Ecological and spatial overlap indicate interspecific competition during North American Canid radiation.

Abstract

Understanding biodiversity patterns and the processes that generate them are key goals in macroevolutionary studies. Diversity-dependent models of diversification have been used to indirectly infer the relevance of interspecific competition on diversification dynamics. In this study, we develop a new approach that more explicitly incorporates spatial and eco-morphological overlap among species to test how interspecific competition may affect diversification dynamics in deep time. We build different metrics that capture temporal and spatial coexistence, and ecological overlap to test the hypothesis that an increase in the intensity of competition would result in a decrease in speciation and an increase in extinction rate. We test our predictions using the fossil record of North American canids, a group that has been extensively studied and well characterized both ecologically and from a paleontological point of view. We find that interspecific competition only affected diversification dynamics during the early stages of the radiation of canids, resulting in the suppression of speciation rate at the time the clade was expanding in diversity. We find no association between the intensity of the competition and extinction dynamics, nor an association between changes in diversification dynamics and changes in temperature. We discuss the relevance of different factors on driving diversification dynamics changes over time and how evaluating the role of interspecific competition using different metrics that better capture the intensity of competition (as opposed to diversity dependent models) might be a way forward to investigate the role of biotic interactions at deep time.