Data from: Shared genetic diversity across the global invasive range of the Monk parakeet suggests a common restricted geographic origin and the possibility of convergent selection

While genetic diversity is hypothesized to be an important factor explaining invasion success, there is no consensus yet on how variation in source populations or demographic processes affect invasiveness. We used mtDNA and microsatellites to investigate genetic patterns and reconstruct the history of replicate invasions on three continents in a globally invasive bird, the monk parakeet (Myiopsitta monachus). We evaluated whether genetic diversity at invasive sites could be explained by (1) the native source populations from which they were derived, and (2) demographic bottlenecks during introduction. Genetic data indicated a localized source area for most sampled invasive populations, with limited evidence for admixing of native source populations. This pattern largely coincides with historical data on pet-trade exports. However, the invasive populations are genetically more similar than predicted from the export data alone. The extent of bottleneck effects varied among invasive populations. The low genetic diversity, evidence of demographic contraction and restricted source area observed do not support the hypothesis that invasion is favored by the mixing and recombining of genetic variation from multiple source populations. Instead, they suggest that reduced genetic variation through random processes may not inhibit successful establishment and invasion in this species. However, convergent selection across invasive sites could also explain the observed patterns of reduction and similarity in genetic variation and/or the restricted source area. In general, the alternative explanation of intraspecific variation in invasive potential among genotypes or geographic areas is neglected but warrants more attention as it could inform comparative studies and management of biological invaders.

尽管遗传多样性被假设为解释入侵成功的关键因素，但学界目前对于源种群变异或种群统计过程如何影响入侵性尚未达成共识。本研究以全球入侵鸟类和尚鹦鹉（Myiopsitta monachus）为研究对象，利用线粒体DNA（mtDNA）和微卫星标记，探究其遗传模式，并重建其在三大洲的多批次入侵历史。本研究评估了入侵位点的遗传多样性是否可由以下两个因素解释：(1) 其起源的本土源种群；(2) 引种过程中发生的种群瓶颈效应。遗传数据分析显示，多数被采样的入侵种群具有局限的源种群区域，且鲜有证据表明其存在本土源种群的遗传混合。这一模式与宠物贸易出口的历史记录大体相符。但相较仅基于出口数据的预测结果，入侵种群间的遗传相似性更高。不同入侵种群的瓶颈效应程度存在差异。本研究观测到的低遗传多样性、种群收缩迹象以及源种群区域受限的结果，并不支持"多个源种群的遗传变异混合与重组可促进入侵"这一假说。反之，研究结果表明，由随机过程导致的遗传多样性降低，未必会阻碍该物种的成功定殖与入侵。不过，入侵位点间的趋同选择，同样可以解释观测到的遗传变异降低与相似性模式，以及源种群区域受限的现象。总体而言，"不同基因型或地理区域的入侵潜能存在种内变异"这一替代性解释常被忽视，但该方向值得更多关注——其研究结果可为入侵生物的比较研究与管理工作提供参考。