Complex patterns shape immune genes diversity during invasion of common raccoon in Europe – selection in action despite genetic drift

Rapid adaptation is common in invasive populations and is crucial to their long-term success. The primary target of selection in the invasive species’ new range is standing genetic variation. Therefore, genetic drift and natural selection acting on existing variation are key evolutionary processes through which invaders will evolve over a short timescale. In this study, we used the case of the raccoon Procyon lotor invasion in Europe to identify the forces shaping the diversity of immune genes during invasion. The genes involved in the defence against infection should be under intense selection pressure in the invasive range where novel pathogens are expected to occur. To disentangle the selective and demographic processes shaping the adaptive immune diversity of its invasive and expanding populations, we have developed species-specific SNP markers located in the coding regions of targeted immune-related genes. We characterised the genetic diversity of 110 functionally important immune ..., The methods were described in detail in the article and the supplementary files (https://doi.org/10.1111/eva.13517),