• Animal cells and systems
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• v.14 no.4
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• pp.315-322
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• 2010

We studied and compared the age structure, body size, and growth rates of field populations of two Korean salamander species (Hynobius yangi and Hynobius quelpaertensis) to elucidate important aspects of basic population dynamics of these two endemic Hynobius species. In both populations, females were sexually mature at three years of age, while H. yangi and H. quelpaertensis males matured at two and three years of age, respectively. Both males and females of H. yangi and H. quelpaertensis attained a maximum age of 11 years and 10 years, respectively. In both species, the snout-vent length (SVL) and body weight (BW) of the females were greater than those of the males. The SVL, BW, and asymptotic SVL of both male and female H. yangi were smaller than those of H. quelpaertensis. The adult growth rates after sexual maturation of male and female H. yangi were lower than those of H. quelpaertensis, possibly resulting in the smaller body size of the former, although overall growth coefficients were not significantly different between the two species. We also compared the age structure and growth rates of three Korean and three Japanese species of Hynobius.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.342-347
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• 2012

This study was conducted to demonstrate the relationship between experience of cannibalism and difference of phenotype in the Korean salamander Hynobius leechii from March to April 2011. We examined whether the different polyphenism of larval salamander is induced as a result of indirect cannibalism in early life cycle. We divided into two groups(one group continuously exposed to the indirect cannibalism and the other group never exposed to the cannibalism). We measured the head width at the level of eyes(HWE), the largest head width(LHW) and snout-vent length(SVL) of the each larva then calculated the ratio of the head size by dividing HWE by LHW. We found that exposure of indirect cannibalism in early life cycle cause the different polyphenism. Our result means the larval salamander responded to the chemical cue from conspecific.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.477-483
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• 2015

Characteristics of snake reproductive organs that are relatively less affected by external environmental conditions can be used as an important means of classification; additionally, such characteristics can provide useful information on a species' reproductive system. In this study, we compared the testis weights, hemipenis lengths and retractor muscle lengths of male Oocatochus rufodorsatus and Rhabdophis tigrinus in Colubridae and Gloydius saxatilis, G. brevicaudus and G. ussuriensis in Viperidae. The snake snout-vent lengths (SVLs) were positively related to the three reproductive organ sizes, but the body weight only exhibited a positive relationship with the testis weight. The three organs did not significantly differ on the left and right sides. The relative testis weights and retractor muscle lengths (divided by the body weight and SVL, respectively) of the Colubridae snakes were greater than for the Viperidae snakes, but the relative hemipenis lengths (divided by SVL) did not differ between the two groups. The relative testis weight of G. saxatilis and the relative retractor muscle lengths of the Viperidae snakes were smaller compared with the Colubridae snakes. The relative hemipenis length of O. rufodorsatus was greater than for R. tigrinus, G. saxatilis and G. brevicaudus. Additional comparisons were not significant. Our results may facilitate further studies on hemipenial morphology and mating competition in Korean snakes. This is the first study on Korean snake reproductive organs.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.68-74
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• 2014

Scientific study has investigated the body condition differences by habitat characteristics in larvae Korea salamander (Hynobius leechii) from March to April in 2012. To examine the sensitivity of external environment (predation risk), we divided two groups according to habitat characteristic; 1) Permanent pond and 2) Temporary pond. Howere, each larva was measured by head width at the level of the eye (HWE), largest head width (LHW) and snout-vent length, and we calculated the ratio of the head size by dividing HWE/LHW. As a result, larvae were larger in permanent pond group, had a faster growth rate than in temporary pond group. When exposed to the predator, larvae in permanent pond were smaller HWE/LHW than larvae in permanent pond. Therefore, these results indicate larvae in temporary pond more sensitive to the external environment.

• Korean Journal of Environmental Biology
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• v.27 no.1
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• pp.20-30
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• 2009

To study reproductive dynamics of a Gold-spotted pond frog (Rana chosenica) population located at Gangnae, Cheongwon, Chungbuk, Korea, we monitored the population over 207 days between April 17$^{th}$ 2007 and December 18$^{th}$ 2008 using a drift fence accompanied with 20 pitfall traps. The population was located in an agricultural wetland, compromising three small ponds. Gold-spotted pond frogs immigrated into the wetland between April 16$^{th}$ and June 17$^{th}$ and emigrated from the wetland between September 21$^{st}$ and November 12$^{th}$. Precipitation showed a positive correlation with the number of migrated frogs in Autumn 2007 and Spring 2008, but other environmental factors such as air and water temperatures and relative humidity did not show any significant relationships. In general, small frogs first migrated into and from the wetland, but the trend was not strong. Female gold-spotted pond frogs were bigger than males. During the autumn migration, small frogs of which snout-vent length was smaller than 20 mm were found, indicating that successful breeding occurred in the population. Our results could be useful to conserve this endangered species in Korea.

• Journal of Ecology and Environment
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• v.30 no.4
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• pp.287-292
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• 2007

We monitored a breeding population of the Asian toad (Bufo gargarizans), in the Wonheunge pond at Sannamdong, Chungju, from 5 March to 11 April, 2006 and 14 February to 31 March, 2007 to investigate their movement patterns, breeding population sizes, and physical characteristics. Terrestrial migration to the pond started on 5 March in 2006 and 14 February in 2007. We captured a total of 266 immigrating individuals (213 males, 53 females) in 2006 and 307 (222 males, 85 females) in 2007, and found 50 adults apparently killed by motor vehicles while migrating to the pond in 2007. Emigration from the pond to terrestrial sites started on 15 March 2006 and 5 March 2007. We captured a total of 245 emigrating toads (181 males, 65 females) in 2006 and 99 (92 males, 7 females) in 2007. An additional 10 emigrating adults were found dead on the road. During both the immigration and emigration periods, two peaks in capture frequency appeared for each sex in each breeding season. The immigration peaks corresponded with higher temperatures, while the emigration peaks corresponded with high humidity. Migrating Asian toads showed sexual size dimorphism and a male-biased sex ratio. Body weights and SVL (snout-vent length) of immigrating and emigrating individuals were negatively related with migration dates.

• Journal of Life Science
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• v.34 no.4
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• pp.264-270
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• 2024

This study is conducted to analyze environmental factors that affect the ecology of boreal digging frog and use them as basic data for selecting (or creating) suitability of alternative habitats for survival and monitoring method from 2020 to 2022 after boreal digging frog were relocated to the alternative habitats in 2019. Analyzing the environment of the alternative habitats showed that the criteria suited the followings: distance from wetlands, grasslands and rivers was within 5 m, the low-rise grassland was 6,000 m², soft soil was at a depth of ≥20 cm, and the area of permanent wetlands was 5,000 m² wide. As a result of the correlation analysis between meteorological factors and population (n) and breeding, there was a significant correlation between rainfalls and breeding (p<0.01). During the monitoring, it was confirmed that the SVL (Snout-Vent Length) and BM (Body Mass) of the translocated population were maintained (p>0.05), and it was found that the proximity of the habitat and spawning pond, securing food space (grasslands), soil quality, and wetlands could function as an alternative habitat if conditions were met. As a result of analyzing the meteorological factors affecting the population of boreal digging frog, the SVL had a statistical impact on the minimum temperature, maximum temperature, relative humidity, and the rainfall (p<0.05). In the case of breeding, rainfall was found to be affected (p<0.01), and the population was statistically affected by the average temperature, minimum temperature, and relative humidity (p<0.05).

• Korean Journal of Environment and Ecology
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• v.28 no.5
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• pp.531-541
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• 2014

This research investigated the reproduction cycle, litter size, and the effects of factors of red-tongue viper snake inhabiting in Jeju Island, to delve into their life strategy. Field survey was conducted in Jeju Island from May 2006 to November 2008. Reproduction cycle was analyzed through measurements of testis and follicle sizes in laboratory from March 2009 to December 2010. According to the research results, the sizes of red-tongue viper snake's testis and follicle clearly changed seasonally. The number of eggs within the oviduct were greater on the right side ($2.6{\pm}1.0$ eggs, n=16) than on the left side ($1.8{\pm}0.5$ eggs, n=16) (t=-2,721, p<0.05). Average (${\pm}SD$) of survival litter size (SLS) was $4.4{\pm}1.7$ (1~9, range), while total litter size (TLS) was $4.7{\pm}1.5$ (3~9, range), which were not statistically significant. However, their litter sizes were similar to the number of eggs within the oviduct (t=0.039, P>0.05). Relative litter mass (RCM) was $0.42{\pm}0.13$ (0.18~0.79, n=33), and tended to increase, as maternal condition of pre-parturition (MCPPI) was getting better. The sexual ratio of delivered litters showed no significant difference between male and female red-tongue viper snakes (♂:♀ = 1.15:1, n=73 ; ${\chi}^2$=0.342, P>0.5). Average neonate mass showed a weak correlation with maternal mass of pre-parturition (MMPP1) (r=0.387, P<0.05, n=33). Average neonate Snout-vent length (SVL) also demonstrated a weak correlations with maternal SVL (r=0.399, P<0.05, n=33) and MMPP1 (r=0.344, P<0.05, n=33). Average neonate mass and maternal SVL approached significant probability (r=0.323, P=0.067, n=33). This indicates that mother snakes can bear bigger litter due to its larger size. In some cases, litter's weight decreases as mother snakes are bearing more litter; however, the red-tongued viper snake did not show such exchange relationship. From this, it can be conjectured that a red-tongued viper snake has peculiarity of its own species. The research results are predicted to be used as the basis to find a life history of red-tongued viper snake.