Parasitic lineages have acquired suites of new traits compared to their nearest free-living relatives. When and why did these traits arise? We can envision lineages evolving through multiple stable intermediate steps such as a series of increasingly exploitative species interactions. This view allows us to use non-parasitic species that approximate those intermediate steps to uncover the timing and original function of parasitic traits, knowledge critical to understanding the evolution of parasitism. The dauer hypothesis proposes that free-living nematode lineages evolved into parasites through two intermediate steps, phoresy and necromeny. Here we delve into the proposed steps of the dauer hypothesis by collecting and organizing data from genetic, behavioral, and ecological studies in a range of nematode species. We argue that hypotheses on the evolution of parasites will be strengthened by complementing comparative genomic studies with ecological studies on non-parasites that approximate intermediate steps.

与最近的自由生活亲属相比，寄生谱系获得了一系列新特征。这些特征是何时以及为何出现的？我们可以设想谱系通过多个稳定的中间步骤进化，例如一系列日益剥削的物种相互作用。这种观点使我们能够使用近似这些中间步骤的非寄生物种来揭示寄生特征的时间和原始功能，这些知识对于理解寄生的进化至关重要。dauer 假说提出，自由生活的线虫谱系通过两个中间步骤，即 phoresy 和 necromeny 进化成寄生虫。在这里，我们通过收集和组织来自一系列线虫物种的遗传、行为和生态研究的数据来深入研究 dauer 假设的建议步骤。