EVOLUTIONARY SIGNIFICANCE OF ADAPTATIONS IN HETEROMYID RODENTS IN BAJA CALIFORNIA, MEXICO Item Type text; Dissertation-Reproduction (electronic) Authors Roth, Edward Lee, 1944- 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 26/09/2021 00:15:38 Link to Item http://hdl.handle.net/10150/289490 INFORMATION TO USERS This material was produced from a microfilm copy of the original document. 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 original submitted. 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University Microfilms International 300 North Zeeb Road Ann Arbor, Michigan 48106 USA St. John's Road, Tyler's Green High Wycombe, Bucks, England HP10 8HR 77-6047 ROTH, Edward Lee, 1944- EVOLUTIONARY SIGNIFICANCE OF ADAPTATIONS IN HETEROMYTD RODENTS IN BAJA CALIFORNIA, MEXICO. The University o£ Arizona, Ph.D., 1976 Zoology Xerox University Microfilms, Ann Arbor, Michigan 48106 EVOLUTIONARY SIGNIFICANCE OF ADAPTATIONS IN HETEROMYID RODENTS IN BAJA CALIFORNIA, MEXICO by Edward Lee Roth 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 WITH A MAJOR IN ZOOLOGY In the Graduate College THE UNIVERSITY OF ARIZONA 19 7 6 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by Edward Lee Roth entitled Evolutionary Significance of Adaptations In Heteromyld Rodents In Baja California, Mexico be accepted as fulfilling the dissertation requirement for the degree of Doctor of Philosophy ' lit Lwv- I £ a-u-Cj /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. 'C~ /h<cj )f7{ ft /? 7 (, a J? /^7C /V /?7L Lui 'Ms^JLjJa^, /L-J. A- /?76 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 ful­ fillment 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 acknowledgment 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 head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: ACKNOWLEDGMENTS I wish to thank Dr. E. Lendell Cockrum for his help­ ful advice and many hours of discussion throughout my graduate work at The University of Arizona. I am especially grateful for his assistance with the manuscript. I also thank Dr. Stephen M. Russell, Dr. Robert B. Chiasson, Dr. Charles Mason and Dr. Willard Van Asdall for reading the manuscript and offering many helpful suggestions. During the course of this investigation I came in contact with many citizens of the Republic of Mexico. In all cases they were most courteous and helpful. To these many people I extend a very sincere thanks. For allowing me to examine specimens in their care I would like to thank the following persons and their institu­ tions: Dr. Sydney Anderson, American Museum of Natural History; Dr. Charles 0. Handley and Dr. Don E. Wilson, U. S. National Museum; Dr. Emmet T. Hooper, University of Michigan Dr. Robert Hoffman, University of Kansas; and Dr. Joseph t Jehl, San Diego Society of Natural History. I would also like to thank Mario Luis Cossio, Direccion General de la Fauna Silvestre, for providing the necessary permits for collecting in the Republic of Mexico. iii iv Special appreciation is extended to Yar Petryszyn for his help and companionship during the many weeks spent in Baja California. His assistance was invaluable. This research was supported in part by a grant from the Theodore Roosevelt Memorial Fund of the American Museum of Natural History. Without this support the necessary travel to museums would have been difficult. Finally, I am especially grateful to my wife, Beth, for her support and encouragement throughout this study and for her valuable assistance in recording the data taken from hundreds of specimens. TABLE OF CONTENTS Page LIST OF TABLES vi LIST OF ILLUSTRATIONS vii ABSTRACT viii INTRODUCTION 1 METHODS AND MATERIALS . 4 DESCRIPTION OF BAJA CALIFORNIA AND ACCOUNTS OF SPECIES 6 Lower Colorado Valley 8 Central Gulf Coast 11 Magdalena Province 12 Vizcaino Province 13 San Pedro Martir Province 14 Giganta-Laguna Province 14 Perognathus arenarius Merriam 18 Perognathus baileyi Merriam 22 Perognathus spinatus Merriam 27 Perognathus formosus Merriam 31 Perognathus fallax "Merriam 35 Dipodomys merriami Mearns 38 Dipodomys" peninsularis (Merriam) 42 Dipodomyi" agilis Gambel 46 ANCESTRAL HETEROMYID MORPHOLOGY AND HABITATS ..... 50 DISCUSSION 53 CONCLUSIONS 70 APPENDIX A: SKIN AND SKULL MEASUREMENTS FOR SPECIMENS USED IN THIS STUDY 72 REFERENCES CITED 78 v LIST OF TABLES Table Page 1. Summary of some characteristics of the six phytogeographical provinces described in text . 10 2. Selected measurements and indices for Perognathus arenarius 21 3. Selected measurements and indices for Perognathus baileyi 25 4. Selected measurements and indices for Perognathus spinatus 30 5. Selected measurements and indices for Perognathus formosus 34 6. Selected measurements and indices for Perognathus fallax 37 7. Selected measurements and indices for Dipodomys merriami 41 8. Selected measurements and indices for Dipodomys peninsularis 45 9. Selected measurements and indices for Dipodomys agilis 48 10. Number of individuals and biomass of rodents for two localities in Baja California, Mexico . 59 11. Species diversity of heteromyid and cricetid rodents for selected areas in North America . 62 12. Average number of species of heteromyidae and cricetidae present in the non-desert and desert areas listed in Table 11 63 13. Relative specialization of Perognathus and Dipodomys from Baja California, Mexico .... 68 vi LIST OF ILLUSTRATIONS Figure Page 1. Map of Baja California, Mexico 9 2. Map showing the distribution of Perognathus arenarius in Baja California 19 3. Map showing the distribution of Perognathus baileyi in Baja California 24 4. Map showing the distribution of Perognathus spinatus in Baja California 28 5. Map showing the distribution of Perognathus formosus in Baja California 32 6. Map showing the distribution of Perognathus fall ax in Baja California 36 7. Map showing the distribution of Dipodomys merriami in Baja California 39 8. Map showing the distribution of Dipodomys peninsularis in Baja California 43 9. Map showing the distribution of Dipodomys agilis in Baja California 47 \ vii ABSTRACT Rodents of the family heteromyidae primarily inhabit arid and semi-arid regions in the southwestern United States and northwestern Mexico. In the past, evolutionary relation­ ships within this family have been based on specializations of the auditory and locomotor systems. These specializations were thought to have arisen as a response to increased desertification during the Miocene and Pliocene which pro­ duced a more arid climate and a more sparse, open vegetation. Examinations of those features of the auditory and i locomotor systems thought to be adaptive in nature and thus to have evolutionary implications are presented for five species of Perognathus and three species of Dipodomys occur­ ring in Baja California, Mexico. Morphological features for 1296 specimens from 118 localities are quantified and com­ pared with the various degrees of desertification found in Baja California. In Baja California where there is an increase in openness of 20 to 30 percent, a greater development of the morphological specialization of the auditory bullae, hind feet, and tail is seen in heteromyid population. Further increase in openness (to 88 percent or more) does not necessarily result in additional specialization.