Data from: Is a larger refuge always better? Dispersal and dose in pesticide resistance evolution

The evolution of resistance against pesticides is an important problem of modern agriculture. The high-dose/ refuge strategy, which divides the landscape into treated and non-treated (refuge) patches, has proven effective at delaying resistance evolution. However, theoretical understanding is still incomplete, especially for combinations of limited dispersal and partially recessive resistance. We reformulate a two-patch model based on the Comins model and derive a simple quadratic approximation to analyze the effects of limited dispersal, refuge size and dominance for high efficacy treatments on the rate of evolution. When a small but substantial number of heterozygotes can survive in the treated patch, a larger refuge always reduces the rate of resistance evolution. However, when dominance is small enough, the evolutionary dynamics in the refuge population, which is indirectly driven by migrants from the treated patch, mainly describes the resistance evolution in the landscape. In this case, for small refuges, increasing the refuge size will increase the rate of resistance evolution. Our analysis distils major driving forces from the model, and can provide a framework for understanding directional selection in source-sink environments.

农药抗药性演化是现代农业面临的关键科学问题。高剂量-庇护所策略（high-dose/refuge strategy）将农田景观划分为施药斑块与非施药（庇护所）斑块，经证实可有效延缓抗药性的演化进程。然而当前的理论认知仍存在不足，尤其针对有限扩散与部分隐性抗药性共同作用的情形。本研究基于康因斯模型（Comins model）重构双斑块模型，并推导出简洁的二次近似解，用以分析有限扩散、庇护所面积、抗性显性程度对高防效施药场景下抗药性演化速率的影响。当施药斑块中存在少量但可观的杂合子存活个体时，更大面积的庇护所始终会降低抗药性演化速率。但若抗性显性程度足够低，则由施药斑块迁入个体间接驱动的庇护所种群演化动态，将成为农田景观中抗药性演化的主要表征。在此情形下，对于面积较小的庇护所，扩大其面积反而会提升抗药性演化速率。本研究通过分析提炼出模型的核心驱动因素，可为理解源汇环境（source-sink environments）中的定向选择提供理论框架。