Collaborative Research: Hybrid Plants and Zones as 'Sinks' for Herbivores: A Model System for Integrating Ecology, Genetics and Physiology of a Plant Herbivore Interaction

植物杂交区很常见，通常代表着植物的遗传防御机制混合在一起的自然实验，是研究植物与草食动物的生态和进化相互作用以及抗性机制的理想工具。这项研究将研究甜菜夜蛾如何选择寄主，以及对狭叶棉杨和天然杂交种狭叶杨树的反应。将提出两组相互关联的问题。关于这种相互作用的生态、进化和生物地理的第一个问题将涉及：a.在许多复制的河流排水系统上是杂交种植物和草食动物的“汇区”，使得少数易受影响的植物支持大多数害虫种群？？b.如果一个克隆(即一棵树及其无性派生的后代)对蚜虫敏感，它是否也容易受到其他种类的食草动物的影响，如麋鹿和伐木甲虫？以及，C.极其敏感的克隆的存在是否阻止了草食动物成功地攻击抗性克隆，或者敏感植物只是作为水库，从那里攻击其他种群？为了解决抗性和敏感性的机制，第二个问题提出了以下问题：A.成功地为该系统开发了分子遗传技术(RFLP)后，能否在纯区和杂交区标记抗病和/或感病基因并筛选树木的抗病；B.由于单个克隆可以是遗传马赛克(即，同一棵树的不同部分在遗传上是不同的)杂交无性系和纯寄主无性系之间的马赛克模式是什么，它们与紧张的生长条件有什么关系？C.因为个别无性系也可能是发育中的抗性马赛克(即，同一棵树的不同树枝或同一克隆的树干随着年龄的变化而在抗性上有所不同)，杂交种和纯寄主在发育抗性上有何差异？以及D.由于生理库源关系影响个体无性系的抗性性状，它们在影响个体无性系内的发育抗性模式中是否也很重要。

Plant hybrid zones are common and often represent natural experiments in which the genetically based defenses of plants have been mixed and are ideal for examining the ecological and evolutionary interactions of plants and herbivores as well as the mechanisms of resistance. This study will examine how the gall aphid, Pemphigus betae, selects hosts and responds to narrowleaf cottonwood, Populus angustifolia, and natural hybrids with Fremont cottonwood, P. fremontii. Two interrelated sets of questions will be asked. The first concerning the ecology, evolution and biogeography of this interaction will address: a. over many replicate river drainage systems are hybrid plants and zones "sinks" for herbivores such that a few susceptible plants support most of the pest population?, b. if a clone (i.e. a tree and its asexually derived progeny) is susceptible to aphids, will it also be susceptible to other kinds of herbivores such as elk and woodboring beetles?, and, c. does the presence of extremely susceptible clones prevent herbivores from successfully attacking resistant clones or do susceptible plants simply serve as reservoirs from which they attack the rest of the population? The second question, to address the mechanisms of resistance and susceptibility asks , a. having sucessfully developed molecular genetic techniques (RFLPs) for this system, can the genes for resistance and/or susceptibility be marked and trees screened for resistance in the pure and hybrid zones, b. since individual clones can be genetic mosaics (i.e., different parts of the same tree are genetically different) what are the patterns of mosaicism between hybrid and pure host clones and how are they related to stressful growing conditions?, c. because individual clones can also be developmental mosaics of resistance (i.e., different branches of the same tree or trunks of the same clone vary in resistance as a function of age), how do hybrids and pure hosts vary in their developmental resistance?, and d. because physiological sink-source relationships affect the resistance traits of individual clones, are they also important in affecting patterns of developmental resistance within individual clones.