study also revealed significant differences in average adult snout-vent length (SVL) and age among female populations, but not in males.

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]

In anuran mate choice, advantaged males are generally known to be larger or older individuals. To test whether male mating success in the foam-nesting treefrog Rhacophorus omeimontis, a species distributed in western China, correlated with body size and age, we analysed differences in body size and age among three types of males. Males were classified as mated, joining or unmated at the time of sampling with joining males being additional males joining pairs in amplexus. Our results showed that there were no significant differences in body size among the three types of males. However, age was an important factor, with mated males being significantly older than joining and unmated males, which indicated that older individuals tended to have greater mating success than younger frogs. [ABSTRACT FROM AUTHOR]

The article focuses on testis asymmetry in dark-spotted frog Rana nigromaculata. Testis asymmetry is common in some animals and it was explained that this happens because one testis grows more to compensate for the reduced function of the other testis. The authors conducted the study with the goal of testing whether frogs possessed significant differences in left and right testes size. The male R. nigromaculata were collected in northeastern Sichuan, western China and the testes comparison was done using a paired t-test. They found that the R. nigromaculata's left testes were significantly larger and added that it was much larger in larger and older male dark-spotted frogs.

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]