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Herbivore Effects on Plant Coexistence and Diversity Brent Mortensen Iowa State University

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Herbivore Effects on Plant Coexistence and Diversity Brent Mortensen Iowa State University Iowa State University Capstones, Theses and Graduate Theses and Dissertations Dissertations 2017 Herbivore effects on plant coexistence and diversity Brent Mortensen Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/etd Part of the Agriculture Commons, Biodiversity Commons, Ecology and Evolutionary Biology Commons, Natural Resources and Conservation Commons, Natural Resources Management and Policy Commons, and the Plant Sciences Commons Recommended Citation Mortensen, Brent, "Herbivore effects on plant coexistence and diversity" (2017). Graduate Theses and Dissertations. 15382. https://lib.dr.iastate.edu/etd/15382 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Graduate Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. Herbivore effects on plant coexistence and diversity by Brent Mortensen A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Ecology and Evolutionary Biology Program of Study Committee: Brent Danielson, Co-Major Professor W. Stan Harpole, Co-Major Professor Karen Abbott Aaron Gassmann Brian Wilsey Iowa State University Ames, Iowa 2017 Copyright © Brent Mortensen, 2017. All rights reserved. ii DEDICATION To my wife, Lara, who with patience endured this long road beside me and my children, Colter, Ally, Calvin, and Kyndra who gave me reason to keep going. iii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ............................................................................................... vi CHAPTER 1 INTRODUCTION....................................................................................... 1 Trade-Offs and Herbivory in Ecological Theory .......................................................... 1 Dissertation Outline ....................................................................................................... 5 References ..................................................................................................................... 9 CHAPTER 2 HERBIVORES SAFEGUARD PLANT DIVERSITY BY REDUCING VARIABILITY IN DOMINANCE ............................................................. 14 Summary ..................................................................................................................... 15 Introduction ................................................................................................................. 17 Materials and Methods ................................................................................................ 20 Results ......................................................................................................................... 25 Discussion ................................................................................................................... 28 Acknowledgements ..................................................................................................... 36 References ................................................................................................................... 36 Tables .......................................................................................................................... 48 Figures ......................................................................................................................... 50 Supporting Information ............................................................................................... 56 CHAPTER 3 LIGHT IS NOT A LIMITING FACTOR TO SPECIES RICHNESS IN TALLGRASS PRAIRIES ............................................................................................ 70 Abstract ....................................................................................................................... 70 Introduction ................................................................................................................. 71 Methods ....................................................................................................................... 73 iv Page Results ......................................................................................................................... 82 Discussion ................................................................................................................... 85 Acknowledgements ..................................................................................................... 91 References ................................................................................................................... 92 Tables ........................................................................................................................ 101 Figures ....................................................................................................................... 103 Appendix: Supporting Tables .................................................................................... 110 CHAPTER 4 DEFENSIVE TRADE-OFFS ARE NOT PREREQUISITES TO PLANT DIVERSITY IN A TWO SPECIES MODEL ................................................... 112 Abstract ..................................................................................................................... 112 Introduction ............................................................................................................... 113 Model ......................................................................................................................... 116 Growth-Defense Trade-off ........................................................................................ 124 Competition-Defense Trade-off ................................................................................ 127 Comparison to Plants with Logistic Growth ............................................................. 129 Conclusions ............................................................................................................... 130 Acknowledgements ................................................................................................... 132 Literature Cited .......................................................................................................... 132 Table .......................................................................................................................... 138 Figures ....................................................................................................................... 139 Appendix 1: Solving for Equilibria ........................................................................... 144 Appendix 2: Parameter Estimates with Supporting Values ...................................... 155 Appendix 3: Parameter Combinations Tested ........................................................... 160 v Page Appendix 4: Description of Intersection in Figure 4A .............................................. 161 Appendix 5: Analogous Effects of Carrying Capacity to Growth Rate in Defensive Trade-Offs ................................................................................................ 162 Appendix 6: Logistic Growth Model ........................................................................ 172 CHAPTER 5 BUILDING SCHEMAS TO IMPROVE STUDENT LEARNING IN ECOLOGY ................................................................................................................. 176 Abstract ..................................................................................................................... 176 Introduction ............................................................................................................... 177 Methods ..................................................................................................................... 182 Results ....................................................................................................................... 188 Discussion ................................................................................................................. 190 Acknowledgements ................................................................................................... 200 Works Cited ............................................................................................................... 200 Tables ........................................................................................................................ 204 Figures ....................................................................................................................... 207 Supplementary Materials: Assignment Prompts ....................................................... 210 Supplementary Materials: Survey Questions and Potential Responses .................... 212 Supplementary Materials: Quiz ................................................................................. 215 Supplementary Materials: Institutional Review Board (IRB) Exemption ................ 219 Supplementary Table ................................................................................................. 220 Reflection .................................................................................................................. 222 CHAPTER 6 CONCLUSIONS ..................................................................................... 226 References ................................................................................................................
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