Collaborative Research: Modeling the Origin and Evolution of Hawaiian Plants

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Where we find species living today reflects not only how and when their direct ancestors evolved, but also where they evolved. The inseparable relationship between geological and evolutionary history is especially pronounced in volcanic island systems, where the formation, erosion, and subsidence of islands are expected to drive the origin of new species. Within the Hawaiian Islands, such processes have occurred dozens of times and given rise to over 1,000 flowering plant species found nowhere else in the world. Understanding how the Hawaiian flora originated and diversified can help direct conservation efforts, particularly for rare plants. This research will develop a suite of new statistical modeling software to reconstruct how, when, and where groups of closely related species originate, disperse, and go extinct among regions with complex geological histories. The project will integrate existing museum collections and newly collected plant specimens to generate a large genomic dataset for nearly 400 understudied Hawaiian plant populations, then infer how this diversity originated with the newly developed software. In addition to training numerous undergraduate, graduate, postdoctoral, and garden-affiliated researchers through the research project itself, two computational biogeography workshops to train early career researchers will be offered, and a series of publicly available teaching modules on the biogeography of Hawaiian plants will be developed.The project has two overarching objectives. The first objective will develop stochastic models and inference methods to jointly model speciation, extinction, and dispersal processes in the context of a spatiotemporally variable geography. These modeling tools will be made freely available through the open source Bayesian phylogenetics software, RevBayes, to enable other researchers to repurpose the new methods for systems apart from Hawaiian plant biogeography. The second objective will reconstruct the biogeographical histories of 12 understudied, but ecologically diverse, Hawaiian plant radiations. For this, the researchers will collect new plants and tissues to complete several genus-level collections managed by the National Tropical Botanical Garden. The researchers will then generate standardized phylogenomic datasets, using the Angiosperm-353 protocol, for two purposes. First, by evaluating the new phylogenomic data in concert with morphological, ecological, and biogeographical data, the researchers will resolve long-standing puzzles regarding the taxonomy of the 12 plant radiations, including ecologically and morphologically distinctive genera. Second, the new phylogenetic software will be used to infer evolutionary relationships, origination times, and biogeographical histories for the flora, to gain new insights into the biogeographical drivers of island plant radiations.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.