SPATIOTEMPORAL DYNAMICS OF BUTTERFLIES AND THEIR FLORAL RESOURCES A Thesis Submitted to the Graduate Faculty of the North Dakota State University of Agriculture and Applied Science By Adrienne Kendra Antonsen In Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Major Department: Entomology June 2020 Fargo, North Dakota North Dakota State University Graduate School Title SPATIOTEMPORAL DYNAMICS OF BUTTERFLIES AND THEIR FLORAL RESOURCES By Adrienne Kendra Antonsen The Supervisory Committee certifies that this disquisition complies with North Dakota State University’s regulations and meets the accepted standards for the degree of MASTER OF SCIENCE SUPERVISORY COMMITTEE: Jason Harmon Chair Torre Hovick Ryan Limb Benjamin Geaumont Approved: 07/02/2020 Frank Casey Date Department Chair ABSTRACT Butterflies fulfill a unique role among insect pollinators as long-distance flyers. This makes butterflies particularly valuable as vectors of genetic diversity among spatially isolated plant populations. Like many insects, though, butterfly populations have experienced significant declines in recent years. To help inform conservation efforts, and to investigate community and species level dynamics, I studied butterflies and their floral resources as part of a three year pollinator survey across the state of North Dakota. At the community level, I analyzed butterfly- flower interaction networks across space and time. I then examined the specialization of individual species within those networks and their contributions to network structure. I also evaluated spatial and temporal distribution patterns of monarch butterflies, regal fritillaries, and their plant resources. Results revealed dynamic spatiotemporal relationships between butterflies and their plant resources that have important implications for conservation efforts and the study of ecological communities. iii ACKNOWLEDGEMENTS First and foremost I would like to acknowledge my research advisor Jason Harmon. Your knowledge and continual encouragement made this thesis possible. More important than any tangible product, I have grown immensely as a person because of your guidance. Thank you so much, I could never have completed this process without you! To my mom and dad, thank you for cheering me on in my educational endeavors since I was a kid. Reaching this point, graduating with my master’s degree, has been a lifelong journey that started with asking for extra math homework “for fun” in kindergarten. Onward through high school, undergraduate, and graduate school, your support has been a vital driving force behind my continued efforts. Finally, thank you to Gretchen O’Neil, worm fossil queen of the geosciences department. Grad school would have been way less fun without you by my side. iv DEDICATION This thesis is dedicated to my sweet fur baby, Prince, the best little data entry helper and writing buddy there ever was. v TABLE OF CONTENTS ABSTRACT ................................................................................................................................... iii ACKNOWLEDGEMENTS ........................................................................................................... iv DEDICATION ................................................................................................................................ v LIST OF TABLES ......................................................................................................................... ix LIST OF FIGURES ........................................................................................................................ x LIST OF APPENDIX FIGURES.................................................................................................. xii 1. PLANT-POLLINATOR INTERACTION NETWORKS: WHAT QUESTIONS, TAXA, AND REGIONS ARE WE STUDYING? ......................................................................... 1 1.1. Introduction .......................................................................................................................... 1 1.2. Methods ................................................................................................................................ 3 1.3. Results .................................................................................................................................. 4 1.3.1. Questions ....................................................................................................................... 4 1.3.2. Taxa ............................................................................................................................... 6 1.3.3. Regions .......................................................................................................................... 7 1.4. Discussion ............................................................................................................................ 8 1.4.1. Questions ....................................................................................................................... 9 1.4.2. Taxa ............................................................................................................................. 10 1.4.3. Regions ........................................................................................................................ 11 1.5. Conclusions ........................................................................................................................ 12 1.6. References .......................................................................................................................... 12 2. SPATIOTEMPORAL DYNAMICS OF BUTTERFLY-FLOWER INTERACTION NETWORKS ................................................................................................................................ 19 2.1. Introduction ........................................................................................................................ 19 2.2. Methods .............................................................................................................................. 23 2.2.1. Study Area ................................................................................................................... 23 vi 2.2.2. Butterfly Survey Methods ........................................................................................... 25 2.2.3. Floral Survey Methods ................................................................................................ 26 2.2.4. Network Analysis ........................................................................................................ 26 2.2.5. Network-Level Characteristics .................................................................................... 27 2.2.6. Modular Roles ............................................................................................................. 28 2.2.7. Species-Level Characteristics ...................................................................................... 30 2.3. Results ................................................................................................................................ 32 2.3.1. Summary Data ............................................................................................................. 32 2.3.2. Network-Level Characteristics .................................................................................... 32 2.3.3. Modular Roles ............................................................................................................. 33 2.3.4. Temporal Correlations of Species Characteristics ...................................................... 34 2.3.5. Spatial Correlations of Species Characteristics ........................................................... 35 2.4. Discussion .......................................................................................................................... 36 2.4.1. Network-Level Characteristics .................................................................................... 37 2.4.2. Modular Roles ............................................................................................................. 39 2.4.3. Species-Level Characteristics ...................................................................................... 43 2.4.4. Conclusions ................................................................................................................. 44 2.5. References .......................................................................................................................... 45 3. DISTRIBUTIONS OF THE MONARCH BUTTERFLY (DANAUS PLEXIPPUS), REGAL FRITILLARY (SPEYERIA IDALIA), AND THEIR FOOD RESOURCES THROUGH SPACE AND TIME ................................................................................................. 54 3.1. Introduction ........................................................................................................................ 54 3.2. Methods .............................................................................................................................. 56 3.2.1. North Dakota Grasslands ............................................................................................. 56 3.2.2. Monarch Butterfly Natural History ............................................................................. 57 3.2.3. Regal Fritillary Natural History ................................................................................... 59 vii 3.2.4. Butterfly Survey Methods ..........................................................................................