DISSERTATION RESEARCH: Fossils, fruits, and phylogeny: an integrative approach to understanding the historical biogeography of palms over the last 100 million years

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Palms are found abundantly throughout tropical regions worldwide and have important roles in ecosystems and the global economy. Palms are an interesting group of plants from both an evolutionary and environmental perspective. They have a long evolutionary history stretching back at least 90 million years, evidenced by a rich and widespread fossil record, and are useful indicators of past environmental conditions due to the narrow climatic range within which most can survive. By using the fossil record to inform the evolutionary history of palms, this research seeks to understand their geographical range, and how they have responded to changing environments throughout their history. This research will test current hypotheses on palm evolution, and generate publicly available databases of living and fossil palm diversity. One graduate student will be trained in diverse systematics methods, and datasets generated by this research will also be used to train undergraduates from underrepresented groups. Materials from the research will also be used to develop interactive exhibits for teaching about plant structure, diversity, and evolution to the public. This project investigates the historical biogeography of the palm family by incorporating empirical data from the geologic record into phylogenetic and model-based biogeographic analyses. It will test current hypotheses of a Laurasian origin of the crown node of Arecaceae and of the biogeographic origins of the major subfamilies. This work will also investigate the role of shifting continental geography in the radiation of palms, and how climatic changes correlate with shifts in dispersal and extinction rates over the last 100 million years. A comprehensive database of the palm fossil record will be compiled and the data incorporated into a dispersal-extinction-cladogenesis (DEC) model to infer historical ranges of taxa, and a dispersal-extinction-sampling model to compute dispersal and extinction rates over time, which can be correlated with climate data. Fossil fruits with sufficient characters for inclusion in a phylogenetic analysis will be studied using X-ray micro-computed tomography, and will be used to generate a time-calibrated phylogeny for use in the DEC analysis. Outcomes include a comprehensive fossil record database for palms, 3D morphological data on living palms, a tribe-level chronogram for the family, and new insights into the historical biogeography of this important group of plants.