UC Irvine UC Irvine Electronic Theses and Dissertations Title Plant-pollinator interactions and environmental change: effects of experimental changes in phenology and water availability on a montane wildflower Permalink https://escholarship.org/uc/item/8b2263f7 Author Gallagher, Megan Katherine Publication Date 2017 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA, IRVINE PLANT–POLLINATOR INTERACTIONS AND ENVIRONMENTAL CHANGE: EFFECTS OF EXPERIMENTAL CHANGES IN PHENOLOGY AND WATER AVAILABILITY ON A MONTANE WILDFLOWER DISSERTATION submitted in partial satisfaction of the requirements for the degree of DOCTOR OF PHILOSOPHY in Ecology and Evolutionary Biology by Megan Katherine Gallagher Dissertation Committee: Professor Diane R. Campbell, Chair Professor Travis E. Huxman Professor Jennifer B. H. Martiny Professor Kailen A. Mooney 2017 Chapter 1 © 2017 John Wiley and Sons, Inc. All other materials © 2017 Megan Katherine Gallagher DEDICATION “You must do something to make the world more beautiful.” ― Ms. Rumphius, by Barbara Cooney ii TABLE OF CONTENTS Page DEDICATION II LIST OF FIGURES IV LIST OF TABLES VI ACKNOWLEDGMENTS VII CURRICULUM VITAE VIII ABSTRACT OF THE DISSERTATION IX INTRODUCTION 1 Literature Cited 4 CHAPTER 1: SHIFTS IN WATER AVAILABILITY MEDIATE PLANT-POLLINATOR INTERACTIONS 7 Introduction 7 Materials and Methods 9 Results 18 Discussion 20 Literature Cited 27 CHAPTER 2: FLOWERING PHENOLOGY INFLUENCES POLLINATION BY ALTERING VISITATION RATE AND POLLINATOR EFFECTIVENESS 43 Introduction 43 Materials and methods 46 Results 59 Discussion 62 Literature Cited 70 CHAPTER 3: EXPERIMENTAL ENVIRONMENTAL CHANGE ALTERS PLANT–POLLINATOR INTERACTIONS AND SEED SET 85 Introduction 85 Methods 88 Results 96 Discussion 99 Literature Cited 106 iii LIST OF FIGURES Page Figure 1.1 Mean daily maximum soil volumetric moisture content for (a) 2013 and (b) 2014. 37 Figure 1.2 Effects of experimental variation in soil moisture on (a) corolla width, (b) corolla length, and (c) nectar volume. 38 Figure 1.3 Effects of variation in soil moisture on (a) peak floral abundance and (b) ramet height. 39 Figure 1.4 Effects of experimental variation in soil moisture on (a) pollinator visitation rate per plot and (b) mean seed set per plot. 40 Figure 1.5 Effects of variation in flower size on pollinator visitation rate of individual ramets by (a) corolla length at high site; (b) corolla length at low site; (c) corolla width at high site; (d) corolla width at low site. 41 Figure 1.6 Effects of pollinator visitation rate per plot on mean seed set. 42 Figure 2.1 Floral abundance of ten Mertensia ciliata plants per week. 77 Figure 2.2 Effects of variation in flowering phenology on (a) pollinator visitation rate and (b) pollinator type. 78 Figure 2.3 Effects of variation in flowering phenology on pollen loads of (a) conspecific and (b) heterospecific pollen. 79 Figure 2.4 Effects of variation in flowering phenology on seed set of (a) experimental plants and (b) unmanipulated plants. 80 Figure 2.5 Effects of variation in flowering phenology on seed mass. 81 Figure 2.6 Flowering phenology of all co-flowering species. 82 Figure 2.7 Weekly (a) total and (b) per species floral abundance of co-flowering species. 83 Figure 2.8 Single-visit pollinator effectiveness of different insect visitors on (a) conspecific and (b) heterospecific pollen receipt, (c) seed set, and (d) seed mass. 84 Figure 3.1 Mean (a) soil moisture of three water treatment levels and (b) floral abundance per array over four phenology weeks. 112 Figure 3.2 Effects of variation in soil moisture and flowering phenology on (a) corolla width, (b) corolla length, (c) nectar volume and (d) nectar sugar concentration. 113 Figure 3.3 Effects of variation in soil moisture and flowering phenology on floral abundance per plant. 114 Figure 3.4 Effects of variation in soil moisture and flowering phenology on (a) the likelihood of a pollinator visit, (b) pollinator visitation rate and (c) iv the percent of pollinator visits that were comprised of bumblebees, flies, and solitary bees. 115 Figure 3.5 Effects of experimental variation in soil moisture and flowering phenology on (a) seeds set and (b) seed mass. 116 v LIST OF TABLES Page Table 1.1 Effects of water availability on floral abundance measurements. 32 Table 1.2 Results of zero-inflation model analysis testing effects of experimental variation in soil moisture pollinator visitation rate per plot. 33 Table 1.3 Results for zero-inflation model analysis testing responses of pollinator visitation to differences in corolla width and length at two sites. 34 Table 1.4 Standardized directional (S') and quadratic (g) selection differentials of pollinator visitation on corolla traits. 35 Table 1.5 Standardized directional (S') selection differentials on corolla traits. 36 Table 2.1 Final model components for analyses testing the extent to which experimental variation in flowering time affects pollination and plant fitness. 75 Table 2.2 Relative expected and observed effects of variation in flowering phenology on (a) conspecific pollen receipt and (b) seed set per flower. 76 Table 3.1 Results from analyses testing the effects of experimental variation in phenology and water treatments on floral traits, pollinator type, seed set, and seed mass. 110 Table 3.2 Results from analyses testing the effects of experimental variation in phenology and water treatments on pollinator visitation. 111 vi ACKNOWLEDGMENTS This doctoral dissertation has been completed with the generous help of many people. I am especially grateful to my advisor, Dr. Diane Campbell, for her patient supervision and invaluable expertise. I am thankful to have her as a mentor and role model. In addition, I am deeply appreciative of the members of my committee, Dr. Jennifer Martiny, Dr. Kailen Mooney, and Dr. Travis Huxman, for their guidance and encouragement throughout this process. A special thank you to the members of the Campbell lab past and present, particularly my lab mates, Wilnelia Recart and Daniella Bruckman, and the many undergraduate researchers and summer field assistants who helped with lab and fieldwork. I am grateful to Dr. Stuart Wagenius, Dr. Nancy Aguilar-Roca, Dr. Ann Sakai, and Dr. Steve Weller who have also been mentors to me throughout my graduate career. I also thank the faculty and staff of the Ecology and Evolutionary Biology Department at the University of California, Irvine (UCI) and the Rocky Mountain Biological Laboratory (RMBL) for their support and friendship. My friends have been particularly supportive throughout this process. Thank you to Christiana Harkulich (née Molldrem), without your keen insight I would never have considered starting down this path. Thank you also to Sara Maskornick (née Mabry) and Evangeline Ridgaway (née Rich) for your enthusiasm, encouragement, and perspective. To LuAnna Dobson and the rest of my friends at UCI, I am grateful every day that I was able to a part of this fun and supportive community. To the inspiring friends that I made while completing this work at RMBL, thank you for the wonderful memories. Finally, I am deeply thankful for my caring family. To my siblings, Brian, and John and to Brian’s wife, Magdalen, thank you for lending an ear when I needed one and providing comic relief, even when I didn’t know I needed it. To my mom, Adrienne, and my dad, Barney, thank you for always encouraging me to dream big and for giving me the tools I need to achieve my big dreams without you none of this would have been possible. I thank John Wiley and Sons, Inc. for permission to include Chapter one of my dissertation, which is published in New Phytologist. Financial support was provided by the University of California, Irvine, NSF Grant DEB-1601191, The Botanical Society of America, the Rocky Mountain Biological Laboratory, Sigma-Xi and Western Ag. Inc. vii CURRICULUM VITAE EDUCATION 2017 Ph.D. Ecology and Evolutionary Biology, University of California, Irvine 2011 M.S. Plant Biology and Conservation, Northwestern University 2006 B.A. with Honors in International Relations, Minor in Biology, Wellesley College PROFESSIONAL APPOINTMENTS 2011 – 2017 Teaching Assistant, Dept. of Biological Sciences, University of California, Irvine 2014 – 2015 Pedagogical Fellow, University of California, Irvine 2011; 2012 Research Assistant, Campbell Lab, Rocky Mountain Biological Laboratory 2010 – 2011 Lab Manager, Population Biology Lab, Chicago Botanic Garden 2010 Teaching Assistant, Dept. of Biological Sciences, Northwestern University 2009; 2010 Research Assistant, Echinacea Project, Chicago Botanic Garden 2007 – 2009 Project Associate, Xerimis, Inc. SELECTED ACADEMIC HONORS 2016 - 2017 Public Impact Fellowship - University of California, Irvine 2016 Doctoral Dissertation Improvement Grant - National Science Foundation 2014 - 2015 Pedagogical Fellowship - University of California, Irvine 2012 - 2015 Graduate Fellowship - Rocky Mountain Biological Laboratory 2014 Edward Steinhaus Teaching Award - University of California, Irvine 2013 Graduate Student Research Award - Botanical Society of America 2013 Grants-in-Aid of Research Award - Sigma Xi 2010 - 2011 Fellowship in Ecological Restoration - Garden Club of America PUBLICATIONS Gallagher, M.K. & D.R. Campbell. 2017. Shifts in water availability mediate plant-pollinator interactions. New Phytologist. DOI: 10.1111/nph.14602 Gallagher, M.K. & S. Wagenius. 2015.