Evolution and Systematics of the Neotropical Clade of Schefflera (Araliaceae)

Gregory Plunkett and collaborators

A major goal of botanists is to describe and name the vast diversity of plant species found on our planet and to understand how, when, and where plants evolved. This is particularly challenging for groups with very large numbers of species, especially when they are difficult to observe because they grow in hard to reach places. Tropical trees are among the most under-studied plants, creating a significant gap in our knowledge. To overcome this gap, an efficient and effective strategy is needed to discover, describe, understand and conserve this large and important part of the world’s biodiversity. This research project will develop a streamlined strategy, using the genus Schefflera (a member of the ivy family, Araliaceae) in tropical America as a model group. More than 400 species of Schefflera occur in this vast region, especially in the very mountainous areas of the northern Andes. Many of these species have only been seen by scientists once or a few times, and almost half do not yet have scientific names. Moreover, very few tools are available to recognize and identify these ecologically important plants, and we know almost nothing about how they evolved into so many different forms, or how they were able to adapt to the wide range of habitats. The strategy of this study, which includes field work in four Andean countries (Bolivia, Colombia, Ecuador and Peru), aims to improve our understanding of these evolutionary processes. It will also focus on identifying and naming the species that occur in a limited number of places and are most threatened with extinction (mostly by tropical deforestation) so that they can be targeted by conservation efforts. The information generated by the project will be made available on-line to a wide range of users, both within and beyond the scientific community. To help develop the next generation of plant systematists, undergraduate students will be trained in summer internship programs at the Missouri and New York Botanical Gardens, and more advanced students will participate in a tropical field botany program, joining the project scientists to gain hands-on experience during field work in South America.

The research will involve constructing phylogenies for the species of Andean Schefflera using DNA-based evidence, taking advantage of recent advances in technology, especially high-throughput approaches to DNA sequencing. The phylogenies will provide a greater understanding of the major lineages of these 400+ species, which in turn will provide a framework for classifying and naming them, and for understanding their evolutionary and geographic relationships. A streamlined ‘green-listing’ approach to assessing conservation status of the species that are most likely to be threatened will inform priorities for naming and conserving new and rare Andean members of Schefflera. Intensive herbarium studies will provide sources of geographic, morphological, and molecular data, and will guide field work in the countries of the central and northern Andes, targeting sites with the highest concentration of species that remain unsampled, and focusing on areas in southern Ecuador and northern Peru where the group appears to have undergone exceptional diversification. Time-dated phylogenies will be used to explore biogeographic scenarios and to test for correlations among morphology, ecology, geography and evolutionary history, providing insights into the evolution of plant diversity in the Andes. These studies will be conducted with the collaboration of local botanists and students from each of the four South American countries where field work will be done. This will promote a long-term network of international researchers capable of sustaining the long-term goals of fully documenting and understanding the tremendous diversity of Schefflera in the tropical Andes.