Format: ORAL

Joyce G. Onyenedum1, Israel L. Cunha Neto1, Chun Su1, Pedro Acevedo-Rodrguez1

1 Department of Environmental Studies, New York University, New York 10012, NY, USA 2 Department of Botany, Smithsonian National Museum of Natural History, 10th Street and Constitution Avenue NW, Washington, DC 20560, USA

Climbing woody vines lianas are the snakes of the plant kingdom, capable of wrapping around host trees in search of light at the top of the forest canopy. Intriguingly, this lifeform has evolved independently multiple times, and in accordance, lianas have independently evolved significant modifications to their stem anatomy to meet the unique demand to twist without breaking. Unlike the stems of most trees and shrubs, comprised of a core of wood (xylem) sheathed by inner bark (phloem), lianas often have vascular variants, expressed as aberrations in the typical distribution and abundance of xylem and phloem. In this study, we sought to elucidate the evolution of development of vascular variants in a large neotropical liana tribe, Paullinieae (Sapindaceae), comprised of 11 vascular variants across 495 species. We here leverage the newly developed molecular phylogeny of Paullinieae, comprised of 75% species of the tribe, together with robust developmental anatomy dataset to address the following questions: (1) How many times did each type of vascular variant evolve? (2) Do vascular variants have systematic value in defining clades? (3) How did changes in the mode and tempo (heterochrony), spatial reorganization (heterotopy), tissue identity transformations (homeosis), and the re-purposing of old tools (exaptation) contribute to the diversity of vascular architecture in lianas? This study represents the power of an integrative approach, bridging developmental anatomy, within a robust phylogenetic context, to elucidate the evolution of development of complex traits.