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

[摘要]柯林。植物抗性性状的渗入：杂交柳树的草食性SlugOrians和Fritz将研究渗入在适应性进化中的重要性。他们将测试一种假设，即适应性植物抗性性状可以在杂交柳树基因型中得到青睐，这是由于食草蛞蝓的选择。该系统是具有广泛同域分布范围的一对杂交柳树物种，目前在其重叠区域内氢化，并且似乎经历了过去的渐渗。PI将从每个柳树种的纯亲本中产生F2个后代，然后将其中一些后代交给引入的蛞蝓A. fasciatus食草。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。第一个实验将测试蛞蝓食草性是否会导致选择倾向于具有较高酚苷浓度的F2表型。实验二将涉及确定与父辈相比，F2后代之间选择性进食鼻涕虫的化学基础。在实验3中，PI将测量选择和控制的F2后代对另外两种主要的柳树噬菌体，日本甲虫和柳树叶锈病的抗性。这将决定F2中对鼻涕虫更高抗性的选择是否有生态成本，或者，对鼻涕虫的抗性是协同的还是独立于对其他物种的抗性。实验4将包括两代回交和蛞蝓的选择，以确定酚苷性状是否在回交中持续存在，并提高一些基因型相对于非选择回交与头柳的适合度。这个实验将直接测试渗入模型，并将允许测试具有不同化学防御的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.