Evolution transforms pushed waves into pulled waves

Understanding the dynamics of biological invasions is crucial for managing numerous phenomena, from invasive species to tumours. While the Allee effect (where individuals in low-density populations suffer lowered fitness) is known to influence both the ecological and evolutionary dynamics of an invasion, the possibility that an invader's susceptibility to the Allee effect might itself evolve has received little attention. Since invasion fronts are regions of perpetually low population density, selection should be expected to favour vanguard invaders that are resistant to Allee effects. This may not only cause invasions to accelerate over time, but, by mitigating the Allee effects experienced by the vanguard, also make the invasion transition from a pushed wave, propelled by dispersal from behind the invasion front, to a pulled wave, driven instead by the invasion vanguard. To examine this possibility, we construct an individual-based model in which a trait that governs resistance to the...

理解生物入侵的动态对于管理从入侵物种到肿瘤等诸多现象至关重要。尽管阿利效应（低密度种群中个体的适合度会降低）已知会影响入侵的生态和进化动态，但入侵者对阿利效应的敏感性本身可能发生进化这一可能性却鲜少受到关注。由于入侵前沿是种群密度持续较低的区域，选择作用应倾向于青睐对阿利效应具有抗性的先锋入侵者。这不仅可能导致入侵随时间加速，还可能通过缓解先锋种群所经历的阿利效应，使入侵从由入侵前沿后方扩散推动的推波（pushed wave）转变为由先锋种群驱动的拉波（pulled wave）。为验证这一可能性，我们构建了一个基于个体的模型（individual-based model），其中一个调控对阿利效应抗性的性状……