Data from: Rapid increase in dispersal during range expansion in the invasive ladybird Harmonia axyridis

The evolutionary trajectories associated with demographic, genetic and spatial disequilibrium have become an issue of growing interest in population biology. Invasive species provide unique opportunities to explore the impact of recent range expansion on life-history traits, making it possible to test for a spatial arrangement of dispersal abilities along the expanding range, in particular. We carried out controlled experiments in laboratory conditions to test the hypothesis of an increase in dispersal capacity with range expansion in Harmonia axyridis, a ladybird that has been invading Europe since 2001. We found a marked increase in the flight speed of the insects from the core to the front of the invasion range in two independent sampling transects. By contrast, we found that two other traits associated with dispersal (endurance and motivation to fly off) did not follow the same spatial gradient. Our results provide a striking illustration of the way in which predictable directional genetic changes may occur rapidly for some traits associated with dispersal during biological invasions. We discuss the consequences of our results for invasion dynamics and the evolutionary outcomes of spatially expanding populations.与种群统计、遗传及空间失衡相关的演化轨迹，已成为种群生物学中日益受到关注的研究议题。入侵物种为探究近期种群范围扩张对生活史性状的影响提供了独特契机，尤其便于检验扩散能力沿扩张范围的空间分布格局。本研究在实验室条件下开展对照实验，以验证“在2001年起入侵欧洲的异色瓢虫（Harmonia axyridis）中，扩散能力随种群范围扩张而增强”这一假说。在两条独立的样带中，我们观察到昆虫的飞行速度从入侵范围的核心区域到前沿区域显著提升。与之形成对比的是，另外两项与扩散相关的性状（飞行耐力与起飞动机）并未呈现相同的空间梯度。本研究结果清晰展现了生物入侵过程中，部分与扩散相关的性状可快速发生可预测的定向遗传改变。我们还讨论了本研究结果对入侵动态以及空间扩张种群演化结局的启示。