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方面至关重要： 宿主更有可能将疾病专门传播给近邻（即局部传播）， 预期寄生虫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，这一理论尚未在现实生活中得到验证 系统这项建议利用蜜蜂（Apis mellifera）和它们的破坏性， 狄斯瓦螨（Varroadestructor）的毒力进化的空间结构的作用。 瓦螨是世界范围内蜂群损失的最大原因， 通过常规改变传播条件， 人口结构。密集养蜂增加了全球螨传播， 无意中选择毁灭性寄生虫的可能性。该提案有三个具体的 目的：（1）在前所未有的规模上进行实验性的进化研究，这将改变相对的进化过程。 确定螨传播如何影响毒力的局部与全球螨传播的重要性 （2）发展毒力进化模型，研究空间结构在 农业系统，这将适用于蜜蜂瓦螨系统，使具体的 建议养蜂方法，以防止选择高毒性;（3）一个大的 规模交叉感染实验，以测试目前的养蜂做法是否选择了 更高的毒力，这将比较螨从密集管理，轻度管理和野生 蜜蜂大规模田间试验与理论发展相结合， 系统的蜜蜂和螨将是强大的发展重要的见解，在空间的作用， 在疾病传播、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.