Echolocation call divergence in bats: a comparative analysis

Animal vocalizations experience pressures from ecological conditions, but their diversification may be constrained by morphology and evolutionary history. To date, the relative contribution of these factors to acoustic diversity is unclear in most vertebrate groups. Bats constitute one of the most speciose and diverse mammal groups, and most bat species rely on vocalizations for orientation, foraging, and communication. Here, we examine echolocation calls of 207 bat species across 17 families to weigh the relative role of phylogenetic inertia, natural selection, and morphological constraints in shaping echolocation call diversity in bats. Using the large dataset, we confirm that foraging guilds, phylogenetic relationships, and forearm length account for the majority of the variation in call parameters among bats. Foraging guilds play a major role in influencing call parameters in low duty cycle bats. At the family level, the variation in call parameters is primarily explained by differences in body size and phylogenetic relationships. Path analyses indicate that phylogeny determines call output not only by their direct effect on call parameters but also by having an indirect effect via foraging guilds and body size. These results demonstrate that natural selection, phylogenetic constraint, and morphological constraint shape echolocation call divergence in bats. Our findings underscore the importance of both adaptive and non-adaptive mechanisms underlying the evolution of echolocation calls in bats.