Abstract
Vocal learning ability has evolved in a limited range of vertebrates, including some lineages of birds, bats, and whales. In birds, vocal learning contributes to the development of song, which is related to reproductive context. Birdsong is regarded as a sexual trait acquired through sexual selection. Generally, only male birds produce songs, and females prefer to mate with males that have elaborate songs. If song is an honest indicator of male quality, it is adaptive for female birds to choose a mate based on his song performance. To shed light on the evolution of song learning, we review the literature for both phylogenetic studies that reconstruct the evolutionary patterns of song traits and studies of behavioral ecology that consider selection pressures by investigating the costs (e.g., developmental stress) of producing complex songs. Furthermore, we discuss the evolution of song in two songbird species, the white-rumped munia and its domesticated strain, the Bengalese finch. The two strains differ in morphology and song, probably because domestication has modified selection pressures.
