Collaborative Research: RUI: Introgression of Plant Resistance Traits: Selection on Hybrid Willows by an Herbivorous Slug

摘要 Colin M .Orians DEB-9981568 和 Robert S. Fritz DEB 9981406 塔夫茨大学瓦萨学院合作研究 RUI：植物抗性性状的基因渗入：草食性蛞蝓对杂交柳树的选择 Orians 和 Fritz 将研究基因渗入在适应进化中的重要性。 他们将测试这样一个假设：由于草食性蛞蝓的选择，适应性植物抗性性状可能在杂交柳树基因型中受到青睐。 该系统是一对杂交的柳树物种，具有广泛的同域范围，目前在其重叠区域进行杂交，并且似乎已经经历了过去的基因渗入。 PI将从每个柳树品种的纯亲本中产生F2后代，然后将其中一些后代置于引入的蛞蝓A. fasciatus的草食性之下。初步证据表明，蛞蝓的食草性和幼苗的死亡率与植物化学有关。第一个实验将测试食草蛞蝓是否会导致有利于酚苷浓度较高的 F2 表型的选择。实验二将涉及确定 F2 后代与亲代相比选择性蛞蝓喂养的化学基础。 在实验 3 中，PI 将测量选定的 F2 后代和对照 F2 后代对另外两种主要柳植噬菌体（日本甲虫和柳叶锈病）的抗性。 这将决定F2中是否存在选择对蛞蝓具有更高抗性的生态成本，或者对蛞蝓的抗性是否与对这些其他物种的抗性是协同的还是独立的。 实验4将包括两代回交和蛞蝓选择，以确定酚糖苷性状是否在回交中持续存在，并相对于与柳树S. eriocephala的非选择回交提高一些基因型的适应性。 该实验将直接测试基因渗入模型，并将允许测试具有不同化学防御的基因渗入植物之间的分配和生态成本。

Abstract Colin M .Orians DEB-9981568 & Robert S. Fritz DEB 9981406Tufts University Vassar CollegeCollaborative Research RUI: Introgression of Plant Resistance Traits: Selection on Hybrid Willows by an Herbivorous SlugOrians and Fritz will study the importance of introgression in the evolution of adaptations. They will test the hypothesis that adaptive plant resistance traits can be favored among hybrid willow genotypes due to selection by a herbivorous slug. The system is a hybridizing pair of willow species that have broadly sympatric ranges, currently hydridize throughout their zone of overlap and appear to have undergone past introgression. The PI's will make F2 progeny from pure parents of each willow species and then subject some of these progeny to herbivory by the introduced slug, A. fasciatus. Preliminary evidence suggests that slug herbivory and mortaility of seedlings is related to plant chemistry. The first experiment will test if slug herbivory causes selection favoring F2 phenotypes with higher concentrations of phenolic glycosides. Experiment two will involve determination of the chemical basis of selective slug feeding among F2 progeny compared to parentals. For Experiment 3, the PI's will measure the resistance of selected and control F2 progenies to two other major willow phytophages, Japanese beetles and willow leaf rust. This will determine if there are ecological costs of selection for higher resistance to slugs in F2's ,or, if resistance to slugs is synergistic or independent of resistance to these other species. Experiment 4 will include two generations of backcrossing and selection by slugs to determine if phenolic glycoside traits persist in backcrosses and improve the fitness of some genotypes relative to non-selected backcrosses to the willow S. eriocephala. This experiment will directly test the Introgression model, and will permit tests of allocational and ecological costs among introgressed plants with different chemical defenses.