Data and code from: Disentangling the evolutionary cause-effect relationships of environment, sexual selection and body size with birdsong frequency

This project integrates a large comparative dataset and phylogenetic information to study the evolution of birdsong across 472 Neotropical passerine species. The dataset includes acoustic, morphological, and ecological variables (birdsong_data.csv), additional model coefficients (coefficients-1.csv), and 100 phylogenetic trees (birdstrees_100_McTavish.nex). An accompanying R script (Code_PPA_birdsong-evolution.r) performs all analyses, model selection, and figure generation. Using these data, the study employs Phylogenetic Path Analysis to test causal relationships among habitat structure, sexual dimorphism, morphology, and song frequency parameters. Across all phylogenies, a single causal structure was consistently supported. The analyses show that greater tree cover increases minimum, peak, and maximum song frequencies, while bandwidth remains unaffected. Sexual dimorphism decreases bandwidth and influences frequency values, whereas morphological traits impose biomechanical constraints on song frequencies and shape bandwidth differently. Habitat structure and sexual dimorphism also affect morphological traits, producing additional indirect pathways that influence birdsong. Furthermore, tree cover itself impacts sexual dimorphism, embedding it within a broader causal network. Together, the dataset and analyses reveal that the evolution of birdsong emerges from interacting environmental, sexual, and morphological forces. The results support key hypotheses—including acoustic adaptation, sexual selection, and morphological constraints—and demonstrate that trait evolution is best understood through multicausal and phylogenetically informed models, rather than simple linear associations.