| dc.description.abstract | Modern-day birdsong is exceptionally diverse, with each of over 4,000 extant songbird species effectively singing a unique and recognizable song. Since song is a learned behavior, its evolutionary dynamics may be complex and encompass cultural transmission as well as classical natural and sexual selection on both song itself and related genetically heritable traits. Researchers have long posited that certain life history traits might have influenced how song has changed throughout evolutionary history. Here, I investigate the interacting forces of sexual selection and the learning process and how both forces influence the evolution of song features associated with more difficult performance or greater complexity. I use phylogenetic comparative methods to show that polygyny in songbird ancestral history drives faster evolution of song complexity, tending away from extremely simple or extremely complex songs. Using similar methods, I demonstrate that an extended duration of song plasticity is correlated with greater song complexity. Finally, I assemble a large-scale database of community-science recordings for two species of songbirds in a region that recently experienced an extremely abnormal drought. Through analysis of these data, I test a novel hypothesis that links environmental changes to cultural evolution via impaired learning and present evidence that drought stress may significantly perturb song at the population level. | |
