Diversity, evolutionary specialization and geographic distribution of a mutualistic ant-plant complex: Macaranga and Crematogaster in South East Asia.

摘要

A study was conducted on the species-rich ant-plant mutualism found in the pioneer tree genus Macaranga and the community ecology of the ant (Crematogaster) species involved. Distribution and occupancy data were collected from 1984 to 1998 in Malaysia (Malay Peninsula, Sabah and Sarawak), Indonesian Borneo (Kalimantan), Thailand, Sumatra and on Riau, Lingaa Archipelago, Nias, Siberut and Banyak Islands. Plants were sampled randomly as they were encountered and ant specimens obtained from plants ofall sizes and ages. Data were collected in primary and secondary habitats with different degrees of disturbance. In total, 21 myrmecophytic Macaranga species were surveyed, of which 19 were colonized by Crematogaster ants. Details of the ant species, geographical distribution and the possible basis of specificity are presented. All ant-inhabited species were restricted to the moister parts of Borneo, Sumatra, South and East Thailand and Peninsular Malaysia. A strict and similar altitudinal zonation of myrmecophytic Macaranga species was observed in all regions. A total of 2163 ant queens were identified, which belonged to at least 8 (morpho)species of the small subgenus Decacrema as well as to one non-Decacrema (probably Atopogyne). The ant species were not randomly distributed among the Macaranga species but distinct patterns of association emerged. Despite common sympatric distribution of Macaranga species, in most cases a surprisingly high specificity of ant colonization was maintained which was, however, often not species-specific but groups of certain plant species with identical ant partners were observed. These colonization patterns usually mirrored existing taxonomic sections within the genus Macaranga.