Data from: Trade-offs and evolution of thermal adaptation in the Irish potato famine pathogen Phytophthora infestans

Temperature is one of the most important environmental parameters with crucial impacts on nearly all biological processes. Due to anthropogenic activity, average air temperatures are expected to increase by a few degrees in coming decades, accompanied by an increased occurrence of extreme temperature events. Such global trends are likely to have various major impacts on human society through their influence on natural ecosystems, food production and biotic interactions, including diseases. In this study, we used a combination of statistical genetics, experimental evolution and common garden experiments to investigate the evolutionary potential for thermal adaptation in the potato late blight pathogen, Phytophthora infestans, and infer its likely response to changing temperatures. We found a trade-off associated with thermal adaptation to heterogeneous environments in P. infestans, with the degree of the trade-off peaking approximately at the pathogen's optimum growth temperature. A genetic trade-off in thermal adaptation was also evidenced by the negative association between a strain's growth rate and its thermal range for growth, and warm climates selecting for a low pathogen growth rate. We also found a mirror effect of phenotypic plasticity and genetic adaptation on growth rate. At below the optimum, phenotypic plasticity enhances pathogen's growth rate but nature selects for slower growing genotypes when temperature increases. At above the optimum, phenotypic plasticity reduces pathogen's growth rate but natural selection favours for faster growing genotypes when temperature increases further. We conclude from these findings that the growth rate of P. infestans will only be marginally affected by global warming.温度是最重要的环境参数之一，对几乎所有生物过程均具有关键性影响。受人类活动驱动，未来数十年全球平均气温预计将升高数摄氏度，同时极端温度事件的发生频率亦将显著增加。此类全球气候变化趋势可通过影响自然生态系统、粮食生产以及包括病害在内的生物间相互作用，对人类社会产生多方面重大影响。本研究结合统计遗传学、实验进化与同质园实验方法，探究了马铃薯晚疫病菌（致病疫霉，*Phytophthora infestans*）的热适应进化潜力，并推测其对温度变化的潜在响应。研究发现，致病疫霉在异质环境下的热适应存在权衡效应，且该权衡效应的强度在病菌的最适生长温度附近达到峰值。菌株生长速率与其生长温度范围之间的负相关关系，以及温暖气候对低生长速率病菌的选择压力，进一步证实了热适应过程中的遗传权衡效应。本研究还揭示了表型可塑性与遗传适应对病菌生长速率的镜像效应：在温度低于最适值时，表型可塑性可提升病菌生长速率，但随着温度升高，自然选择会倾向于生长速率较慢的基因型；而在温度高于最适值时，表型可塑性会降低病菌生长速率，但当温度进一步升高时，自然选择则会青睐生长速率更快的基因型。基于上述研究结果，本研究得出结论：全球变暖对致病疫霉生长速率的影响仅为轻微程度。