UNIVERSITY of CALIFORNIA RIVERSIDE the Cost of Bearing a Sword
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UNIVERSITY OF CALIFORNIA RIVERSIDE The Cost of Bearing a Sword: Locomotor Costs and Compensations in Relation to a Sexually Selected Trait in Xiphophorus A Dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Evolution, Ecology and Organismal Biology by Christopher E. Oufiero December 2010 Dissertation Committee: Dr. Theodore Garland, Jr., Chairperson Dr. David N. Reznick Dr. Mark A. Chappell Copyright By Christopher E. Oufiero 2010 The Dissertation of Christopher E. Oufiero is approved: _________________________________________________ _________________________________________________ _________________________________________________ Committee Chairperson University of California, Riverside Acknowledgements I am thankful to many people for their help and support, without them, this dissertation would not have been possible. I would first like to thank my dissertation committee; my advisor Dr. Theodore Garland, Jr., Dr. David N. Reznick and Dr. Mark A. Chappell. They have all been instrumental in helping me throughout my graduate career; have offered me support, intellectual feedback, and guidance. I would like to thank Ted for his guidance, support and making me a better scientist. I have learned a lot working with Ted, my knowledge of statistics and experimental design have improved greatly in the years I have worked with him. Specifically, I feel fortunate to have been able to learn phylogenetic comparative methods from someone who was instrumental in the field in its beginnings. He managed to take the time to explain these methods and the theory behind them during my graduate career. I am grateful to have had the opportunity to work with him and learn these methods. David was my unofficial co-advisor. Working in a lab that did not focus primarily on fish, David took me in as one of his own lab members and offered me support at the beginning stages of my dissertation when none was available. I feel privileged to have been able to work with a scientist that is so admired by others. I have learned a great deal about the fish I knew little about when I entered from him. It was always nice to have unplanned meetings with David while checking fish in the vivarium, discussing science, papers and the husbandry of our fish. I am also thankful to Mark for his expertise in many areas of physiology and behavioral ecology, as well as the use of various pieces of equipment. Whenever I could not find the right equipment to measure something, Mark always seemed to have iv the right tool lying around somewhere in his lab. Without Mark I would not have been able to measure oxygen consumption in water or begin filming fish swimming with a high speed video camera. Mark was always approachable and never hesitated to offer a minute to discuss research. There are several other professors and labs at UCR that were instrumental during my dissertation. First, I would like to thank Dr. Douglas A. Altschuler for guidance in my scientific career and use of equipment. Without Doug, I would not have been able to finish recording high speed videos. His lab was always helpful working out a schedule for me to use their equipment. His support was very generous. Doug was also always willing to discuss research and my future as an academic, I am thankful for the advice he had. I would also like to thanks Drs. Kimberly A. Hammond and Richard Cardullo and their labs for additional support and use of essential equipment throughout my dissertation research. Finally, I would like to thank Daphne J. Fairbairn for her enthusiasm and discussions about sexual selection. There have also been many graduate students and postdocs that have been helpful throughout my graduate career. First and foremost, I would like to thank past and present members of the Garland lab. Although we may work on different taxa, or sub- disciplines of biology, the members of the Garland lab have always offered advise, support, and constructive criticism that have made me a better scientist. Therefore, I thank Gabe Gartner, Brooke Keeney, Tom Meek, Jessica Malisch, Scott Kelly, Erik Kolb, Kevin Middleton, Heidi Schutz, Rob Hannon, and Wendy Acosta for their support and helpful discussions throughout my graduate career. I would also like to thank members of the Reznick lab past and present for their help and support including Matt Walsh and v Bart Pollux. Finally I would like to thank Rob Meredith for completing the phylogeny of Xiphophorus , which was essential for my dissertation. Several other people at UCR helped me throughout graduate school. I would first like to thank Teri Orr for her support, friendship, and many discussions about science, music, lomography and what it truly means to be punk rock. Without her and our many excursions, including countless trips to Disneyland, I would not have been able to remain sane or have fun while I swam hundreds of fish. I would also like to thank Mandy Banet for her friendship and support during my time at UCR. Without Mandy, I would not only have never learned to clean a fish tank, but also would have never learned what a real high five is or how to have some fun in graduate school. I am grateful to Libby King for her continued friendship. Libby was extremely helpful during the last few months of my dissertation, she was always willing to talk about my research and offer advice. I would also like to thank Matt Van Sant for his continued support, friendship and expertise in physiology (from Terre Haute, IN to Riverside, CA). Finally, I’d like to thank Michael Goerger for countless discussions about science and philosophy while watching reality television. I have also had the pleasure to have many undergraduates work and volunteer for me. Without them, much of this research would never have been completed. Kristine Jugo and Paulina Tran were always positive and eager to take on a new task, without their help much of my dissertation would not have been completed. Without Ted Yau, Danielle Wickman and Erica Farris fish would still be waiting to be dissected. Finally, several undergraduates offered me their time to clean fish tanks including Tuan Do, Liz Miller, and Bowen Yang. vi There are several people outside of UCR I would also like to thank for their help during my dissertation. I would like to thank Matt McHenry and Adam Summers for ‘lending’ the flow tunnel. Mike Ryan, Molly Morris, Manfred Schartl and the Xiphophorus stock center for providing fish. I would also like to thank Kathy Dickson for helping me finish the final part of my dissertation, examining enzyme activity. Friday Harbor Laboratories and the Fish Swimming class of 2005 for teaching me how to swim fish. And finally, various funding agencies for making this research possible including the National Science Foundation, UCR Graduate School, UCR Biology Department and Shoemaker award. I would also like to thank Michael Vamstad and the U.S. National Park Service for a year of support and allowing me to escape swimming fish and explore beautiful Joshua Tree helping to conserve treefrogs. Finally, last, but certainly not least I am grateful to my family for their continued support. My parents have always been a source of support, reason, and inspiration. Without them I would have never become interested in Biology and science; blame it on the trips to the American Museum of Natural History or the Bronx Zoo, or the various creatures they allowed me to keep including various Poeciliid fish. They have always been available for me to vent about various frustrations, and continue to be a positive influence on my life. I am also grateful to my sisters, Shiloh and Jess, and their husbands, Bill and Pete, for not only increasing my inclusive fitness by having 5 children total (Gavin, Peter, Emma, Sophie and Chloe) while I was in graduate school, but also for their support and reminding me where I come from. vii Chapter One is reproduced with permission from the following published manuscript. Oufiero, C. E., and T. Garland, Jr. 2007. Evaluating performance costs of sexually selected traits. Functional Ecology 21: 676-689. Chapter Two is reproduced with permission from the following published manuscript. Oufiero, C.E. and T. Garland, Jr. 2009. Repeatability and correlation of swimming performances and morphology over varying time scales in the guppy ( Poecilia reticulata ). Functional Ecology. 23: 969-978. viii ABSTRACT OF THE DISSERTATION The Cost of Bearing a Sword: Locomotor Costs and Compensations in Relation to a Sexually Selected Trait in Xiphophorus by Christopher E. Oufiero Doctor of Philosophy, Graduate Program in Evolution, Ecology, and Organismal Biology University of California, Riverside, December 2010 Dr. Theodore Garland, Jr., Chairperson Some of the most compelling traits to evolutionary biologists are sexually selected traits. The ‘un-natural’ expression of these traits has puzzled biologists since the time of Charles Darwin. Why would a trait evolve that seems to decrease survival? Most of these traits evolve because they increase the reproductive fitness of the bearer, either through intra-sexual or inter-sexual competition. However, these sexually selected traits must meet the demands of both natural and sexual selection. It is therefore assumed that there are ‘costs’ associated with the trait that limits their expression. In this dissertation I examined the performance costs of a sexually selected trait, expressed as an exaggerated morphological structure. I first introduce a more integrative approach to the study of detecting costs of sexually selected traits. This approach incorporates additional aspects of the organism’s phenotype that may have evolved to offset the costs of the sexually selected trait. I show ix that ignoring these ‘compensatory’ traits may mask the cost of the sexually selected trait using synthesized data.