Ecology and Evolution of Young Leaf Defenses in Tropical Rainforest Legumes

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DEB-0108150 ColeyPlants and herbivores comprise the majority of the earth's biodiversity, and nowhere are their interactions as intense as in tropical forests. The evolutionary interactions between herbivores and plants has led to an "arms race" in which innovations in plant defenses are met by counter adaptations on the part of herbivores. For example, plants have a battery of physical, chemical and phenological defenses which help to protect their leaves against herbivores and pathogens. And herbivores have a staggering array of mechanisms for avoiding, detoxifying and even using plant defenses for their own benefit. Despite the wide acceptance that many traits of plants and herbivores result from an "arms race", we know very little about the underlying evolutionary mechanisms or ecological conditions that would lead to the evolution of novel defenses. To address this, we will study the defenses of rainforest trees in the family Leguminosae, quantifying various defenses, including alkaloids, measuring rates of leaf-feeding by herbivores and characterizing growth and defensive traits of herbivores. The work will be conducted at the Smithsonian Tropical Research Institute in Panama and at the University of Utah. This basic research is necessary for understanding how natural selection favors the evolution of novel defenses as well as why suites of defenses tend to co-occur in different species of plants, as well as how plant defenses may constrain the behaviors, growth and defenses of the herbivores that feed on them. In addition, the research has applications for forest management, and for the development of medicinal drugs and agricultural crops using genes and defensive compounds from wild plants.