THE PRIMITIVE EPIDENDROIDEAE (ORCHIDACEAE): PHYLOGENY, CHARACTER EVOLUTION AND THE SYSTEMATICS OF PSILOCHILUS (TRIPHOREAE) A Dissertation Presented in Partial Fulfillment of the Requirements for The Degree Doctor of Philosophy in the Graduate School of the Ohio State University By Erik Paul Rothacker, M.Sc. ***** The Ohio State University 2007 Doctoral Dissertation Committee: Approved by Dr. John V. Freudenstein, Adviser Dr. John Wenzel ________________________________ Dr. Andrea Wolfe Adviser Evolution, Ecology and Organismal Biology Graduate Program COPYRIGHT ERIK PAUL ROTHACKER 2007 ABSTRACT Considering the significance of the basal Epidendroideae in understanding patterns of morphological evolution within the subfamily, it is surprising that no fully resolved hypothesis of historical relationships has been presented for these orchids. This is the first study to improve both taxon and character sampling. The phylogenetic study of the basal Epidendroideae consisted of two components, molecular and morphological. A molecular phylogeny using three loci representing each of the plant genomes including gap characters is presented for the basal Epidendroideae. Here we find Neottieae sister to Palmorchis at the base of the Epidendroideae, followed by Triphoreae. Tropidieae and Sobralieae form a clade, however the relationship between these, Nervilieae and the advanced Epidendroids has not been resolved. A morphological matrix of 40 taxa and 30 characters was constructed and a phylogenetic analysis was performed. The results support many of the traditional views of tribal composition, but do not fully resolve relationships among many of the tribes. A robust hypothesis of relationships is presented based on the results of a total evidence analysis using three molecular loci, gap characters and morphology. Palmorchis is placed at the base of the tree, sister to Neottieae, followed successively by Triphoreae sister to Epipogium, then Sobralieae. Tropidieae form a clade with the advanced Epidendroideae, ii and this sister to Nervilieae and Gastrodieae. Diceratostele gabonensis groups within this clade. These results support a primitive condition of plicate leaves with absent or reduced leaves evolving a minimum of five times. An objective of this study was to investigate anther evolution. Among the basal members we find anthers that are erect or exhibit varying degrees of incumbency. It is clear that the erect anthers of some orchids evolved independently from those observed in the Orchidoideae, and the primitive condition among the basal Epidendroideae is suberect/subincumbent. Epidendroid incumbency is achieved via combinations of bending in different regions of the anther, with the primitive condition being in the column region and to a lesser extent, the basal region of the anther. The primitive condition for pollinia is free monads with tetrads evolving twice, and sectile pollinia four times. Some authors have suggested that the type III stigma of Cephalanthera, possessing other primitive features, was evidence that it was intermediate between Neottieae and advanced Epidendroideae. Given its position in the Neottieae, this condition in Cephalanthera is a case of convergence. Based on the results of other studies using nonorchids, it was expected that we would find higher rates of nucleotide substitutions and divergence rates in taxa that lack chlorophyll when compared to green relatives. This study confirms this for both nuclear ITS and mitochondrial nad1 for which there were significant numbers of achlorophyllous taxa represented. These taxa had lower transition:transversion ratios (TI:TV) than chlorophyllous taxa in the same clade and generally lower than other taxa. As part of the study of the basal Epidendroideae, a monograph of the orchid genus Psilochilus (Triphoreae) was prepared in order to better understand the natural variation within the genus. Based on this work, there are seven species recognized, of which one is iii a newly described species, Psilochilus ecuadoriensis, from lowlands of western Ecuador. A molecular phylogenetic study of the genus, representing five of the seven species, was performed using the plastid trnL-F intergenic spacer. Psilochilus physurifolius is at the base of the genus. A grouping is formed between Psilochilus modestus and P. macrophyllus and a clade of P. mollis and P. ecuadoriensis. Conditions of the labellum and vegetative leaf characters were mapped onto the strict consensus of the parsimony analysis including gaps. In the Triphoreae the primitive condition is to have clasping or apetiolate ovate leaves and a labellum with acute lateral lobes and three calli. Psilochilus has two calli and a petiolate leaf, with apetiolate leaves evolving again in P. macrophyllus; elliptic leaves evolved in P. physurifolius. The lateral lobes of the labellum are acute in most of the taxa with rounded or blunted lateral lobes evolving in the clade of P. mollis and P. ecuadoriensis. The clade of Psilochilus modestus and P. macrophyllus is distinguished from the clade of P. mollis and P. ecuadoriensis by a labellum with acute lateral lobes and ovate leaves. This is the first significant study of the basal Epidendroideae in which both taxon and locus sampling were increased. It had been previously suggested by other authors that the diversity of the Epidendroideae might be the result of a rapid evolutionary radiation, as indicated by the short branch lengths and low support obtained. The implication was that a hypothesis of relationships among the basal tribes of the Epidendroideae might not be possible to obtain. These results prove that the epidendroid problem is not intractable, and while still showing low support, there is considerable structure to the topology obtained. iv Dedicated to my loving wife, Birgit, who has stood by me from the beginning, gave me encouragement and support, worried for me when I did not, and deserves this as much as me. To my son, Nathan, who is my muse and my inspiration for enjoying the little things, and to my parents, who fostered a love of nature and learning. v ACKNOWLEDGMENTS I wish to thank my adviser, Dr. John V. Freudenstein for the intellectual support, guidance and love of orchids, which gave me the encouragement to pursue this. Moreover his patience, and endless hours of draft corrections were greatly appreciated, and have helped to make this document the best that it could be. I would also like to thank my committee members, Dr. John Wenzel and Dr. Andrea Wolfe for their support and constructive criticism, and the members of the Phylogenetic Discussion Group for stimulating debate and a forum for the working out intellectual and philosophical issues. In addition, there are a number people that have helped in so many ways. Thanks to my colleague and friend Lou Jost for his help in Ecuador and his efforts in finding populations of Psilochilus; I am glad that he finally took his eyes from the trees and took time to look down at the ground. I greatly appreciate the assistance of Sr. Andres Maduro for his hospitality and assistance in working in Panama and Vladimir Melgarejo and Eric Olmos for field assistance, the staff of the Smithsonian Tropical Research Institute for making Barro Colorado islands long steps and big tree available to me. Thanks to: Dr. Mark Chase, Dr. Meg Daly, Dr. Robert Dressler, Dr. Emerson R. Pansarin, Dr. Mark vi Whitten and lab, and Dr. Mesfin Tedesse, all of whom have provided material and intellectual support, without which this may not have been possible; and finally, my lab partners and colleagues, Dr. Shawn Krosnick, Jeff Morrawetz, and Craig Barrett for coffee, moral support and discussion. I would also like to acknowledge funding from the Janice Carson Beatley Fund for funding research travel to Panama and Ecuador. vii VITA December 10, 1971 …………….……...…. Born, Charleston, South Carolina, USA 2000 ………………………………………. M.Sc. Biology, Department of Biology, DePaul University, Chicago IL. 1997 ……………………………………….. B.Sc. Department of Biology, DePaul University, Chicago IL. 2001-present ……………………………….. Graduate Teaching associate, The Ohio State University 1997-2000 …………………………………. Graduate Teaching Associate, DePaul University, Chicago, IL. 1996 – 2000 ……………………………….. Intern, Field Museum of Natural History, Chicago, IL. PUBLICATIONS 1. Rothacker. 2005. Triphoreae. Pp. 605-616 in Pridgeon, A. M., P. J. Cribb, M. W. Chase and F. N. Rasmussen (eds.), Genera Orchidacearum. Oxford Univ. Press, Oxford. 2. Rothacker. 2000. Stable isotopic and morphometric characterization of Peregrine migration with an emphasis on determining the importance of particular habitat types. June 2000. MSc. Thesis. DePaul University, Chicago, IL. 3. Kharas, Karras, Michna, Grajzer, Karins, Kontzias, Rothacker, McManigal, Dian, and Watson. 2001. Novel Copolymers of Trisubstituted Ethylenes with Styrene - 1. 2- Halophenyl-1,1-dicyanoethylenes, J. Macromol. Sci., A38, 889-896. viii 4. Kharas, Karras, Michna, Grajzar, Karins, Rothacker, McManigal, and Watson. 1999. Novel copolymers of halogen ring substituted 2-Phenyl-1,1-Dicyanoethylenes and styrene. Polymer Preprints. Vol. 40:1. FIELDS OF STUDY Major Field: Evolution, Ecology and Organismal Biology ix TABLE OF CONTENTS Page Abstract ……………………………………………………………………………… ii Dedication ………………………………………………………………………….... v Acknowledgments ………………………………………………………………….... vi Vita …………………………………………………………………………………... vii List of Tables ………………………………………………………………………… xiv List of Figures ……………………………………………………………………….. xvi Chapters: 1. Systematic