SEED MASS AND DETERIORATION: IMPLICATIONS FOR IN SITU SURVIVAL AND EX SITU LONGEVITY By NICHOLAS GERARD GENNA A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2019 © 2019 Nicholas Gerard Genna To Ricky and Franklin and Arnold and Albert ACKNOWLEDGMENTS I firstly thank my family for their continual and unwavering support. I especially thank my advisor, Héctor Pérez, for his persistent encouragement and motivation. I would not have achieved success as an undergraduate or graduate researcher without your mentorship. I also thank my dissertation committee including Jamie Gillooly, Alfred Huo, Michael Kane, and Christina Walters for challenging my proposed work and for providing thoughtful insight. I want to recognize the years of support and constructive criticism of lab members Amber Gardener and Tia Tyler. I also want to acknowledge the technical and resource support provided by Terry Zinn of Wildflowers of Florida Inc. and Karen Kelly and Rudy Alvarado of the UF ICBR EM core. Finally, I want to recognize the support of Alec Chin-Quee: thank you for the years of technical support and for giving me the opportunity to lead you in the beginning of your research career. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 8 LIST OF FIGURES ........................................................................................................ 10 ABSTRACT ................................................................................................................... 12 CHAPTER 1 SEED MASS VARIATION AND ITS ECOLOGICAL EFFECTS .............................. 14 Problem Statement ................................................................................................. 14 Seed Deterioration .................................................................................................. 17 Evidence of Mass-Dependent Intraspecific Seed Deterioration .............................. 22 Conclusion .............................................................................................................. 23 Hypotheses ............................................................................................................. 25 Hypothesis 1: Inherent Physical and Physiological Differences Will Correlate with Seed Mass and Manifest from Developmental Location. ....... 25 Hypothesis 2: Higher Mass Seeds Will Deteriorate at a Slower Rate During In Situ Burial Compared to Lower Mass Seeds. ............................................ 27 Hypothesis 3: Seed Mass Will Promote Differential Deterioration In Ex Situ Storage.......................................................................................................... 28 Experimentally Demonstrating Differential Viability Loss of Variable Mass Seeds In Situ and Ex Situ ............................................................................................... 28 2 CHARACTERIZING GERMINATION ECOLOGY, DEVELOPMENT, DISTRIBUTION, AND INTRACELLULAR ANATOMY IN RUDBECKIA MOLLIS (ASTERACEAE) SEEDS OF DIFFERENT MASS .................................................. 34 Introduction ............................................................................................................. 34 Materials and Methods............................................................................................ 35 Plant Material and Establishing Mass Classes ................................................. 35 Germination of Fresh Seeds ............................................................................. 37 Greenhouse Study ........................................................................................... 37 Plant establishment .................................................................................... 37 Developmental study ................................................................................. 38 Seed mass distribution study ..................................................................... 39 Comparative Seed Anatomy ............................................................................. 40 Seed Density .................................................................................................... 41 Statistical Analyses .......................................................................................... 41 Germination testing .................................................................................... 41 Seed mass distribution ............................................................................... 42 Developmental study, comparative seed anatomy, true density ................ 43 5 Results .................................................................................................................... 43 Germination Testing When Fresh ..................................................................... 43 Developmental Study ....................................................................................... 44 Seed Mass Distribution .................................................................................... 45 Comparative Seed Anatomy and Density ......................................................... 48 Discussion .............................................................................................................. 49 Germination Testing When Fresh ..................................................................... 49 Developmental Study and Distribution of Seed Mass ....................................... 51 Comparative Seed Anatomy and Density ......................................................... 53 Conclusion .............................................................................................................. 54 3 DOES INTRA-POPULATION SEED SURVIVAL DURING BURIAL FOLLOW INTERSPECIFIC RELATIONSHIPS BETWEEN SEED MASS AND COAT THICKNESS? ......................................................................................................... 71 Introduction ............................................................................................................. 71 Materials and Methods............................................................................................ 74 Plant Material and Establishing Mass Classes ................................................. 74 Seed Burial ....................................................................................................... 74 Germination Testing Following Burial ............................................................... 75 Allocation to Physical Defenses ....................................................................... 75 Statistical Analyses .......................................................................................... 76 Results .................................................................................................................... 77 Air and Soil Climate .......................................................................................... 77 Seed Count Data .............................................................................................. 77 Germination Following Burial ............................................................................ 78 Allocation to Physical Defenses ....................................................................... 79 Discussion .............................................................................................................. 80 Conclusion .............................................................................................................. 84 4 NO EVIDENCE OF MASS DEPENDENT SEED LONGEVITY FOLLOWING STORAGE OR REPEATED RELATIVE LONGEVITY ASSESSMENTS ................ 95 Introduction ............................................................................................................. 95 Materials and Methods.......................................................................................... 100 Plant Material and Establishing Mass Classes ............................................... 100 Water Sorption Isotherms ............................................................................... 100 Seed Storage Treatments .............................................................................. 101 Saturated Salt Accelerated Aging (SSAA) ...................................................... 102 Statistical Analyses ........................................................................................ 103 Results .................................................................................................................. 103 Water Sorption Isotherms ............................................................................... 103 Seed Storage Treatments .............................................................................. 103 Saturated Salt Accelerated Aging ................................................................... 104 Discussion ............................................................................................................ 105 Conclusion ............................................................................................................ 110 6 5 CONCLUSIONS ................................................................................................... 119 LIST OF REFERENCES 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