DISSERTATION RESEARCH: A Paradigm Shift for Avian Malaria: A Parasite of Mosquitoes That Relies on Birds for Transmission

疟疾寄生虫通常被认为是依靠蚊子媒介传播的脊椎动物寄生虫，因此大多数研究都集中在脊椎动物与寄生虫的相互作用上。与人类或啮齿动物疟疾不同，禽类疟疾通常在北美其脊椎动物宿主的野生种群中发现，通常在鸟类身上没有明显的临床症状。然而，仅靠鸟类与寄生虫的相互作用不能令人满意地解释最近关于禽类疟疾的分子研究中出现的一些主要发现，例如一些寄生虫谱系的高度遗传多样性和地理定位。与蚊子宿主共适应可能导致禽类疟疾寄生虫的地理定位。我们将通过控制不同种类和种群的鸟类喂养蚊子物种的感染来检验这一假设，以比较它们使用仅限于美国东部的寄生虫谱系传播寄生虫的能力。如果蚊子和寄生虫的共同适应在这个系统中确实很重要，那么只有东部蚊子应该有子孢子。这些实验将通过明确测试蚊子和寄生虫的相互作用是否会影响疟疾寄生虫谱系的地理分布，填补关于疟疾寄生虫生态学和进化的快速增长的知识体系的空白。这项研究的结果可能有助于预测气候变化对媒介传播疾病分布的影响，并可能支持将疟疾重新定义为依赖脊椎动物传播的蚊子寄生虫。

Malaria parasites are usually regarded as vertebrate parasites that rely on a mosquito vector for transmission, such that most research has focused on vertebrate-parasite interactions. Unlike human or rodent malaria, avian malaria is commonly found in wild populations of its vertebrate host in North America, usually without obvious clinical signs in the birds. Bird-parasite interactions alone, however, do not satisfactorily explain some of the major findings that have emerged from recent molecular studies on avian malaria, such as the high genetic diversity and geographic localization of some parasite lineages. Coadaptation with mosquito hosts may result in the geographic localization of avian malaria parasites. We will test this hypothesis by controlled infections of different species and populations of bird-feeding mosquito species to compare their ability to transmit parasites using a parasite lineage that is restricted to the eastern U.S. If mosquito-parasite coadaptation is indeed important in this system, only eastern mosquitoes should harbor sporozoites.These experiments will fill a gap in a rapidly growing body of knowledge concerning the ecology and evolution of malaria parasites by explicitly testing whether mosquito-parasite interactions can influence the geographic distribution of malaria parasite lineages. Results from this study could inform efforts to predict the effects of climate change on vector-borne disease distribution, and could support an ecological redefinition of malaria as a mosquito parasite that relies on vertebrates for dispersal.