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),快速适应是入侵种群的常见特征，且对其长期存续至关重要。入侵物种在新定殖区域的选择压力主要作用于现存遗传变异（standing genetic variation）。因此，遗传漂变与作用于现存变异的自然选择，是入侵物种短期内演化的核心进化过程。本研究以欧洲入侵的浣熊（*Procyon lotor*）为研究对象，旨在解析入侵过程中塑造免疫基因多样性的演化力量。在入侵区域中，新型病原体大概率会出现，因此参与抗感染免疫的基因将承受强烈的选择压力。为厘清塑造其入侵与扩张种群适应性免疫多样性的选择与种群历史过程，我们开发了靶向免疫相关基因编码区的物种特异性单核苷酸多态性（Single Nucleotide Polymorphism, SNP）标记。我们对110个功能重要的免疫基因的遗传多样性进行了表征……相关方法已在本文及补充材料中详细阐述（https://doi.org/10.1111/eva.13517）