Constraint and convergence in the evolution of vertebrate sound production.

Abstract

Understanding vertebrate sound production offers powerful insights into constraint and convergence in evolution. Sound production falls into two broad categories: muscle-driven and airflow-driven. Muscle-driven mechanisms, widespread among fish, are tightly limited by muscle contraction rates, producing lower-frequency signals that often radiate poorly. In contrast, airflow-driven mechanisms, especially those using myoelastic aerodynamic (MEAD) principles, overcome these limits, enabling long-distance communication across a vast frequency range. MEAD-based laryngeal sound production dominates in tetrapods and convergently evolved in novel vocal organs in birds and toothed whales-all supporting complex, long-distance communication and new acoustic niches. In this review, we show how physical and physiological constraints shaped convergent innovations, positioning MEAD as a central evolutionary strategy underlying the remarkable diversity of vertebrate sounds.