The article "Complex Signal Function: Developing a Framework of Testable Hypotheses" by Eileen Hebets and Daniel R. Papaj explores the evolution and function of complex animal signals, which often involve multiple components and modalities. The authors argue that past research has often focused on single signals or sensory specialists, neglecting the complexity of many animal displays. They propose a framework for understanding the evolution of complex signals, distinguishing between content-driven (ultimate) and efficacy-driven (proximate) selection pressures. The framework includes hypotheses such as multiple messages, redundant signals, and inter-signal interactions, each addressing different aspects of signal function. The article also discusses empirical approaches to studying complex signal function and highlights the importance of considering both content and efficacy in the evolution of complex signaling. Examples from various animal systems, including courtship displays, warning signals, and multimodal signaling, are provided to illustrate the application of these hypotheses. The authors emphasize the need for a comprehensive framework to integrate and advance research on complex signal function.The article "Complex Signal Function: Developing a Framework of Testable Hypotheses" by Eileen Hebets and Daniel R. Papaj explores the evolution and function of complex animal signals, which often involve multiple components and modalities. The authors argue that past research has often focused on single signals or sensory specialists, neglecting the complexity of many animal displays. They propose a framework for understanding the evolution of complex signals, distinguishing between content-driven (ultimate) and efficacy-driven (proximate) selection pressures. The framework includes hypotheses such as multiple messages, redundant signals, and inter-signal interactions, each addressing different aspects of signal function. The article also discusses empirical approaches to studying complex signal function and highlights the importance of considering both content and efficacy in the evolution of complex signaling. Examples from various animal systems, including courtship displays, warning signals, and multimodal signaling, are provided to illustrate the application of these hypotheses. The authors emphasize the need for a comprehensive framework to integrate and advance research on complex signal function.