Data from: Soil-mediated eco-evolutionary feedbacks in the invasive plant Alliaria petiolata

Ecological and evolutionary processes historically have been assumed to operate on significantly different time scales. We know now from theory and work in experimental and model systems that these processes can feed back on each other on mutually relevant time scales. Here, we present evidence of a soil-mediated eco-evolutionary feedback on the population dynamics of an invasive biennial plant, Alliaria petiolata. As populations age, natural selection drives down production of A. petiolata's important anti-mycorrhizal allelochemical, sinigrin. This occurs due to density dependent selection on sinigrin, which is favored under interspecific, but disfavored under intraspecific, competition. We show that population stochastic growth rates (λS) and plant densities are positively related to sinigrin concentration measured in seedling roots. This interaction is mediated by sinigrin's positive effect on seedling and summer survival, which are important drivers of λS. Together, these illustrate how the evolution of a trait shaped by natural selection can influence the ecology of a species over a period of just years to decades, altering its trajectory of population growth and interactions with the species in the soil and plant communities it invades. Our findings confirm predictions that eco-evolutionary feedbacks occur in natural populations. Furthermore, they improve our conceptual framework for projecting future population growth by linking variation in plant demography to a critical competitive trait (sinigrin) whose selective advantages decrease as populations age.

长期以来，生态过程与演化过程（ecological and evolutionary processes）被认为在显著不同的时间尺度上运作。我们现已通过理论研究与实验、模型系统的相关工作证实，两类过程可在彼此匹配的时间尺度上产生相互反馈。在此，我们报道了土壤介导的生态-演化反馈（eco-evolutionary feedback）对入侵性二年生植物大蒜芥（Alliaria petiolata）种群动态影响的相关证据。随着种群年龄增长，自然选择会降低大蒜芥体内重要的抗菌根化感物质（anti-mycorrhizal allelochemical）黑芥子苷（sinigrin）的合成量。这一现象源于黑芥子苷所受的密度依赖选择（density dependent selection）：在种间竞争（interspecific competition）环境下，该物质会受到正向选择；而在种内竞争（intraspecific competition）条件下则会被负向选择淘汰。我们的研究表明，种群随机增长率（population stochastic growth rates，λS）与植株密度，均与幼苗根系中的黑芥子苷浓度呈正相关关系。这一相互作用由黑芥子苷对幼苗存活率与夏季存活率的正向效应所介导，而这两项存活率正是影响种群随机增长率的关键驱动因子。综上，上述结果阐释了受自然选择塑造的性状演化，如何仅在数年至数十年的时间尺度上就对物种种群生态学特征产生影响，进而改变其种群增长轨迹，以及它在入侵生境中与土壤和植物群落内其他物种的相互作用模式。本研究结果验证了"生态-演化反馈存在于自然种群中"的理论预测。此外，本研究将植物种群统计特征（plant demography）的变异与关键竞争性状（competitive trait）黑芥子苷关联起来——该性状的选择优势会随种群年龄增长而逐渐降低，从而完善了我们预测未来种群增长的概念框架。