UNLV Retrospective Theses & Dissertations 1-1-1998 Analysis of courtship behaviors of the desert tortoise, Gopherus agassizii Rebecca Lynn Holte University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Holte, Rebecca Lynn, "Analysis of courtship behaviors of the desert tortoise, Gopherus agassizii" (1998). UNLV Retrospective Theses & Dissertations. 956. http://dx.doi.org/10.25669/uvae-jcng This Thesis 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 Thesis 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. 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GOPHERUS AGASSIZII by Rebecca Lynn Holte Bachelor of Arts in Biology Gustavus Adolphus College, St. Peter, Minnesota 1995 A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biological Sciences Department of Biological Sciences University of Nevada, Las Vegas May 1999 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMX Number: 1393917 Copyright 1999 by H olte, Rebecca Lynn All rights reserved. UMI Microform 1393917 Copyright 1999, by UMI Company. All rights reserved. This microform edition Is protected against unauthorized copying under Title 17, United States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. © 1999 Rebecca Lynn Holte All Rights Reserved Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Thesis Approval UNTV The Graduate College University of Nevada, Las Vegas January 19 1999 The Thesis prepared by Rebecca Lynn Holte Entitled Analysis of courtship behaviors of the desert tortoise, Gopherus agassizii. is approved in partial fulfillment of the requirements for the degree of Master of Science in Biological Sciences_________ Examination Committee Chair Dean o f the Examination Committee Member Examination Committee Memoer Graduate College Faculty Representative U Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Analysis of courtship behaviors of the desert tortoise,Gopherus agassizii by Rebecca Lynn Holte Dr. Charles Douglas, Examination Committee Chair Adjunct Professor of Biological Sciences University o f Nevada, Las Vegas General descriptions of courtship behavior have been published for the desert tortoise, Gopherus agassizii. However, the amount and sources of variation in courtship behaviors have not been documented. I examined courtship behavior by analyzing videotaped interactions between captive males and females. 1 calculated duration of three courtship phases (trailing, subduing, and mounting) and quantified the number and rate of rams and bites. Male courtship behavior changed with increased courtship experience, and smaller males showed more variable behavior than larger males. Larger males bit small females at higher rates than did smaller males. Courtship varied in response to female size. Large males bit smaller females at faster rates than they bit larger females, an indication of behavioral plasticity. Males in successful matings were larger, mounted longer, rammed less, and bit more than males in unsuccessful matings. These results lend insight into the sources and amount of variability in reptilian reproductive behaviors. m Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ABSTRACT........................................................................................................................... iii LIST OF TABLES..................................................................................................................v LIST OF FIGURES...............................................................................................................vi ACKNOWLEDGEMENTS..................................................................................................ix CHAPTER 1 INTRODUCTION .........................................................................................I Variation in behavior................................................................................................. I Turtle courtship ......................................................................................................... 4 Courtship in family Testudinidae..............................................................................8 Genus Gopherus courtship behavior...................................................................... 10 Hypotheses................................................................................................................ 11 CHAPTER 2 METHODS................................................................................................... 13 CHAPTER 3 RESULTS..................................................................................................... 22 CHAPTER 4 DISCUSSION...............................................................................................52 REFERENCES .................................................................................................................... 58 VITA .....................................................................................................................................64 IV Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF TABLES Table I. Three size categories of sexually mature desert tortoises................................. 15 Table 2. Typical desert tortoise courtship behaviors observed in Phases I. 2. and ......3 17 Table 3. Frequency of behaviors not previously described............................................... 24 Table 4. Percent of matings which appeared successful, categorized by month..............26 Table 5. Percent of successful matings by size class...................................................... 28 Table 6. Means of behavior counts and durations for two male size classes................. 41 Table 7. Means of behavior counts and durations for two female size classes.............. 44 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. LIST OF FIGURES Figure 1. Percentage o f interactions initiated by female, male, and both sexes in complete interactions................................................................................................................27 Figure 2. Mean time spent in each courtship phase and total time for all complete interactions................................................................................................................29 Figure 3. Mean percent o f total time spent in each courtship phase for all complete interactions................................................................................................................29 Figure 4. Mean number of rams and bites observed in Phase 2 (Subduing) for all complete interactions...............................................................................................30 Figure 5. Mean number of rams and bites per minute in Phase 2 (Subduing) for all complete interactions...............................................................................................30