Does Life History Shape Sexual Size Dimorphism in Anurans
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DOES LIFE HISTORY SHAPE SEXUAL SIZE DIMORPHISM IN ANURANS: A COMPARATIVE ANALYSIS A Thesis Presented to The Faculty of Graduate Studies of The University of Guelph by XU HAN In partial fulfilment of requirements for the degree of Master of Science March, 2008 © Xu Han, 2008 Library and Bibliotheque et 1*1 Archives Canada Archives Canada Published Heritage Direction du Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-41825-3 Our file Notre reference ISBN: 978-0-494-41825-3 NOTICE: AVIS: The author has granted a non L'auteur a accorde une licence non exclusive exclusive license allowing Library permettant a la Bibliotheque et Archives and Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par Plntemet, prefer, telecommunication or on the Internet, distribuer et vendre des theses partout dans loan, distribute and sell theses le monde, a des fins commerciales ou autres, worldwide, for commercial or non sur support microforme, papier, electronique commercial purposes, in microform, et/ou autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in et des droits moraux qui protege cette these. this thesis. Neither the thesis Ni la these ni des extraits substantiels de nor substantial extracts from it celle-ci ne doivent etre imprimes ou autrement may be printed or otherwise reproduits sans son autorisation. reproduced without the author's permission. In compliance with the Canadian Conformement a la loi canadienne Privacy Act some supporting sur la protection de la vie privee, forms may have been removed quelques formulaires secondaires from this thesis. ont ete enleves de cette these. While these forms may be included Bien que ces formulaires in the document page count, aient inclus dans la pagination, their removal does not represent il n'y aura aucun contenu manquant. any loss of content from the thesis. Canada ABSTRACT DOES LIFE HISTORY SHAPE SEXUAL SIZE DIMORPHISM IN ANURANS: A COMPARATIVE ANALYSIS Xu Han Advisor: University of Guelph, 2008 Professor Jinzhong Fu The evolution of sexual size dimorphism (SSD) is constrained by life history traits, and therefore, mating combat, length of breeding season, female fecundity and parental care are expected to be correlated with male and/or female body sizes. Using phylogenetic comparative methods, correlations between SSD and life history traits were examined in 545 anuran species. Data were analyzed with phylogenetic independent contrasts and a maximum likelihood method. A positive correlation was found between mating combat and body size. Egg size, clutch size and clutch volume were also positively correlated with female body size and SSD. Furthermore, body size and SSD were positively correlated in all anurans and in the family Bufonidae, but were negatively correlated in the family Dicroglossidae. Female fecundity may mainly influence the evolution of SSD, and the general pattern of SSD in anurans does not follow Rensch's rule, although SSD does so follow in the family Dicroglossidae. ACKNOWLEDGEMENTS I would like to express my gratitude to all those who have supported me during the completion of this thesis. First, I would like to thank my supervisor, Dr. Jinzhong Fu, for his guidance, suggestions and encouragement during my research. His perpetual energy and enthusiasm in science has motivated me. In addition, he was always accessible and willing to help throughout my Master's study. Dr. James Bogart and Dr. Beren Robinson deserve special thanks as my thesis committee members. Dr. Bogart's encyclopedic knowledge of anurans was an invaluable resource. His patience and kindness are greatly appreciated. Dr. Robinson gave up hours of his time to advise me, and I cannot thank him enough for his attention and passion in training new scientists. Dr. Paul Herbert and Dr. Andrew MacDougall sat on my examination committee. Their excellent suggestions resulted in substantial improvement in the final version of this thesis. I was delighted to interact with Dr. Thomas Nudds by attending his "Scientific Communication" classes and with Dr. Robert Hanner in his "Molecular Evolution" class. Dr. Nudds' instructions on critical thinking and proposal design were extremely helpful for this project and will be good for my future scientific career. Dr. Hanner taught me phylogenetic methodologies, which were very useful in the data analyses of this project. I was also grateful to the Department of Integrative Biology at the University of Guelph for giving me permission to commence this thesis in the first case. Moreover, this project would not have been possible without the McLaughlin Library at the University 1 of Guelph. It allowed me to access all of the data relevant to this research. Thanks as well to the Natural Sciences and Engineering Research Council of Canada, who funded this project through my advisor Dr. Jinzhong Fu. Many other people assisted me with this project. My labmates in the Fu labs, especially Kate Crosby, Daniel Noble, Ke Bi, John Urquhart, Marina Amato, Owen Lonsdale, and Zhonge Hou, gave me valuable hints and assistance throughout the project. Members in the Boulding lab, including Dr. Elizabeth Boulding, Matthew Lemay, Hyuk Je Lee, Mark Culling, and Heather Freamo provided constructive criticism and stimulating suggestions on my research through lab meetings. Thanks also go to Daniel Noble, Mark Sherrard, Heather Freamo, and my comrades in Zoology House, Alison Fischer and Anibal Castillo, who looked closely at early versions of the thesis for English style and grammar, and offered suggestions for improvement. My experience of being a teaching assistant with Graham Nancekivell in the "Vertebrate Structure and Function" course has been proven to be invaluable to this research. I learned many important evolutionary concepts and terminologies in this course and enjoyed the work due to Graham's cheerful personality. In addition, I would like to thank all my friends in Canada for the support and good company they have provided me with. My deepest gratitude goes to my family for their unflagging love and support throughout my life. Without them, I would never have made it this far. I am indebted to my father, Zongqi Han, for his care and love. As a typical father in a Chinese family, he worked industriously to support the family and spared no effort to provide the best possible environment for me to grow up and attend school. My mother, Donghua Lin, 11 was extremely influential in encouraging me to study abroad. Her constant support encouraged me to keep moving forward when I encountered difficulties. I would like to give my special thanks to my husband, Renji Lu, whose patient love and thoughtfulness enabled me to complete this work. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS i TABLE OF CONTENTS iv LIST OF TABLES vii LIST OF FIGURES .....viii INTRODUCTION 1 Mating Related Life History Traits 4 Mating Combat. 4 Length of Breeding Season 6 Breeding Related Life History Traits 7 Egg Size, Clutch Size and Clutch Volume 7 Parental Care 8 Rensch's Rule 9 Objectives 10 METHODS 13 Taxa Included for Comparative Analyses 13 Body Size and Life History Traits 13 Body Size 13 Sexual Size Dimorphism .14 Mating Combat 17 Length of Breeding Season 18 Egg Size, Clutch Size, and Clutch Volume 19 Parental Care ..20 iv Phytogeny Reconstructions 20 Criteria for Choosing Phytogenies.... 21 Supertree Constructions 22 Phylogenetic Comparative Analyses 24 Phylogenetic Independent Contrasts 24 BayesDiscrete 29 Comparative Analyses 32 RESULTS 35 Sexual Size Dimorphism 35 SSD and Mating Related Life History Traits 38 Correlation between SSD and Mating Combat 38 Correlation Between SSD and Length of Breeding Season. 39 SSD and Breeding Related Life History Traits 39 Correlation between SSD and Clutch Volume 39 Correlation between SSD and Egg Size 40 Correlation between SSD and Clutch Size 41 Correlation between SSD and Parental Care 41 Rensch'sRule 42 Summary of Correlations 43 DISCUSSION: 47 Sexual Size Dimorphism 47 SSD and Mating Related Life History Traits 48 Correlation between SSD and Mating Combat 48 v Correlation between SSD and Length of Breeding Season -. 49 SSD and Breeding Related Life History Traits 50 Correlation between SSD, Clutch Volume, Egg Size, and Clutch Size 50 Correlation between SSD and Parental Care 51 Rensch's Rule 53 Suggestions for Future Research 56 CONCLUSION 61 REFERENCES..... 62 APPENDIX 1 Data of body size, egg size, clutch size, reversed sexual size dimorphism, mating combat, breeding season and parental care in anurans 93 APPENDIX 2 References for body size, egg size, clutch size, mating combat, length of breeding season, and parental care in anurans species 108 APPENDIX 3 A manually constructed phylogenetic supertree for 545 anuran species across 37 anuran families 133 APPENDIX 4 Result of the correlation tests among body size, body size dimorphism and life history traits in the all-anuran analysis and in the within-family analyses using the program of Comparative Analysis via Independent Constrasts (CAIC) and the BayesDiscrete program 143 vi LIST OF TABLES Table 1. Summary of character states for body size and body size dimorphism 15 Table 2. Phylogenetic comparative analyses, indicating correlations tested, corresponding programs applied and predictor variables used 33 Table 3. Correlations ranked by the order of statistical significance (high to low) 46 APPENDIX 4 Table 1. Correlations between body size and mating related life history traits 144 APPENDIX 4 Table 2. Correlations between body size dimorphism and mating related life history traits 145 APPENDIX 4 Table 3. Correlations between body size and breeding related life history traits.... 147 APPENDIX 4 Table 4. Correlations between body size dimorphism and breeding related life history traits 148 APPENDIX 4 Table 5.