論文

Body size and age of two populations of the endangered species Pelophylax porosus porosus from the Kanto Plain, Japan (paddy fields in valley bottoms [Zushi] and open plains [Hayamajima]) were investigated. Age was estimated by skeletochronology of the phalanges. Frogs grew rapidly between 0 and 1 year of age in both populations. The asymptotic snout-vent length (SVL) of both sexes peaked at 2 years. Age at sexual maturity was estimated to be 0-1 years for males, but 1-2 years for females. SVL in adults ranged from 45.2 to 67.2 mm in males, and 60.2 to 88.8 mm in females. In both populations, females were significantly larger than males. However, the SVL was not significantly different between the populations or between age classes in both sexes. Lines of arrested growth (LAGs) were observed in the periosteal tissue. Longevity was estimated to be 3 and 4 years in males and females, respectively. Pelophylax p. porosus is suggested to be the most short-lived and the first to reach sexual maturity compared with the other Pelophylax species in Japan, although the age structure differed between the populations. In both sexes, when comparing the age of 1 year old or older frogs, the Zushi population was significantly older than the Hayamajima population, but the longevity of the Hayamajima population was shorter than that of the Zushi population. As the two study sites differed in agricultural management, it is possible that the resulting environmental conditions influenced the longevity of P. p. porosus.

Citizen and community science is an important approach for advancing research, education, and conservation, and currently, various projects are being implemented and trialled worldwide. We conducted surveys of participants in the City Nature Challenge, an international event in which participants engaged in monitoring wildlife and plants in their neighbourhoods. We received responses from 361 participants representing 12 countries including the United States, Japan, the United Kingdom, and Malaysia. There were significant differences in terms of socio-demographic attributes and participants’ perceptions of citizen/community science activities. Regression analysis revealed that the more participants learned about the animals and plants in their areas, the more they self-reported their intention to participate in similar activities in the future in both the United States and Japan. This suggests that managers of citizen/community science projects could tailor the message and contents of the activities to enhance participants’ learning about local biodiversity to increase their continued involvement in future events. Key policy insights In both the United States and Japan, the more participants learned about the animals and plants in their local area through citizen/community science activities, the more they were willing to participate in similar activities in the future. Cross-cultural comparison of participants in citizen/community science activities revealed significant differences in terms of socio-demographic attributes (e.g. participants in Japan and Malaysia were younger than those in the United States and the United Kingdom). Survey results revealed differences in participants’ perceptions of the citizen/community science activities (e.g. participants from Malaysia were more likely to be aware of the threats to animals and plants in their neighbourhood than those in the United States, Japan, and the United Kingdom).

The body size and age at maturity of female Rana porosa porosa were investigated in two valley bottoms in Tama Hills, Japan. Frogs collected during the breeding season, not showing the male secondary sexual characteristics, were subjected to injection of HCG and were kept with mature males. Individuals that did not ovulate after the dosage were dissected to determine sexes and maturity status on the basis of gonadal morphology. The snout-vent length (SVL) of the smallest mature female was 58.3 mm. The clutch size ranged from 1465 to 2726, and showed a significant positive correlation with SVL. The one-year-old age group of females included both mature and immature individuals, whereas two- and three-year-old females were invariably mature. © 2009 by The Herpetological Society of Japan.