Larval life history variation in two populations of the Japanese salamander Hynobius kimurae (Amphibia, Urodela)

Abstract

Larval life histories of Kyoto and Tokyo populations of the stream breeding salamander Hynobius kimurae are compared in the field. The Kyoto population has smaller adults and ovarian egg numbers, but larger egg sizes. Minimum water temperature is lower, and the stream partly dries up between late October and late November in Kyoto, while the amount of water is always stable in Tokyo. In Kyoto, metamorphosis occurs between late July and late September and no larva is found in the water in and after October. In Tokyo, only 21% of larvae metamorphose in the first year and most overwinter and metamorphose between late May and mid June of the second year. Size of hatched larvae does not differ between Kyoto and Tokyo, but metamorphs from Kyoto are smaller than first year metamorphs from Tokyo, which in turn are smaller than the second year metamorphs. Differences seen in larval life histories between the two populations may represent adaptations for differential stability of water level and water temperature, and resultant differences in the size of metamorphs possibly induce differential adult body size, and hence fecundity.