Department of Botany and Zoology, Stellenbosch University, Stellenbosch, South Africa.
Departamento de Biodiversidad, Ecología y Evolución, Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Ciudad Universitaria, Madrid, Spain.
Mol Ecol. 2022 Mar;31(6):1649-1665. doi: 10.1111/mec.16045. Epub 2021 Jul 7.
The link between the successful establishment of alien species and propagule pressure is well-documented. Less known is how humans influence the post-introduction dynamics of invasive alien populations. The latter requires studying parallel invasions by the same species in habitats that are differently impacted by humans. We analysed microsatellite and genome size variation, and then compared the genetic diversity and structure of invasive Poa annua L. on two sub-Antarctic islands: human-occupied Marion Island and unoccupied Prince Edward Island. We also carried out niche modelling to map the potential distribution of the species on both islands. We found high levels of genetic diversity and evidence for extensive admixture between genetically distinct lineages of P. annua on Marion Island. By contrast, the Prince Edward Island populations showed low genetic diversity, no apparent admixture, and had smaller genomes. On both islands, high genetic diversity was apparent at human landing sites, and on Marion Island, also around human settlements, suggesting that these areas received multiple introductions and/or acted as initial introduction sites and secondary sources (bridgeheads) for invasive populations. More than 70 years of continuous human activity associated with a meteorological station on Marion Island led to a distribution of this species around human settlements and along footpaths, which facilitates ongoing gene flow among geographically separated populations. By contrast, this was not the case for Prince Edward Island, where P. annua populations showed high genetic structure. The high levels of genetic variation and admixture in P. annua facilitated by human activity, coupled with high habitat suitability on both islands, suggest that P. annua is likely to increase its distribution and abundance in the future.
成功建立外来物种与繁殖体压力之间存在关联，这一点已有充分记录。而人类如何影响入侵外来种群的引入后动态则鲜为人知。后者需要研究同一物种在受人类影响不同的生境中的平行入侵。我们分析了微卫星和基因组大小的变异，然后比较了两个亚南极岛屿（有人居住的马里恩岛和无人居住的爱德华王子岛）上入侵的 Poa annua L. 的遗传多样性和结构。我们还进行了生态位建模，以绘制该物种在两个岛屿上的潜在分布。我们发现，P. annua 的遗传多样性水平很高，并且存在明显的遗传分化谱系之间的广泛混合。相比之下，爱德华王子岛的种群遗传多样性较低，没有明显的混合，并且基因组较小。在两个岛屿上，人类登陆点的遗传多样性都很高，在马里恩岛上，人类住区周围也是如此，这表明这些地区多次受到引入和/或作为入侵种群的初始引入点和次要来源（桥头堡）。马里恩岛上一个气象站 70 多年来的持续人类活动导致该物种在人类住区周围和步道沿线分布，这有助于地理上分离的种群之间持续的基因流。相比之下，爱德华王子岛并非如此，P. annua 种群的遗传结构很高。人类活动促成了 P. annua 高水平的遗传变异和混合，再加上两个岛屿上的高栖息地适宜性，表明 P. annua 未来很可能会增加其分布和丰度。
