Data from: Plasticity of plant defense and its evolutionary implications in wild populations of Boechera stricta

Phenotypic plasticity is thought to impact evolutionary trajectories by shifting trait values in a direction that is either favored by natural selection (“adaptive plasticity”) or disfavored (“nonadaptive” plasticity). However, it is unclear how commonly each of these types of plasticity occurs in natural populations. To answer this question, we measured glucosinolate defensive chemistry and reproductive fitness in over 1,500 individuals of the wild perennial mustard Boechera stricta, planted in four common gardens across central Idaho, USA. Glucosinolate profiles—including total glucosinolate concentration as well as the relative abundances and overall diversity of different compounds—were strongly plastic both among habitats and within habitats. Patterns of glucosinolate plasticity varied greatly among genotypes. Plasticity among sites was predicted to affect fitness in 27.1% of cases; more often than expected by chance, glucosinolate plasticity increased rather than decreased relative fitness. In contrast, we found no evidence for within-habitat selection on glucosinolate reaction norm slopes (i.e., plasticity along a continuous environmental gradient). Together, our results indicate that glucosinolate plasticity may improve the ability of B. stricta populations to persist after migration to new habitats.

表型可塑性（phenotypic plasticity）被认为可通过将性状值向自然选择青睐（即“适应性表型可塑性”）或排斥的方向偏移，来影响进化轨迹。然而，目前尚不清楚这两类可塑性在自然种群中的发生频率。为解答该问题，我们在美国爱达荷州中部的4个同质园（common garden）试验点中，种植了超过1500株野生直立弯蕊芥（Boechera stricta）个体，并测定了其硫代葡萄糖苷（glucosinolate）防御化学组成与繁殖适合度。硫代葡萄糖苷谱——包括总硫代葡萄糖苷浓度、不同化合物的相对丰度及整体多样性——在生境间与生境内均表现出显著的可塑性。不同基因型间的硫代葡萄糖苷可塑性模式差异极大。据预测，位点间的可塑性会在27.1%的案例中影响适合度；相较于随机预期，硫代葡萄糖苷可塑性更倾向于提升而非降低相对适合度。与之相反，我们未发现生境内选择作用于硫代葡萄糖苷反应规范（reaction norm）斜率（即沿连续环境梯度的可塑性）的证据。综上，本研究结果表明，硫代葡萄糖苷可塑性或可提升直立弯蕊芥种群迁移至新栖息地后的存续能力。