Data from: Evolution of drug-tolerant nematode populations in response to density reduction

Resistance to xenobiotics remains a pressing issue in parasite treatment and global agriculture. Multiple factors may affect the evolution of resistance, including interactions between life-history traits and the strength of selection imposed by different drug-doses. We experimentally created replicate selection lines of free-living Caenorhabditis remanei exposed to Ivermectin at high and low doses to assess whether survivorship of lines selected in drug-treated environments increased, and if this varied with dose. Additionally, we maintained lines where mortality was imposed randomly to control for differences in density between drug-treatments and to distinguish between the evolutionary consequences of drug-treatment vs ecological processes due to changes in density-dependent feedback. After 10 generations we exposed all of the selected lines to high-dose, low-dose and drug-free environments to evaluate evolutionary changes in survivorship as well as any costs to adaptation. Both adult and juvenile survival was measured to explore relationships between life-history stage, selection regime and survival. Intriguingly, both drug-selected and random-mortality lines showed an increase in survivorship when challenged with Ivermectin; the magnitude of this increase varied with the intensity of selection and life-history stage. Our results suggest that interactions between density-dependent processes and life-history may mediate evolved changes in susceptibility to control measures.

对外源生物异源物质（xenobiotics）的抗药性，仍是寄生虫治疗与全球农业领域亟待解决的关键问题。诸多因素可影响抗药性的演化进程，其中涵盖生活史特征间的相互作用，以及不同药物剂量所施加的选择压力强度。本研究通过实验构建了暴露于高、低剂量伊维菌素（Ivermectin）的自由生活雷氏隐杆线虫（Caenorhabditis remanei）重复选择系，旨在评估经药物环境筛选的线虫系存活率是否提升，且该存活率变化是否随剂量而异。此外，我们还设立了一组随机施加死亡的对照线虫系，用以平衡药物处理组间的密度差异，并区分药物处理带来的演化后果与密度依赖反馈变化所引发的生态过程差异。在历经10代筛选后，我们将所有选择系分别置于高剂量、低剂量及无药物的环境中，以评估存活率的演化变化以及适应性演化可能存在的适合度代价。研究同时测定了成体与幼体的存活率，以探究生活史阶段、选择方案与存活率三者间的关联。值得注意的是，经药物筛选与随机死亡处理的线虫系，在伊维菌素攻毒试验中均表现出存活率提升，且该提升幅度随选择强度与生活史阶段而异。本研究结果表明，密度依赖过程与生活史间的相互作用，或可介导宿主对防治措施敏感性的演化变化。