Collaborative Research: Diverse selective pressure on fruit chemical traits from mutualists and antagonists as a major driver of chemical evolution at the whole plant level

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Much of the diversity in plant form and function observed in nature can be understood as the coevolutionary result of interactions with other living organisms. Plant chemistry represents an underappreciated dimension of diversity that is critical for mediating plant interactions and, ultimately, plant fitness. Metabolomics is a rapidly growing field with over 200,000 described secondary metabolites in the plant kingdom. However, there is a paucity of data for tropical species, and the vast majority of data are from leaves. The investigators will take advantage of recent advances in metabolomics and bioinformatics, long-term ecological monitoring data, and field studies to interpret the metabolomics data in ways that will provide a new whole-plant perspective on the evolution of plant defense. All metabolomics data will be made publicly available because ripe, fleshy fruits dispersed by vertebrates tend to be toxic to microorganisms and insects but non-toxic to vertebrates, making them an underappreciated and novel source of potential drugs. Public archival of these data will contribute to potential drug discovery. Student scholars will gain experience in research methods in tropical field biology and chemical ecology. Results will be used to develop student-centered, inquiry-based course materials for undergraduate biology classrooms. All educational materials will be translated into Spanish and disseminated in Latin America via Verde Elemental. To communicate research the investigators will collaborate with Utah Public Radio and Impact Media Lab to produce multimedia, including public radio podcasts, short-films, and an interactive website.A fundamental question in plant biology is: why do plants produce so many different chemical compounds? Most theory and empirical research in plant chemical ecology has focused on the defense of leaves, yet fruits thread a more complicated chemical path, simultaneously defending against enemies and attracting dispersers. Thus, the investigators hypothesize that much of the secondary metabolite diversity observed in plants has its origins in fruits. Specifically, the project tests the hypothesis that the diverse selective pressures on fruit chemical traits are a major driver of phytochemical diversification and evolution at the whole-plant level. Complementary approaches of comparative metabolomics, observational field studies, and phylogenetically-controlled experimentation will be used to test the hypothesis. First, contemporary patterns of secondary metabolite diversity across plant tissues and species will be measured to detect a signature of selection from fruit-frugivore interactions. A metabolomics approach to characterize phytochemistry of 50 phylogenetically-controlled comparisons of tree and shrub species that vary in dispersal mode will be carried out. Second, how patterns of fruit and leaf secondary metabolite diversity mediate natural variation in plant interactions with fruit and leaf consumers will be examined using an observational study of fruit removal and damage on pulp, seeds, and leaves for these same species. Third, whether fruit secondary metabolites reflect the adaptations to specific dispersal modes will be experimentally determined using a phylogenetically-controlled subset of bat-, bird-, and abiotically-dispersed species. The study will be conducted in one of the most well-studied tropical forest systems on Earth, Barro Colorado Island, Panama.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.