Rate of resistance evolution and polymorphism in long- and short-lived hosts

Recent theoretical work has shown that long-lived hosts are expected to evolve higher equilibrium levels of disease resistance than shorter-lived hosts, but questions of how longevity affects the rate of resistance evolution and the maintenance of polymorphism remain unanswered. Conventional wisdom suggests that adaptive evolution should occur more slowly in long-lived organisms than in short-lived organisms. However, the opposite may be true for the evolution of disease-resistance traits where exposure to disease, and therefore the strength of selection for resistance increases with longevity. In a single locus model of innate resistance to a frequency-dependent, sterilizing disease, longer-lived hosts evolved resistance more rapidly than short-lived hosts. Moreover, resistance in long-lived hosts could only be polymorphic for more costly and more extreme resistance levels than short-lived hosts. The increased rate of evolution occurred in spite of longer generation times because longe...近年来的理论研究表明，相较于短寿命宿主，长寿命宿主理论上可演化出更高水平的稳态疾病抗性，但关于寿命如何影响抗性演化速率以及遗传多态性的维持机制这一问题，目前仍未得到解答。传统观点认为，长寿命生物的适应性演化速率应慢于短寿命生物。然而针对疾病抗性性状的演化而言，实际情况可能恰好相反：随着宿主寿命延长，疾病暴露频率提升，相应的抗性选择强度也随之增强。在针对频率依赖性致不育疾病的单基因座先天抗性模型中，长寿命宿主的抗性演化速率显著快于短寿命宿主。此外，相较于短寿命宿主，长寿命宿主的抗性仅能在代价更高、抗性程度更强的表型下维持遗传多态性。尽管长寿命生物的世代周期更长，但其演化速率仍得以提升，原因在于longe...