Although oscine bird song is widely thought to have evolved under the influence of sexual selection, few studies have used phylogenetic comparative methods to investigate how these vocalizations have changed historically. In the present study, we use a molecular phylogeny based on mitochondrial sequence data to reconstruct vocal evolution in the oropendolas and caciques, an oscine group with diverse taxon-specific song patterns and a wide range in levels of sexual size dimorphism. Our reconstructions show that large changes in song organization and structure have occurred on branches of the phylogeny with relatively high levels of size dimorphism. The particular vocal components that changed, however, often differed in different phylogenetic lineages. These patterns indicate that sexual selection has had important influences on song evolution in these birds, but has targeted different components of song in different taxa. Our results provide insight into how sexual selection influences bird song and suggest directions for future research to uncover the behavioral mechanisms driving vocal evolution.
Bibliographical noteFunding Information:
We thank Andrea Priori at the Macaulay Library of Natural Sounds for assistance in obtaining song recordings, and the curators and staff at the following institutions for acquiring and loaning tissue samples: Academy of Natural Sciences Philadelphia, Field Museum of Natural History, Louisiana State University Museum of Natural Science, Smithsonian National Museum of Natural History, Smithsonian Tropical Research Institute, University of Kansas Museum of Natural History, and University of Washington Burke Museum. Jeff Podos, Elizabeth Price, Robert Zink, and three anonymous reviewers provided valuable comments on the manuscript. Financial support for this work was provided by the Bell Museum of Natural History.
- Behavioral evolution
- Independent contrasts
- Mating display
- New World blackbirds