A Morphological and Molecular Investigation of Castaneoid Evolution

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9707945 Manos The ecologically and economically important family Fagaceae of oaks, beeches, and chestnuts is most familiar to temperate-zone botanists from a relative handful of species. But the family has many tropical species, and is especially diverse in southeast Asia, where Dr. Paul Manos of Duke University will be conducting field work to sample the two largest genera, Castanopsis and Lithocarpus. These two genera comprise nearly half of the species diversity in the family and represent an even greater range of morphological diversity in the characteristic cupule (the burr or acorn) than found in the temperate-zone members of the family. One goal of the research is to infer genealogical or phylogenetic relationships among the many tropical species, by integrating traditional morphological knowledge of these plants with new molecular data from DNA sequencing of nuclear ribosomal genes, which provide a direct measure of mutational differences between samples. This phylogenetic framework in turn will allow analysis of the history of development of various cupule morphologies in the lineages of tropical and subtropical Fagaceae, especially among cupule types that are indistinguishable at maturity but suspected of convergent evolution from different juvenile stages. The range and history of species diversification in the "tropical chestnuts" or castaneoids are poorly known. Field work, study of existing herbarium collections, and new DNA sequence data will be brought together to improve our understanding of the basic taxonomy and phylogeny of these plants. Tropical diversity often contains key elements to understand the evolutionary history of plants in the temperate zone, and this is likely to be the case with the diverse, insect-pollinated Castanopsis and Lithocarpus of southeast Asia. The studies will prove useful in interpreting morphological evolution, and will place the major groups of castaneoids into a geographical as well as phylogenetic framework.