Change in biomass of symbiotic ants throughout the ontogeny of a myrmecophyte, Macaranga beccariana (Euphorbiaceae)
- 336 Downloads
Macaranga myrmecophytes (ant-plants) provide their partner symbiotic ants (plant-ants) with food bodies as their main food, and they are protected by the plant-ants from herbivores. The amount of resource allocated to food bodies determines the plant-ant colony size and consequently determines the intensity of ant defense (anti-herbivore defense by plant-ants). As constraints in resource allocation change as plants grow, the plant-ant colony size is hypothesized to change with the ontogenesis of Macaranga myrmecophyte. To determine the ontogenetic change in the relative size of the plant-ant colony, we measured the dry weights of the whole plant-ant colony and all of the aboveground parts of trees at various ontogenetic stages for a myrmecophytic species (Macaranga beccariana) in a Bornean lowland tropical rain forest. Ant biomass increased as plant biomass increased. However, the rate of increase gradually declined, and the ant biomass appeared to reach a ceiling once trees began to branch. The ant/plant biomass ratio consistently decreased as plant biomass increased, with the rate of decrease gradually accelerating. We infer that the ontogenetic reduction in ant/plant biomass ratio is caused by an ontogenetic change in resource allocation to food rewards for ants related to the physiological changes accompanying the beginning of branching.
KeywordsAnt–plant interactions Biotic defense Mutualism Ontogenetic change Resource allocation South-East Asian tropics
We thank L. Chong, J. J. Kendawang and other staff members of the Forest Research Centre, Sarawak, and Forest Department of Sarawak for providing access to the study site as well as kind assistance. We are also grateful to T. Nakashizuka, M. Ichikawa, N. Yamamura and S. Sakai for supporting our research activities. This work was supported by Grants-in-Aid from the Japan Society for the Promotion of Science (JSPS) to T. I. (No. 17405006) and to C. H. as a JSPS Fellow and from the Research Institute for Humanity and Nature (project numbers 2-2, D-04).
- Davidson DW, Fisher BL (1991) Symbiosis of ants with Cecropia as a function of light regime. In: Huxley CR, Cutler DF (eds) Ant-plant interactions. Oxford University Press, Oxford, pp 289–309Google Scholar
- Davidson DW, McKey D (1993) The evolutionary ecology of symbiotic ant-plant relationships. J Hymenopt Res 2:13–83Google Scholar
- Davies SJ (2001) Systematics of Macaranga sects. Pachystemon and Pruinosae (Euphorbiaceae). Harv Pap Bot 6:371–448Google Scholar
- Hashimoto Y, Yamane S, Itioka T (1997) A preliminary study on dietary habits of ants in a Bornean rain forest. Jpn J Entomol 65:688–695Google Scholar
- Hölldobler B, Wilson EO (1990) The ants. Belknap Press of Harvard University Press, CambridgeGoogle Scholar
- Itioka T, Nomura M, Inui Y, Itino T, Inoue T (2000) Difference in intensity of ant defense among three species of Macaranga myrmecophytes in a Southeast Asian dipterocarp forest. Biotropica 32:318–326Google Scholar
- Mori S, Yamaji K, Ishida A, Prokushkin SG, Masyagina OV, Hagihara A et al (2010) Mixed-power scaling of whole-plant respiration from seedlings to giant trees. Proc Natl Acad Sci USA 107:1447–1451Google Scholar
- Roubik DW, Sakai S, Karim AAH (eds) (2005) Pollination ecology and the rain forest: sarawak studies. Springer, New YorkGoogle Scholar
- R Development Core Team (2008) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, AustriaGoogle Scholar