Parasite ecology, evolution and population genetics: the evolutionary ecology of epidemiological triangles

缺乏关于病媒传播疾病的进化生态学的知识，即生态和历史上的相互作用，以及由病媒传播给宿主的三组生物体的种群遗传结构的变化；病媒(例如蚊子和扁虱)、宿主(脊椎动物)和病原体(例如细菌和病毒)。扁虱是北美最重要的人类传染病宿主和传播者，它们负责将病原体传播给家畜和野生动物。在加拿大有30多种扁虱，但对于许多物种，我们对它们所含细菌的类型(即物种和菌株)知之甚少。在接下来的5年里，我的研究组中的研究生和本科生将在流行病三角中进行关于种群遗传学和生物共同进化的创新和令人兴奋的研究项目，其中媒介是不同种类的扁虱，它们的生活史、所使用的宿主类型和/或它们的相对宿主特异性不同。分子技术将被用来量化扁虱、细菌和小型哺乳动物的群体遗传学，以寻找多个遗传标记。此外，还将探讨壁虱种群和不同细菌菌株遗传结构的空间和时间变化。通过对扁虱、其细菌和宿主的种群遗传学和共同进化关系的详细了解，可以了解媒介传播疾病流行病学中的异常现象，否则可能会解释这些异常现象。我们的发现将对影响流行病三角种群遗传结构的生态和进化因素提供关键的见解，并为构建微生物传播的生态流行病学模型和媒介传播疾病的种群动力学提供关键信息。这项工作也很重要，因为一些扁虱物种正在扩大它们在加拿大的地理范围，这对人类和动物的健康构成了越来越大的威胁。

There is a lack of knowledge regarding the evolutionary ecology of vector-borne diseases, that is, the ecological and historical interactions, and changes in the population genetic structure of the three groups of organisms that make up an 'epidemiological triangle'; vectors (e.g. mosquitoes & ticks), hosts (vertebrates), and pathogens (e.g., bacteria & viruses) transmitted by vectors to hosts. Ticks are the most important reservoirs and vectors of human infectious diseases in North America, and they are responsible for transmitting pathogenic agents to domestic animals and wildlife. There are over 30 tick species that occur in Canada, yet for many species, we know very little of the types (i.e. species and strains) of bacteria they contain. Over the next 5 years, graduate and undergraduate students in my research group will conduct innovative and exciting research projects on the population genetics and coevolution of organisms in epidemiological triangles, in which the vectors are different species of tick that differ in their life cycles, types of hosts used and/or their relative host specificity. Molecular techniques will be used to quantify the population genetics of ticks, bacteria and small mammals for multiple genetic markers. Spatial and temporal changes in the genetic structure of tick populations and of different bacterial strains will also be explored. Detailed knowledge of the population genetics and coevolutionary relationships of ticks, their bacteria and hosts, permits an understanding of anomalies in the epidemiology of vector-borne diseases, which might otherwise go explained. Our findings will provide key insights into the ecological and evolutionary factors influencing the population genetic structure of epidemiological triangles, and provide critical information for the construction of ecological epidemiological models of microbial transmission and the population dynamics of vector-borne diseases. Such work is also of importance because some tick species are expanding their geographical ranges in Canada, which poses an increased threat to human and animal health.