MOLECULAR SYSTEMATIC^ AND BIOGEOGRAPHY OF THE NEW WORLD TURTLE GENERA TRACHEMYS A N D KINOSTERNON A Dissertation DAVID EDWARD STARKEY Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 1997 Major Subject: Genetics Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. MOLECULAR SYSTEMATICS AND BIOGEOGRAPHY OF THE NEW WORLD TURTLE GENERA TRACHEMYS AND KINOSTERNON A Dissertation by DAVID EDWARD STARKEY Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Approved as to style and content by: Scott K. Davis James N. Derr (Chair of Committee) (Member) David W. Owens *feremy F. Taylor (Member) Member) Bryan H. Johnson (Head of Department) (Chair of Genetics Faculty) May 1997 Major Subject: Genetics Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Molecular Systematics and Biogeography of the New World Turtle Genera Trachemys and Kinosternon. (May 1997) David Edward Starkey, B.S., Illinois State University; M.S., University of Illinois Chair of Advisory Committee: Dr. Scott K. Davis The order Testudines has evolved to include a diverse array of taxa that inhabit freshwater, marine, and terrestrial ecosystems. The most widely accepted classification scheme divides the turtles into two suborders: Pleurodira and Cryptodira. These suborders are further divided into 13 families with 88 genera and 256 species. Extensive morphological diversity among turtles has led to a vast array of hypothesized phylogenies based on a wide variety of methodologies, however no current phylogeny is universally accepted. The present study addresses turtle relationships using mitochondrial DNA sequence data. Over 230 taxa representing all extant families were examined for a total of 250,000 basepairs. The mtDNA data support much of the previous research i.e., monophyly of turtle families and a basal diversification into Pleurodires and Cryptodires. However, hypothesized sister relationships between snapping and big headed turtles and either the Old World pond turtles or tortoises and the New World pond turtles are not evident. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Instead, the sequence data supports a close relationship between the Old World pond turtles and tortoises. A novel finding of this study is a delineation between a primitive (Trionychidae and Carettochelyidae) and an advanced dade (all remaining families) within the Cryptodira. Finally, the biogeography of the broadly distributed New World families Kinostemidae and Emydidae was examined. These two groups were chosen because of the potential insights they may bring to the biogeography of this region. Each family has had North America proposed as their point of origin and, although this study confirms the Emydidae as North American, Central America is confirmed as the point of origin for the Kinostemidae. The radiation of the Emydid genus Trachemys across North, Central, and South America and the Caribbean appears to have occurred rapidly >10 million years ago. The Kinostemidae appear to be much older and migrated northward and southward out of Central America and Mexico. This migration resulted in two expansions into North America and two separate expansions into South America. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. V For M y Father, Bill & In Loving Memory of My Mother, Mary Jo Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGMENTS The majority of DNA and/or tissue samples were provided by Mr. Robert Guthrie, Mr. Bill McCord, Dr. John Iverson, Mr. Dennis Uhrig, and Dr. Mike Forstner and without their assistance this project would not have become a reality. Various other specimens were provided by Dr. Jim Dixon, the Bronx Zoo, the Jakarta Ragunan Zoo, the Gladys Porter Zoo, the Fort Worth Zoo, the Dallas Zoo, and Strictly Reptiles. Laboratory assistance was provided by Trina Guerra, Audra Whatley, and Mark Holder. I also wish to thank Dr. Forstner and Mrs. Jenna McKnight-Forstner for their continuing support and their little "kickus o'gluteus maximus" that were needed to finish the writing of this manuscript. I also wish to thank the other members of the Davis lab, especially Dr. Kelly Hogan, Dr. Peter Dutton, Dr. Elizabeth Holder, Dannialle Stillwell, Cathi Lehn, Catherine Malone, and Gwen Estes, who were there when a little encouragement was needed. I also wish to thank my committee members, Dr. Jerry Taylor and Dr. Jim Derr, for their encouragement and support. I owe a special debt of thanks to Drs. Dave Owens and J. Alan Houtchens for stepping in at the last minute as my final committee member and GCR. To my advisor Dr. Scott Davis, I say thank you, because without your help and guidance I would have never reached this goal. And finally, I wish to thank all of my family, in particular, my mother for starting me off on this career, and my father for always being there whenever I needed anything. Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS Page ABSTRACT..................................................................................................................iii DEDICATION...............................................................................................................v ACKNOWLEDGMENTS........................................................................................... vi TABLE OF CONTENTS............................................................................................vii LIST OF FIGURES....................................................................................................... ix LIST OF TABLES....................................................................................................... xii CHAPTER I INTRODUCTION.................................................................................. 1 History of Turtles...................................................................... 1 Continental Drift and Regional Faunas ...............................5 Introduction to Turtle Families ............................................. 9 Familial Systematics................................................................ 15 Systematics of North American Turtles .............................21 Trachemys...................................................................... 21 Kinosternon....................................................................27 Mitochondrial DNA .................................................................33 H MATERIALS AND METHODS......................................................... 36 m RESULTS.................................................................................................51 Families...................................................................................... 51 Emydidae ....................................................................................72 Kinostemidae ............................................................................ 80 IV DISCUSSION AND CONCLUSIONS.............................................. 88 Families...................................................................................... 88 Emydidae .................................................................................. 93 Kinostemidae ...........................................................................103 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. V lll TABLE OF CONTENTS (Cont) Page Conclusions ............................................................................ 109 REFERENCES..............................................................................................................113 APPENDIX.................................................................................................................. 132 VITA.............................................................................................................................149 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. IX LIST OF FIGURES FIGURE Page 1 Hypothesized relationships of the extinct and extant turtle families based on Gaffney, 1984 ....................4 2 Proposed relationships of the extant turtle families ......17 3 Hypothesized relationships of the Emydidae based on Gaffney and Meylan, 1988 and Seidel and Adkins, 1987 .............................................................................23 4 Hypothesized relationships for the genus Trachemys...28 5 Hypothesized relationships of the Kinostemidae based on Seidel et al., 1986 .................................................... 34 6 Hypothesized relationships of the Kinostemidae based on Iverson, 1991 ............................................................35 7 Selected primers used in this study and the relative locations of each in the mitochondrial genome .............. 40 8 Plot of the first (o), second (x), and third (A) positions versus known divergence times from the fossil record.54 9 Neighbor Joining analysis of the total data set presented as a phylogram .......................................................56 10 Results of the Neighbor Joining analysis of the total data