Life History Models of Symbiosis

弗兰克9627259大多数生物体内都有细菌、病毒和其他微生物组成的群落。这些微生物被称为共生体。其中一些共生体是寄生的，对宿主造成了伤害。在其他情况下，宿主依靠共生体获得营养、消化酶和防御其他寄生虫。本研究分析了共生体生活史特征的演化。这些特征包括寄主内的繁殖率、感染的时间进程(寿命)、寄主之间的传播方式以及对寄主的伤害或益处。还将分析宿主控制共生体的潜力。例如，一些宿主似乎操纵了共生体繁殖和传播的时间和模式。这种寄主控制可能会对共生体从有害伙伴演变为有益伙伴的趋势产生强烈影响。这项研究开发了数学和计算机模型，以阐明影响宿主-共生体进化的基本过程。然后，一般模型被应用于广泛的特定系统。一个例子集中在细菌对宿主造成的不同程度的伤害(毒力)。第二个例子是共生体的传播方式和生活史之间的关系，这些共生体有助于昆虫宿主的消化过程。

Frank 9627259 Most organisms have a community of bacteria, viruses and other microorganisms living within their bodies. These microorganisms are called symbionts. Some of these symbionts are parasitic, causing harm to their hosts. In other cases the hosts depend on their symbionts for nutrients, digestive enzymes and defense against other parasites. This study analyzes the evolution of symbiont life history traits. These traits include reproductive rate within the host, the time-course (life-span) of infection, mode of transmission between hosts, and harm or benefit to the host. The host's potential to control their symbionts will also be analyzed. For example, some hosts appear to manipulate the timing and mode of their symbionts' reproduction and transmission. Such host control may have a strong influence on the tendency of symbionts to evolve from harmful to beneficial partners. This research develops mathematical and computer models to clarify the basic processes that influence host-symbiont evolution. The general models are then applied to a wide range of particular systems. One example focuses on the varying degree of harm (virulence) that bacteria cause their hosts. A second example is the relationship between mode of transmission and the life history of symbionts that aid the digestive processes of their insect hosts.