Dissertation Research: Sick in the city? Hosts and parasites in urban and non-urban habitats

随着城市越来越大，越来越多的动物在城市栖息地安家，了解城市生活对动物健康的影响变得越来越重要。寄生虫感染可以对动物的生存和生理产生重大影响，城市栖息地可以从几个方面改变寄生虫感染。例如，城市栖息地可能会改变动物所经历的压力源和它们对寄生虫的免疫抵抗力。然而，人们对城市和非城市脊椎动物种群中的寄生虫知之甚少，包括它们如何影响动物健康，以及城市动物是否有不同水平的应激激素或对寄生虫的免疫力。这项研究将提供关于鸟类在城市地区生存所必须抵御的寄生虫的关键知识，这将为未来在城市栖息地的保护工作提供信息。这项工作还将有助于保护人类健康，因为城市鸟类是人类疾病的潜在宿主；例如，城市鸟类比非城市鸟类更容易感染西尼罗河病毒。了解城市鸟类感染了哪些寄生虫，以及与这些感染相关的生理状态，可以帮助我们更好地预防疾病从鸟类传播给人类。为了更好地了解城市化对寄生和寄主生理的影响，研究人员将研究一种鸣禽，黑眼Junco (Junco hyemalis)，来自加州多个城市和非城市栖息地。先前的研究发现，城市和邻近的非城市juncos种群在表型和寄生方面存在相当大的差异。在非城市人口中，需要媒介传播的寄生虫流行率较高。在邻近的城市人群中，直接传播和环境传播的寄生虫，包括一种肠道寄生虫，球虫（Isospora sp.）的患病率和强度更高。城市寄主与非城市寄主在内分泌生理上也存在差异。该项目将结合广泛的实地调查和鸟舍实验，以测试1)城市化是否始终导致环境传播与媒介传播寄生虫的相同模式；2)观察到的城市和非城市人群球虫感染强度的差异是由于宿主的性状（与应激反应和免疫功能有关）还是由于寄生虫的性状。通过结合疾病生态学和生态免疫学的方法，本项目将解决栖息地特征、寄生和宿主表型之间的关键联系。

As cities grow larger and more species of animals make their homes in urban habitats, it becomes increasingly important to understand the effects of city life on animal health. Parasite infections can have significant impacts on animal survival and physiology, and urban habitats may change parasite infections in several ways. For example, urban habitats may change both the stressors that animals experience and their immune resistance to parasites. However, little is known about parasites in urban vs non-urban populations of vertebrate animals, including how they affect animal health and whether urban animals have different levels of stress hormones or immunity to parasites. This research will provide critical knowledge about the parasites that birds must withstand in order to survive in urban areas, which will inform future conservation efforts in urban habitats. This work will also help protect human health, since urban birds are potential reservoirs of human diseases; for example, urban birds are more likely to be infected with West Nile Virus than non-urban birds. Understanding what parasites urban birds are infected by, and what physiological states are associated with these infections, can help us better prevent disease spread from birds to humans. In order to better understand the effects of urbanization on parasitism and host physiology, the researchers will study a songbird, the Dark-eyed Junco (Junco hyemalis), from multiple cities and non-urban habitats across California. Previous research has found considerable variation in phenotype and parasitism between an urban and neighboring non-urban population of juncos. In a non-urban population, there was higher prevalence of parasites that require vectors for transmission. In the neighboring urban population, there was greater prevalence and intensity of directly and environmentally transmitted parasites, including an intestinal parasite, coccidia (Isospora sp.). Urban hosts also differed in endocrine physiology from non-urban birds. This project will combine extensive field surveys and aviary experiments to test 1) whether urbanization consistently results in these same patterns for environmentally transmitted versus vector-borne parasites; and 2) whether the observed difference in coccidia infection intensity between the urban and non-urban populations is due to traits of the host (relating to stress response and immune function) or traits of the parasite. By combining approaches from disease ecology and eco-immunology, this project will address the critical links among habitat characteristics, parasitism, and host phenotypes.