DISSERTATION RESEARCH: Life History Coevolution Between an Aging Bacterium and its Bacteriophage

许多寄生虫通过两种不同的途径建立感染：垂直传播到受感染宿主的后代，以及水平传播到未受感染的宿主。这项研究探讨了一个关键的，未探索的问题，关于寄生虫的行为：如何主机老化影响寄生虫传播？宿主-寄生虫动力学的数学模型预测随着宿主年龄的增加和繁殖能力的下降，水平传播会增加。来自模型细菌系统的初步结果证实了这一预期。使用这种细菌系统的进一步实验将检查寄生虫在引入具有不同老化模式的宿主后的行为。这些新宿主的初始寄生虫行为将识别寄生虫检测和响应宿主老化差异的任何一般能力。实验室进化实验随后将探索寄生虫的行为，需要专门化到一个特定的主机。这些研究从理论和实证两个角度探讨了宿主衰老对寄生虫传播行为的影响，建立了宿主衰老对寄生虫传播行为影响的数学模型和实验系统。本研究为今后垂直传播寄生虫的研究提供了理论和实验工具。这类寄生虫包括艾滋病和癌症等人类疾病的病原体，以及农作物和牲畜的传染性病原体。因此，了解这些寄生虫的基本行为将有助于有效地管理对人类健康和经济产生负面影响的生物体。

Many parasites establish infections through two different pathways: vertical transmission to offspring of infected hosts, and horizontal transmission to uninfected hosts. This study examines a key, unexplored question regarding parasite behavior: how does host aging influence parasite transmission? A mathematical model of host-parasite dynamics predicts increased horizontal transmission as host age increases and reproduction declines. Preliminary results from a model bacterial system confirm this expectation. Further experiments using this bacterial system will examine the behavior of parasites upon introduction to hosts with varying aging patterns. Initial parasite behavior in these new hosts will identify any general ability of parasites to detect and respond to differences in host aging. Laboratory evolution experiments will subsequently explore parasite behaviors that require specialization to a particular host. Taken together, these efforts explore the role of host aging in shaping parasite transmission behavior from both theoretical and empirical perspectives.This study develops both a mathematical modeling framework and an experimental system for exploring the effects of host aging on parasite behavior. This research thus provides theoretical and experimental tools for future research on vertically transmitted parasites. This class of parasites includes agents of human disease such as AIDS and cancer, as well as infectious agents of crops and livestock. Understanding the basic behavior of such parasites will therefore assist in effectively managing organisms that detrimentally impact human health and the economy.