How and Why Species Multiply

List of Illustrations xi List of Tables xv Preface xvii CHAPTER ONE: The Biodiversity Problem and Darwin's Finches 1 Biodiversity 1 The Choice of Organisms 2 Darwin's Finches 3 Diversity of Darwin's Finch Species 5 Species and Populations 8 Overview of the Book 11 CHAPTER TWO: Origins and History 13 Introduction 13 Phylogeny 14 Ancestors 16 The Time of Arrival 16 Colonization 17 The Ecological Theater 18 A Change of Scenery 21 The Evolutionary Play 22 Recent History 22 Summary 25 CHAPTER THREE: Modes of Speciation 26 The Formation of New Species 26 Two Groups from One 27 Divergence in Allopatry 28 Coexistence in Sympatry 29 Sympatric Speciation 30 Parapatric Speciation 31 Testing the Models 33 Summary 33 CHAPTER FOUR: Colonization of an Island 35 Speciation: The Initial Split 35 Establishment of a New Population 35 Founder Effects: Expectations from Theory 36 A Colonization Event 38 Inbreeding 39 Recurrent Immigration 39 An Alternative Phenology of Founder Effects 42 Conclusion 42 Species Elsewhere 44 Summary 45 CHAPTER FIVE: Natural Selection, Adaptation, and Evolution 46 Adaptation 46 Beak Sizes and Diets 47 Adaptive Evolution When the Environment Changes 50 Natural Selection 52 Evolution 54 Oscillating Directional Selection 55 Extrapolating from Short to Long Term 58 The Sources of Variation 58 How Beaks Are Formed 59 Depth and Width 59 Length 62 Summary 63 CHAPTER SIX: Ecological Interactions 65 Introduction 65 Competition 66 Patterns of Coexistence 66 Diets Inferred from Beaks 67 Interpreting the Patterns 67 Character Displacement and Release 68 Character Displacement Observed 68 The Competitive Role of G. Magnirostris 69 Selection under Contrasting Conditions 73 Evolution of Character Displacement 73 Summary 75 CHAPTER SEVEN: Reproductive Isolation 76 Pre-mating Barrier to Interbreeding 76 Factors Involved in the Discrimination between Species 76 Beaks 77 Song 77 Learning 79 Song Differences between Species 80 Song Divergence in Allopatry 81

Peter R. Grant and B. Rosemary Grant are professors emeriti at Princeton University. In recognition of their decades of work studying the ecology, behavior, genetics, and evolution of Darwin's Finches, they were awarded the 2005 Balzan Prize and the 2009 Kyoto Prize.

"One of the most compelling documentations of the operation of natural selection. In this book, the Grants aim to capture the key insights provided by Darwin's finches into mechanisms of adaptation and speciation generally. They succeed in making a complex topic accessible without losing the excitement inherent in tackling a difficult problem. There is enough depth to stimulate serious students of evolutionary biology, enough explanation for general readers and an approachable style that will please both."--Roger Butlin, Times Higher Education