Using Digitized Herbarium Specimens to Predict Potential
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USING DIGITIZED HERBARIUM SPECIMENS TO PREDICT POTENTIAL DISTRIBUTIONS OF TENNESSEE’S HISTORICAL ANGIOSPERM SPECIES By Erica A. Rylander Joey Shaw David Aborn UC Foundation Professor of Biology, Geology, Associate Professor of Biology, Geology, and and Environmental Science Environmental Science (Chair) (Committee Member) Nyssa Hunt GIS Analyst (Committee Member) USING DIGITIZED HERBARIUM SPECIMENS TO PREDICT POTENTIAL DISTRIBUTIONS OF TENNESSEE’S HISTORICAL ANGIOSPERM SPECIES By Erica A. Rylander A Thesis Submitted to the Faculty of the University of Tennessee at Chattanooga in Partial Fulfillment of the Requirements of the Degree of Master of Science: Environmental Science The University of Tennessee at Chattanooga Chattanooga, Tennessee May 2020 ii Copyright © 2020 By Erica Anne Rylander All Rights Reserved iii ABSTRACT Species distribution models (SDMs) have become an essential tool in focusing conservation efforts for species with incomplete distribution records. SDMs enable conservation managers to increase field survey efficiency by prioritizing areas to invest time and financial resources. This application is invaluable for historical species which remain suspended between extant and extirpated, having not been documented in many years, but lack sufficient evidence to be determined extirpated. Identifying suitable habitat and previously unknown locations for species of conservation-concern has historically represented an overwhelming and often impractical task, however the development of model-based sampling approaches has made this task more feasible. Here, SDMs are trained using digitized herbarium specimens to identify suitable habitat and therefore, the potential distribution of 16 historical plant species in Tennessee. The ultimate goal of this work is to provide conservation managers with an effective tool for guiding sampling strategies, enabling the rediscovery of Tennessee’s lost plant species. iv ACKNOWLEDGMENTS I would like to acknowledge the members of the Shaw Lab, who have provided me with encouragement and thoughtful feedback throughout my work on this project. A tremendous thank you to Courtney Alley, Caleb Powell, John Shelton, and Dax Ledesma. The completion of this project truly would not have been possible without your steadfast support, collaboration, and comic relief. I would like to thank Dr. Joey Shaw for his advice, guidance, and encouragement throughout this process, and for providing me the opportunity to join him on a project which would ultimately lead me to pursue my master’s degree. You have always helped me get back on track when I found myself straying, and for that I am grateful. I must acknowledge Nyssa Hunt, as both a committee member and friend, thank you for always finding a way to resolve my ArcGIS frustrations and for always providing snacks. Thank you to Dr. David Aborn for your thoughtful insights and conservation expertise while serving on my committee. Furthermore, for being a wonderful professor, I am grateful to have learned so much across a variety of disciplines from you throughout my undergraduate and graduate careers. I would like to thank Dr. Thomas Wilson, whose passion for ecology, biology, and geospatial sciences have inspired me and encouraged me to grow as a scientist. A heartfelt thank you to Benjamin Jones, who has stood by my side and helped keep me sane through this entire process. Finally, I would like to thank my parents for their unwavering support and guidance throughout my life and my educational career. v TABLE OF CONTENTS ABSTRACT ....................................................................................................................................... iv ACKNOWLEDGEMENTS ............................................................................................................... v LIST OF TABLES ............................................................................................................................. viii LIST OF FIGURES ........................................................................................................................... xi LIST OF ABBREVIATIONS ............................................................................................................ xiii CHAPTER I. INTRODUCTION ............................................................................................................... 1 II. TENNESSEE’S HISTORICAL PLANT SPECIES ............................................................ 4 Introduction ........................................................................................................................ 4 Tennessee’s Historical Angiosperm Species Profiles ......................................................... 11 Agalinis setacea ....................................................................................................... 12 Agrostis mertensii .................................................................................................... 12 Calopogon oklahomensis ......................................................................................... 13 Carex alopecoidea ................................................................................................... 14 Carex sterilis ............................................................................................................ 14 Carex vestita ............................................................................................................ 15 Clematis pitcheri ...................................................................................................... 15 Crotalaria purshii .................................................................................................... 16 Helianthemum bicknellii .......................................................................................... 16 Helianthemum canadense ........................................................................................ 17 Juncus trifidus .......................................................................................................... 18 Lachnocaulon anceps .............................................................................................. 18 Leavenworthia exigua var. lutea .............................................................................. 19 Rhynchospora alba .................................................................................................. 19 Rhynchospora latifolia ............................................................................................. 20 Rhynchospora wrightiana ........................................................................................ 20 Scrophularia lanceolata .......................................................................................... 21 Seymeria cassioides ................................................................................................. 21 Sida hermaphrodita ................................................................................................. 22 Silene regia .............................................................................................................. 23 Tetragonotheca helianthoides .................................................................................. 24 vi III. SPECIES DISTRIBUTION MODELING OF HISTORIC SPECIES IN TENNESSEE USING HERBARIUM SPECIMENS ................................................................................. 25 Introduction ......................................................................................................................... 25 Species Distribution Models for Rare Species .................................................................... 26 Utilizing Presence Only-Data from Herbarium Specimens for Predictive Modeling .................................................................................................................. 28 Maximum Entropy Modeling .............................................................................................. 30 Materials and Methods ........................................................................................................ 32 Acquisition of Herbarium Specimen Data ............................................................... 32 Data Cleaning .......................................................................................................... 33 Species Selection ..................................................................................................... 36 Environmental Variable Selection and Processing .................................................. 36 Accounting for Sample Bias .................................................................................... 37 Model Algorithm and Settings Selection ................................................................. 41 Model Evaluation and Analysis ............................................................................... 42 Analysis of Variable Contribution and Environmental Profile ................................ 45 Results and Discussion ........................................................................................................ 46 Agalinis setacea (threadleaf false foxglove) ............................................................ 51 Carex alopecoidea (foxtail sedge) ........................................................................... 57 Carex sterilis (dioecious sedge) ............................................................................... 62 Clematis pitcheri (bluebill) .....................................................................................