Biotic and Chemical Defense Systems of Myrmecophytic Cecropia

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Interspecific, environmental and development differences in biotic and chemical defense systems of myrmecophytic Cecropia trees will be studied in relation to plant associations with herbivores and symbotic ants in Amazonian rain forest. Seedlings of six Cecropia species will be grown from seed under high and low light regimes in temperate greenhouse and transplant gardens in southeastern Peru'. Ant attracting traits, leaf tannin concentrations, and toughness will be monitored in relation to plant performance, especially growth rates and leaf lifetimes (thought to determine the pattern of investment in chemical and ant-defense). Performance data on transplanted seedlings with and without herbivores will test specific hypotheses for habitat specificity in these trees. Short-term experiments with cultivated seedlings will test for 1) habitat and host specificity in four specialized symbiotic ants; 2) rates of host resource supply to ants as a determinant of the species composition of symbiotic relationships: 3) habitat and species specificity in effects of different ants on herbivory rates, host performances, and colony growth and reproduction. Natural seedling populations are used to investigate species specificity in host choice by queens and host mechanisms for excluding certain ants. Results of studies will be synthesized to test hypotheses that: plant resource environments determine predictable patterns of investment in alternative defense systems and patterns of defense investment determine the species composition of ant-plant associations. Findings will contribute to basic ecological science and will also add to the knowledge base on the biodiversity of tropical forests. //