The proposed research will investigate adaptation in a group of plant species very common throughout the Old and New World tropics. Studies will focus on a group of closely related species that live in slightly different habitats within a single tropical rainforest in Mexico. The experiments, including field, greenhouse, and laboratory studies, will test several predictions based on the general hypothesis that success in disturbed habitats requires responses that tend to maximize the capture and utilization of light, water, and nutrients, while success in shady habitats depends on conservative responses that minimize the prospects for critical shortages of these resources. Results of these experiments should be useful both in answering general questions about how evolution shapes species for different habitats and in establishing criteria for plant success in disturbed and undisturbed rainforest habitats. Though the proposed research is basic in its orientation, it should yield information with short-term applicability. Tropical rainforests are important both economically and culturally, but rainforest destruction is proceeding at a high rate. At present, rainforest biology is too poorly understood for managers to design effective reforestation techniques and to implement programs of rainforest resource utilization that preserve the integrity and functionality of the forest. The proposed research, by focusing on the mechanisms that allow plants to grow in disturbed and undisturbed habitats, will begin to give managers the necessary background.
