Career: Developmental Tradeoffs and Host Race Formation in Rhagoletis Pomonella

[9508559]费德：农民和种群生物学家都对绦虫蝇（Rhagoletis pomonella）很感兴趣。这些苍蝇不仅是苹果的主要经济害虫，而且它们可能正在形成物种。虽然pomonella通常被称为“苹果蛆”，但苹果并不是这些苍蝇的原生寄主植物。这种区别属于山楂。在19世纪中期，纽约哈德逊河谷地区的一部分波蒙菌种群从山楂转移到苹果作为新的寄主植物。从那以后，寄生在苹果上的波蒙氏R.菌已经扩散到美国东部，最近还被引入加州、俄勒冈州和华盛顿州。遗传学研究表明，苹果和山楂褐皮菌群体是部分分离的个体。苹果蝇和山楂蝇的六个基因一致显示出频率差异。这些研究表明，Rhagoletis蝇在专门寻找新的寄主植物的过程中可能具有同地性（即没有地理隔离）。拟议研究的目标有两个方面：1)为了确定波蒙菌如何适应其生活史，使其能够成功地攻击作为新寄主植物的苹果。2)。为了确定这些生活史上的变化在将苹果与山楂蝇类分离的过程中所起的作用。由于波蒙氏蝇每年只有一代，成虫寿命只有一个月左右，因此苹果蝇和山楂蝇有很强的选择压力，使它们的发育与各自寄主植物的发育相匹配。为了验证这一假设，费德博士将在实验室中操纵果蝇的饲养条件，以诱导宿主种族之间不同的六种遗传标记的环境依赖性变化。实际上，他将尝试从基因上把山楂寄主种族转变为苹果种族（反之亦然），方法是选择山楂蝇，就好像它们会侵害苹果早期物候的果实一样。我们将从拟议的研究中学到什么？首先，实验将阐明波蒙菌是否以及如何改变了它的生活史，从而能够攻击苹果。其次，研究结果将确定哪些环境因素对波蒙奈菌在成功的宿主转移中克服最为重要。通过随后测量这些因素在田间作用的强度，将有可能衡量寄主相关选择在繁殖隔离苹果方面的有效性以及使番茄红霉适应苹果的发育性状。这些信息将有助于我们制定新的措施来控制苹果蛆和其他害虫。随着这种害虫向美国新的水果种植区蔓延，研究结果还将帮助我们预测哪些作物可能容易受到Rhagoletis的攻击。费德博士还致力于将种群生物学的知识传授给他人。这项职业补助金也将允许他继续追求他的教学兴趣。他将在本科和研究生阶段讲授一系列三门课程，让学生了解构成本研究和其他种群生物学和系统学研究基础的一般原理和概念。

9508559 FEDER The Tephritid fly Rhagoletis pomonella is of interest to both farmers and population biologists alike. Not only are these flies major economic pests of apples, but they may also be in the process of speciating. Although R. pomonella is commonly referred to as the "Apple Maggot", apples are not the native host plant of these flies. That distinction belongs to hawthorns (thornapples). In the mid-1800's a portion of the R. pomonella populations in the Hudson Valley region of New York shifted from hawthorns and started attacking apples as a new host plant. Since then, apple-infesting populations of R. pomonella have spread across the eastern United States and have recently been introduced into California, Oregon and Washington. Genetic studies indicate that apple and hawthorn populations of R. pomonella are partially isolated entities. Six genes consistently display frequency differences between the apple and hawthorn fly races. These studies suggest that Rhagoletis flies may speciate sympatrically (i.e. without geographic isolation) in the process of specializing on new host plants. The goals of the proposed research are two-fold:1.) To ascertain how R. pomonella has adapted its life history to allow it to successfully attack apples as a new host plant. 2.) To determine the role that such changes in life history play in isolating apples from hawthorn races of the fly. Because R. pomonella flies have only one generation per year and adults live for only about a month, there is strong selection pressure on apple and hawthorn flies to match their development to that of their respective host plants. To test this hypothesis, Dr. Feder will manipulate rearing conditions for flies in the laboratory to induce environment dependent changes at the six genetic markers differing between the host races. In effect, he will be attempting to genetically transform the hawthorn host race into the apple race (and vice-versa) by selecting on hawthorn flies as if they were infesting f ruits with the earlier phenology of apples. What will we learn from the proposed research? First, the experiments will elucidate whether and how R. pomonella has altered its life history so that it can attack apples. Second, the results will pinpoint which environmental factors are most important for R. pomonella to overcome in a successful host shift. By subsequently measuring the intensity with which these factors act in the field, it will be possible to gauge how effective host-associated selection is at reproductively isolating apple and of the development traits adapting R. pomonella to apples. Such information will aid us in devising new measures to control the Apple Maggot and other fruit fly pests. The results will also help us predict what crops are potentially vulnerable to attack by Rhagoletis, as this pest spreads into new, fruit growing regions of the United States. Dr. Feder also has a strong commitment to transfer knowledge of population biology to others. This CAREER grant will also allow him to continue to pursue his teaching interest. He will teach a series of three classes at the undergraduate and graduate levels, exposing students to the general principles and concepts that form the basis for this and other research in population biology & systematics.