US-UK Collab: Understanding the effects of spatial structure on the evolution

理论表明，空间结构在驱动毒力进化中至关重要：当 宿主更有可能将疾病专门传播给近邻(即本地传播)， 寄生虫预计会进化出比宿主可能感染远程宿主时更低的毒力 个人(即全球传播)。然而，这一理论在现实生活中仍未得到检验。 系统。这一提议利用了蜜蜂(Apis Melvena)及其破坏性 寄生螨(Varroa Destructor)，研究空间结构在毒力进化中的作用。 瓦螨是全球蜂群损失和养蜂的最大单一原因。 实践很可能通过常规地改变传播条件来驱动这种寄生虫的毒力 和人口结构。集约化养蜂增加了全球螨类传播，因此 无意中选择毁灭性寄生虫的可能性。这项建议有三个具体的 目标：(1)史无前例的实验进化研究，它将改变相对 确定局部与全球粉尘传播对毒力的影响的重要性 (2)毒力进化模型的发展，以研究空间结构在 农业系统，这将应用于蜜蜂-瓦罗亚系统，以使具体 关于防止选择高毒力的养蜂做法的建议；以及(3)大型 规模交叉感染实验，以测试当前的养蜂实践是否选择了 更高的毒力，这将比较密集管理、宽松管理和野生的螨类 蜜蜂。大型野外试验与理论发展相结合的可操纵性 蜜蜂和螨虫系统将在发展关于空间角色的重要见解方面发挥强大的作用 疾病传播、流行病学和进化中的结构和宿主异质性。

Theory has shown that spatial structure is crucially important in driving virulence evolution: when hosts are more likely to transmit disease exclusively to close neighbors (i.e. local transmission), parasites are expected to evolve lower virulence than when hosts are likely to infect remote individuals (i.e. global transmission). However, this theory remains untested in a real-life field system. This proposal takes advantage of honeybees (Apis mellifera) and their destructive parasitic mites (Varroa destructor) to study the role of spatial structure in virulence evolution. Varroa mites are the single largest cause of honeybee colony losses worldwide, and beekeeping practices are likely to drive this parasite's virulence by routinely altering transmission conditions and population structure. Intensive beekeeping increases global mite transmission and thus has the potential to unintentionally select for devastating parasites. This proposal has three specific aims: (1) an experimental evolution study at an unprecedented scale, which will vary the relative importance of local versus global mite transmission to determine how this affects virulence evolution; (2) development of virulence evolution models to study the role of spatial structure in agricultural systems, which will be applied to the honeybee-Varroa system to make specific recommendations on beekeeping practices to prevent selection of high virulence; and (3) a large scale cross-infection experiment to test whether current beekeeping practices have selected for higher virulence, which will compare mites from intensively managed, lightly managed and feral bees. The combination of large-scale field experiments and theory development on the tractable system of bees and mites will be powerful in developing important insights in the role of spatial structure and host heterogeneity in disease transmission, epidemiology and evolution.