Colony size as the main driver of the evolution of song diversity and composition in weaverbirds

Birdsong is a complex signal shaped by multiple factors and has been explored mostwidely through the lens of sexual selection, but with mixed results. Here, we focus onthe evolution of two song parameters, diversity, which is widely studied, andcomposition, which is poorly understood. We assessed the potential role of matingsystem as a proxy of sexual selection, but in addition, investigated whether colony size,a proxy of sociality, and phylogenetic history influence the evolution of theseparameters in weaverbirds family (Aves: Ploceidae). Using comparative and pathanalyses we find that, as expected, species living in larger colonies present greatersong diversity and had similar song composition. However, contrary to expectations,polygamous species do not present higher song diversity, nor more similar acousticcomposition than monogamous species. A relatively high effect of phylogeny wasdetected on both song variables. Our results thus suggest that, in this family, socialityis a stronger driver of song diversity and composition than sexual selection. Thesefindings highlight the importance of testing multiple factors when studying bird songevolution and the relevance of sociality.