Data from: Long live the alien: is high genetic diversity a pivotal aspect of crested porcupine (Hystrix cristata) long-lasting and successful invasion?

Studying the evolutionary dynamics of an alien species surviving and
continuing to expand after several generations can provide fundamental
information on the relevant features of clearly successful invasions.
Here, we tackle this task by investigating the dynamics of the genetic
diversity in invasive crested porcupine (Hystrix cristata) populations,
introduced to Italy about 1500 years ago, which are still growing in size,
distribution range and ecological niche. Using genome-wide RAD markers, we
describe the structure of the genetic diversity and the demographic
dynamics of the H. cristata invasive populations and compare their genetic
diversity with that of native African populations of both H. cristata and
its sister species, H. africaeaustralis. First, we demonstrate that
genetic diversity is lower in both the invasive Italian and the North
Africa source range relative to other native populations from sub-Saharan
and South Africa. Second, we find evidence of multiple introduction events
in the invasive range followed by very limited gene flow. Through
coalescence-based demographic reconstructions, we also show that the
bottleneck at introduction was mild and did not affect the introduced
genetic diversity. Finally, we reveal that the current spatial expansion
at the northern boundary of the range is following a leading-edge model
characterized by a general reduction of genetic diversity towards the edge
of the expanding range. We conclude that the level of genome-wide
diversity of H. cristata invasive populations is less important in
explaining its successful invasion than species-specific life-history
traits or the phylogeographic history in the native source range.

研究外来物种历经多代仍存活并持续扩张的演化动力学，可为阐释成功生物入侵的相关特征提供基础依据。在此，我们通过调查入侵冠豪猪（Hystrix cristata）种群的遗传多样性动态来解决该研究问题——该种群于约1500年前被引入意大利，目前仍在规模、分布范围与生态位上持续扩张。我们利用全基因组RAD标记，刻画了该入侵种群的遗传多样性结构与种群动态，并将其遗传多样性与非洲本土的冠豪猪（Hystrix cristata）及其姊妹物种非洲帚尾豪猪（Hystrix africaeaustralis）的本土种群进行对比。其一，相较于撒哈拉以南非洲与南非的本土种群，入侵意大利的冠豪猪种群以及北非来源种群的遗传多样性均更低。其二，我们在入侵分布区内发现了多次引入事件的证据，且后续基因交流极为有限。通过基于溯祖理论的种群历史重建，我们还证实引入阶段所经历的瓶颈效应较为温和，并未对引入的遗传多样性产生影响。最后，我们揭示出该种群当前在分布区北缘的空间扩张遵循前沿扩张模型（leading-edge model），该模型的典型特征为：随着向扩张范围的边缘地带推进，遗传多样性整体呈下降趋势。综上，相较于冠豪猪的物种特异性生活史特征，或是其本土来源种群的系统地理历史，入侵种群的全基因组多样性水平，并非解释其成功入侵的核心因素。