Rapid evolution accelerates plant population spread in fragmented experimental landscapes

Predicting the speed of biological invasions and native species migrations requires an understanding of the ecological and evolutionary dynamics of spreading populations. Theory predicts that evolution can accelerate species’ spread velocity, but how landscape patchiness—an important control over traits under selection—influences this process is unknown. We manipulated the response to selection in populations of a model plant species spreading through replicated experimental landscapes of varying patchiness. After six generations of change, evolving populations spread 11% farther than nonevolving populations in continuously favorable landscapes and 200% farther in the most fragmented landscapes. The greater effect of evolution on spread in patchier landscapes was consistent with the evolution of dispersal and competitive ability. Accounting for evolutionary change may be critical when predicting the velocity of range expansions.

预测生物入侵与本土物种迁移的速率，需要深入理解扩散种群的生态与进化动态。已有理论预测，进化可加快物种的扩散速率，但景观斑块性（landscape patchiness）——这一对受选择性状具有关键调控作用的因素——如何影响这一过程，目前仍未明确。我们以一种模式植物物种为研究对象，在斑块性程度各异的重复实验景观中开展扩散实验，对其种群的选择响应进行人工调控。经过六代演化后，在持续适宜的景观中，发生演化的种群扩散距离较未演化种群多出11%；而在高度破碎化的景观中，这一差距高达200%。进化在斑块性更强的景观中对扩散的促进作用更为显著，这一结果与扩散能力与竞争能力的演化方向相一致。在预测物种分布范围扩张的速率时，将演化变化纳入考量或许是至关重要的环节。