Molecular and cellular studies reveal that the resistance of hosts to parasites and pathogens is a cascade-like process with multiple steps required to be passed for successful infection. By contrast, much of evolutionary reasoning is based on strongly simplified, one- or two-step infection processes with simple genetics or on resistance being a quantitative trait. Here we attempt a conceptual unification of these two perspectives with the aim of cross-fostering research and filling some of the gaps in our concepts of the ecology and evolution of disease. This conceptual unification has a profound impact on the way we understand the genetics and evolution of host resistance, ecological immunity, evolution of virulence, defence portfolios, and host–pathogen coevolution.

分子和细胞研究表明，宿主对寄生虫和病原体的抵抗力是一个类似级联的过程，需要成功通过多个步骤。相比之下，许多进化推理都基于具有简单遗传学的高度简化的一步骤或两步感染过程，或基于抗性为数量性状。在这里，我们尝试将这两种观点进行概念上的统一，以期促进研究的发展并填补我们在生态学和疾病演变方面的空白。这种概念上的统一对我们理解宿主抗性的遗传和进化，生态免疫，毒力的进化，防御能力以及宿主-病原体协同进化的方式产生了深远的影响。