Signatures of differential local adaptation indicate climate matching with specific native-range habitats in invasive raccoons (Procyon lotor)

Invasive species pose a major threat to ecosystems through habitat destruction, disease transmission and competition for resources. Invasion success depends on the adaptive potential (i.e. the ability to respond to selection pressures that is dependent on the levels of genetic variation) of the invading species. Here, we used reduced representation sequencing of native and European invasive raccoon populations to identify putatively adaptive changes across geographic regions. Our findings indicate that invasive raccoon populations experienced a genome-wide reduction in genetic diversity; however, we detected putative signatures of selection that could be related to local adaptation within the invasive range. Analysis of candidate loci, associated with either native or invasive populations, revealed putative parallel selection pressures between the invasive range and one of the native populations, all inhabiting similar climatic and habitat niches. In contrast, the native population from a different climatic region experienced distinct selective pressures. These results highlight the importance of habitat similarity in invasion processes. They demonstrate that, when predicting the potential range of an invasive species, it is not only the geographic distribution of the native range that should be considered, but also the specific characteristics of the habitat. Candidate genomic regions were linked to traits that promote rapid expansion, including reproduction, cognitive function, stress response, immunity and energy production. Overall, this study illuminates how contemporary selection in raccoons may accelerate the invasion process.