The evolution of resistance and virulence in structured populations

抗性和毒力的地理格局取决于这些性状和种群结构的适应度结果。社会寄生性的造奴蚁使用异体工蚁——在突袭中偷来的工蚁——来抚养它们的后代。寄主发展出防御措施来逃避寄生——例如一种新发现的诱导防御——或者减轻被奴役后的成本，如“奴隶叛乱”特征：被奴役的Temnothorax工人被观察到杀死制奴蚂蚁Protomognathus americanus的蛹。随之减少的寄生虫巢穴的增长导致越来越少的破坏性袭击。我们分析了摧毁幼虫是否通过降低附近相关宿主殖民地的袭击风险来提高被奴役工蜂的包容性适合度。基因分析发现了脆弱的宿主结构和在袭击中幸存下来的宿主殖民地，这可能直接受益于它们的奴隶亲属的反叛。仿真结果表明，宿主结构和防御成本会影响奴隶反抗特征的传播。成本可能包括错误杀死自己的幼虫，以及寄生虫和宿主种群在地理上的共同变化。我们现在计划探索防御的局部结构和成本/收益如何解释不同防御性状性状表达的种群间和种群内变异。通过理论模型，我们将分析元种群结构如何影响防御或毒性等位基因在种群中持续存在的机会。我们将开发计算方法来估计宿主-寄生虫相互作用的参数在超种群环境。

Geographic patterns of resistance and virulence depend on the fitness consequences of these traits and the population structure. Socially parasitic slavemaking ants use allospecific workers – stolen during raids – to raise their young. Hosts developed defenses to evade parasitism – e.g. a newly found inducible defense – or to mitigate its costs after enslavement like the “slave rebellion” trait: enslaved Temnothorax workers were observed to kill pupae of the slavemaking ant Protomognathus americanus. The ensuing reduced growth of parasite nests leads to fewer and less destructive raids. We analyzed whether brood destruction raises the inclusive fitness of enslaved workers by reducing the raiding risk for related host colonies nearby. Genetic analyses detected weak host structure and host colonies that survived raids, which could directly benefit from rebellion of their slave relatives. A simulation showed that host structure and the costs of defense influence whether the slave rebellion trait can spread. Costs could include the erroneous killing of own brood and killing rates of parasite and host populations co-varied geographically. We now plan to explore how local structure and the costs / benefits of defenses explain the inter- and intra-population variation in trait expression for various defense traits. With theoretical models we will analyze how metapopulation structure affects the chances of defense or virulence alleles to persist in a population. We will develop computational methods to estimate parameters of host-parasite interactions in a metapopulation context.