Systematic study of lucidophyllous woody plants in perhumid tropical forests of SE Asia

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17570079
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Biodiversity/Systematics
• Research Institution: Kyoto University
• Principal Investigator: NAGAMASU Hidetoshi Kyoto University, The Kyoto University Museum, Assoc. Prof., 総合博物館, 准教授 (90218024)
• Project Period (FY): 2005 – 2006
• Keywords: Tropics / Asia / Lucidophyllous forest / Systematics / Borneo / Sumatra / Symplocaceae

Research Abstract

Lucidophyllous evergreen forests widely cover the southwestern part of Japan, and the most of the dominant taxonomic groups of the trees in the forests are belived to have Laurasia-origin although they have many relatives in the perhumid tropical rainforests of SE Asia (Malesian region). In the present study, I tried a comparative study of diversification and speciation between the same taxonomic group (Symplocos; Symplocaceae) occurring in Japan and in SE Asia. Herbarium surveys were made at many botanical institutes in France, Indonesia, Japan, Malaysia, Netherlands, Singapore, and UK. The taxonomic and phytogeographic analyses of Fasculata Group and Odoratissima Group, which have wide distribution in Malesia, revealed that the distribution of the members clearly separated to the western and eastern groups. In the west a single species had wide distribution area, while in the east several local species were scattered in the archipelago, especially in the latter group. This distribution pattern suggests that the isolation of rainforests on Borneo during the glacier period caused the difference on the same, island and that the isolation by ocean especially out of the Sunda shelf, the islands on which were connected in the glacier period, caused the neoendemism or relictism. The taxonomic revision of Symplocaceae of Sumatra and Borneo showed the distinct endemism of certain groups on the higher mountains more than 3000 m alt., in Atjeh and W Sumatra (Sumatra) and on Mt. Kinabalu (Borneo). This result indicates that the distributed higher mountains in Malesia also similarly function as isolated islands for evolution of Symplocaceae.