Salathé Marcel, Scherer Almut, Bonhoeffer Sebastian
Ecology and Evolution, ETH Zürich, ETH-Zentrum NW, CH 8092 Zürich, Switzerland.
Ecol Lett. 2005 Sep;8(9):925-932. doi: 10.1111/j.1461-0248.2005.00794.x. Epub 2005 Jul 5.
Pathogens are a main driving force of the evolution of plants and animals. Being resistant to diseases confers a high selective advantage to hosts, yet many host-pathogen systems show a remarkable degree of polymorphism of host resistance and pathogen virulence. The most common explanation of this phenomenon is that both resistance and virulence genes are costly and that there is selection against those genes when they are unnecessary. Here, we use stochastic multi-locus simulations to show that the origin and the maintenance of genetic polymorphism in plant-pathogen systems can be explained without costs. In multi-locus gene-for-gene systems, temporal domination of a super pathogen can cause polymorphism in resistance through neutral drift. With an increasing number of susceptible alleles in the host population, pathogen types other than the super race are able to cause infections and invade the population, leading to higher pathogen diversity and in turn to higher host diversity.
病原体是动植物进化的主要驱动力。对疾病具有抗性会赋予宿主很高的选择优势，然而许多宿主-病原体系统显示出宿主抗性和病原体毒力的显著多态性。对这一现象最常见的解释是抗性基因和毒力基因的代价都很高，并且当这些基因不必要时会受到选择淘汰。在这里，我们使用随机多位点模拟来表明，植物-病原体系统中遗传多态性的起源和维持无需代价即可得到解释。在多位点基因对基因系统中，超级病原体的暂时主导可通过中性漂变导致抗性多态性。随着宿主群体中易感等位基因数量的增加，超级小种以外的病原体类型能够引发感染并侵入群体，导致更高的病原体多样性，进而导致更高的宿主多样性。
