| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2004: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Many tropical plants house ants and thereby gain protection from herbivores. Most of these myrmecophyte-ant systems include scale insects as the third associate. Scale insects live inside the plant hollow stem, suck the plant sap, and provide honeydew to the ants. We investigate the evolution of the three-way interaction among myrmecophytic Macaranga plants, their inhabitant Crematogaster (Decacrema) ants, and the trophobiont Coccus scale insects. Previous studies show that these three genera have a tight association although a few other genera are sometimes involved.
The mtDNA COI phylogenies of comprehensively-sampled ants and scales reveal ten and five well-supported lineages, respectively. Comparisons of the two phylogenies and a published Macaranga phylogeny indicate an absence of cospeciation. Whereas the ant-scale and plant-scale interactions are diffuse, the ant-plant one is specific in the sense that host shifts have been constrained by plant stem traits that are themselves correlated with Macaranga phylogeny. Applying COI divergence rates of 1.5% per My, the Decacrema ants and the Coccus scales from Macaranga are inferred to be at least 12, and 10 My old, respectively, indicating that they have been diversifying contemporaneously since the mid-Miocene in the wet forest community of Southeast Asia.
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