Dissertation Research: The Evolution of a Host-Parasitoid Association.

9700696 ROOT种群分化在物种相互作用进化中的作用还没有很好的文献记载。选择可能因种群而异，导致某些地区的共同进化相互作用和其他地区的非互惠进化。豌豆蚜虫是豆科作物的一种害虫，受到拟寄生虫蚜虫的攻击。在纽约，专门寄生于紫花苜蓿的豌豆蚜虫比专门寄生于三叶草的豌豆蚜虫的抗寄生能力强两到三倍。耐药性是由基因决定的，并以生理为基础。它不是寄主植物诱导效应的产物，也不是任何一种昆虫对两种作物的影响。拟议的研究主要集中在三个方面。1)对另外两个地理区域（马里兰州和法国）的豌豆蚜虫对这两种作物的调查将表明所观察到的相对抗性模式的普遍性。2)在实验室中进行的互惠移植实验将确定昆虫是否在其地理区域内具有本地适应性。3)通过试验确定苜蓿和苜蓿豌豆蚜虫抗性遗传变异的相对大小。这将表明，三叶草中较低水平的遗传变异是否可能减缓抗性的进化，尽管这两种作物都有很强的选择。本研究对加强对物种相互作用进化的基本认识具有重要意义，并将为物种相互作用进化对生物防治方案效果的影响提供见解。

9700696 ROOT The role of population differentiation in the evolution of species interactions is not well documented. Selection can differ by population, leading to coevolutionary interactions in some areas and non reciprocal evolution in other areas. The pea aphid, a pest of legume crops, is attacked by the parasitoid, Aphidius ervi. Pea aphids in New York which specialize on alfalfa are two or three times more resistant to parasitism than pea aphids specialized on clover. Resistance is genetically determined and physiologically based. It is not a product of host-plant induced effects or either insect species on the two crops. The proposed research focuses on three areas. 1) A survey of pea aphids on both crops from two other geographical area, Maryland and France, will indicate the generality of the observed pattern of relative resistance. 2) Reciprocal transplant experiments in the lab will determine whether the insects are locally adapted within their geographic region. 3) An experiment will be performed to ascertain the relative magnitude of genetic variation for resistance in pea aphids from clover and from alfalfa. This will indicate if lower levels of genetic variation in clover could be slowing the evolution of resistance despite strong selection in both crops. This research is important in enhancing a basic understanding of the evolution of species interactions, and will provide insight in the effects of the evolution of species interactions on the efficacy of biological control programs.