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EVOLUTION of PHENOTYPIC PLASTICITY: INSIGHTS from ECHINOID LARVAE by BENJAMIN G. MINER a DISSERTATION PRESENTED to the GRADUATE

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EVOLUTION of PHENOTYPIC PLASTICITY: INSIGHTS from ECHINOID LARVAE by BENJAMIN G. MINER a DISSERTATION PRESENTED to the GRADUATE EVOLUTION OF PHENOTYPIC PLASTICITY: INSIGHTS FROM ECHINOID LARVAE By BENJAMIN G. MINER A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2003 Copyright 2003 by Benjamin G. Miner This dissertation is dedicated to my parents, who always supported my dreams. ACKNOWLEDGMENTS This dissertation could not have been completed and would not have been as enjoyable without the help and support of many people. I would like to first acknowledge my late advisor Larry R. McEdward for his encouragement and support. I will miss him. I also thank my current advisors, Craig Osenberg and Colette St Mary, for adopting me and challenging me to think more critically. Marta Wayne, David Julian, Gustav Paulay, Dan Brazeau, and Kaoru Kitajima helped me to think more broadly. In addition, I thank Diana Padilla, Steven Morgan, Greg Wray, Richard Strathmann, John Lawrence, and Richard Emlet for all their time and help. My fellow graduate students provided an excellent learning environment. I would especially like to thank James Vonesh for almost always being louder than me, and for his contagious excitement for science. I would also like to thank my co-conspirators (Nat Seavy, Mike McCoy, Suhel Quader, Becca Hale, Kavita Isvaran, Eric Sanford, Bruno Pernet, Jenny Hoffman, Jason Hodin, and Marney Pratt) who helped distract me with many side projects. My 13 labmates exposed me to a variety of disciplines and organisms through their various research interests. I benefited greatly from our lab discussions. Members of the Friday Harbor Laboratories Losers Club, Jon Allen (president), Scot Santagata (ex-president), Eric Edsinger-Gonzalez, Tansy Clay, and Melissa Wilson, made my time at FHL much more enjoyable. I thank the directors of the Friday Harbor Laboratories, Dennis Willows; and the Bodega Marine Laboratories, Ernie Chang, for providing me with space. I thank the staff iv at both institutions for their assistance. Grants in aid of research from the Society of Comparative and Integrated Biology, and Sigma XI; and the Alan Kohn, Robert Fernald, McLaughlin, and Grinter fellowships funded my dissertation research. Lastly, I thank Melissa Wilson and my family for their support, encouragement, and love. v TABLE OF CONTENTS Page ACKNOWLEDGMENTS.................................................................................................. iv LIST OF TABLES ...........................................................................................................viii LIST OF FIGURES............................................................................................................ix ABSTRACT........................................................................................................................x 1 INTRODUCTION: A BRIEF REVIEW OF PHENOTYPIC PLASTICITY.............. 1 Introduction.................................................................................................................. 1 What is Phenotypic Plasticity?..................................................................................... 2 Types of Phenotypic Plasticity..................................................................................... 4 Adaptive vs. Nonadaptive Phenotypic Plasticity ......................................................... 7 Testing for Adaptive Phenotypic Plasticity ............................................................... 11 The Evolutionary and Ecological Consequences of Plasticity................................... 14 2 DIFFERENT CUES FOR DIFFERENT FOLKS: THE TIMING AND CUES OF INDUCIBLE OFFENSES IN ECHINOID LARVAE............................................... 16 Introduction................................................................................................................ 16 Materials and Methods............................................................................................... 17 Results........................................................................................................................ 23 Discussion.................................................................................................................. 26 Pre-Feeding Response......................................................................................... 26 Different Species Use Different Cues................................................................. 27 3 EVOLUTION OF PHENOTYPIC PLASTICITY IN SEA URCHIN LARVAE: A TRADE-OFF BETWEEN ARM LENGTH AND STOMACH SIZE....................... 30 Introduction................................................................................................................ 30 Materials and Methods............................................................................................... 32 Results........................................................................................................................ 36 Discussion.................................................................................................................. 38 vi 4 EFFECTS OF FINE GRAIN ENVIRONMENTAL VARIABILITY ON MORPHOLOGICAL PLASTICITY ......................................................................... 43 Introduction................................................................................................................ 43 Materials and Methods............................................................................................... 46 Results........................................................................................................................ 50 Discussion.................................................................................................................. 52 5 EFFECTS OF ENVIRONMENTAL VARIATION ON THE EVOLUTION OF PHENOTYPIC PLASTICITY................................................................................... 56 Introduction................................................................................................................ 56 The Model.................................................................................................................. 58 Reaction Norms .................................................................................................. 58 Environmental Variation..................................................................................... 59 Within-Individual Variation ............................................................................... 60 Among-Individual Variation............................................................................... 61 Benefits ............................................................................................................... 62 Costs.................................................................................................................... 63 Calculating Fitness.............................................................................................. 64 Results........................................................................................................................ 65 Discussion.................................................................................................................. 67 6 SUMMARY AND CONCLUSIONS ........................................................................ 72 Adaptive Plasticity in Plutei....................................................................................... 72 Environmental Variation and Phenotypic Plasticity .................................................. 75 Future Directions........................................................................................................ 76 Adaptive Larval Feeding-Structure Plasticity..................................................... 76 Environmental Variation and the Evolution of Plasticity................................... 76 Other Directions.................................................................................................. 77 APPENDIX A FITNESS CALCULATIONS FOR THE SLOPE OF PLASTICITY ....................... 78 B FITNESS CALCULATIONS FOR THE RANGE OF PLASTICITY...................... 79 LIST OF REFERENCES .................................................................................................. 80 BIOGRAPHICAL SKETCH ............................................................................................ 93 vii LIST OF TABLES Table page 2-1. Results of a nested ANCOVA .................................................................................. 23 3-1. Results of a nested 2-factor ANCOVA..................................................................... 37 6-1. Review of studies demonstrating feeding-structure plasticity in echinoids.............. 74 viii LIST OF FIGURES Figure page 1-1. Graph of a reaction norm............................................................................................ 2 2-1. Photomicrograph of a pluteus (S. purpuratus).......................................................... 21 2-2. Response of postoral arm length in sea urchin larvae (S. purpuratus) to putative cues.. ........................................................................................................................ 24 2-3. Response of postoral arm length in sanddollar larvae (D. excentricus) to putative cues.. ........................................................................................................................ 25 3-1. Photomicrograph of a pluteus (S. purpuratus).........................................................
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