Phenotypic evolution in the invasive cane toad (Rhinella marina): adaptations for dispersal A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy Cameron Marshall Hudson School of Life and Environmental Sciences The University of Sydney Australia January 2017 Supervisor Statement This is to certify that I have been Cameron’s primary supervisor during his PhD candidature and have overseen the production of this thesis. In my opinion Cameron’s thesis is sufficiently well presented to be examined, and it does not exceed the prescribed word limit or any extended word limit for which prior approval has been granted. Rick Shine University of Sydney i Declaration I hereby certify that the work presented in this thesis is my own (except where I provide references specifically acknowledging otherwise). This thesis has not been submitted to attain the degree of Doctor of Philosophy at another University. Cameron Hudson Sydney, January 2017 ii Preface In accordance with the guidelines for a PhD thesis in the Faculty of Science at the University of Sydney, all data chapters of this thesis are presented as stand-alone manuscripts that are either published in peer-reviewed journals, currently under consideration for publication, or in preparation for submission. This method of presentation means that there is some unavoidable repetition of background information and methodology in each chapter. All of the chapters within this thesis have been written with various co-authors, including my supervisors, Professor Richard Shine and Dr. Gregory Brown, along with other colleagues: Dr. Ben Phillips, Dr. Colin McHenry, Matthew McCurry, and Petra Lundgren. These individuals contributed to the initial planning of the research, participated in discussions and final editing of the manuscripts, and in some cases aided in laboratory experiments. However, I conducted all of the research associated with this thesis, including the field work, laboratory experiments, data analysis, manuscript drafting and writing. Approval for this research was provided by the University of Sydney Animal Care and Ethics Committee (Approval number: AEC 6075). iii Acknowledgements I owe thanks to a great number of people for their help, support, friendship, and encouragement during these past 3.5 years, and I wish to expound their virtues at length. After all, it’s not every day that you get a chance to express your gratitude to the people that you care about in a printed volume. I can only hope that the words I’ve chosen here will convey how sincerely thankful I am to all of you. I must begin with my supervisor, Professor Rick Shine, for without him, none of this would have been possible. Rick, I’m sure that by now, after supervising so many students, you’ve heard every variation on how to sing your praises. That, in itself is a testament to how inspiring and outstanding you are as a scientist. I consider myself incredibly lucky to have been a part of your lab, and I cannot thank you enough for the opportunities you have afforded me. Throughout this PhD I have both literally, and figuratively, travelled around the world in search of cane toads to measure. You have nurtured my toad-measuring obsession with enthusiasm, and consistently amaze me with your intellect. I can say with all honesty that this PhD has been a dream come true. So thank you for taking a chance on an excitable Canadian from the Queen’s University Biological Station. To my co-supervisor and compatriot, Dr. Greg Brown, you have proven to be an endless font of knowledge and wisdom throughout my time here. I sometimes worry that I have come to rely on you too much, because you are so consistently helpful. I will miss popping into your office to pester you about toads and statistics. Thank you for sharing your little slice of the Territory with me. I hope that one day I can return to Middle Point to find you still driving the Fogg Dam wall in search of keelbacks. My fellow Shine labbers, my Bufo Bandits, my Rhinella Rangers, it has been a wild ride. We’ve survived our various cohabitations in the Top End, Hawai’i, and French Guiana, and I think we’ve come out better for it. I hate to lump you all into a giant wall of bold text iv here, but there are just too damn many of you! So thank you to Melanie Elphick (especially for all of her hard work making this thesis coherent), Dr. Michael Crossland (who deserves special mention for putting up with me and my various office pets for three years), Dr. Jayna DeVore, Dr. Matt Greenlees, Dr. Camila Both, Dr. Simon Ducatez, Dr. Wei Chen, Dr. Chris Friesen, Georgia Ward-Fear, Jodie Gruber, Sam McCann, Greg Clarke, Georgia Kosmala, Uditha Wijethunga, Dan Natusch, Chalene Bezzina, Sarsha Gorissen, Dan Selechnik, Damien Holden, Felicity Nelson, Patt Finnerty and Katarina Stuart. I’ve made some fantastic memories with you all, and will miss you dearly once I’ve left Australia. Of course I need to give thanks to our favourite invasive anuran, Rhinella marina. Despite how much people in Australia tend to hate them, I find it hard not to love the little toads. After all, it’s not their fault that they’re here, and in a bizarre way, their introduction to Australia in the 1930s lead to all of my PhD experiences. So thank you to the 5000+ toads that I’ve measured over the course of my research for their unwilling participation in our study of evolution. I’d like to thank my collaborators, Dr. Ben Phillips, Dr. Marta Vidal-García, Dr. Colin McHenry, Matthew McCurry, Petra Lundgren, Dr. Bill Mautz, Michelle Quayle, Crystal Kelehear and James Mertins for all of their time and hard work. It was truly a pleasure working with all of you, and I can only hope that we will continue to do so in the future. During my time here I’ve been lucky enough to interact with some wonderful people who may or may not be involved in cane toad research, but have proven to be great friends along the way. Many thanks to Martin Mayer, George Madani, Maddie Sanders, Kevin Donmoyer, Tiago Dalcin, Damian Lettoof, Dr. Cathy Shilton, Jack Reid, Andrea West, Lee-Ann Rollins, and Mark Richardson. I also can’t leave out my favourite non-human Australian, Trampers the frill-neck, one solid lizard. v My former academic supervisors, Dr. Stephen Lougheed, Dr. Jinzhong Fu, and Dr. Kat Stewart deserve special thanks for laying the foundation of my academic career, and propelling me on this life trajectory. Without your help and mentoring during my undergraduate and master’s degrees, I do not think I would have made it to where I am today. To the Hudson, Fleming, Simmons, Lemmen, Penfound, and Henson families, thank you all for being so amazing. I have always felt a strong sense of love and encouragement from you. I could not wish for a better group of people to call my family. I must thank my brother Dr. Zachary Hudson, who I often credit as my inspiration to become a scientist for his guidance over the years, and my parents Michael and Susan Hudson for everything. I can’t really think of a better way to put it into words. Thank you mom and dad, for everything. Finally, to my darling Kimberley Lemmen, I know that I’ve asked a lot of you since moving to Australia. The distance alone would be too daunting for most people, not to mention the unique isolation of Middle Point, but you’ve stuck by my side throughout. Through all the international flights, dropped calls, and nights apart you have patiently waited for me. At times I feel undeserving of your unwavering devotion to our relationship, but these past seven years with you have been truly wonderful. I cannot wait to see where life takes us next. And so, my love, I dedicate this thesis to you. vi Table of Contents Supervisor Statement .................................................................................................................. i Declaration ................................................................................................................................. ii Preface....................................................................................................................................... iii Acknowledgements ................................................................................................................... iv Table of Contents ..................................................................................................................... vii Abstract ...................................................................................................................................... 1 Chapter 1. General Introduction and Thesis Synopsis ........................................................ 3 Literature Cited .............................................................................................................. 8 Chapter 2. Virgins in the Vanguard: Low Reproductive Frequency in Invasion-Front Cane Toads ............................................................................................................................. 12 Abstract ........................................................................................................................ 13 Introduction .................................................................................................................. 14 Materials and Methods ................................................................................................. 15 Results .......................................................................................................................... 18 Discussion