Diversity-dependent effects probably influenced the diversification of species-rich crown ant subfamilies during the Cenozoic

Abstract Disentangling the influence of biotic interactions from abiotic environmental changes is a central challenge in macroevolution. While ants’ evolutionary history has been widely studied, often in relation to abiotic factors or plant associations, the role of intra- and inter-lineage interactions, whether competitive or facilitative, remains poorly understood. In this study, we use birth–death models within a Bayesian framework, integrating fossil and extant data, to investigate how interactions between the five most species-rich crown ant subfamilies may have shaped their diversification during the Cenozoic. Our results suggest that negative intraclade interactions within Dolichoderinae, Dorylinae, Formicinae and Ponerinae probably affected their diversification. We detect a signal of interactions between Formicinae and Myrmicinae and Dolichoderinae and Dorylinae, possibly reflecting long-term co-evolutionary dynamics. Notably, contrary to earlier hypotheses suggesting competition between Ponerinae and Myrmicinae, our results indicate a facilitative interaction between these two groups, but also between Formicinae and Dolichoderinae and Ponerinae and Myrmicinae, suggesting that coexistence sometimes promotes rather than inhibits diversification. Overall, our study provides the first assessment of diversity-dependent effects on the evolutionary history of ants, establishing biotic interactions as a fundamental and quantifiable force in shaping macroevolutionary patterns of one of Earth’s most successful animal groups.