Dissertation Research: Phylogenetic analysis of the Neotropical plant genus Clusia (Clusiaceae)

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Clusia is a tropical group of about 300 species of shrubs and trees in the mangosteen family (Clusiaceae). Clusia plants have a number of notable characteristics that make them important for study. In addition to being one of the few trees and shrubs to grow on other plants (epiphytes), Clusia is the only known tree group to have Crassulacean Acid Metabolism (CAM) photosynthesis in which carbon (CO2) is absorbed during the night, when temperatures are lower and water loss is reduced. It is also one of only two groups of flowering plants in which flowers of some species produce floral resins instead of nectar as reward for pollinators. This project seeks to use genome-wide DNA sequence data to understand how species of Clusia are related to each other, and to estimate the evolutionary history of CAM photosynthesis and floral resins in the group. Results will enable the researchers to understand patterns of plant adaptation to water stress, and provide new insights into the evolution of pollination reward systems. Taken together, these results will permit a better understanding of how plants have evolved and how they have adapted to different environments. One graduate student and an undergraduate will be trained in molecular systematic and anatomical methods. Data from the project will also be used to enhance a summer research program at Rancho Santa Ana Botanical Garden that provides research experiences and training for students from Principally Undergraduate Institutions across the U.S. Results from the study will also be broadly disseminated in popular science magazines. This work focuses on reconstructing phylogenetic relationships in the Neotropical plant genus Clusia (Clusiaceae) using phylogenomic data. The resulting phylogeny will be used to: 1) test the monophyly of currently recognized sections and revise the classification for the genus, 2) investigate the distribution of CAM photosynthesis within the group and reconstruct the pattern of its evolution, and 3) reconstruct the evolution of resin-producing flowers within the genus. The resulting analyses will provide a better general understanding of plant physiology and plant-pollinator interactions.