t in}? Lair}. : a... .24? ‘ .w..v.....vr».fiufisa ,gwflumng... fiabwfi Emma: f _._. .. < . ”,3 3; Ian u. it:Kiev»: 3 {tot «5.72 2-. :3. ST... 2: ‘ 3...!.5... SAP}... r 4VLV-rv“s-\v ‘. CID. ‘ 1 II 1 v .1 30E . .(a < 3351...... 4%.“ .. .5. St¢ L : . , :35; s . r 55:.“ .. _ .3. on? This is to certify that the dissertation entitled Generalization in plant pollination systems and its effect on floral evolution within and among populations of wild radish (Raphanus raphanistrum) presented by Heather Farrah Sahli has been accepted towards fulfillment of the requirements for the Doctoral degree in Plant BiologL MM / ajor Professor’ 5 Signature 7/ / 9/09 Date MSU is an Affirmative Action/Equal Opportunity Institution Michigan State University PLACE IN RETURN BOX to remove this checkout from your record. TO AVOID FINES return on or before date due. MAY BE RECALLED with earlier due date if requested. DATE DUE DATE DUE DATE DUE 2/05 p:/ClRC/DaleDue.indd-p.1 GENERALIZATION IN PLANT POLLINATION SYSTEMS AND ITS EFFECT ON FLORAL EVOLUTION Wl'l‘HIN AND AMONG POPULATIONS OF WILD RADlSl-l (1m FHA \ US RA PHA NISTR bill) Heather Farrah Sahli A DlSSliR'lXNl‘lON Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Plant Biology Program in Ecology, Evolutionary Biology, and Behavior 2006 ABSTRACT GENERALIZATION IN PLANT POLLINATION SYSTEMS AND ITS EFFECT ON FLORAL EVOLUTION WITHIN AND AMONG POPULATIONS OF WILD RADISH (RAPHANUS RAPHANISTR UM) By Heather Farrah Sahli While specialists are thought to be well adapted to their resources, gcneralists are thought to be a jack of-all-trades but master of none. However, few studies have examined how selection by multiple resources influences the evolution of morphological traits in generalists. AS most plants are dependent upon pollinators for reproduction. pollinators are important, and often essential, plant resources. I examined the degree of generalization in wild radish (Raphanus raphanislrum) and how selection by multiple pollinators influences adaptation to each taxon individually, both within and among populations. Although previous studies of generalization in plant-pollination systems have focused primarily on estimates of Species richness, pollinators exhibit great variation in visitation rates. I found that diversity indices, which take into account both species richness and evenness, provide a more useful estimate of pollinator generalization. l characterized generalization in the pollinator assemblage of the widespread agricultural weed, wild radish, and studied how pollinators differed in their selection on several floral traits. Although wild radish iS effectively pollinated by at least 14 pollinator genera, few of these taxa actually selected on floral traits. My findings suggest that wild radish is able to adapt to a subset of its pollinators without trading offthe ability to effectively use other taxa. Finally, I examined how selection and drift have contributed to differentiation of floral and phenological traits of wild radish by comparing estimates of population differentiation in quantitative traits (Qs-r) to population differentiation in allele frequencies (F 51‘). I found that differences in most floral traits among populations can be explained by drift alone. I also found that life history traits such as ovule number and flowering time were under strong divergent selection across populations, suggesting life history traits may have been important in colonization and adaptation to new habitats. Overall. my results indicate that wild radish has successfully evolved to use many pollinators to effect reproduction, that it can adapt to a subset of these pollinators without trading off the ability to use others effectively, and that its success as a generalist may be one reason for its successful invasion in many non-native environments. Dedicated to myfamily, especially my parents, Brenda and .zl/uhammad Sahli, ti'lzofirst planted the idea of getting a Ph. D. in my head be/Ore 1 even knew what one was. Their love and support are with me always. And to my grandmother, Nancy Payne, who helped make me the person I am today. ACKNOWLEDGEMENTS My thesis could not have been possible without the intellectual, physical, moral, inspirational, and Spiritual support of many people. I would first like to thank the best advisor I could have hoped for, Jeff Conner. Besides his advice on research matters. he has also provided much needed moral support over the past Six years. Jeff has been a wonderful role model, a great teacher. and a good mentor, and I am very thankful to have been advised by him. I also want to thank my committee members, Alan Prather, Doug Schemske, and Rich Lenski. They all provided great feedback on manuscripts and grant proposals, pushed my research to a higher level, and made committee meetings, and even comprehensive exams, enjoyable! I especially want to thank Alan for allowing me to be part of his lab while I was on campus and for his collaboration on a paper that was never published, but which was the source of inspiration for my dissertation. I would also like to thank Doug for lending me camera equipment and for broadening my thinking on many topics. Many undergraduates helped with major portions of this thesis and I am indebted to them for their help. Trent Thompson has provided hours help in the field as well as much laughter, and Amanda McFarlin and Emi Fergus watched pollinators with me and put up with stinging sweat bees. Katie Szekely and Steve Howe Spent countless hours photographing flowers and without them I certainly would not have completed the research for my fifth chapter. Lisa Robertson and Allison Lale also did a great deal of the DNA extraction and gel running for my dissertation. I am extremely thankful for all the wonderful people in my lab. From the very beginning, Christy Stewart eased me into life in the Conner lab. She helped me with much field and molecular work and has been a wonderful friend. Cindy Mills also provided great conversations as well as molecular support. As our molecular guru, she has taught me a lot and I am very grateful for her help and friendship. Finally, I want to thank my excellent labmates Angie Roles, Frances Knapczyk, and Meg Duffy. I am grateful not only for their friendship, but also their help in the field, their comments on manuscripts, many enlightening discussions, and great potlucks. In addition to my labmates, the other members of my fabulous cohort, Sarah Emery and Erica Garcia deserve a Special place in my acknowledgements. Without the friendship and support of my cohort from our very first year here I might not be writing this now. I am also thankful for the spiritual support of Sarah, Nicole Reid, Greg and Fran Houseman, and Claire McSwiney, and long distance, Katie Flinn. They have truly enriched my life. I need to thank Katie also for her constant friendship despite the long distance and the botanical chats over the phone. She has been an anchor throughout my graduate career. Alice Gillespie, Sally Shaw, and John Gorentz have patiently answered many questions in the past Six years. Nina Consolatti not only helped with my general equipment needs, but was also my beekeeping support at KBS. Cindy Wei provided many instructions on beekeeping and Zachary Huang provided me with a hive of honeybees for my research. My bumblebees and I also thank the KBS volunteers, who built and disassembled my pollinator cages and built a nice church for the bumblebees. I also thank all the postdocs, grad students, and faculty at KBS for providing such an enriching and congenial atmosphere in which to get one'S Ph.D. 1 have received advice and help from so many people. Finally, I thank my family for all their love and support. My parents were always a source of encouragement and motivation. My loving husband, Doug Powless, faced lightning and pesticides to help me with my research with only a few grumbles. Most importantly, he has encouraged me constantly, inspired me to be a better scientist and person, and has challenged me to pursue goals that I would have never thought possible. His love has been an amazing surprise. vi TABLE OF CONTENTS LIST OF TABLES .......................................................................................................... x LIST OF FIGURES ...................................................................................................... xiii CHAPTER 1 INTRODUCTION .......................................................................................................... I Background ............................................................................................................. 1 Organization of the dissertation ............................................................................... 2 CHAPTER 2 CHARACTERIZING ECOLOGICAL GENERALIZATION IN PLANT- POLLINATION SYSTEMS ............................................................................................ 6 Abstract ................................................................................................................... 6 Introduction ............................................................................................................. 6 Methods ................................................................................................................ 10 Visitation vs. importance ................................................................................... 13 Results ..................................................................................................................