Evolution

Wallace Arthur is Professor of Zoology at the National University of Ireland, Galway. He is one of the founding editors of the journal Evolution & Development. He obtained his PhD from the University of Nottingham, and held positions at several British universities before moving to Galway in 2004. He has been a Visiting Research Scholar at Harvard University and a Visiting Associate of Darwin College, Cambridge.

Preface x PART I Foundations 3 1 Introduction 4 1.1 From Darwin to Development 4 1.2 Development; and Evolutionary Changes in Development 9 1.3 Development and the Realm of Multicellularity 11 2 What is Evo-Devo? 15 2.1 Forerunners of Evo-Devo 15 2.2 Nineteenth-Century Comparative Embryology 16 2.3 Diverse Antecedents-1900-1980 19 2.4 Conclusions from History; Messages for the Present 24 2.5 The Advent of Evo-Devo in the 1980s 25 2.6 Broad and Narrow Views of Evo-Devo 27 2.7 Too Few Laws, Too Many Facts? 28 3 Development, Cells and Molecules 34 3.1 Analysing the Developing Organism 34 3.2 Cells and Development: The Basics 37 3.3 Genes: Structure, Expression and Developmental Function 40 3.4 Signalling Pathways Within and Between Cells 45 3.5 Signalling: From Cell to Embryo 48 3.6 Long-Range Signalling and Developmental Processes 51 4 Natural Populations 54 4.1 The Ecological Theatre and the Evolutionary Play 54 4.2 Types of Creature; Types of Population 55 4.3 Spatial Structure 60 4.4 Age Structure 64 4.5 Genetic Structure 65 4.6 Natural Selection 67 PART II Developmental Repatterning 75 5 Mutation and Developmental Repatterning 77 5.1 Mutation in Terms of Altered DNA Sequence 77 5.2 Mutation in Terms of Proximate Functional Consequences 80 5.3 Developmental Repatterning at Molecular and Higher Levels 82 5.4 Developmental Repatterning at the Level of the Whole Organism 88 5.5 Developmental Repatterning and Fitness 89 6 Heterochrony 93 6.1 What is Heterochrony? 93 6.2 Types and Levels of Heterochrony 94 6.3 Heterochrony at the Organismic Level 95 6.4 Heterochrony at the Molecular Level 99 6.5 Heterochrony and Fitness 102 7 Heterotopy 106 7.1 What is Heterotopy? 106 7.2 Heterotopic Processes Involving Left-Right Asymmetry 107 7.3 Heterotopic Processes Involving the A-P and D-V Axes 112 7.4 Other Types of Heterotopy 116 7.5 Concluding Remarks 119 8 Heterometry 121 8.1 What is Heterometry? 121 8.2 Increasing Relative Size 122 8.3 Decreasing Relative Size 124 8.4 Bi-directional Heterometry 128 8.5 Heterometric Compensation 132 9 Heterotypy 135 9.1 What is Heterotypy? 135 9.2 Altered Products of Developmental Genes 137 9.3 Altered Pigmentation 139 9.4 Altered Morphology and the Origin of Novelty 140 9.5 The Origin of New Cell Types 144 10 The Integrative Nature of Repatterning 148 10.1 Repatterning is a Complex Process 148 10.2 Different Kinds of Repatterning can Produce a Similar Result 149 10.3 Compound Repatterning at a Single Level of Organisation 151 10.4 The Kind of Repatterning can Change Between Levels of Organisation 155 10.5 Categories and Subcategories of Repatterning 157 10.6 The Causes of Repatterning 159 11 Mapping Repatterning to Trees 161 11.1 Pattern, Process, Homology and Trees 161 11.2 The Origin(s) of Animal Segmentation 163 11.3 The Vertebrate Fin-to-Limb Transition 169 11.4 The Origin of Flowers 176 11.5 General Conclusions on Repatterning and Selection 179 PART III The Direction of Evolution 183 12 Adaptation, Coadaptation and Exaptation 185 12.1 Natural Selection on a Continuously Variable Character 185 12.2 Natural Selection on Two Characters; and the Idea of an Adaptive Landscape 190 12.3 Developmental and Functional Coadaptation 191 12.4 Morphological Geometry and Selection 194 12.5 Long-term Evolution and Exaptation 196 13 Developmental Bias and Constraint 200 13.1 A Key Question about Evolution's Direction 200 13.2 Making Sure the Question is about Processes, not Terminology 204 13.3 Dependence versus Independence of Different Characters 208 13.4 Evo-Devo Meets Quantitative Genetics 209 13.5 Developmental Bias and 'Routine' Evolution 211 13.6 Developmental Bias and the Origin of Evolutionary Novelties 216 14 Developmental Genes and Evolution 218 14.1 The Direction of Evolution at the Developmental/Genetic Level 218 14.2 Developmental Genes: An Overview 219 14.3 Developmental Genes: Examples 223 14.4 The Hox Genes 225 14.5 Gene-Level Forms of Developmental Bias and Coadaptation 230 14.6 Changes in Regulatory versus Coding Regions of Genes 231 15 Gene Co-option as an Evolutionary Mechanism 234 15.1 What is Gene Co-option? 234 15.2 Co-option in the Evolution of Segments and Eyes 237 15.3 Appendage Evolution and Gene Co-option 241 15.4 Co-option in the Evolution of Zygomorphic Flowers 244 15.5 Evolution of the 'Genetic Toolkit' 245 15.6 Co-option, Exaptation and Developmental Bias 249 16 Developmental Plasticity and Evolution 252 16.1 Types of Developmental Plasticity 252 16.2 Discrete Variants: Winged and Wingless Forms of Insects 254 16.3 Meristic Variation: the Number of Segments in Centipedes 257 16.4 Continuous Variation: Plant Growth 259 16.5 Plasticity and Developmental Genes 260 16.6 The Evolution of Patterns of Plasticity 261 17 The Origin of Species, Novelties and Body Plans 272 17.1 Is Evolution Scale-dependent? 272 17.2 Speciation 273 17.3 The Origin of Novelties 281 17.4 Body Plans I: Overview 284 17.5 Body Plans II: the Origin of the Vertebrates 285 17.6 Body Plans III: the 'Cambrian Explosion' 286 18 The Evolution of Complexity 291 18.1 Defining Complexity 291 18.2 The Lack of a 'Law of Increasing Complexity' 293 18.3 Increases in the Complexity of Adults 299 18.4 Changes in the Complexity of Life-histories 302 18.5 Complexity at the Molecular Level 306 PART IV Conclusions 311 19 Key Concepts and Connections 312 19.1 Introduction: From Original Idea to Mature Scientific Discipline 312 19.2 A List of The Book's Main Points, and the Emergence of Key Concepts 314 19.3 How do They Inter-Connect? 319 20 Prospects 327 20.1 Introduction: From the Present into the Future 327 20.2 Molecular Evo-Devo 327 20.3 Integrative Evo-Devo and General Evolutionary Theory 332 20.4 Wider Challenges 334 Glossary 336 Appendix 1: A Little Bit of History 355 Appendix 2: Naming of Genes and Proteins 359 Appendix 3: Geological Time 363 Appendix 4: Inferring Evolutionary Trees from Comparative Data 366 References 370 Index 383 This book has a companion website: www.wiley.com/go/arthur/evolution