1. Dep. of Biosphere Resources Science; Nagoya Univ.; Furo-cho, Chikusa-ku Nagoya Aichi 464-8601 Japan
2. Research Institute for Humanity and Nature; 457-7 Motoyama, Kamigamo, Kita-ku Kyoto 603-8047 Japan
3. Center for Ecological Research; Kyoto Univ.; 509-3, 2-chome, Hirano Otsu Shiga 520-2113 Japan