UNLV Theses, Dissertations, Professional Papers, and Capstones 1-1-2013 A Comprehensive Research Framework for Geographic Parthenogenesis in Whiptail Lizards (Genus Aspidoscelis) Adam Leland University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/thesesdissertations Part of the Biology Commons, and the Genetics Commons Repository Citation Leland, Adam, "A Comprehensive Research Framework for Geographic Parthenogenesis in Whiptail Lizards (Genus Aspidoscelis)" (2013). UNLV Theses, Dissertations, Professional Papers, and Capstones. 1747. http://dx.doi.org/10.34917/4332728 This Dissertation is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Dissertation in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/or on the work itself. This Dissertation has been accepted for inclusion in UNLV Theses, Dissertations, Professional Papers, and Capstones by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. A COMPREHENSIVE RESEARCH FRAMEWORK FOR GEOGRAPHIC PARTHENOGENESIS IN WHIPTAIL LIZARDS (GENUS ASPIDOSCELIS) by Adam Bohrer Leland Bachelor of Science & Bachelor of Arts University of California, San Diego 2001 Master of Science San Diego State University 2007 A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy in Biological Sciences School of Life Sciences College of Sciences The Graduate College University of Nevada, Las Vegas December 2012 Copyright by Adam B. Leland, 2013 All Rights Reserved THE GRADUATE COLLEGE We recommend the dissertation prepared under our supervision by Adam Leland entitled A Comprehensive Research Framework for Geographic Parthenogenesis in Whiptail Lizards (Genus Aspidoscelis) be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biological Sciences School of Life Sciences Brett Riddle, Ph.D., Committee Chair Daniel Thompson, Ph.D., Committee Member David Bradford, Ph.D., Committee Member Matthew Lachniet, Ph.D., Graduate College Representative Tom Piechota, Ph.D., Interim Vice President for Research & Dean of the Graduate College December 2012 ii ABSTRACT A Comprehensive Research Framework for Geographical Parthenogenesis in Whiptail Lizards (genus Aspidoscelis) by Adam Bohrer Leland Dr. Brett R. Riddle, Examination Committee Chair Professor University of Nevada, Las Vegas One of the most compelling topics in biology has been the ubiquity of sexual reproduction in living organisms. Because the ecological and evolutionary advantages of sex are well founded, those organisms that reproduce asexually remain enigmatic. Parthenogenesis, the clonal reproduction of an all‐female species without the need for males, is a relatively common form of asexual reproduction in vertebrates, and has been subject of numerous academic investigations. Many parthenogenic organisms also share aspects of their geographic distributions, such as inhabiting higher latitudes, higher altitudes, islands or island‐like habitats, xeric environments, and marginal, disturbed or ecotonal habitats relative to their sexual congeners, a pattern termed “geographical parthenogenesis” (Vandel, 1928). This has led to the development of numerous hypotheses to account for the geographic distribution and persistence of parthenogenic organisms relative to their sexual relatives. These hypotheses often consider overlapping biological processes, complicating efforts to create a simplified model accounting for parthenogenic reproduction. Instead iii of treating hypotheses individually, a better approach is to categorize common biological patterns underlying the suite of hypotheses posited in the literature to develop a Comprehensive Research Framework that tests for overall patterns based on their commonalities and differences. In this way, we may tease apart the relative contribution of a particular hypothesis. In this chapter, we review the hypotheses regarding geographic parthenogenesis generated in the literature and emphasize the underlying biological processes. Using these biological processes as our framework, we develop a five‐part Comprehensive Research Framework that encompasses the range of biological phenomena acting on parthenogenic organisms: (1) the Population Genetics of Sexual Populations; (2) Hybridity and Heterosis; (3) Clonal Ecological Strategy; (4) Exclusion or Coexistence; and (5) Evolutionary History. In each section, we suggest potential methods and studies that explicitly test biological processes acting at that level, which have the potential to illuminate the biological conditions where parthenogenic reproduction is successful. Using the Comprehensive Research Framework, we conclude with two test studies that each examine the expectations of one of the five parts identified above, using parthenogenic hybrid whiptail lizards (genus Aspidoscelis) as our model species. We explicitly test the Hybridity and Heterosis (Chapter Two) and Clonal Ecological Strategy (Chapter Three) sections, utilizing the methods suggested in the Comprehensive Research Framework. These studies demonstrate the utility of the framework we developed, supporting its use as a road‐map for developing further research programs into additional taxa where parthenogenic reproduction occurs. iv ACKNOWLEDGEMENTS For the successful completion of this dissertation, I must thank all who served me through my academic career: Dr. Brett Riddle, my advisor who encouraged my research direction and focus, Dr. Daniel Thompson and Dr. David Bradford whose criticisms, suggestions and discussions improved the quality and content of the research and manuscript, and Dr. Matthew Lachniet (UNLV Geosciences), my graduate college representative whose solid advocacy provided me an anchor in difficult times. My deepest gratitude I also extend to Dr. Andrew Bohonak (SDSU Biology Department) who provided me with lab space and access to lab equipment while conducting genetics research in San Diego. My research also greatly benefited from numerous discussions with colleagues. I thank members of the Riddle Lab: Sean Neiswenter for his expertise regarding AFLP protocols, Tereza Jezkova for the numerous discussions and suggestions regarding modeling and Maxent, and Mallory Eckstut for her selfless assistance with completing and submitting this document to the Graduate College. I also wish to recognize Cheryl Vanier, who not only provided invaluable statistical advice, but also served as a mentor for my teaching experiences. The unwavering support of family and friends provided the foundation on which I could build my academic career, and all deserve my heartfelt appreciation. In particular I wish to thank my good friend Dean Leavitt, who participated in my first field trip and almost single handedly sparked my interest in herpetology. My parents and my mother‐ in‐law were incredibly important to my successes and offered unsolicited support v throughout all stages of my pursuits. Finally I must also thank the support of my wife, Kelly, who was the bedrock on which I attached myself during this process, and she frequently held me fast when I was at risk of being washed away, even while she was enveloped in her own pursuit of a law degree. This project couldn’t have been completed without the financial support of ASIH Gaige Award (2008) and the UNLV Graduate & Professional Student Association Grants (2007 ‐ 2009). vi TABLE OF CONTENTS Abstract ....................................................................................................................... iii Acknowledgements ....................................................................................................... v Table of Contents ........................................................................................................ vii List of Tables ................................................................................................................ ix List of Figures ................................................................................................................ x Chapter 1: A Comprehensive Research Framework on Geographical Parthenogenesis ............................................................................................... 1 Introduction ..................................................................................................................... 1 Hypotheses ...................................................................................................................... 3 The Comprehensive Research Framework ...................................................................... 8 1. Population Genetics of Sexual Congeners .............................................................. 9 2. Hybridity and Heterosis ........................................................................................ 11 3. Clonal Ecological Strategy ..................................................................................... 14 4. Exclusion or Coexistence ....................................................................................... 15 5. Evolutionary History .............................................................................................