Dissertation Research: Systematics, biogeography and taxonomy of the pantropical legume genus Cynometra

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Legumes are the third largest family of flowering plants. These economically and ecologically significant plants range in size from tiny desert herbs to giant rainforest trees. While recent research has elucidated relationships among the major lineages in the family, little is known about many of the nearly 20,000 species, especially the processes that generate this diversity. This study will use recently developed 'next generation' DNA sequencing methods and statistical computer modeling to resolve the evolutionary relationships among a large and widespread group of tropical legumes and to infer what role, if any, adaptation to new environments has played in the diversification of these species. Given their wide distribution and ecological diversity, understanding the relationships among these species will provide a framework for future comparative studies and enhance our understanding of the overall evolution of the legume family. The project will also include a significant training component to expose undergraduates in STEM fields to the latest tools and analytic methods.This study will combine phylogenomics, ecological niche modeling, and information from the fossil record to elucidate the relationships among the species of the tropical genera Cynometra and Maniltoa and will investigate the role niche conservatism plays in biogeography and speciation mechanisms. Next generation sequencing is revolutionizing the practice of systematics, biogeography, and evolutionary biology. While the technology has been applied to both very deep and very shallow evolutionary questions, its application to species level phylogenetics, particularly in plants, remains limited. However, it is at the species level that these new techniques hold the greatest promise to resolve previously intractable relationships. In addition, when combined with ecological niche modeling and geographic range data, the well resolved phylogenies these methods are capable of producing allow researchers to study speciation mechanisms and the role of niche conservatism in generating observed patterns of diversity. If, for example, allopatric sister species consistently segregate along environmental axes, then ecologically mediated selection may have a role in speciation, whereas if allopatric sister species are consistently identical or nearly identical in abiotic niche space, then ecological divergence is not a major factor driving speciation. To address this question, the researchers will: 1) conduct field work and visit herbaria in Brazil (the center of diversity for the genus) to better characterize diversity and distributions of Brazilian species; 2) reconstruct a well resolved species level phylogeny using data generated with targeted sequence capture techniques; and 3) characterize the abiotic niche of the constituent species using ecological niche modeling and distribution data. Analyses of these data will provide a much more precise understanding of evolutionary and biogeographic history of Cynometra and Maniltoa and the mechanisms driving these processes.