University of Colorado, Boulder CU Scholar Ecology & Evolutionary Biology Graduate Theses & Ecology & Evolutionary Biology Dissertations Spring 1-1-2011 The good, the bad and the flexible: interactions of Erysimum capitatum with pollinators and herbivores over space and time Claire Ruth Lay University of Colorado at Boulder, [email protected] Follow this and additional works at: http://scholar.colorado.edu/ebio_gradetds Part of the Biology Commons, and the Ecology and Evolutionary Biology Commons Recommended Citation Lay, Claire Ruth, "The oodg , the bad and the flexible: interactions of Erysimum capitatum with pollinators and herbivores over space and time" (2011). Ecology & Evolutionary Biology Graduate Theses & Dissertations. Paper 19. This Dissertation is brought to you for free and open access by Ecology & Evolutionary Biology at CU Scholar. It has been accepted for inclusion in Ecology & Evolutionary Biology Graduate Theses & Dissertations by an authorized administrator of CU Scholar. For more information, please contact [email protected]. THE GOOD, THE BAD AND THE FLEXIBLE: INTERACTIONS OF ERYSIMUM CAPITATUM WITH POLLINATORS AND HERBIVORES OVER SPACE AND TIME by CLAIRE RUTH LAY B.S., Truman State University, 2002 A thesis submitted to the Faculty of the Graduate School of the University of Colorado in partial fulfillment of the requirement for the degree of Doctor of Philosophy Department of Ecology and Evolutionary Biology 2011 This thesis entitled: The good, the bad and the flexible: interactions of Erysimum capitatum with pollinators and herbivores over space and time written by Claire Ruth Lay has been approved for the Department of Ecology and Evolutionary Biology Dr. Pamela K. Diggle Dr. Yan B. Linhart Dr. Deane Bowers Dr. Carol A. Kearns Dr. Gregory Carey Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. iii Lay, Claire Ruth (Ph.D., Ecology and Evolutionary Biology) The good, the bad and the flexible: interactions of Erysimum capitatum with pollinators and herbivores over space and time Thesis directed by Professors Pamela K. Diggle and Yan B. Linhart The diversity of flower structure and flowering characteristics in angiosperms has long inspired researchers to study evolutionary mechanisms that have produced it. Darwin’s recognition of many apparent flower adaptations to pollinators led to a focus on animal pollinators as selective forces, but recently, the importance of simultaneously considering other selective agents has been recognized. Particularly, herbivores can select for plant traits, and can interact with or limit selection by pollinators in complex ways. Assemblages of pollinators and herbivores can vary greatly among plant populations. In plants with generalized pollination systems and multiple herbivores, the potentially complex effects of these biotic selective forces may lead to local adaptation. Conversely, conflicting selection by multiple herbivores and pollinators may limit local adaptation and maintain variation within populations. Erysimum capitatum (Brassicaceae) is a widespread and variable plant species with generalized pollination that is attacked by a number of herbivores. I studied interactions of E. capitatum with pollinators and herbivores in four populations over an elevational gradient in the Rocky Mountains, and tested for local adaptation to suites of pollinators and herbivores. I used observational and experimental methods in natural populations, and performed a common garden iv experiment using plants grown from two of the original four source populations. Plant traits varied among natural populations, and individuals of E. capitatum were visited by diverse groups of pollinators and herbivores that shifted in abundance and importance in time and space. Both pollinators and herbivores preferentially visited plants with more flowers, and herbivory reduced pollinator visitation in some populations and years. Pollinators did not select on plant traits in any year or population, but herbivores sometimes selected for plant traits. These results suggest that plant plasticity may mediate interactions with both pollinators and herbivores. Pollination and herbivory both changed plant fitness, but I found no signs of local adaptation to pollinators and herbivores in the common garden experiment. However, non-local plants did have lower reproductive success than local ones, and may be locally adapted to other factors. v ACKNOWLEDGEMENTS Many people have helped me to get through graduate school and finish my thesis. Thanks go first of all to Pamela Diggle for taking me on as a student and for keeping me on once she realized I wouldn’t stay out of the field. Her great insights into big ideas behind evolution and plant development, and her unique way of looking at results have helped me to consider many perspectives I wouldn’t have found on my own. In addition, her excellent teaching skills have helped me to improve my own. I’m also very grateful to my second adviser, Yan Linhart, who took me on as a student. He has shepherded me through some of the challenges of field work and graduate school and his constant enthusiasm for the natural world is inspiring. Deane Bowers has been an impressive source of ideas, knowledge and excitement about the biological and chemical world. She also gave me an opportunity to work in the entomology collection at the museum. Carol Kearns generously lent me a her property for field work, and although the pocket gophers that shared it with me thwarted the inclusion of the data here, I very much thank her for the space. She also provided data that helped me to know what to expect when doing observations on my plants. Thanks to Greg Carey for the statistical mentorship. Greg’s skill and easy manner helped me love multivariate statistics and get this project done. Thanks to the other members of my two labs. Rob Baker has been a good friend and collaborator. In addition to hours of field and greenhouse labor, and comments on drafts and talks, he has generously given me data to play with, problems to solve, and professional inspiration. Chi-Chih Wu has also given me interesting things to work on, and listened to talks. Erin Bissell helped me in the field and led the way to the light at the end of the thesis-writing tunnel. April Randle was a great help in organizing my thoughts for the third chapter. Bianca Breland, Ken Keefover-Ring and Kailen Mooney were good companionship as the last students vi of the Linhart lab, and Bianca sat out watching for flies on one memorably drizzly and cold day. Ken snapped my favorite picture of my study species. Additional thanks go to the members of the Plant Animal Interactions reading group, the members of the Friedman and Bowers labs and some other great graduate students I’ve interacted with in my time here. Jennifer Winther always made me soup when I was sick and entertained me in the lab when we were there early or staying late. Jonathan Krieger, Sarah Wise and Heidi Schutz were good for scientific talk and indoor climbing. Ned Friedman has an enthusiasm for the history of biology and the beauty of ideas and life that have always made me smile, and it was a privilege to see his inspiring and entertaining teaching lectures when working as his teaching assistant. I have deep gratitude to John Basey for mentoring me through my first semesters as a general biology teaching assistant—his support helped me to develop skills and confidence in front of a classroom. Thanks also to Stephanie Mayer for all the time we spent preparing labs, and for the plant-centered teaching assistantships I’ve been fortunate enough to have with her. Thom Lemieux has helped me with the details of planting and greenhouse work, and has been fun to know. Virginia Scott, Boris Kondratieff, Lubo Masmir, Leticia Sanchez, Evan Lampert and Andy Hicks helped me identify insects. I could not have completed my fieldwork or lab work without the dedicated help of some amazing student employees and volunteers. Special thanks go to John Murgel and Mark Gorman for their hard work and skill in field logistics. I also give special thanks also to Carli Busse, who spent hundreds of hours counting seeds and measuring fruits for no pay and no credit just because she wanted to help. Every time I found her counting and sorting seeds, I was surprised and grateful. Thanks also to Sharanya Thurman, Stephanie Miller, Rachel Merriweather, Chris vii Chalstrom, Thomas Gabel, Lisa Friedman, Jamie Buckner, Tegan McGillivray, and Alex Steinberg. This work was supported by grants from the EEB department, the John Marr Fund, the CU Museum Walker Van Riper Fund, the Colorado Mountain Club, and a Beverly Sears Graduate student grant. Many thanks go to our departmental staff, Bill Franz, Linda Bowden, Jill Skarstad, Melanie Green, and Melissa Keller for helping with administrative details, computers and office necessities. Boulder City and County Open Space, and the CU Mountain Research Station all permitted me to use land for field studies, and to do collections of seeds and insects. Thanks to Lynn Riedel for the help. Lastly, thanks to my fantastic family of friends and relatives who helped me in the field and in life while I was picking up bits of information and translating them into something coherent. My exceedingly bright and energetic stepdaughters, Sophia and Charissa, helped me plant a garden, recapture marked beetles, water and record data. Both of them had a remarkable command of scientific thought and attention to detail for people under age 13. In addition to being great field help, they are way cooler than I ever was and I am glad to have them in my life. Thanks to all my beautifully bright, fun, creative and hard-working Burning Man family. They’ve provided quiet places to stay when I needed to get work done, noisy places to dance when I needed a break, and a creative community of deep friendship the rest of the time.