RUI: Three-Trophic Level Interactions in an Aquatic Macrophyte Hybrid Zone

这项研究将调查香茅杂交区的三个营养级别的相互作用。这三个层次的相互作用包括：香茅和杂交种，以香茅种子为食的食草动物，以及感染以种子为食的食草动物的寄生虫。为了研究这三种香蒲之间的食草性差异，野外实验将研究这些香蒲在广泛的地理范围内所承受的食草动物负载。杂交和导入在影响草食性和寄生虫率方面的作用将通过使用不同杂交组合的盆栽植物进行的移植研究来解决。食草动物排除和添加实验将检验1)杂交香茅上食草性减少的模式是否可归因于植物特性或寄生虫，2)一种食籽草食动物对另一种食草动物的依赖程度。虽然植物杂交是造成植物种内和种间遗传变异的30-70%的原因，但人们对杂交区内发生的三向相互作用知之甚少。通过重点研究食草动物和食草动物-天敌相互作用的模式，植物杂交区的动态性质将被阐明。这项研究将对理解杂交在植物种群中的作用和天敌的控制做出重要贡献。

This research will investigate a three trophic level interaction in a hybrid zone of cattails. The three levels of interactions include: the cattails and the hybrid, herbivores that eat the seeds of the cattails, and parasites that infect the seed-eating herbivores. To study how herbivory varies among the three types of cattails, field experiments will examine the herbivore loads sustained by these cattails over a broad geographic range. The role that hybridization and introgression play in influencing rates of herbivory and parasitoidism will be addressed with a transplant study using potted plants of various crosses. Herbivore exclusion and addition experiments will examine 1) whether the pattern of reduced herbivory on the hybrid cattails can be attributed to plant properties or parasites, 2) the degree of dependence that one species of seed eating herbivore has on the presence of another. %%% ALthough hybridization of plants has been responsible for 30-70% of the genetic variation in and among plant species, little is known about the three-way interactions that occur in zones of hybridization. By focussing on the patterns of herbivory and the herbivore-natural enemy interactions, the dynamic nature of plant hybrid zones will be elucidated. This research will make an important contribution to understanding the role of hybridization and control of natural enemies in plant populations.