Stuart West is professor of evolutionary biology at the University of Oxford.

"Understanding mating strategies and the allocation of resources to male versus female reproduction has long been a major goal of evolutionary studies. In this comprehensive synthesis, West makes several important contributions to the field of evolutionary biology... Because the work primarily focuses on how natural selection shapes sex allocation for given sex determination systems, sex allocation is proven an important phenomenon for studying adaptation. This thorough conceptual perspective, blending theory and data, summarizes sex allocation theory and how different areas are applied to different organisms."--Choice "After reading this book, I now have greater confidence in my understanding of where this field stands and where future research would most profitably be directed. This book will unquestionably benefit students and professional scientists who are seeking either a basic introduction to sex allocation biology or a comprehensive sourcebook that integrates the major issues of the field. Additionally, this book would serve as an excellent resource for specialized graduate-level courses in evolutionary biology. Overall, this is an outstanding and comprehensive book that extends beyond the topic of sex allocation and is an essential tool for anyone with a serious interest in behavioral or evolutionary ecology."--Daniel A. Warner, Integrative and Comparative Biology "[T]his book is worth taking the time to read and think about whether you are new to the field of sex allocation, think you know it all already, or are mainly interested in the evolution of other social and reproductive traits. It might influence the way you think about your own research and if nothing else you will learn some cool facts about the impressive subtleties of sex allocation in the natural world."--Suzanne H. Alonzo, Evolution

• Acknowledgments xi Chapter 1: Sex Allocation 1 1.1 What Is Sex Allocation? 1 1.2 A Potted History 2 1.3 Why Is This Book Needed? 8 1.4 What Is in This Book 8 1.5 What Is Not in This Book 10 1.6 How To Read This Book 11 1.7 Language and Sex Ratios 12 Chapter 2: The Dusing-Fisher Theory of Equal Investment 14 2.1 Introduction 14 2.2 Fisher's Theory of Equal Investment 15 2.3 Darwin to Today 16 2.4 Differential Mortality 19 2.5 Testing Fisher's Theory 20 2.6 Conclusions and Future Directions 31 Chapter 3: Interactions between Relatives I: Cooperation and Competition 33 3.1 Introduction 33 3.2 Basic Theory 34 3.3 Local Resource Enhancement 40 3.4 Local Resource Competition 53 3.5 Conclusions and Future Directions 69 Chapter 4: Interactions between Relatives II: Local Mate Competition 73 4.1 Introduction 73 4.2 Classic Local Mate Competition Theory 74 4.3 Empirical Tests of Local Mate Competition Theory across Populations or Species 83 4.4 Facultative Adjustment of Offspring Sex Ratios by Individuals 93 4.5 Conclusions and Future Directions 107 Chapter 5: Interactions between Relatives III: Extended Local Mate Competition Theory 109 5.1 Introduction 109 5.2 Partial LMC 110 5.3 Variable Clutch Size 116 5.4 Sibmating and Split Sex Ratios in Haplodiploids 131 5.5 Inbreeding Depression 134 5.6 Limited Dispersal and Relatedness between Foundress Females 136 5.7 Haystacks 140 5.8 Asymmetrical Larval Competition 143 5.9 Fertility Insurance 143 5.10 Variance and Precision 151 5.11 Other Population Structures 154 5.12 Stochasticity 155 5.13 Conclusions and Future Directions 156 Chapter 6: Conditional Sex Allocation I: Basic Scenarios 162 6.1 Introduction 162 6.2 Theory 165 6.3 Solitary Parasitoid Wasps and Host Size 167 6.4 Maternal Quality in Ungulates 174 6.5 Maternal Quality and Related Factors in Nonungulates 182 6.6 Mate Attractiveness in Birds and Lizards 187 6.7 Environmental Sex Determination 191 6.8 Sex Change 198 6.9 Conclusions and Future Directions 205 Chapter 7: Conditional Sex Allocation II: Population Consequences and Further Complications 210 7.1 Introduction 210 7.2 Population-Level Patterns 211 7.3 Sex Change Complications 225 7.4 ESD Complications, Especially in Reptiles 243 7.5 Multiple Selective Forces: LMC and Host Size in Parasitoid Wasps 251 7.6 Simultaneous Hermaphrodites 254 7.7 Conclusions and Future Directions 255 Chapter 8: Sex Allocation When Generations Overlap 257 8.1 Introduction 257 8.2 Exceptional Mortality 258 8.3 Exceptional Recruitment 263 8.4 Cyclical Models 265 8.5 Conclusions and Future Directions 273 Chapter 9: Conflict I: Between Individuals 276 9.1 Introduction 276 9.2 Conflict under Fisherian Selection 277 9.3 Conflict under LMC, LRC, and LRE 278 9.4 Sibling Conflict in Haplodiploids and Single-Sex Broods 281 9.5 Polyembryonic Parasitoids 282 9.6 Sex Allocation Conflicts in the Eusocial Hymenoptera 287 9.7 Conclusions and Future Directions 311 Chapter 10: Conflict II: Sex Allocation Distorters 316 10.1 Introduction 316 10.2 Classification of Sex Ratio Distorters 317 10.3 Case Studies 329 10.4 Consequences of Sex Ratio Distorters 344 10.5 Conclusions and Future Directions 351 Chapter 11: General Issues 353 11.1 Introduction 353 11.2 The Success of Sex Allocation 354 11.3 The Use of Sex Allocation 355 11.4 Outstanding Problems 375 References 379 Index 463

Stuart West is professor of evolutionary biology at the University of Oxford.

"Understanding mating strategies and the allocation of resources to male versus female reproduction has long been a major goal of evolutionary studies. In this comprehensive synthesis, West makes several important contributions to the field of evolutionary biology... Because the work primarily focuses on how natural selection shapes sex allocation for given sex determination systems, sex allocation is proven an important phenomenon for studying adaptation. This thorough conceptual perspective, blending theory and data, summarizes sex allocation theory and how different areas are applied to different organisms."--Choice "After reading this book, I now have greater confidence in my understanding of where this field stands and where future research would most profitably be directed. This book will unquestionably benefit students and professional scientists who are seeking either a basic introduction to sex allocation biology or a comprehensive sourcebook that integrates the major issues of the field. Additionally, this book would serve as an excellent resource for specialized graduate-level courses in evolutionary biology. Overall, this is an outstanding and comprehensive book that extends beyond the topic of sex allocation and is an essential tool for anyone with a serious interest in behavioral or evolutionary ecology."--Daniel A. Warner, Integrative and Comparative Biology "[T]his book is worth taking the time to read and think about whether you are new to the field of sex allocation, think you know it all already, or are mainly interested in the evolution of other social and reproductive traits. It might influence the way you think about your own research and if nothing else you will learn some cool facts about the impressive subtleties of sex allocation in the natural world."--Suzanne H. Alonzo, Evolution

• Acknowledgments xi Chapter 1: Sex Allocation 1 1.1 What Is Sex Allocation? 1 1.2 A Potted History 2 1.3 Why Is This Book Needed? 8 1.4 What Is in This Book 8 1.5 What Is Not in This Book 10 1.6 How To Read This Book 11 1.7 Language and Sex Ratios 12 Chapter 2: The Dusing-Fisher Theory of Equal Investment 14 2.1 Introduction 14 2.2 Fisher's Theory of Equal Investment 15 2.3 Darwin to Today 16 2.4 Differential Mortality 19 2.5 Testing Fisher's Theory 20 2.6 Conclusions and Future Directions 31 Chapter 3: Interactions between Relatives I: Cooperation and Competition 33 3.1 Introduction 33 3.2 Basic Theory 34 3.3 Local Resource Enhancement 40 3.4 Local Resource Competition 53 3.5 Conclusions and Future Directions 69 Chapter 4: Interactions between Relatives II: Local Mate Competition 73 4.1 Introduction 73 4.2 Classic Local Mate Competition Theory 74 4.3 Empirical Tests of Local Mate Competition Theory across Populations or Species 83 4.4 Facultative Adjustment of Offspring Sex Ratios by Individuals 93 4.5 Conclusions and Future Directions 107 Chapter 5: Interactions between Relatives III: Extended Local Mate Competition Theory 109 5.1 Introduction 109 5.2 Partial LMC 110 5.3 Variable Clutch Size 116 5.4 Sibmating and Split Sex Ratios in Haplodiploids 131 5.5 Inbreeding Depression 134 5.6 Limited Dispersal and Relatedness between Foundress Females 136 5.7 Haystacks 140 5.8 Asymmetrical Larval Competition 143 5.9 Fertility Insurance 143 5.10 Variance and Precision 151 5.11 Other Population Structures 154 5.12 Stochasticity 155 5.13 Conclusions and Future Directions 156 Chapter 6: Conditional Sex Allocation I: Basic Scenarios 162 6.1 Introduction 162 6.2 Theory 165 6.3 Solitary Parasitoid Wasps and Host Size 167 6.4 Maternal Quality in Ungulates 174 6.5 Maternal Quality and Related Factors in Nonungulates 182 6.6 Mate Attractiveness in Birds and Lizards 187 6.7 Environmental Sex Determination 191 6.8 Sex Change 198 6.9 Conclusions and Future Directions 205 Chapter 7: Conditional Sex Allocation II: Population Consequences and Further Complications 210 7.1 Introduction 210 7.2 Population-Level Patterns 211 7.3 Sex Change Complications 225 7.4 ESD Complications, Especially in Reptiles 243 7.5 Multiple Selective Forces: LMC and Host Size in Parasitoid Wasps 251 7.6 Simultaneous Hermaphrodites 254 7.7 Conclusions and Future Directions 255 Chapter 8: Sex Allocation When Generations Overlap 257 8.1 Introduction 257 8.2 Exceptional Mortality 258 8.3 Exceptional Recruitment 263 8.4 Cyclical Models 265 8.5 Conclusions and Future Directions 273 Chapter 9: Conflict I: Between Individuals 276 9.1 Introduction 276 9.2 Conflict under Fisherian Selection 277 9.3 Conflict under LMC, LRC, and LRE 278 9.4 Sibling Conflict in Haplodiploids and Single-Sex Broods 281 9.5 Polyembryonic Parasitoids 282 9.6 Sex Allocation Conflicts in the Eusocial Hymenoptera 287 9.7 Conclusions and Future Directions 311 Chapter 10: Conflict II: Sex Allocation Distorters 316 10.1 Introduction 316 10.2 Classification of Sex Ratio Distorters 317 10.3 Case Studies 329 10.4 Consequences of Sex Ratio Distorters 344 10.5 Conclusions and Future Directions 351 Chapter 11: General Issues 353 11.1 Introduction 353 11.2 The Success of Sex Allocation 354 11.3 The Use of Sex Allocation 355 11.4 Outstanding Problems 375 References 379 Index 463

Stuart West is professor of evolutionary biology at the University of Oxford.

"Understanding mating strategies and the allocation of resources to male versus female reproduction has long been a major goal of evolutionary studies. In this comprehensive synthesis, West makes several important contributions to the field of evolutionary biology... Because the work primarily focuses on how natural selection shapes sex allocation for given sex determination systems, sex allocation is proven an important phenomenon for studying adaptation. This thorough conceptual perspective, blending theory and data, summarizes sex allocation theory and how different areas are applied to different organisms."--Choice "After reading this book, I now have greater confidence in my understanding of where this field stands and where future research would most profitably be directed. This book will unquestionably benefit students and professional scientists who are seeking either a basic introduction to sex allocation biology or a comprehensive sourcebook that integrates the major issues of the field. Additionally, this book would serve as an excellent resource for specialized graduate-level courses in evolutionary biology. Overall, this is an outstanding and comprehensive book that extends beyond the topic of sex allocation and is an essential tool for anyone with a serious interest in behavioral or evolutionary ecology."--Daniel A. Warner, Integrative and Comparative Biology "[T]his book is worth taking the time to read and think about whether you are new to the field of sex allocation, think you know it all already, or are mainly interested in the evolution of other social and reproductive traits. It might influence the way you think about your own research and if nothing else you will learn some cool facts about the impressive subtleties of sex allocation in the natural world."--Suzanne H. Alonzo, Evolution

• Acknowledgments xi Chapter 1: Sex Allocation 1 1.1 What Is Sex Allocation? 1 1.2 A Potted History 2 1.3 Why Is This Book Needed? 8 1.4 What Is in This Book 8 1.5 What Is Not in This Book 10 1.6 How To Read This Book 11 1.7 Language and Sex Ratios 12 Chapter 2: The Dusing-Fisher Theory of Equal Investment 14 2.1 Introduction 14 2.2 Fisher's Theory of Equal Investment 15 2.3 Darwin to Today 16 2.4 Differential Mortality 19 2.5 Testing Fisher's Theory 20 2.6 Conclusions and Future Directions 31 Chapter 3: Interactions between Relatives I: Cooperation and Competition 33 3.1 Introduction 33 3.2 Basic Theory 34 3.3 Local Resource Enhancement 40 3.4 Local Resource Competition 53 3.5 Conclusions and Future Directions 69 Chapter 4: Interactions between Relatives II: Local Mate Competition 73 4.1 Introduction 73 4.2 Classic Local Mate Competition Theory 74 4.3 Empirical Tests of Local Mate Competition Theory across Populations or Species 83 4.4 Facultative Adjustment of Offspring Sex Ratios by Individuals 93 4.5 Conclusions and Future Directions 107 Chapter 5: Interactions between Relatives III: Extended Local Mate Competition Theory 109 5.1 Introduction 109 5.2 Partial LMC 110 5.3 Variable Clutch Size 116 5.4 Sibmating and Split Sex Ratios in Haplodiploids 131 5.5 Inbreeding Depression 134 5.6 Limited Dispersal and Relatedness between Foundress Females 136 5.7 Haystacks 140 5.8 Asymmetrical Larval Competition 143 5.9 Fertility Insurance 143 5.10 Variance and Precision 151 5.11 Other Population Structures 154 5.12 Stochasticity 155 5.13 Conclusions and Future Directions 156 Chapter 6: Conditional Sex Allocation I: Basic Scenarios 162 6.1 Introduction 162 6.2 Theory 165 6.3 Solitary Parasitoid Wasps and Host Size 167 6.4 Maternal Quality in Ungulates 174 6.5 Maternal Quality and Related Factors in Nonungulates 182 6.6 Mate Attractiveness in Birds and Lizards 187 6.7 Environmental Sex Determination 191 6.8 Sex Change 198 6.9 Conclusions and Future Directions 205 Chapter 7: Conditional Sex Allocation II: Population Consequences and Further Complications 210 7.1 Introduction 210 7.2 Population-Level Patterns 211 7.3 Sex Change Complications 225 7.4 ESD Complications, Especially in Reptiles 243 7.5 Multiple Selective Forces: LMC and Host Size in Parasitoid Wasps 251 7.6 Simultaneous Hermaphrodites 254 7.7 Conclusions and Future Directions 255 Chapter 8: Sex Allocation When Generations Overlap 257 8.1 Introduction 257 8.2 Exceptional Mortality 258 8.3 Exceptional Recruitment 263 8.4 Cyclical Models 265 8.5 Conclusions and Future Directions 273 Chapter 9: Conflict I: Between Individuals 276 9.1 Introduction 276 9.2 Conflict under Fisherian Selection 277 9.3 Conflict under LMC, LRC, and LRE 278 9.4 Sibling Conflict in Haplodiploids and Single-Sex Broods 281 9.5 Polyembryonic Parasitoids 282 9.6 Sex Allocation Conflicts in the Eusocial Hymenoptera 287 9.7 Conclusions and Future Directions 311 Chapter 10: Conflict II: Sex Allocation Distorters 316 10.1 Introduction 316 10.2 Classification of Sex Ratio Distorters 317 10.3 Case Studies 329 10.4 Consequences of Sex Ratio Distorters 344 10.5 Conclusions and Future Directions 351 Chapter 11: General Issues 353 11.1 Introduction 353 11.2 The Success of Sex Allocation 354 11.3 The Use of Sex Allocation 355 11.4 Outstanding Problems 375 References 379 Index 463