Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Glagoljaška 8, SI-6000 Koper, Slovenia.
Evolution. 2012 Aug;66(8):2514-27. doi: 10.1111/j.1558-5646.2012.01613.x. Epub 2012 Mar 27.
A number of ecologically and economically important pathogens exhibit a complex transmission dynamics that involves distinct transmission modes. In this paper, we study the evolutionary dynamics of pathogens for which transmission includes direct host-to-host as well as indirect environmental transmission. Different routes of infection spread require specific adaptations of the parasite, which may result in conflicting selection pressures. Using the framework of Adaptive dynamics, we investigate how these conflicting selection pressures are resolved in the course of evolution and determine the conditions for evolutionary diversification of pathogen strains. We show that evolutionary branching and subsequent evolution of specialist strains occurs in wide parameter regions but evolutionary bistability and evolution of generalist pathogens are possible as well. Our analysis reveals that the relative contributions of direct and environmental transmission, as well as the underlying ecological dynamics, play a crucial role in shaping the course of pathogen evolution. Our findings may explain the coexistence of high and low virulence strains observed in several pathogenic organisms using different transmission modes (e.g., influenza viruses) and highlight the importance of considering ecological dynamics in virulence management.
一些具有重要生态和经济意义的病原体表现出复杂的传播动态，涉及不同的传播模式。在本文中，我们研究了病原体的进化动态，这些病原体的传播包括直接的宿主-宿主传播和间接的环境传播。不同的感染途径需要寄生虫的特定适应，这可能导致冲突的选择压力。我们使用适应性动态的框架，研究这些冲突的选择压力如何在进化过程中得到解决，并确定病原体菌株进化多样化的条件。我们表明，进化分支和随后的专化菌株的进化发生在广泛的参数区域，但也可能发生进化的两态性和普遍适应的病原体的进化。我们的分析表明，直接传播和环境传播的相对贡献以及潜在的生态动态在塑造病原体进化过程中起着关键作用。我们的研究结果可以解释在使用不同传播模式（例如流感病毒）的几种致病生物体中观察到的高毒力和低毒力菌株共存的现象，并强调了在毒力管理中考虑生态动态的重要性。
