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序列的情况下修改基因功能的过程如何影响加拉帕戈斯嘲鸟对一种引入的有时是致命的寄生蝇的防御。这种修改可以使寄主对寄生做出快速反应，并减少其负面影响。这种寄生虫生活在加拉帕戈斯群岛这种和其他鸟类的巢中，以雏鸟为食，对它们的生存构成威胁。研究这种修饰如何起到快速防御寄生虫的作用，将为动物如何适应新的环境威胁提供见解。这个项目将包括对本科生进行野外生物学技术和科学写作方面的培训。该项目还将包括为加拉帕戈斯国家公园护林员和导游举办的研讨会，以帮助制定监测和控制加拉帕戈斯地区这种害虫物种的策略。该项目将分析在四个野外季节研究的模仿鸟的DNA甲基化模式：两个模仿鸟对苍蝇寄生虫P.down si耐受，两个模仿鸟导致高死亡率。在实地研究期间，知更鸟的鸟巢要么用氯氰菊酯(一种能杀死寄生虫的稀释杀虫剂)熏蒸，要么用假烟熏作为对照，让鸟巢自然侵袭。比较了被寄生和未被寄生雏鸟的生长、健康和雏鸟成活率，并在雏鸟孵化期内两次采集雏鸟血液。这些血液样本，以及后来成年后重新捕获的研究鸟类的样本，将被分析甲基化模式的变异。DNA甲基化分析将使研究人员能够识别在耐受与不耐受年份中受寄生虫影响的基因，并调查甲基化变化是否会持续到成年，甚至可能是可遗传的。这项研究的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.