Data from: Tolerance to deer herbivory and resistance to insect herbivores in the common evening primrose (Oenothera biennis)

The evolution of plant defence in response to herbivory will depend on the fitness effects of damage, availability of genetic variation, and potential ecological and genetic constraints on defence. Here we examine the potential for evolution of tolerance to deer herbivory in Oenothera biennis while simultaneously considering resistance to natural insect herbivores. We examined: i) the effects of deer damage on fitness; ii) the presence of genetic variation in tolerance and resistance; iii) selection on tolerance; iv) genetic correlations with resistance that could constrain evolution of tolerance; and v) plant traits that might predict defence. In a field experiment, we simulated deer damage occurring early and late in the season, recorded arthropod abundances, flowering phenology, and measured growth rate and lifetime reproduction. Our study showed that deer herbivory has a negative effect on fitness, with effects being more pronounced for late-season damage. Selection acted to increase tolerance to deer damage, yet there was low and non-significant genetic variation in this trait. In contrast, there was substantial genetic variation in resistance to insect herbivores. Resistance was genetically uncorrelated with tolerance, whereas positive genetic correlations in resistance to insect herbivores suggest there exists diffuse selection on resistance traits. In addition, growth rate and flowering time did not predict variation in tolerance, but flowering phenology was genetically correlated with resistance. Our results suggest that deer damage has the potential to exert selection because browsing reduces plant fitness, but limited standing genetic variation in tolerance is expected to constrain adaptive evolution in O. biennis.植物针对植食性取食的防御演化，取决于损伤对植株适合度的影响、遗传变异的可获得性，以及防御策略所面临的潜在生态与遗传限制因素。本研究以二年生月见草（Oenothera biennis）为对象，探讨其针对鹿类植食的耐受演化潜力，同时考量对天然昆虫植食者的抗性。本研究考察了以下5项核心内容：（1）鹿类取食损伤对植株适合度的影响；（2）耐受与抗性性状的遗传变异存在性；（3）耐受性状所受的选择压力；（4）可能限制耐受性状演化的、与抗性相关的遗传相关性；（5）可预测防御策略的植株性状。本研究通过田间试验，模拟了季节早期与晚期的鹿类取食损伤，记录节肢动物丰度与开花物候，并测定植株生长速率与终生繁殖量。研究结果显示，鹿类植食会对植株适合度产生负面影响，且晚期取食的损伤效应更为显著。选择压力倾向于提升植株对鹿类取食的耐受能力，但该性状的遗传变异水平较低且不显著。与之相反，植株对昆虫植食者的抗性则存在大量的遗传变异。抗性与耐受性状之间不存在遗传相关性，但昆虫抗性各组分间存在正向遗传相关性，这表明抗性性状受到弥散选择作用。此外，植株生长速率与开花时间无法预测耐受性状的变异，但开花物候与抗性性状存在遗传相关性。本研究结果表明，鹿类取食损伤具备施加选择压力的潜力，因为啃食会降低植株适合度；但二年生月见草的耐受性状现存遗传变异有限，这或将限制其适应性演化。