Data from: Transgenerational effects of extreme weather: perennial plant offspring show modified germination, growth and stoichiometry

1) Climate change is predicted to increase the frequency and magnitude of extreme climatic events. These changes will directly affect plant individuals and populations and thus modify plant community composition. Little is known, however, about transgenerational effects (i.e. the influence of the parental environment on offspring phenotype and performance beyond the effects of transmitted genes) of climate extremes and community composition. Perennial plants have been particularly neglected. This impedes projections on species adaptations and population dynamics under climate change. 2) Maternal plants of two widespread dwarf-shrub species (Genista tinctoria and Calluna vulgaris) recurrently experienced extreme weather event manipulations each year (drought and heavy rain). To test for transgenerational effects of community composition, C. vulgaris maternal plants were grown in communities differing in the number of neighbouring species. After six years, seeds of maternal plants were collected at least 2 month after the final weather treatments. We assessed transgenerational effects of the extreme events and of altered community composition on germination and monitored the development of offspring over two years. 3) We show that extreme events experienced by maternal plants influence offspring germination and growth beyond the seedling stage. Seeds produced by maternal plants experiencing stress, indicated by increased tissue die-back, germinated earlier in both observed species. We observed differences in leaf stoichiometry and growth rates for G. tinctoria offspring throughout the first year: Offspring from heavy rain-treated mothers showed reduced leaf C:N ratio and higher growth rates. Results further indicate that not only community density, as investigated in prior studies, but also community composition trigger transgenerational effects. 4) Synthesis: Our findings show that variation in the maternal environment not only affects number, but also performance of offspring. Extreme climatic events, terminated before seed set, induce transgenerational effects. Species richness of mother communities can affect the stress level of target species and thereby germination regardless of community density. In contrast to prior studies, which revealed direct effects of chronic stress on plant individuals, this study emphasizes the importance of addressing transgenerational effects of extreme weather events when projecting future ecological responses and adaptation to climate change.

1) 据预测，气候变化将加剧极端气候事件的发生频率与强度。此类变化将直接影响植物个体与种群，进而改变植物群落组成。然而，目前对于极端气候与群落组成所引发的跨代效应（transgenerational effects，即亲本环境对后代表型与生长表现的影响超出传递基因的作用范围）的认知仍较为匮乏，其中多年生植物更是被严重忽视。这一现状阻碍了对气候变化背景下物种适应性与种群动态的预测。2) 本研究选取两种广泛分布的矮灌木物种——染料木（Genista tinctoria）与帚石楠（Calluna vulgaris），对其母株每年重复开展极端天气操控处理（包括干旱与强降雨）。为验证群落组成的跨代效应，研究将帚石楠母株种植于邻物种种数各异的群落中。持续处理六年后，于末次天气处理至少2个月后采集母株所结种子。本研究评估了极端事件与群落组成改变所引发的跨代效应对种子萌发的影响，并连续两年监测了后代植株的生长发育过程。3) 研究结果表明，母株所经历的极端事件会对后代的萌发与幼苗期后的生长产生影响。在两个受试物种中，母株遭遇胁迫（以组织枯亡程度加剧为表征）所结的种子萌发更早。在实验第一年，染料木后代的叶片化学计量学特征与生长速率存在显著差异：经强降雨处理的母株所产生的后代，其叶片碳氮比更低，生长速率更高。研究结果进一步显示，除既往研究所关注的群落密度外，群落组成同样会引发跨代效应。4) 研究总结：本研究结果显示，亲本环境的差异不仅会影响后代的数量，还会改变其生长表现。在结籽前终止的极端气候事件，同样会引发跨代效应。母株所在群落的物种丰富度可影响目标物种的胁迫水平，进而改变种子萌发情况，且该效应不受群落密度的影响。与既往研究揭示的慢性胁迫对植物个体的直接效应不同，本研究强调，在预测未来生态响应与气候变化适应性时，需重视极端天气事件的跨代效应。