The diversity of animal signals has been widely documented, and the generality of animal signals also tantalizingly suggests that there are common mechanisms that have selected for their origin. However, while much progress has been made on some fronts, we still lack a general theory about why the diversity of signaling structures exist. Our compilation will directly address this gap by focusing on an exciting new arena of sexual selection, namely using functional approaches to understand signaling. This approach is rooted in the idea that many signals are designed to transmit important functional imformation that is both important for issues of male quality (and hence male competition), and female choice. The increasing use of technology in sexual selection studies has enabled researchers to test whether signaling is either constrained by, or accurately transmits information about functional capacities. Further, in animals that fight vigorously, functional capacities such as endurance or strength may make the difference between winning and losing.
This volume brings together a diverse collection of researchers who are actively investigating how function and signaling are related. These researchers use both a variety of methods and taxa to study animal signaling, and we believe that this integrative view is important to open up fresh vistas for why animal signals have evolved.
Contributors ix 1 INTRODUCTION 1 Duncan J. Irschick, Mark Briffa, and Jeffrey Podos References 7 2 EARLY LIFE-HISTORY EFFECTS, OXIDATIVE STRESS, AND THE EVOLUTION AND EXPRESSION OF ANIMAL SIGNALS 11 Nick J. Royle, Josephine M. Orledge, and Jonathan D. Blount Introduction 11 Signaling 12 Early Life-History Effects and Resource Allocation Trade-Offs 13 Oxidative Stress as a Mediator of Resource Allocation Trade-Offs 15 Signals Expressed During Development 20 Signals Expressed During Adulthood 25 Competition-Dependent Sexual Signals 32 Conclusions 34 Acknowledgments 36 References 36 3 A PERFORMANCE-BASED APPROACH TO STUDYING COSTS OF RELIABLE SIGNALS 47 Jerry F. Husak, Justin P. Henningsen, Bieke Vanhooydonck, and Duncan J. Irschick Introduction 47 Receiver-Independent Costs 51 Receiver-Dependent Costs 55 Compensatory Traits 59 Conclusions 63 Acknowledgments 64 References 65 4 COGNITIVELY DRIVEN CO-OPTION AND THE EVOLUTION OF COMPLEX SEXUAL DISPLAYS IN BOWERBIRDS 75 Gerald Borgia and Jason Keagy Introduction 75 Cognition, Co-Option, and Complex Display 78 Delayed Male Maturity, Male Male Courtship, and Display Trait Acquisition 81 Female Signaling to Affect Male Display Intensity: An Innovation that Improves Courtship Success 82 Mate Searching and Flexibility in Adaptive Decision-Making 83 Female Uncertainty and Flexibility in Active Mate Assessment 84 Long-Term Age-Related Improvement in Decoration Display: Symmetrical Decoration Displays on Older Males Bowers 84 Anticipation of Male Routes During Courtship: Paths on Display Courts of Spotted Bowerbirds 86 Some Other Possible Cognitive Display-Related Behaviors of Bowerbirds 87 Construction of Successive Scenes for Females Visiting the Bower 88 Cognitive Aspects of Bower Building: Age-Related Improvement in Construction and Novel Techniques for Maintaining Symmetry 90 Cognitive Flexibility and Innovation in Display 93 Decoration Stealing: An Innovation for Display Trait Acquisition 94 Cooperating with Relatives for Display: An Innovation to Reduce Sexual Competition 95 Vocal Mimicry: Learning and Innovation in Use of Co-Opted Displays 96 Co-Option Mechanism 98 Cognition in Display Trait Acquisition 100 References 101 5 INTEGRATING FUNCTIONAL AND EVOLUTIONARY APPROACHES TO THE STUDY OF COLOR-BASED ANIMAL SIGNALS 111 Darrell J. Kemp and Gregory F. Grether Introduction 111 Color Signal Production in More Detail 115 Signals, Honesty, and Condition-Dependence 116 Coloration as an Honest Advertisement 117 Trinidadian Guppies (Poecilia Reticulata) 118 Pierid Butterflies (Subfamily Coliadinae) 122 Birds 127 Discussion/Conclusion/Future Work 129 Acknowledgments 131 References 131 6 AGONISTIC SIGNALS: INTEGRATING ANALYSIS OF FUNCTIONS AND MECHANISMS 141 Mark Briffa Animal Contests and the Evolution of Agonistic Signals 141 Empirical Approaches to Testing Theory: Physiological Costs, Stamina, and Performance 154 Energy Status and Agonistic Signals 156 Whole Body Performance and Agonistic Signals 159 Conclusions 164 References 167 7 ACOUSTIC SIGNAL EVOLUTION: BIOMECHANICS, SIZE, AND PERFORMANCE 175 Jeffrey Podos and S.N. Patek Introduction 175 Biomechanics 178 Body Size 183 Performance 187 Concluding Remarks 194 Acknowledgments 195 References 195 8 DISHONEST SIGNALING DURING AGGRESSIVE INTERACTIONS: THEORY AND EMPIRICAL EVIDENCE 205 Robbie S. Wilson and Michael J. Angilletta Jr. Introduction 205 The Evolution of Signaling 206 The Theory of Dishonesty 208 Dishonest Signaling in Aggressive Interactions Between Conspecifics 209 Conclusions 223 References 223 9 FUNCTIONAL APPROACH TO CONDITION 229 Dustin J. Wilgers and Eileen A. Hebets Introduction 229 Practical Approaches to Condition 230 Condition and Animal Performance 235 Condition and Mate Choice 239 Summary 241 References 242 Index 253