入侵植物密度依赖的亲属互作与避荫反应和根际激发效应的关系

植物亲属识别和个体间正相互作用是国际生态学研究前沿热点，然而有关植物亲属互作性质（互利或竞争）的研究结果长期存在巨大争议。并且生态位完全重叠的种内亲属间存在正相互作用是无法由传统生态位理论来解释的。我们近期发现，一种入侵植物的亲属互作存在“基因型的来源地”和“种群密度”的交互作用：在较高密度下入侵地基因型为互利（正相互作用），原产地基因型为竞争（负相互作用）；而在较低密度下两者差异不显著。这表明植物基因型和种群密度是影响亲属互作性质的主要因子，但其相关生态学机制有待系统研究。基于此，本项目以入侵种喜旱莲子草原产地和入侵地基因型为研究材料，以密度依赖的亲属间正相互作用为切入点，从植物避荫反应和根际激发效应角度剖析外来植物入侵中密度依赖的亲属互作从竞争（原产地负相互作用）到互利（入侵地正相互作用）的基本规律和关键生态学机制。本项目的实施，将为植物亲属识别与互作研究、外来植物入侵机制研究等提供新

Kin recognition and positive interaction are hot topics at the international leading edge of ecological research. However, there has been a long-standing controversy in the study results of the direction of kin interactions (i.e. positive or negative). Moreover, the positive kin interactions cannot be explained by traditional niche theory because of completely overlapping niche. We recently found that there was a significant interaction between " origin of genotypes" and "density" in the kin interaction of an invasive plants: growing at higher density, introduced genotypes showed kin facilitation (positive interaction), but native genotypes showed kin competition (negative interaction); By contrast, growing at lower densities, the performance of individuals growing with kins did not vary between introduced and native genotypes. This indicates that origin of genotypes and population density are the main factors affecting the direction of kin interactions (positive or negative), but less is known about the underlying ecological mechanism. Accordingly, here we focus on the density-dependent interaction between kins in native and introduced genotypes of an invasive plant, Alternanthera philoxeroides. We explore how kin interactions shift from the negative to the positive for this plant species from the perspective of shade avoidance responses and rhizosphere priming effect. This project will provide new ideas and paradigms for the study of plant kin recognition and interaction, and the mechanism of alien plant invasions .