Microhabitat and Elevational Patterns in Thermal Tolerance and Thermoregulation of Neotropical Army Ants (Formicidae: Dorylinae)
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Microhabitat and elevational patterns in thermal tolerance and thermoregulation of Neotropical army ants (Formicidae: Dorylinae) A Thesis Submitted to the Faculty of Drexel University by Kaitlin Mari Baudier in partial fulfillment of the requirements for the degree of Doctor of Philosophy April 2017 All content © Kaitlin Mari Baudier 2017 unless otherwise specified ii Dedication This work is dedicated to the tiny lives that affect us all and to the tremendous individuals who teach us to notice them. iii Acknowledgments I thank my advisor, mentor, and friend, Sean O’Donnell for guiding all areas of this project. I thank Susan Kilham (chair), Jacob Russell, Michael O’Connor, and John T. Longino for serving on my committee. I thank my post-doctoral and graduate student labmates for their support: Susan Bulova, Sara DeLeon, Nicole Dauphine, Meghan Barrett, Catherine Fiocca, Kevin Purce, and Robert Driver. Many undergraduate and post-baccalaureate students assisted with lab and field work: Catherine D’Amelio, Elizabeth Sulger, Rumaan Malhotra, Abigail Mudd, Shayna Erickson, Iris Nagai, Kelsey Capobianco, Vishakha Hariawala, and Sharon Stein. I also thank high school students at the Monteverde Friends School and Siobhan O’Donnell for assisting in the field. I am thankful for the support of all faculty, staff, and the graduate community in the departments of Biodiversity, Earth and Environmental Science and Biology, particularly Dan Marenda, Jim Spotilla, Tom Radzio, Aliki Panagopoulou, Dane Ward, Yi Hu, Paul Sesink, Anna Jaworski, and Stephen Mason. I thank Area Conservacion de Guanacaste, the Organization for Tropical Studies, the Monteverde Cloud Forest Reserve, the Monteverde Conservation League, the Curi Cancha Reserve, Historic Monteverde, the Dixon family, Mary Rockwell, the Joyce family, the Stuckey family, the Guindon family, Alan Pounds, Martha Cambel, Mills Tandy, and Mark Wainwright for allowing access to private lands and national forests surveyed in this study. Permits for this work were issued by the Costa Rican Ministry of Environment and Energy (MINAE) to Kaitlin Baudier. Work was funded by the Organization for Tropical Studies Tyson Research Fellowship, the William L. McLean III Fellowship for the study of Environmental Science and Ornithology, and the Claudio Elia Memorial Fellowship in Environmental Science or Environmental Engineering to Kaitlin Baudier. Additional funding came from NSF grant 1209072 and Drexel Start-up funds to Sean O’Donnell. Lastly, I thank my immensely supportive family: Raymond, Teena, Brynn, and Robin Baudier. For taking me outside as a child, for encouraging me to pursue this path, for copy-editing (Robin Baudier), and for watching my cat many times while I was in the field, I thank you. iv Table of Contents LIST OF TABLES ........................................................................................................................ vi LIST OF FIGURES ...................................................................................................................... vii ABSTRACT ................................................................................................................................... ix CHAPTER 1: WEAK LINKS AND TEMPERATURE EXPLORERS: HOW INDIVIDUAL DIFFERENCES IN THERMAL PHYSIOLOGY CONSTRAIN AND ENABLE ANIMAL SOCIETIES ................................................................................................................................... 1 Introduction ....................................................................................................................... 1 Behavioral predictions ....................................................................................................... 2 Causes of critical temperature diversity ............................................................................ 4 Dynamics of environmental variability ............................................................................. 5 Latitudinal gradients: linking climate and caste diversity ................................................. 7 Climate change .................................................................................................................. 8 Complications and qualifying factors ................................................................................ 9 Implications for future research ....................................................................................... 10 CHAPTER 2: MICROHABITAT AND BODY SIZE EFFECTS ON HEAT TOLERANCE ...................................................................................................................................................... 14 Introduction ...................................................................................................................... 14 Methods .......................................................................................................................... 16 Results .............................................................................................................................. 22 Discussion ........................................................................................................................ 24 CHAPTER 3: PHYSIOLOGICAL AND ECOLOGICAL EFFECTS ON THERMAL TOLERANCE ACROSS ELEVATIONS ................................................................................. 35 Introduction ...................................................................................................................... 35 v Methods ........................................................................................................................... 39 Results .............................................................................................................................. 45 Discussion ........................................................................................................................ 48 CHAPTER 4: STRUCTURE AND THERMAL BIOLOGY OF SUBTERRANEAN ARMY ANT BIVOUACS IN TROPICAL MONTANE FORESTS (Labidus praedator) ................. 60 Introduction ..................................................................................................................... 60 Methods ......................................................................................................................... 64 Results ............................................................................................................................. 67 Discussion ....................................................................................................................... 72 CHAPTER 5 AMBIENT TEMPERATURE AND BROOD STAGE CONSTRAIN SOCIAL THERMOREGULATION OF ARMY ANT BIVOUACS (Eciton burchellii parvispinum) . 81 Introduction ...................................................................................................................... 81 Methods ........................................................................................................................... 86 Results ............................................................................................................................. 90 Discussion ....................................................................................................................... 92 LIST OF REFERENCES ......................................................................................................... 103 APPENDICES ........................................................................................................................... 115 Apendix A Supplementary material for Chapter 2 ........................................................ 115 Apendix B Supplementary material for Chapter 4 ........................................................ 117 Apendix C . Supplementary material for Chapter 5 ....................................................... 133 VITA .......................................................................................................................................... 134 vi List of Tables Table 2-1. Individual and colony sample sizes and results of CTmax assays for nine species in the genera Eciton, Labidus and Neivamyrmex related to environmental temperatures ...................... 28 Table 2-2. Average daily maximum, minimum, mean and range in temperature as recorded by ibutton thermal probes at soil surface and 10-cm subsurface ....................................................... 29 Supplementary Table S2-1. Summary of maximum infrared temperature readings taken at raids of several above-ground foraging army ants ............................................................................... 115 Table 3-1. Degree of aboveground activity of army ant species sampled .................................... 53 vii List of Figures Figure 1-1. Predicted alternative behavioral response strategies to weak-link effects ................ 12 Figure 1-2. Predictions of weak link and strong link thermal tolerance responses to environmental variation over an evolutionary time scale ............................................................. 13 Figure 2-1. Characteristics used to estimate head width and relative eye-size index (RESI) ...... 30 Figure 2-2. Temperatures collected from probes at two soil depths ............................................ 31 Figure 2-3. Comparison of CTmax values, ibutton data-logger measurements, and maximum infrared surface raid temperatures in Monteverde ........................................................................ 32 Figure 2-4. Phylogenetically uncorrected