Environmental factors and cultural drift influence song evolution in New World Sparrows

Variation in bird song is often assumed to be determined by sexual selection, rather than natural selection. However, most investigations to date have drawn their conclusions from a handful of species due to the challenges with manually processing sound data. Here, we use deep machine learning to investigate nearly all species of New World Sparrows. We leverage existing data to identify the processes that structure variation in bird song and to determine how this variation corresponds to patterns in genes and traits. Song variation in ~40% of species can be explained by environment, geography, and time. Across a community and global scale, the action of natural selection on the evolution of song is at least as impactful as it is on other genetically-determined traits.