生物入侵的研究有重要的现实意义和理论价值，生物入侵的机制是研究热点之一。在EICA假说基础上发展的SDH假说提出入侵机制可以用外来种在入侵地的防御进化来解释，该假说强调植物的化学防御可分为两种：针对所有植食动物并耗费较多资源的数量型防御；针对普食性动物的质量型防御。在原产地，植物同时受这两类动物的选择压力。在入侵地，由于专性植食动物的缺失，入侵植物将提高质量型防御，降低数量型防御，节约的资源可以在生长和繁殖方面有更多的投入。这使外来种更有优势，从而竞争胜利，成功入侵。欧洲千里光是在我国广泛分布的入侵种，吡咯里西啶生物碱是其质量型化学防御物质。本项目拟收集原产地和入侵地种群的种子，通过自然条件下实验、温室实验和受控条件下生物测试等方法来查明欧洲千里光入侵种群是否逃离了专性植食动物，发生化学防御的进化并增加了竞争能力。本项目有助于对欧洲千里光入侵机制的理解，为其防治和利用提供科学参考。

The research of biological invasion is valuable in relation to the theoretical and practical aspects. The reason for success of invasion is one of the hotspots of the researches about biological invasion. As an extension of the Evolutionary of Increase Competition Ability (EICA) Hypothesis, the Shift Defense Hypothesis (SDH) argues that the success of plant invasion can be explained by the evolution of chemical defense in the invasive populations. The chemical defense of plants can be divided into two kinds: quantitative defense, which is expensive to produce and effective to all herbivores; and qualitative defense, which is toxic to generalist herbivores, adapted by and even attractive to specialist herbivores. In invasive area, the plants are attacked by both kinds of herbivores. In invasive area, alien plants are released from specialist herbivores, increase the qualitative defense and reduce the quantitative defense. Thus they allocated more resource to growth and reproduction, which leads to the more fitness and successful invasion of the plants. Senceio vulgaris is an invasive species wildly distributed in China. It is clear that the pyrrolizidine alkaloids are part of the qualitative defense of Senecio plants. I plan to collect seeds of this species from the native and invasive populations. I will grow the plants in gardens and climate rooms. I will also do bioassays in climate chambers to test the plants' resistance to herbivores. Trough all of this experiments, I aim to test whether the invasive populations of S. vulgaris have released from specialist herbivores, whether the shift defense occurred and the fitness are improved in these populations. This study will offer understanding of why S. vulgaris is succefully invade in China and provide scientific opinions on how to control and use this species.