CRANIOMANDIBULAR STRUCTURE AND FUNCTION IN MORMOOPID BATS A Thesis Presented to the faculty of the Department of Biological Sciences California State University, Sacramento Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in Biological Sciences by Jeffrey B. Changaris FALL 2017 © 2017 Jeffrey B. Changaris ALL RIGHTS RESERVED ii CRANIOMANDIBULAR STRUCTURE AND FUNCTION IN MORMOOPID BATS A Thesis by Jeffrey B. Changaris Approved by: ____________________________________, Committee Chair Dr. Ronald M. Coleman ____________________________________, Second Reader Dr. Winston C. Lancaster ____________________________________, Third Reader Dr. Joseph Bahlman ___________________________ Date iii Student: Jeffrey B. Changaris I certify that this student has met the requirements for format contained in the University format manual, and that this thesis is suitable for shelving in the Library and credit is to be awarded for the thesis. ____________________________, Graduate Coordinator _________________ Dr. James W. Baxter Date Department of Biological Sciences iv Abstract of CRANIOMANDIBULAR STRUCTURE AND FUNCTION IN MORMOOPID BATS by Jeffrey B. Changaris Neotropical Ghost-Faced bats of the genus Mormoops (Order Chiroptera, Family Mormoopidae) have a radically upturned rostrum, or snout, while the other mormoopid genus, Pteronotus, has only a slight upturning of the rostrum. This type of difference in morphology between closely related taxa is likely to be the result of some sort of specialization. Observation of Mormoops blainvillei, the Antillean Ghost-Faced bat, reveals that they can open their mouths very wide relative to the size of their heads. Mormoopid bats are insectivorous with Mormoops blainvillei having a prey preference of large moths, but related species, such as Pteronotus quadridens, the Sooty Mustached bat, have a more varied diet with a large component of smaller hard-bodied beetles. While there have been many studies on feeding ecology of phyllostomid bats, available research on mormoopids is limited and functional relationships between craniorostral shape and feeding mechanics have not been established. The objectives of this study were to quantify structural and functional differences in craniomandibular function between Mormoops blainvillei and Pteronotus quadridens by analyzing maximum gape, bite force, and masticatory muscle configuration and relate this to prey preference v previously described in the literature. Results showed that Mormoops blainvillei had a much wider maximum active gape and reduced normalized maximum bite force than Pteronotus quadridens which corresponded to the size and hardness of their respective diets. Mormoops blainvillei had a greater percentage of masticatory musculature allocated to wide gape than Pteronotus quadridens where the narrow gape chewing muscles were favored. Upturning of the rostrum reduces range of motion limitations at the craniomandibular joint which could have resulted in the ability to achieve wider gapes in Mormoops blainvillei. _______________________________, Committee Chair Dr. Ronald M. Coleman _______________________________ Date vi ACKNOWLEDGEMENTS First, I would like to thank Dr. Winston C. Lancaster without whose guidance, assistance, companionship, camaraderie, perseverance, and patience this endeavor would have never reached this successful conclusion; I am forever in your debt. I would like to thank Dr. Ron Coleman for assuming the leadership role as committee chairman once Dr. Lancaster moved on in his worldly endeavors. I would also like to thank the rest of my committee, Dr. Rosalee Sprowls, Dr. Rodney Imamura, Dr. Joseph Bahlman, for their patience and valuable input, as well as the graduate committee, Dr. Jamie Kneitel, Dr. James Baxter, and Dr. Robert Crawford. Thanks go to Dr. Tom Schultze for his mathematical advice, Drs. Rafael Diaz and Jamie Kneitel for their statistical advice, Dr. Tim Davidson for his manuscript review and input, and Sulie Ober for her laboratory support. Special thanks go to Dr. Armando Rodríguez-Durán for providing access to Mata de Plátano Field Station and Culebrones Cave in Puerto Rico, and Dr. Betsy Dumont for her bite force assistance and loan of the bite force meter used during field work. Partial funding from California State University, Sacramento for travel to Puerto Rico and equipment came from a Research and Creative Activity (RCA) Award granted to Dr. Lancaster, Academically Related Activities (ARA), Student Academic Development (SAD) awards and Delisle funding granted to the author. I would also like to thank the following bat biologists for their support and assistance over the years and from whom I learned so much: Dr. Scott Pedersen, Dr. Gary vii Kweiznewski, Dr. Rick Adams, Dr. Allen Kurta, Ashley Rolfe, David Wyatt, and Linda Angerer. Major thanks go to Justin Moore for his motivational participation and manuscript review. I would like to thank my colleagues, Marcie Woolsey, Dean Won, Michael Sweet, Ken Kubo, Daniel Slutsky, Tom Peavy, Tom Landerholm, and D.J. Larkey for their support. Lastly, I thank my friends and family, Sherry Kimbrow, Danielle Delucchi, Stephanie Changaris, and Sherry Swim for their continued support. viii TABLE OF CONTENTS Acknowledgements .......................................................................................................... vii List of Tables .................................................................................................................... xi List of Figures .................................................................................................................. xii INTRODUCTION .............................................................................................................. 1 Hypotheses and Objectives ..................................................................................... 6 METHODS ......................................................................................................................... 7 Field Data Collection .............................................................................................. 7 Gape Analysis ....................................................................................................... 13 Jaw Scaling ........................................................................................................... 18 Bite Force Analysis ............................................................................................... 22 Jaw Musculature ................................................................................................... 26 Statistical Analyses ............................................................................................... 30 RESULTS ......................................................................................................................... 33 Gape Analysis ....................................................................................................... 33 Bite Force Analysis ............................................................................................... 38 Jaw Musculature ................................................................................................... 38 DISCUSSION ................................................................................................................... 45 CONCLUSIONS............................................................................................................... 51 Appendix A ....................................................................................................................... 52 Appendix B ....................................................................................................................... 68 Appendix C ....................................................................................................................... 72 Appendix D ....................................................................................................................... 74 ix Appendix E ....................................................................................................................... 75 Literature Cited ................................................................................................................. 77 x LIST OF TABLES Table Page 1. Total Number of Mormoopid Bats Analyzed by Species ..................................... 34 2. Total Video Frames and Bite Force Measurements Analyzed for Two Species of Mormoopid Bats ............................................................................................... 35 3. Maximum Active Jaw Gapes for Two Species of Mormoopid Bats .................... 36 4. Maximum Bite Forces for Two Species of Mormoopid Bats ............................... 39 5. Craniomandibular Muscle Architecture Measurements of Mormoopid Bats by Sex and Species..................................................................................................... 41 6. Craniomandibular Muscle Organization for Two Species of Mormoopid Bats ............................................................................................................................... 42 xi LIST OF FIGURES Figure Page 1. Mormoopid Bats of Interest .................................................................................... 2 2. Rostral Orientations of Two Species of Mormoopid Bats ...................................... 4 3. Map of Puerto Rico showing the location of Culebrones Cave .............................. 8 4. Active Gape Video