Predicting the evolution of vector-borne disease dynamics in a changing world

该项目将促进我们对疾病传播将如何受到环境变化的影响和演变的理解。由蚊子或蜱虫等小型无脊椎动物（病媒）在宿主之间传播的疾病在世界各地呈上升趋势，但我们衡量和预测风险的能力却滞后。要预测病媒传播疾病的风险，就需要了解所有相关物种可能如何受到环境变化的影响，以及这些相互作用可能如何演变。禽疟疾在本地和引进的夏威夷鸟类中的传播是获得这种理解的理想系统。该项目将重点关注夏威夷的蜜鸟，这是一个多样化的群体，包括许多濒临灭绝的物种。通过使用鸟类和疟疾寄生虫的历史标本，该项目将能够记录和模拟过去80年来疾病耐受性和抵抗力的演变。然后，模型方法将可广泛应用于任何疾病系统，其中预计会发生演变，以应对不断变化的环境条件。研究结果也将用于夏威夷鸟类的管理。该项目将支持本科生和研究生的培训以及当地高中生的参与。夏威夷的禽疟疾病原体是一种非本地的血孢子虫寄生虫，即残余疟原虫，由两种非本地的致倦库蚊（Culex quinquefasciatus）混合传播。夏威夷的禽疟疾是一系列重复的自然实验，其中病媒和寄生虫的流行率在几个岛屿上沿着海拔梯度变化，据报道，一些鸟类宿主的耐受性存在平行梯度。尽管P. relictum以前对所有50种夏威夷蜜雀都具有高度毒性，但在至少三种物种中观察到了耐受性（或抗性）的进化，包括amakihi（Chlorodrepanis sp.）。此外，岛屿内部和岛屿之间在宿主物种组成、宿主耐受性、气候（温度和降水）、病媒丰度、病媒能力和病原体适合度方面存在地理差异。该项目将：（1）通过使用博物馆标本，描述在不同海拔、不同岛屿和不同时间复制的寄生虫、宿主和媒介的基因组特征;（2）进行普通花园实验和实验感染，以分别评估媒介和寄生虫菌株之间的能力或毒力差异; 3）将目标1和2纳入当前和未来气候情景下共同进化变化对病媒传播疾病传播影响的预测模型。我们将在多个空间，时间和实验尺度上使用比较基因组学和转录组学，并将联合收割机易感-感染-耐药（SIR）模型与进化博弈论相结合，以捕捉不断变化的种群的相互影响。

This project will advance our understanding of how disease transmission will be affected by and evolve in response to environmental change. Diseases transmitted among hosts by small invertebrates such as mosquitoes or ticks (vectors) are on the rise across the world but our ability to measure and predict risk is lagging. Predicting vector-borne disease risk requires both an understanding of how all the species involved are likely to be affected by environmental change and how those interactions may evolve. The transmission of avian malaria in native and introduced Hawaiian birds is an ideal system to gain this understanding. The project will focus on the Hawaiian honeycreepers, a diverse group that includes many species that are threatened with extinction. Through the use of historical specimens of both the birds and the malaria parasite, the project will be able to document and model the evolution of disease tolerance and resistance over the past 80 years. The model methodology will then be available for broad application into any disease system in which evolution is expected to occur in response to shifting environmental conditions. The results will also be used for management of the bird species in Hawaii. The project will support undergraduate and graduate student training, and participation of local high school students. The agent of avian malaria in Hawaii is a non-native Haemosporidian parasite, Plasmodium relictum, vectored by mixes of two non-native strains of the mosquito Culex quinquefasciatus. Avian malaria in Hawaii occurs as a series of replicated natural experiments in which vector and parasite prevalence vary along elevational gradients on several islands, and a parallel gradient in tolerance among some bird hosts has been reported. Although P. relictum was previously highly virulent to all of the 50 species of Hawaiian honeycreepers, evolution of tolerance (or resistance) has been observed in at least three species including the amakihi (Chlorodrepanis sp.). Additionally, there is geographic variation within and across islands in host species composition, host tolerance, climate (temperature and precipitation), vector abundance, vector competence, and pathogen fitness. This project will 1) characterize the genomic signatures of parasites, hosts and vectors at different elevations replicated across islands and through time, the latter by using museum specimens; 2) perform common-garden experiments and experimental infections to assess differences in competence or virulence among strains of vectors and parasites, respectively; 3) integrate Aims 1 and 2 in predictive models of the impact of co-evolutionary changes on vector-borne disease transmission under current and future climate scenarios. We will use comparative genomics and transcriptomics at multiple spatial, temporal and experimental scales, and combine Susceptible-Infected-Resistant (SIR) models with evolutionary game theory to capture the reciprocal influence of changing populations.