DISSERTATION RESEARCH: Linking functional evolution of odorant receptors to behavioral adaptations and the emergence of herbivory in drosophilids

这项研究调查了密切相关的苍蝇物种从以微生物为食向以植物为食的转变中嗅觉适应的作用。以植物为食的动物是最多样化的一类动物，包括所有命名物种的四分之一。然而，关于昆虫是如何进化到以其他类型的食物中的植物为食的，或者昆虫是如何进化到针对特定种类的植物的，人们知之甚少。这个项目将研究这些苍蝇的嗅觉感受器和潜在的遗传学是如何随着进化时间的推移而改变的，因为它们的食物从酵母转变为植物。它将决定允许切换到新饮食的嗅觉受体的变化，以及潜在的遗传学如何转移到新的寄主植物。这种对嗅觉进化的了解的增加将使我们对生态相互作用的变化有更全面的了解。这项研究可能进一步提供允许操纵昆虫食物选择的见解。因此，由于昆虫经常传播疾病，因此它有可能通过应用于农业和人类健康而广泛影响社会。由于昆虫经常传播疾病。本研究将通过比较黄冠天牛和苍白天牛的嗅觉系统，来研究在生态位变化后嗅觉(嗅觉)的进化。这两种苍蝇关系密切，但饮食不同。黄色沙门氏菌是一种真正的食草动物，以芥末植物为食，而苍白沙门氏菌则保留了更古老的微生物饮食。将使用气相色谱(GC)-电子触角检测(EAD)来区分苍蝇可以检测到哪些寄主物种的叶子产生的挥发性化合物(气味)。这项技术将树叶挥发物流分成两个相同的流。其中一股流被送入GC检测器，通过基本上人工闻到化合物的方式进行识别。另一种是针对苍蝇的，EAD将通过确定化合物是否在单个神经细胞中触发反应来确定该化合物是否自然可检测到。因此，食草性苍蝇检测到的树叶挥发物将被识别出来，并与以微生物为食的苍蝇检测到的挥发性物质进行比较。被GC-EAD鉴定为区分这两个物种的挥发物将被用作嗅觉分析的诱饵，四个含有不同挥发物的校准气流被送入正方形竞技场的角落。然后将测量对每种植物挥发物的吸引力，以确定物种的行为是否与它们的检测轮廓相匹配。最后，看似对区分这两个物种很重要的基因将被改造成黑腹果蝇的模式生物，以测试这些基因对食物选择的影响是否被完全理解。

This research investigates the role of sensory adaptation of smell in closely related species of flies in transitions from feeding on microbes to feeding on plants. Plant-feeding are the most diverse group of animals, including a quarter of all named species. Yet little is known about how insects evolve to feed on plants from other types of diets, or how insects evolve to target specific kinds of plants. This project will study how the smell receptors and underlying genetics of these flies have changed over evolutionary time as their diet switches from yeast to plants. It will determine the changes in smell receptors that allow the switch to new diets and how the underlying genetics shifts to target new host plants. This increased understanding of the evolution of the sense of smell will inform our general understanding of changes in ecological interactions. This research may furthermore provide insights that allow manipulation of insect food choice. It therefore has the potential to broadly impact society through applications to agriculture, where insects are major crop pests, and human health since insects frequently spread disease.This study will investigate the evolution of olfaction (sense of smell) after a niche change by comparing the olfactory systems of Scaptomyza flava and Scaptomyza pallida. These two fly species are closely related but differ in diet. S. flava is a true herbivore feeding on mustard plants, while S. pallida retains the more ancestral diet of microbes. Gas chromatography (GC) -electroantennographic detection (EAD) will be used to differentiate which volatile compounds (smells) produced by leaves of host species the flies can detect. This technique divides a stream of leaf volatiles into two identical streams. One stream is sent into a GC detector for identification by essentially artificially smelling the compound. The other stream is aimed at a fly where EAD will determine if the compound is detectable naturally by determining if the compound triggers a response in single nerve cell. Leaf volatiles that are detected by herbivorous flies will thereby be identified and compared to those detected by flies that feed on microbes. The volatiles identified by GC-EAD as differentiating the two species will then be used as baits in olfactory assays where four calibrated airstreams containing different volatiles are fed into the corners of a square arena. The attraction to each plant volatile will then measured to determine if the species behavior matches their detection profile. Finally, genes that appear to be important in differentiating these two species will be engineered into a model organism Drosophila melanogaster to test if the genes effect on food choice is fully understood.