DISSERTATION RESEARCH: Epigenetic Effects of an Invasive Parasite on an Avian Host

这项研究的目的是了解在不改变DNA序列的情况下改变基因功能的过程如何影响加拉帕戈斯嘲鸟对引入的、有时是致命的寄生蝇的防御。这种改造可以使寄主对寄生反应迅速，减少寄生的负面影响。这种寄生虫生活在加拉帕戈斯群岛的这种鸟类和其他鸟类的巢穴中，以雏鸟为食，对它们的生存构成威胁。研究这种修饰如何作为对寄生虫的快速防御，将有助于了解动物如何适应新的环境威胁。这个项目将包括训练本科生野外生物学技术和科学写作。它还将包括为加拉帕戈斯国家公园护林员和导游举办的讲习班，以帮助制定监测和控制加拉帕戈斯群岛这种有害物种的战略。该项目将分析四个野外季节研究的嘲鸟的DNA甲基化模式：两个季节的嘲鸟对蝇寄生虫P. downsi有耐受性，两个季节的嘲鸟对蝇寄生虫P. downsi有高死亡率。在实地研究中，模仿鸟的巢穴要么用氯菊酯（一种杀死寄生虫的稀释杀虫剂）熏蒸，要么用假熏蒸作为对照，让巢穴自然受到感染。比较了被寄生和未被寄生的雏鸟的生长、健康和羽化成功率，并在雏鸟孵化期间两次采血。这些血液样本，以及从研究鸟身上收集的样本，将被分析甲基化模式的变化。DNA甲基化分析将使研究人员能够识别在耐受性和非耐受性时期受寄生影响的基因，并研究甲基化改变是否持续到成年期，甚至可能遗传。本研究结果将为野生种群快速适应的表观遗传机制提供新的见解。

The goal of this research is to understand how processes that modify the function of genes without changing the DNA sequence affect the defense of Galapagos mockingbirds against an introduced and sometimes lethal parasitic fly. This modification may enable the host to respond quickly to parasitism and reduce its negative effects. The parasite lives in the nests of this and other species of birds in the Galapagos and feeds on nestlings, and is a threat to their survival. Studying how this modification acts as a rapid defense against parasites will provide insights into how animals adapt to new environmental threats. This project will involve training undergraduates in field biology techniques and scientific writing. It will also incorporate workshops for Galapagos National Park rangers and tour guides to help develop strategies for monitoring and controlling this pest species in the Galapagos.This project will analyze DNA methylation patterns of mockingbirds studied during four field seasons: two in which mockingbirds were tolerant to the fly parasite, P. downsi, and two in which the fly caused high mortality. During the field study, mockingbird nests were either fumigated with permethrin, a dilute insecticide, that killed the parasite, or sham-fumigated as a control, that let the nests be naturally infested. Growth, health and fledging success of parasitized and non-parasitized nestlings were compared and nestlings were sampled for blood twice during the nestling period. These blood samples, along with samples collected from study birds later recaptured as adults, will be analyzed for variation in methylation patterns. DNA methylation analysis will allow the researchers to identify genes that are affected by parasitism in tolerant vs. non-tolerant years as well as to investigate whether methylation alterations persist to adulthood and are potentially even heritable. The results of this research will provide new insights into epigenetic mechanisms of rapid adaptation in wild populations.