A way to test the Red Queen hypothesis?

Abstract: We investigated the hypothesis that body size evolution of mammals is strongly influenced by ecological interactions, resulting in evolutionary divergence in body size in species-rich (e.g. mainland) biotas, and convergence on the size of intermediate but absent species in species-poor (e.g. insular) biotas.
While body size evolution is likely to be influenced by a variety of characteristics of the focal islands (e.g. climate, area, isolation and habitat diversity) and species (e.g. diet, resource requirements and dispersal abilities), temporal trends for palaeo-insular mammals indicated that the observed trends for any particular species, island and climatic regime may be strongly influenced by interactions among species. Ultimately, invasion of a competitor often leads to the extinction of the native, insular species.