POLLINATION ECOLOGY AND DEMOGRAPHY OF A DECEPTIVE ORCHID Ryan P. Walsh A Dissertation Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY August 2013 Committee: Helen Michaels, Advisor Timothy J. Murnen Graduate Faculty Representative Karen Root Moira van Staaden Randy Mitchell ii ABSTRACT Helen Michaels, Advisor This dissertation is focused on three main questions addressing the reproductive and demographic effects of pollen limitation, seed predation and deceit pollination in the food deceptive orchid Cypripedium candidum. We conducted two hand pollination field experiments to quantify pollen limitation and inbreeding. Both studies showed strong pollen limitation, with supplemental hand pollinations increasing fruit set in 2009 by 41% and 2011 by 30-35%. Taller plants in the study were more likely to be pollinated, while all other size variables did not influence pollination or fruit set. The 2011 study demonstrated a reduction in seed mass in selfed capsules by 63%. We found high levels of fruit predation in 2009 with 73% of the fruit experiencing pre-dispersal seed predation resulting in an 89% reduction in seed mass. Of the size variables analyzed, shorter plants were more likely to be attacked by weevils. In a nectar addition study we manipulated plants to provide a nectar reward, dyed their pollinia for tracking and compared their reproduction against control plants with no reward. Nectar reward, which had no effect on fruit production, however did result in a nearly threefold increase in selfing. Approximately 26% of non-rewarding C. candidum pollination events result in selfing, while the addition of nectar increased selfing to 78%. Selfed seed capsules had a decreased seed mass as demonstrated in the previous experiment. Finally, we conducted a four year demographic study and produced matrix models that estimated the population growth rate at λ = 1.01 under an average of 22% pre-dispersal seed predation. Elasticity values of the models indicated the stasis and growth of one-flowered individuals to be the most important factors to the population growth iii rate. A model simulating the effects of nectar addition with the average rate of seed predation resulted in λ = 0.99. These studies demonstrate the complex reproductive dynamics of deceptive plants and provide evidence suggesting the evolution of deceit pollination is driven by multiple factors, including predation and decreased fecundity from selfing. iv ACKNOWLEDGMENTS I would like to thank my advisor, Dr. Helen Michaels for mentoring me through both undergraduate and graduate school and dragging me begrudgingly into the world of plant pollinator interactions. I also thank my committee, Dr. Karen Root, Dr. Moira van Staaden and Dr. Randy Mitchell for their feedback throughout my dissertation. Furthermore I would like to thank the Michaels lab: Mike Plenzler, Jennifer Shimola, and Jacob Meier for their feedback through endless versions of this dissertation. Also, thank you to my undergraduate field assistant, Paige Arnold, who worked tirelessly in less than ideal conditions, and was monumental in helping me finish the field research. Furthermore I thank SETGO for funding Paige and my research through the undergraduate research program. I want to thank the Ohio Department of Natural Resources for allowing me to work at Resthaven Wildlife area and particularly Jennifer Windus for her input into the orchid, streamlining of the permit process and valuable data on the C. candidum population at Resthaven. v TABLE OF CONTENTS Page CHAPTER I. GENERAL INTRODUCTION ..................................................................... 1 Introduction ............................................................................................................... 1 Figures ........................................................................................................................ 5 References ................................................................................................................. 7 CHAPTER II. THE ROLE OF POLLINATOR LIMITATION AND SEED PREDATION ON THE DECEPTIVE ORCHID CYPRIPEDIUM CANDIDUM ....................................... 9 Abstract ..................................................................................................................... 9 Introduction ............................................................................................................... 10 Materials and Methods .............................................................................................. 14 Results ...................................................................................................................... 19 Discussion ................................................................................................................. 21 References ................................................................................................................. 26 Tables and Figures .................................................................................................... 31 CHAPTER III. EXAMINING THE ROLE OF FOOD DECEPTION ON REPRODUCTION IN THE DECEPTIVE ORCHID CYPRIPEDIUM CANDIDUM ..... 38 Abstract ..................................................................................................................... 38 Introduction ............................................................................................................... 39 Materials and Methods .............................................................................................. 44 Results ...................................................................................................................... 47 Discussion ................................................................................................................. 49 References ................................................................................................................. 54 vi Tables and Figures .................................................................................................... 57 Appendix ................................................................................................................... 64 CHAPTER IV. THE DEMOGRAPHIC IMPLICATIONS OF SEED PREDATION AND DECEPTION IN THE DECEPTIVE ORCHID CYPRIPEDIUM CANDIDUM MUHL. EX WILLD. ............................................................................................................. 65 Abstract ..................................................................................................................... 65 Introduction ............................................................................................................... 66 Materials and Methods .............................................................................................. 71 Results ...................................................................................................................... 77 Discussion ................................................................................................................. 80 References ................................................................................................................. 86 Tables and Figures .................................................................................................... 90 CHAPTER V. CONCLUSIONS ......................................................................................... 96 Discussion ................................................................................................................. 93 References ................................................................................................................. 100 vii LIST OF TABLES Table Page CHAPTER II 1 MANOVA of the Effect of the Pollination Treatment on Percent Abortion, Percent Capsules Produced and Average Seed Mass. ........................................................... 31 2 The Effect of Number of Flowers, Number of Stems and the Average Height of Flowering Stems on the Initial (A) and Final (B) Fruit Sets of Open and Hand Pollinated Plants. ....................................................................................................... 31 3 The Effect of Treatment, Number of Flowers, Number of Stems, Number of Fruits and the Average Height of Flowering Stems on Rate of Predation Across All Treatments. ................................................................................................................ 32 4 The Effect of Hand Outcross, Hand Selfed and Open Pollination Treatments on Initial Fruit Set, Final Fruit Set, Abortion Rate and Seed Mass. .............................. 32 5 The Effect of Hand Outcross, Hand Selfed and Open Pollination Treatments on Initial and Final Fruit Set for the 2011 Study.. ......................................................... 33 6 The Effect of Hand Outcross, Hand Selfed and Open Pollination Treatments on Seed Mass for the 2011 Study.. ................................................................................ 33 7 The Effect of Hand Outcross, Hand Selfed and Open Pollination Treatments on Abortion Rates for the 2011 Study.. ......................................................................... 34 CHAPTER III 1 The Effect of Nectar Addition, Quadrat, Number of Stems, Number of Flowers and the Distance of the Three Nearest Non-Orchid, Nectar-Producing Neighbors on the viii Percentage of Pollinia, Percent Self Pollinia, and Percent Outcross