Predicting and quantifying coexistence outcomes between resident and invading species using trait and abundance data

A major challenge in invasion ecology is determining which introduced species pose a threat to resident species through competitive displacement. Here, we provide a statistical framework rooted in coexistence theory to calculate coexistence outcomes - including competitive displacement - between resident and invading species. Advantageously, our framework uses readily available trait and abundance data rather than the demographic data traditionally used in coexistence theory applications which is often difficult to collect for most species. Our framework provides methods for predicting displacement that has yet to manifest in incipient invasions, and for quantifying displacement in ongoing invasions. We apply this framework to the native and introduced gecko species on Curacao and predict the displacement of all three native species by introduced species and quantify that the displacement of one native species is already underway. Our results affirm that trait and abundance data are suitable proxies to reasonably predict and quantify coexistence outcomes.