Evolution of resistance by a native competitor can lead to invasion collapse in disease-mediated invasions

Invasive species are often able to establish and spread with the help of diseases they bring that can infect native competitors. But sometimes, seemingly successful invasions, in which the invasive species may reach high densities, suddenly collapse, with abrupt decline and extinction of the invader. Diseases have been implicated in invasion collapses, though the underlying mechanism accounting for the entire invasion arc is unresolved. In this study, we simulated a disease-mediated invasion (DMI) by constructing a susceptible-infected-susceptible model for infection and population dynamics of a native and an invasive species. We found that when a competitively dominant native species became an inferior competitor due to infection with the invader’s disease, the native population could often withstand replacement and could sometimes reverse the invasion by evolving an effective disease defense—a resistance-driven evolutionary rebound leading to invasion collapse. The collapse pattern depended on a lag between the disease advance and the invader advance, creating a region of time and space in which the native populations contended only with the disease, evolving disease resistance before confronting the competing invader. We determined the biological conditions and spatial scale in which a DMI may end in evolutionary rebound and collapse, and we present testable predictions for DMI community dynamics.