Candidate genes for host association in aphids

新的生物物种的起源取决于阻止它们交配和产生成功后代的特征的进化。这种进化过程可能始于对新环境的适应，但这很少会产生完全的繁殖障碍。如果发生了一些杂交，那么与适应不同生境没有直接关系的基因仍然可以共享。我们仍然不太了解进化是如何从这一点到完全防止异种繁殖的。在这个项目中，我们建议研究豌豆蚜虫，因为它的基因组已经测序，并且已知它以几种不同的寄主植物为食，这些寄主植物代表不同的环境。我们知道蚜虫倾向于与使用同一种植物的其他蚜虫一起繁殖。这种趋势在某些情况下比其他情况更强烈，所以我们在向新物种发展的过程中有几个点可以比较。蚜虫利用化学线索来选择它们赖以为生的植物，我们现在知道了识别这些线索的基因类型。我们已经发现了其中一些基因，这些基因很可能与蚜虫在使用不同植物时的行为差异有关。在这个新项目中，我们想要找出这些基因如何受到自然选择的影响，以及它们如何影响蚜虫宿主种族之间其他基因的共享。我们还想找出植物中哪些化学物质被用于识别过程。这将有助于我们了解物种的起源，也可能有助于控制农作物的害虫蚜虫。了解蚜虫如何选择它们想要捕食的植物可以为防止蚜虫的伤害提供新的工具。

The origin of new biological species depends on the evolution of characters that prevent them from mating and producing successful offspring. This evolutionary process may start with adaptation to new environments but this rarely creates a complete reproductive barrier. If some interbreeding occurs, then genes which are not directly involved in adaptation to different habitats can still be shared. We still have little understanding of how evolution proceeds from this point to the point of complete prevention of interbreeding.In this project, we propose to study the pea aphid because its genome has been sequenced and it is known to feed on several different host plant, which represent distinct environments. We know that aphids tend to reproduce with others that use the same plant. This tendency is stronger in some cases than others so we have several points on the progression towards new species that we can compare. Aphids use chemical cues to choose the plant on which they feed and we now know the types of genes underlying recognition of these cues. We have already found some of these genes that are likely to be involved in the differences in behaviour between aphids that use different plants. In this new project we want to find out how these genes are influenced by natural selection and how they affect the sharing of other genes between host races of aphids. We also want to find out which chemicals in the plants are used in the recognition process.This will help us to understand the origin of species and it may also help in control of aphids that are pests of crops. Understanding how aphids choose the plants they want to feed on can provide new tools to prevent aphid damage.