A Comparison of Growth Patterns between Large- and Small-sized Rana tagoi (Amphibia: Ranidae) from Kitayama, Kyoto, Japan

抄録

In the Kitayama-region of Kyoto city, two types of the brown frog Rana tagoi occur syntopically. They are populations of small and large frogs that do not overlap in adult body size and proved to be heterospecific genetically. In order to clarify the cause and significance of this body size difference, we studied the growth pattern in the two populations. For comparison, we also examined an allopatric population of R. tagoi from Shishiga-tani, Kyoto, which is genetically very close to the large type, and occurs without co-inhabiting different sized individuals. We examined sections of periosteal bones, and counted the number of LAGs in the bone to determine ages of individuals. We used logistic model and estimated instantaneous growth rate and asymptotic size, to describe growth pattern. Each of the two types from Kitayama exhibited unique growth pattern, and the Shishiga-tani population showed a growth pattern intermediate between those of the two types in asymptotic size. Difference in size of two types is discussed with relation to the character displacement.