THYROID HORMONE-LIKE FUNCTION IN ECHINOIDS: A MODULAR SIGNALING SYSTEM COOPTED FOR LARVAL DEVELOPMENT AND CRITICAL FOR LIFE HISTORY EVOLUTION By ANDREAS HEYLAND 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 2004 Copyright 2004 by Andreas Heyland To my teacher Larry McEdward who inspired me to think differently. ACKNOWLEDGMENTS I greatly acknowledge the help and support of my late advisor, Larry McEdward, who introduced me to the field of marine larval ecology and the beauty of echinoderm larvae. I wish we could have spent more time together. Many thanks also to the entire Friday Harbor Laboratories (University of Washington) community and the Department of Zoology at the University of Florida for their help and support. Specifically I thank David Julian for taking the responsibility of being my dissertation advisor and for his great support at all times in all aspects of my dissertation. I am grateful to my collaborator Jason Hodin (Friday Harbor Laboratories) who in many respects served as an advisor and strongly influenced my scientific thinking. Leonid Moroz (Whitney Lab, University of Florida) critically evaluated my work in the last stages and gave me a truly new perspective on it. I am also very thankful for his generous financial support that allowed me to finish my thesis in a timely manner. Constructive criticism of my dissertation committee members, including Craig Osenberg, Lou Guillette, Charles Wood and Gustav Paulay, and several other researchers, including Richard Strathmann, Greg Wray, Marty Cohn, Cory Bishop, LeLand Johson, Chris Cameron, Benjamine Miner and Donald Brown significantly improved my work. My stay at various marine stations during the dissertation work has been extremely enjoyable. I would like to thank all the members of the 1999 Embryology and EvoDevo classes at the Friday Harbor Laboratories for sharing a great time with me. This place changed my life. I would like to thank all the people that made this possible including the iv director Dennis Willows and the staff. I thank Billie Swalla for supporting my work during the summer 2001 at the Friday Harbor Laboratories. Furthermore I thank the crew of the Smithsonian Marine Station at Fort Pierce for their great support and help, especially the former director, Marry Rice, and the current director, Valerie Paul, for giving me the opportunity to spend a few enjoyable and productive months at the station. I thank the Link Foundation for providing the financial support for this time. I had a great opportunity to work at the Rosenstiel School of Marine and Atmospheric Science in Miami thanks to Tom Capo and at the Woods Hole Oceanographic Institute thanks to Ken Halanych and Jesus Pineda. I would also like to thank Joel Rothman and Richard Harland for letting me use microscopes and the facilities during the MBL Embryology course 2002. Finally I thank the Director of the Station Biologique in Roscoff (France), Andre Toulmond, for his hospitality during our visit in the summer 2002. Several funding agencies made this work possible: NSF grant OCE-9819593 to Larry McEdward; PADI, Sigma Xi, Alan Kohn, Link Foundation grants and fellowships given to Andreas Heyland and NIH grants R01NS39103 and R01MH60261 given to Leonid Moroz. I benefited greatly from suggestions and help from members of the Laboratories I was working in. I would like particularly to thank my collaborators Adam Reitzel, David Price, Billie Swalla and Michaela Bodnarova for help and discussions. Lastly I thank my wife Svetlana Maslakova for her love, encouragement, help and support. I also thank my parents Sven and Maike and my brother Klaas for their support and continuous interest in my work. v TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES...............................................................................................................x LIST OF FIGURES ........................................................................................................... xi ABSTRACT..................................................................................................................... xiv CHAPTER 1 INTRODUCTION: HORMONE SIGNALING IN EVOLUTION AND DEVELOPMENT: A NON-MODEL SYSTEM APPROACH ...................................1 Cooption and Modularity: The Emergence of a New EvoDevo Paradigm ..................1 Comparative Biology: A Non-Model System Approach to Life History Evolution (LHE) .......................................................................................................................2 Defining Metamorphosis ..............................................................................................4 Nuclear Hormone Receptors: Modules and Development and Evolution....................7 Hormonal Signaling Networks: Modules Coopted for LHTs.....................................10 Hormones and Life History Evolution (LHE)............................................................15 2 HETEROCHRONIC DEVELOPMENTAL SHIFT CAUSED BY THYROID HORMONE IN LARVAL SAND DOLLARS AND ITS IMPLICATIONS FOR PHENOTYPIC PLASTICITY AND THE EVOLUTION OF NON-FEEDING DEVELOPMENT.......................................................................................................25 Introduction.................................................................................................................25 Materials and Methods ...............................................................................................28 Experimental Designs..........................................................................................29 Experimental Treatments.....................................................................................30 Morphometric Measurements and Rudiment Stages...........................................30 Metamorphic Competence and Settlement..........................................................31 Statistics...............................................................................................................32 Results.........................................................................................................................33 Analysis of Thyroxine Effects on Larval and Juvenile Morphology ..................33 Comparison of age and rudiment stage specific analysis.............................33 Analysis of larval, juvenile and stomach growth and development.............33 Metamorphic Competence and Juvenile Size......................................................36 vi Endogenous Hormone Synthesis.........................................................................37 Mortality and Abnormalities ...............................................................................38 Discussion...................................................................................................................39 Thyroid Hormone as a Cue for Adaptive Phenotypic Plasticity in Echinoid Larvae ..............................................................................................................40 Differences Between Thyroid Hormone and Food Effects: Stomach Size .........43 Thyroid Hormones As an Indicator of Larval Nutrition: Implications for Juvenile Size in Echinoids ...............................................................................43 Thyroid Hormones and Life History Evolution in Echinoderms ........................46 3 THYROID HORMONES DETERMINE DEVELOPMENTAL MODE IN ECHINODERMS .......................................................................................................62 Introduction.................................................................................................................62 Materials and Methods ...............................................................................................65 Animal Collection, Culturing of Larvae and Experimental Treatments .............65 Biochemistry........................................................................................................66 Morphological Analysis ......................................................................................68 Settlement and Metamorphosis ...........................................................................70 Statistics...............................................................................................................70 Results.........................................................................................................................70 Discussion...................................................................................................................73 Egg Size and TH as Determinants of Developmental Mode in Echinoids..........73 Juvenile Size in Echinoids...................................................................................76 TH and the Evolution of Lecithotrophy ..............................................................78 4 ENDOGENOUS THYROID HORMONE SYNTHESIS IN NON-FEEDING LARVAE OF THE SAND DOLLAR CLYPEASTER ROSACEUS........................88 Introduction.................................................................................................................88 Materials and Methods ...............................................................................................91 Larval Culturing ..................................................................................................91