Collaborative Research: Eucalypt Hybrid Zones as "Sinks" For Herbiores: Responses of Pests to Natural Hybrids

为了研究植物-食草动物的相互作用， 代表了自然实验，在这些实验中， 通过回交变得混乱。 昆虫研究 杨属（Populus）的害虫表明， 在杂交区和区域内的回交树上。 来自没有混合区的河流系统的害虫表现得更好， 与杂交树种相比， 区界限 这些数据表明，高度易感宿主（即， 自然发生的复杂杂交）不仅支持大多数的 害虫种群，它们的存在可能导致害虫物种 失去或从未进化出处理更大问题的能力 亲本树种的抗性。 这意味着 一项工作是，可以利用易感杂交种来控制害虫， 林业和农业的动态。 由于这一主题的基本和应用影响， 本项目将研究这一现象的普遍性（ 水槽假说）在第二个系统，桉树，其中 杂交是常见的。 研究人员将与 系统学家、遗传学家和生态学家来研究害虫 几个著名的自然混合系统的动力学。 的 将讨论以下问题：1。是杂交的真核生物 这样一小部分潜在的 寄主养活了大部分害虫 2.如果复杂的混血儿 更容易受到一种害虫的影响， 完全不同的昆虫公会 3.是否存在或缺席 杂交区的影响害虫密度在纯寄主区？ 这些问题将在一个自然的系统中得到解决， 有已知基因型树木的花园，并通过记录昆虫 攻击收集的亲本和杂交种标本馆标本 独立于研究。 这些问题的答案还没有 除了棉白杨之外，还检查了任何系统， 对理解生态和 植物和害虫的进化互动。

For studies of plant-herbivore interactions, hybrid zones represent natural experiments in which genetic-based defenses have become scrambled through backcrossing. Studies of insect pests of cottonwoods (Populus) show that pests are concentrated in hybrid zones and, within the zone, on backcrossed trees. Pests from river systems without hybrid zones perform better on the parent tree species than do pests from areas with hybrid zones. These data suggest that highly susceptible hosts (i.e., naturally occurring complex hybrids) not only support most of the pest population, their presence may result in pest species either losing or never evolving the ability to deal with the greater resistance of the parental tree species. An implication of this work is that susceptible hybrids can be used to manage pest dynamics in forestry and agriculture. Because of the basic and applied implications of this topic, this project will examine the generality of this phenomenon (the Sink Hypothesis) in a second system, Eucalyptus, in which hybridization is common. The researchers will collaborate with eucalypt systematists, geneticists, and ecologists to study pest dynamics in several well known natural hybrid systems. The following questions will be addressed: 1. Are hybrid eucalypts sinks for herbivores such that a small proportion of potential hosts support most of the pest population? 2. If complex hybrids are more susceptible to one pest, are they also more susceptible to very different insect guilds? 3. Does the presence or absence of hybrid zones affect pest densities in the pure host zone? These questions will be addressed in a natural system, common gardens with trees of known genotypes, and by documenting insect attacks on herbarium specimens of parents and hybrids collected independent of the study. Answers to these questions have not been examined for any system besides cottonwoods and should be fundamentally important in understanding the ecological and evolutionary interactions of plants and pests.