THE FUNCTION OF THE LABIAL SPINE AND THE EFFECT OF PREY SIZE ON "SWITCHING" POLYMORPHS OF ACANTHINA ANGELICA (GASTROPODA: THAIDIDAE) Item Type text; Dissertation-Reproduction (electronic) Authors Yensen, Nicholas Patrick Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 02/10/2021 13:50:02 Link to Item http://hdl.handle.net/10150/298486 INFORMATION TO USERS This was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted. 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Ml 48106 >313) 761-4700 THE FUNCTION OF THE LABIAL SPINE AND THE EFFECT OF PREY SIZE ON "SWITCHING" POLYMORPHS OF ACANTHINA ANGELICA (GASTROPODA: THAIDIDAE) by Nicholas Patrick Yensen A Dissertation Submitted to the Faculty of the DEPARTMENT OF ECOLOGY AND EVOLUTIONARY BIOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 19 7 9 Copyright 1979 Nicholas Patrick Yensen THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by Nicholas Patrick Yensen entitled The Function of the Labial Spine and the Effect of Prey Size on "Switching" Polymorphs of flcanthina angelica (Gastropoda: Thaididae) be accepted as fulfilling the dissertation requirement for the degree of Doctor of Philosophy AJ3i/. 7<r Dissertation Director Date As members of the Final Examination Committee, we certify that we have read this dissertation and agree that it may be presented for final defense. X r Wu'. l4*dk. 3- 0 AJc~o~'. ///20 7g ><D f<T VWv Q-C zO<a/~ 1 Final approval and acceptance of this dissertation is contingent on the candidate's adequate performance and defense thereof at the final oral examination. STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allow­ able without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manu­ script in whole or in part may be granted by the copyright holder. To Mathew Oliver Xantus A friend, poet, and artist. iii PREFACE The following dissertation conceptually represents more than I had originally intended. It does, however, represent a synthesis of an information sequence provided by my esteemed colleagues and environment. And, as such, the mathematical conception appeared quite fortuitously, yet required two humbling days to realize on paper. After which its simplicity suggested it to be well known and/or trivial. The former abated leaving my thoughts to the latter. Two months elapsed and I included it here. In doing so, I have clearly marked my path. I gratefully acknowledge the members of my commit­ tee, Drs. D. A. Thomson, R. W. Hoshaw, J. H. Brown, E. A. Stull, S. M. Russell and C. T. Mason for their patience, courtesy and helpful advice. Dr. D. A. Thomson, my disser­ tation director, deserves special acknowledgment for his continual backing and support in my endeavors. Dr. R. W. Hoshaw has generously given me access to his laboratory facilities and has helped in numerous ways. R. M. McCourt and J. Hoffman have helped with field work and are greatefully appreciated for this. R. Abugov, G. Byers, E. H. Boyer, C. Brand, R. C. Brusca, M. L. Dungan, L. T. Findley, K. G. Gage, M. R. Gilligan, R. S. Houston, iv V S. Kessler, S. A. Mackie, J. N. Norris, L. Y. Maluf, P. Pepe, E. K. Snyder, J. Eads, P. J. Turk, J. and N. Wilt, and A. E. Yensen have provided assistance without which this study would not have been completed. C. N. Hodges, D. Moore, J. Ure, and 0. Villavicencio have been most helpful in allowing me use of the facilities at Unidad Experimental, Puerto Penasco, Sonora, Mexico. Dr. G. Cubas, Curator of Malacology, has graciously allowed me use of the Malacology Collection at the Universidad Nacional Autonomia de Mexico, Mexico City, D. F., Mexico. Dr. R. S. Felger, C. A. Stigers, R. C. Wilkinson and B. L. Tapper of the Arizona-Sonora Desert Museum have been very generous with their facilities and computer terminal. I have particularly benefited from discussions with Drs. J. H. Connell, J. R. Hendrickson, E. C. Pielou, W. B. Miller, P. E. Pickens, and A. E. Yensen and from graduate students R. Abugov, M. L. Dungan, C. A. Flanagan, C. E. Lehner, P. McKie, J. Short, and R. C. Wilkinson. I would like to thank D. A. Thomson, Ed Gage, and R. Abugov, who have read earlier drafts of the manuscript in its entirety. Any errors, however, are mine. TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS vii LIST OF TABLES viii ABSTRACT ix INTRODUCTION 1 MATERIALS AND METHODS 4 The Study Predator 4 The Field Study Sites 7 Laboratory Studies 13 RESULTS 16 Observations on the Function of the Labial Spine . 16 The Effect of Diet on Spine Size: The Diet- regulator Hypothesis 23 An Optimal Foraging Model with a Barrier Term ... 41 DISCUSSION 46 The Labial Spine 46 Foraging Strategy 47 The Bioenergetic Barrier, the Model and Disruptive Switching 50 CONCLUSIONS 54 APPENDIX A: DICE-LERAAS GRAPH OF 30 ACANTHINA ANGELICA SHELL LENGTH AND SPINE LENGTH MEASUREMENT DIFFERENCES (mm) BETWEEN REPEATED CALIPER-RULER, CALIPER-CALIPER, AND RULER-RULER MEASUREMENTS ... 56 APPENDIX B: LIST OF ACANTHINA ANGELICA SPINE AND SHELL LENGTHS AND DIMENTIONS OF PREY BARNACLES, TETRACLITA STACTALIFEM, IN FORAGING RATE EXPERIMENT #1 58 LITERATURE CITED 59 vi LIST OF ILLUSTRATIONS Figure Page 1. Map of Acanthina distributions in the Gulf of Cal if or nia 5 2. Map of study sites, northern Gulf of California . 8 3. Map of study sites near Puerto Penasco, Mexico . 10 4. Map of primary study site, Playa Estacio'n (Station Beach) 12 5. Scatter graph of 143 Acanthina angelica spine lengths (mm) on shell lengths (mm) ... 25 6. Scatter graph of 332 Acanthina angelica spine lengths (mm) on shell length (mm) ... 26 7. Dice-Leraas graph of Acanthina angelica spine lengths (mm) according to substrates . 27 8. Graph of mean labial spine lengths (mm) of Acanthina angelica on mean barnacle heights (mm) 29 9. Regrowth of broken long spines 30 10. Spine reduction in snails fed small barnacles . 32 11.