Mutualism Stability and Gall Induction in the Fig and Fig Wasp Interaction
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Mutualism Stability and Gall Induction in the Fig and Fig Wasp Interaction Item Type text; Electronic Dissertation Authors Martinson, Ellen O'Hara Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 28/09/2021 01:14:56 Link to Item http://hdl.handle.net/10150/265556 MUTUALISM STABILITY AND GALL INDUCTION IN THE FIG AND FIG WASP INTERACTION by Ellen O. Martinson _____________________ A Dissertation Submitted to the Faculty of the ECOLOGY AND EVOLUTIONARY BIOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2012 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Ellen O. Martinson entitled MUTUALISM STABILITY AND GALL INDUCTION IN THE FIG AND FIG WASP INTERACTION and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy _______________________________________________________________________ Date: 11/02/12 A. Elizabeth Arnold _______________________________________________________________________ Date: 11/02/12 Jeremiah D. Hackett _______________________________________________________________________ Date: 11/02/12 Carlos A. Machado _______________________________________________________________________ Date: 11/02/12 Rob H. Robichaux _______________________________________________________________________ Date: 11/02/12 Noah K. Whiteman Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ________________________________________________ Date: 11/02/12 Dissertation Director: A. Elizabeth Arnold ________________________________________________ Date: 11/02/12 Dissertation Director: Jeremiah D. Hackett 3 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: _______________________________ Ellen O. Martinson 4 ACKNOWLEDGEMENTS I am eternally grateful to my co-advisors A. Elizabeth (Betsy) Arnold and Jeremiah Hackett. Thank you Betsy for letting me join your lab. Your mentorship has left me a better scientist and writer and has taught me the importance of a positive attitude. Thank you Jeremiah for opening your lab to me and always being available to work on a problem. I would like to thank my committee members, Carlos Machado, Noah Whiteman, and Rob Robichaux for their support and feedback. I am especially grateful to Carlos Machado for showing me the fig and fig wasp mutualism first hand and for his support and early advisement. I wish to thank current and former University of Arizona faculty, including David Galbraith, Nancy Moran, Howard Ochman, Michael Nachman, Rich Jorgensen, David Maddison, Robert Steidl, and Peter Reinthal for their advice and excellent instruction. I thank my co-author Allen Herre for his valuable feedback on manuscripts and introducing me to Barro Colorado Island. I am grateful to the Smithsonian Tropical Research Institute for logistical support and the government of Panama for permission to carry out this research. I thank Aldaberto Gomez for teaching me to navigate the Panama Canal and to my fellow researchers and staff on Barro Colorado Island for their feedback and support, especially Egbert Leigh Jr., Oris Acevedo, Robert Horan, Nadia Sitas, Matt McRoy, and Carlos Aguilar. I am grateful for my labmates in the Arnold, Hackett, and Machado labs, including Jen Wisecaver, Will Driscoll, Jana U’Ren, Mary Jane Epps, K. Mali Gunatilaka, Carlos Flores, Wendy Marussich, and Anna Himler for their camaraderie and technical support in the lab. Thank you to the Ecology and Evolutionary Biology staff for their assistance, especially Liz Oxford, Jean Mason, Carol Freeman, Beth Sanchez, and Brian Morton. And I am grateful to the UA IGERT program in genomics, NSF GRFP, and the Smithsonian Institute for funding during my graduate career. For my friends, thank you for your encouragement, friendship, and awesome Halloween costumes. I wish to especially thank Kevin Vogel, Gaelen Burke, Matt Heron, Joel Wertheim, Betsy Wertheim, Joe Deas, Lindsey Sloat, Bryan Helm, Steve Foldi, Erin Kelleher Meisel, and Ming-Min Lee. I am grateful to Bryan Bishop and Greg Hoch for guiding me towards a career in science. I would like to thank my parents Robert and Barbara Suurmeyer, my siblings Nathan, Laura, and Jill, and my in-laws, Joanne and Wynn Martinson, for their incredible support and encouragement throughout my graduate career. Finally, my husband, Vince Martinson, thank you for all of our support, guidance, friendship, and love. 5 DEDICATION To Vince and my family for their endless love and support 6 TABLE OF CONTENTS ABSTRACT.........................................................................................................................7 INTRODUCTION...............................................................................................................9 PRESENT STUDY............................................................................................................23 REFERENCES..................................................................................................................27 APPENDIX A: CULTURE-FREE SURVEY REVEALS DIVERSE AND DISTINCTIVE FUNGAL COMMUNITIES ASSOCIATED WITH DEVELOPING FIGS (FICUS SPP.) IN PANAMA………........................................................................33 APPENDIX B: RATIOS OF POISON SAC AREA:EGGS SUGGEST A SIMILAR IMPORTANCE OF THE POISON SAC IN OVIPOSITION BY POLLINATING AND NON-POLLINATING FIG WASPS.................................................................................55 APPENDIX C: METATRANSCRIPTOME ANALYSIS OF FIG FLOWERS REVEALS POSSIBLE MECHANISMS FOR MUTUALISM STABILITY AND GALL INDUCTION.....................................................................................................................75 7 ABSTRACT The interaction between figs (Ficus spp.) and their pollinating wasps (fig wasps; Chalcidoidea, Hymenoptera) is a classic example of an ancient and apparently stable mutualism. A striking property of this mutualism is that fig wasps consistently oviposit in the inner flowers of the fig syconium (gall flowers, which develop into galls that house developing larvae), but typically do not use the outer ring of flowers (seed flowers, which are pollinated and develop into seeds). This dissertation explores the potential differences between gall and seed flowers that might influence oviposition choices, and the unknown mechanisms underlying gall formation. To identify the microbial community that could influence oviposition choice, I identified fungi in both flower types across six species of Ficus. I found that whereas fungal communities differed significantly as a function of developmental stages of syconia and lineages of fig trees, communities did not differ significantly between receptive gall and seed flowers. Because secretions from the poison sac that are deposited at oviposition are thought to be important in gall formation by both pollinating fig wasps and non-pollinating, parasitic wasps, I examined poison sac morphology in diverse galling wasps from several species of Ficus in lowland Panama. I found that the size of the poison sac was positively associated with egg number across pollinating and non-pollinating fig wasps. Finally to determine difference in defense and metabolism between gall and seed flowers, and to identify genes involved in galling, I compared gene expression profiles of fig flowers at the time of oviposition choice and early gall development. I found a prominence of flavonoids and defensive genes in both 8 pollinated and receptive gall flowers of Ficus obtusifolia, and revealed detectable differences between gall flowers and seed flowers before oviposition. Several highly expressed genes were also identified that have implications for the mechanism of gall initiation. This dissertation explores previously unstudied aspects of the fig and fig wasp mutualism and provides important molecular tools for future study of this iconic and ecologically important association. 9 INTRODUCTION 1.1 Literature Review Current evidence suggests that every living organism is involved in at least one mutualistic interaction (Bronstein et al. 2006; Leigh et al. 1995). Mutualism has been classically defined as an interaction