Performance limits on birdsong
This chapter aims to explore how recent advances in our understanding of vocal production mechanisms might inform our understanding of the evolution of bird vocalizations. Analysis of the relationship between mechanism and evolution in biology has a venerable history of morphological systems, but this approach has been applied to animal behavior only sporadically. In animal behavior, proximate mechanisms such as those concerned with development, control, and mechanics can shape evolution by imposing constraints or biases on the direction or magnitude of evolutionary change. The first section of the chapter focuses on the morphology and function of the avian vocal "instrument." The central message is that vocal mechanisms are limited in their potential, and thus the vocal apparatus circumscribes the range of sounds birds can and cannot produce. The second section examines three specific examples: the evolution of species diversity in the Passeriformes (the largest taxonomic grouping of birds); the evolution of vocal novelty in one songbird, the swamp sparrow; and the relationship between morphological evolution and vocal diversity in Darwin's finches. With these examples, the chapter illustrates some of the ways by which mechanisms of vocal production influence patterns of vocal diversity in birds. © 2004 Elsevier Inc. All rights reserved.
